ISO 11171:2010

Hydraulic fluid power - Calibration of automatic particle counters for liquids

ISO 11171:2010 specifies procedures for: a) primary particle-sizing calibration, sensor resolution and counting performance of automatic particle counters (APCs) for liquids capable of analysing bottle samples; b) secondary particle-sizing calibration using suspensions verified with a primary calibrated APC; c) establishing acceptable operation and performance limits; d) verifying particle sensor performance using a truncated test dust; e) determining coincidence and flow rate limits.

Transmissions hydrauliques — Étalonnage des compteurs automatiques de particules en suspension dans les liquides

L'ISO 11171:2010 spécifie des modes opératoires portant sur les aspects suivants: a) l'étalonnage dimensionnel primaire, la résolution des capteurs et les performances de comptage des compteurs automatiques de particules (CAP) en suspension dans les liquides capables d'analyser des échantillons en flacon; b) l'étalonnage dimensionnel secondaire avec des suspensions vérifiées au moyen d'un CAP ayant fait l'objet d'un étalonnage primaire; c) l'établissement de limites acceptables de fonctionnement et de performances; d) la vérification des performances du détecteur de particules en utilisant de la poudre d'essai tronquée; e) la détermination des limites de coïncidence et de débit.

Fluidna tehnika - Hidravlika - Umerjanje naprav za avtomatsko štetje delcev v tekočinah

General Information

• Status: Withdrawn
• Publication Date: 24-Oct-2010
• Withdrawal Date: 24-Oct-2010
• ICS: 23.100.60 - Filters, seals and contamination of fluids
• Technical Committee: ISO/TC 131/SC 6 - Contamination control
• Drafting Committee: ISO/TC 131/SC 6/WG 1 - Sampling, contamination analysis and reporting
• Current Stage: 9599 - Withdrawal of International Standard
• Start Date: 05-Oct-2016
• Completion Date: 13-Dec-2025
• Ref Project: SIST ISO 11171:2014 - Hydraulic fluid power - Calibration of automatic particle counters for liquids

Relations

• Revised: ISO 11171:2016 - Hydraulic fluid power - Calibration of automatic particle counters for liquids
• Effective Date: 28-Nov-2015
• Revises: ISO 11171:1999/Cor 1:2001 - Hydraulic fluid power - Calibration of automatic particle counters for liquids - Technical Corrigendum 1
• Effective Date: 15-Apr-2008
• Revises: ISO 11171:1999 - Hydraulic fluid power - Calibration of automatic particle counters for liquids
• Effective Date: 15-Apr-2008

Standards Content (Sample)

INTERNATIONAL ISO
STANDARD 11171
Second edition
2010-11-01
Hydraulic fluid power — Calibration of
automatic particle counters for liquids
Transmissions hydrauliques — Étalonnage des compteurs
automatiques de particules en suspension dans les liquides

Reference number
©
ISO 2010
PDF disclaimer
This PDF file may contain embedded typefaces. In accordance with Adobe's licensing policy, this file may be printed or viewed but
shall not be edited unless the typefaces which are embedded are licensed to and installed on the computer performing the editing. In
downloading this file, parties accept therein the responsibility of not infringing Adobe's licensing policy. The ISO Central Secretariat
accepts no liability in this area.
Adobe is a trademark of Adobe Systems Incorporated.
Details of the software products used to create this PDF file can be found in the General Info relative to the file; the PDF-creation
parameters were optimized for printing. Every care has been taken to ensure that the file is suitable for use by ISO member bodies. In
the unlikely event that a problem relating to it is found, please inform the Central Secretariat at the address given below.

©  ISO 2010
All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized in any form or by any means,
electronic or mechanical, including photocopying and microfilm, without permission in writing from either ISO at the address below or
ISO's member body in the country of the requester.
ISO copyright office
Case postale 56 • CH-1211 Geneva 20
Tel. + 41 22 749 01 11
Fax + 41 22 749 09 47
E-mail [e-mail]
Web www.iso.org
Published in Switzerland
ii © ISO 2010 – All rights reserved

Contents Page
Foreword .iv
Introduction.v
1 Scope.1
2 Normative references.1
3 Terms and definitions .1
4 Materials and equipment .3
5 Sequence of APC calibration procedures.4
6 Sizing calibration procedure .7
7 Data presentation .14
8 Identification statement .14
Annex A (normative) Preliminary APC check .15
Annex B (normative) Coincidence error procedure .18
Annex C (normative) Flow rate limit determination .23
Annex D (normative) Resolution determination .27
Annex E (normative) Verification of particle-counting accuracy.32
Annex F (normative) Preparation and verification of bottles of secondary calibration suspensions.34
Annex G (informative) APC calibration round robin .37
Annex H (informative) Sample calculations .42
Annex I (informative) Verification of particle size distribution of calibration samples.48
Bibliography.50

Foreword
ISO (the International Organization for Standardization) is a worldwide federation of national standards bodies
(ISO member bodies). The work of preparing International Standards is normally carried out through ISO
technical committees. Each member body interested in a subject for which a technical committee has been
established has the right to be represented on that committee. International organizations, governmental and
non-governmental, in liaison with ISO, also take part in the work. ISO collaborates closely with the
International Electrotechnical Commission (IEC) on all matters of electrotechnical standardization.
International Standards are drafted in accordance with the rules given in the ISO/IEC Directives, Part 2.
The main task of technical committees is to prepare International Standards. Draft International Standards
adopted by the technical committees are circulated to the member bodies for voting. Publication as an
International Standard requires approval by at least 75 % of the member bodies casting a vote.
Attention is drawn to the possibility that some of the elements of this document may be the subject of patent
rights. ISO shall not be held responsible for identifying any or all such patent rights.
ISO 11171 was prepared by Technical Committee ISO/TC 131, Fluid power systems, Subcommittee SC 6,
Contamination control.
This second edition of ISO 11171 cancels and replaces the first edition (ISO 11171:1999), of which it
constitutes a technical revision, including the following modifications to clarify the steps to be performed when
using this International Standard and to minimize several potential sources of variability. Specifically:
a) A definition of an automatic particle counter (APC) has been added as 3.1.
b) In 5.1, the specific sequence of steps to be followed in calibration is not longer mandated.
c) In 5.1, Note 2 has been added to provide guidance on how to detect a change in the calibration of an
APC.
d) 6.3 now explicitly requires that at least 5 000 particles be counted in order to have statistically valid data
for a particular channel setting.
e) B.4 no longer requires that a 0 % sample be prepared and analysed; instead, the regression equation for
coincidence error determined in B.7 is forced through the origin.
f) Annex C now distinguishes between fixed flow rate and adjustable flow rate bottle samplers. Fixed flow
rate instruments simply require verification of their ability to consistently deliver a constant flow rate within
3 %. For adjustable flow rate instruments, this International Standard requires that their working flow rate
and flow rate limits be determined, in addition to verification of their ability to consistently deliver a
constant flow rate within 3 %.
g) D.12 increases the acceptable resolution of an APC from 10 % to 15 %.
h) E.3 requires that NIST RM 8632 dust be used for verification of counting accuracy. Use of ISO UFTD is
no longer acceptable.
i) Annex H now includes an example of how to construct a calibration curve.
It also incorporates the Technical Corrigendum ISO 11171:1999/Cor.1:2001.
iv © ISO 2010 – All rights reserved

Introduction
In hydraulic fluid power systems, power is transmitted and controlled through a liquid under pressure within an
enclosed circuit. The fluid is both a lubricant and a power-transmitting medium. Reliable system performance
requires control of the contaminants in the fluid. Qualitative and quantitative determination of the particulate
contaminants in the fluid medium requires precision in obtaining the sample and in determining the
contaminant particle size distribution and concentration. Liquid automatic particle counters (APCs) are an
accepted means of determining the concentration and size distribution of the contaminant particles. Individual
APC accuracy is established through calibration.
This International Standard establishes a recommended standard calibration procedure for determining
particle sizing and counting accuracy. The primary particle-sizing calibration is conducted using
NIST SRM 2806 suspensions with particle size distribution certified by the United States' National Institute of
Standards and Technology (NIST). A secondary calibration method with traceability to NIST uses suspensions
of ISO MTD which are independently analysed using an APC calibrated by the primary method. Concentration
limits are determined through the use of serial dilutions of a concentrated suspension. Operation and
performance limits are also established using this International Standard.

INTERNATIONAL STANDARD ISO 11171:2010(E)

Hydraulic fluid power — Calibration of automatic particle
counters for liquids
1 Scope
This International Standard specifies procedures for:
a) primary particle-sizing calibration, sensor resolution and counting performance of automatic particle
counters (APCs) for liquids capable of analysing bottle samples;
b) secondary particle-sizing calibration using suspensions verified with a primary calibrated APC;
c) establishing acceptable operation and performance limits;
d) verifying particle sensor performance using a truncated test dust;
e) determining coincidence and flow rate limits.
2 Normative references
The following referenced documents are indispensable for the application of this document. For dated
references, only the edition cited applies. For undated references, the latest edition of the referenced
document (including any amendments) applies.
ISO 3722, Hydraulic fluid power — Fluid sample containers — Qualifying and controlling cleaning methods
ISO 5598, Fluid power systems and components — Vocabulary
ISO 12103-1, Road vehicles — Test dust for filter evaluation — Part 1: Arizona test dust
ISO 16889, Hydraulic fluid power — Filters — Multi-pass method for evaluating filtration performance of a filter
element
ISO 21501-3, Determination of particle size distribution — Single particle light interaction methods — Part 3:
Light extinction liquid-borne particle counter
3 Terms and definitions
For the purposes of this document, the terms and definitions given in ISO 5598 and the following apply.
3.1
automatic particle counter
APC
instrument that automatically counts and sizes individual particles suspended in a fluid, typically relying on
optical light scattering or light extinction principles of particle sizing
NOTE An APC consists of, at a minimum, a particle sensor, a means for delivering a known volume of sample to the
sensor at a controlled rate, a signal processor, an analyser that compiles the sensor output for the sizes of individual
particles into particle size distribution, and a means for outputting particle size distribution results for the sample.
3.2
threshold noise level
minimum voltage setting of an automatic particle counter at which the observed pulse-counting frequency
does not exceed 60 counts/min due to electrical noise in the absence of flow in the sensing volume
3.3
sensing volume
portion of the illuminated region of the sensor through which the fluid stream passes and from which the light
is collected by the optical system
3.4
resolution
measure of the ability of an automatic particle counter to distinguish between particles of similar, but different,
sizes
3.5
coincidence error limit
highest concentration of NIST RM 8632 that can be counted with an automatic particle counter with an error of
less than 5 % resulting from the presence of more than one particle in the sensing volume at one time
3.6
working flow rate
flow rate through the sensor used for sizing calibration and sample analysis
3.7
particle size
projected area equivalent diameter of particles as determined using scanning electron microscopy or as
determined using a calibrated liquid optical single particle automatic particle counter
NOTE 1 Unless otherwise stated, an APC used for particle size determination is calibrated in accordance with this
International Standard.
NOTE 2 NIST uses scanning electron microscopy to determine the projected area equivalent diameter of particles in its
reference materials.
3.8
particle size distribution
number concentration of particles, expressed as a function of particle size
3.9
primary calibration
sizing calibration conducted using NIST standard reference material 2806
NOTE 1 The procedure is specified in Clause 6.
NOTE 2 For details of NIST standard reference material 2806, see 4.4.
3.10
secondary calibration
sizing calibration conducted using calibration suspensions
NOTE The procedure is specified in Clause 6 and the calibration suspensions are prepared in accordance with
Annex F.
2 © ISO 2010 – All rights reserved

4 Materials and equipment
4.1 Polystyrene latex spheres, nearly monodispersed in aqueous suspension. Polystyrene latex spheres
with a nominal diameter of 10 µm are required in Annex D for resolution determination, and polystyrene latex
spheres with other nominal diameters larger than 50 µm are required in Clause 6 if size calibration for particle
sizes of 50 µm and larger is performed. In certain situations, it may also be useful to use additional sphere
sizes. Regardless, the coefficient of variation of each polystyrene latex sphere size shall be less than 5 %.
The supplier of the polystyrene latex spheres shall provide a certificate of analysis with each batch, which
indicates that the sphere particle size has been determined using techniques with traceability to national or
international standards.
Once opened, suspensions of polystyrene latex spheres shall be used within three months unless the size
distribution and cleanliness of the suspension have been verified.
NOTE 1 The size distribution and cleanliness of polystyrene latex spheres can be verified using the method described
in D.13.
NOTE 2 Polystyrene latex spheres in aqueous suspension have a limited shelf-life. Shelf-life is a function of a variety of
factors including temperature and microbial contamination of the suspension.
4.2 Clean dilution fluid, consisting of the test fluid used in ISO 16889 and an antistatic additive that gives
a conductivity of 2 500 pS/m ± 1 000 pS/m at room temperature. The fluid shall contain less than 0,5 % of the
number of particles equal to or larger than the smallest particle size of interest expected to be observed in the
samples.
4.3 Clean aerosol OT dilution fluid, to determine sensor resolution in Annex D (the clean dilution fluid
specified in 4.2 is used for all other operations in this International Standard). It is prepared from a concentrate
made by adding 120 g of aerosol OT to each litre of clean dilution fluid (4.2). Heat the concentrate to about
60 °C and stir until the aerosol OT has completely dissolved. Prepare the aerosol OT dilution fluid by diluting
the concentrate with clean dilution fluid (4.2) to a final concentration of 12 g of aerosol OT per litre. The clean
aerosol OT dilution fluid shall meet the same cleanliness levels as the dilution fluid specified in 4.2.
CAUTION — Follow the precautions for safe handling and usage described in the materials safety data
sheet (available from the supplier of the aerosol OT).
Aerosol OT (dioctyl sulfosuccinate, sodium salt) is a waxy, hygroscopic solid. If it appears to be damp or have
absorbed water prior to use, dry it first for at least 18 h at about 150 °C.
4.4 NIST standard reference material 2806x (SRM 2806x) primary calibration suspension, where x is
the letter used by NIST to designate the batch number of the certified primary calibration suspension,
available from NIST. Primary calibrations shall use SRM 2806.
[3]
NOTE ISO/TR 16144 describes the procedures used to certify the standard reference material SRM 2806.
4.5 NIST reference material 8631 (RM 8631) dust, prepared by drying the dust for at least 18 h at a
temperature between 110 °C and 150 °C, required if secondary calibration is to be performed (see 6.1).
4.6 ISO medium test dust (MTD) in accordance with ISO 12103-1, dried for at least 18 h at a
temperature between 110 °C and 150 °C before use.
4.7 NIST reference material 8632 (RM 8632) dust, prepared by drying the dust for at least 18 h a
temperature between 110 °C and 150 °C before use, if required for determination of coincidence error limit or
in Annexes B, C and E.
NOTE The reference materials specified in 4.4, 4.5, 4.6 and 4.7 are created using “living” documents that may
change as new batches are produced. Users of this International Standard are advised to ensure that they are using the
latest batch available.
4.8 Automatic particle counter (APC) for liquids, with bottle sampler.
4.9 Clean sample containers, with closures (appropriate bottle caps, for example), and volumetric
glassware of at least class B. The cleanliness levels of the sample containers, closures and glassware shall
be less than 0,5 % of the number of particles (larger than the smallest particle size of interest) expected to be
observed in the samples. The cleanliness levels shall be confirmed by ISO 3722.
4.10 Mechanical shaker, such as a paint or laboratory shaker, suitable for dispersing suspensions.
2 2
4.11 Ultrasonic cleaner, with a power density of 3 000 W/m to 10 000 W/m of bottom area.
4.12 Linear-linear graph paper or computer software for generating graphics.
4.13 Log-log graph paper or computer software for generating graphics.
4.14 Analytical or electronic balance with the following minimum specifications:
a) readability: 0,05 mg;
b) accuracy (agreement with true mass): ±0,05 mg;
c) precision (repeatability): ±0,05 mg;
d) front or side doors and a covered top to eliminate the effect of air currents.
5 Sequence of APC calibration procedures
5.1 See Figure 1 for a recommended sequence of steps to be followed when performing a full calibration on
a new APC. Conduct the procedures of this clause when a new APC is received or following the repair or
readjustment of an APC or sensor (see Table 1). Proceed to Clause 6 if neither the APC nor the sensor has
been repaired or readjusted, if no detectable change in the operating characteristics has occurred since the
last sizing calibration was performed, or if the APC has been subjected to the procedures in Annexes A, B, C,
D, and E and the results have been documented. The specific order of annexes and clauses specified in
Figure 1 and Table 1 are recommendations. The operator may follow a different order as long as all required
parts are performed.
NOTE 1 Annexes A, B, C, and D can be performed by an individual laboratory or by the manufacturer of the APC prior
to delivery.
A change in the operating characteristics of the APC can be detected by several different methods, including
but not limited to:
a) using particle data from control samples collected over time and a statistical process control chart, such
as an individuals moving range (IMR) chart, to detect significant changes in calibration;
b) comparing calibration curves over time to detect a significant change in calibration;
c) returning the APC to its manufacturer for evaluation and assessment of the change in calibration;
d) analysing a primary or secondary calibration suspension in accordance with 6.2 and 6.3, then comparing
the resulting particle concentration data to the corresponding particle size distribution for the sample. If
the results agree within the limits for the maximum allowable D given in Table C.2, the ability of the APC
Q
to size and count particles has not been significantly affected. If the results do not agree, a significant
change has occurred and the operator is instructed to proceed as indicated in Table 1; or
e) analysing a primary or secondary calibration suspension and resulting data as described in item d), then
analysing an ISO UFTD sample prepared in accordance with Annex A, then comparing the resulting
particle concentration data with the limits given in Table A.1. If the results agree within the limits given in
Table A.1, the ability of the APC to size and count particles has not been significantly affected. If the
results do not agree with the limits of Table A.1, the APC has experienced a significant change and the
operator is instructed to proceed as indicated in Table 1.
4 © ISO 2010 – All rights reserved

NOTE 2 For the purposes of this clause, repair or readjustment of an APC refers to service or repair procedures that
affect the ability of the APC to accurately size and count particles.
If the light source or any part of the optics is adjusted, repaired or replaced, the procedures of Clause 6 and
Annexes A, B, D, and E shall be repeated.
If the sensor or counting electronics is adjusted, repaired or replaced, the procedures of Clause 6 and
Annexes A, B, C, D, and E shall be repeated.
If the volume measurement system is repaired, replaced or readjusted, the procedures of Annex A shall be
repeated.
It is not necessary to repeat these procedures following normal cleaning procedures, the attachment of cables
or peripheral equipment, the replacement of plumbing lines or connections, or following other operations that
do not involve disassembly of the APC, sensor or volume measurement system.
5.2 Perform the preliminary APC check, which includes volume accuracy, in accordance with Annex A.
5.3 Determine the coincidence error limits of the APC in accordance with Annex B.
5.4 Perform the sizing calibration procedure in accordance with Clause 6.
5.5 Determine the flow rate limits of the APC in accordance with Annex C.
5.6 Determine the APC resolution in accordance with Annex D.
5.7 Verify the particle-counting accuracy in accordance with Annex E.
5.8 In order to conform to the requirements of this International Standard, the APC shall:
a) be calibrated in accordance with 5.4;
b) meet the volume accuracy, resolution and sensor performance specifications determined in 5.2, 5.6
and 5.7;
c) be operated using the calibration curve determined in 5.4 within the coincidence error and flow rate limits
determined in 5.3 and 5.5.
Figure 1 — Sequence of APC calibration procedures
6 © ISO 2010 – All rights reserved

Table 1 — Schedule of APC calibration procedures
Relevant clause and annexes
of this International Standard
Clause 6 Annex A Annex B Annex C Annex D Annex E
a
APC status
Sizing
Preliminary Coincidence Flow rate
calibration Resolution Accuracy
APC check error limits limits
procedure
New APC or existing APC not
calibrated to this International × × × × × ×
Standard
Last calibration was more than 6 to
× — — — — —
12 months ago
Suspicion that calibration has
× — — — — —
changed significantly
Optics (including light source)
× × × — × ×
repaired or readjusted
Sensor or counting electronics
× × × × × ×
repaired or readjusted
Volume measurement components
(e.g. flowmeter, burette, level — × — — — —
detectors) repaired or readjusted
Sensor cleaned No action necessary
Cables or peripheral equipment
No action necessary
attached
Plumbing lines and connections
No action necessary
replaced
Operation performed that does not
involve disassembly of APC, sensor No action necessary
or volume measurement system
a
Repair or readjustment refers only to service or repair procedures that affect the ability of the APC to accurately size and count
particles. In order to verify the ability of an APC to accurately size and count particles, analyse a primary or secondary calibration
suspension in accordance with 6.2 and 6.3, then compare the resulting particle concentration data to the corresponding particle size
distribution for the sample. If the results agree within the limits given for the maximum allowable D in Table C.2, the ability of the APC
Q
to size and count particles has not been significantly affected. If the results do not agree, proceed as indicated in this table.

6 Sizing calibration procedure
6.1 Refer to Figure 2 for a flow chart describing the sizing calibration procedure. Conduct the sizing
calibration every three to six months, when a new APC is received, or after the repair or readjustment of an
APC or sensor. For primary calibrations, use NIST calibration suspensions (see 4.4). For secondary
calibrations, use calibration suspensions prepared in accordance with Annex F.
Figure 2 — Sizing calibration procedure
After a suitable calibration history for an APC and sensor has been developed, the frequency of calibration
can gradually decrease, but the time interval between successive calibrations shall not exceed one year.
All phases of the calibration shall be conducted at the same flow rate. The flow rate limits of the APC are
determined in Annex C. Any data obtained at flow rates outside these limits shall be discarded and the
corresponding part of the procedure repeated using the proper flow rate.
Conduct the sizing calibration using the same sample volume used in 5.2. If a different volume is used, the
procedure in 5.2 shall be repeated using the new sample volume to avoid volume measurement errors.
8 © ISO 2010 – All rights reserved

It is recommended that the threshold noise level of the APC be determined using the method in A.2 before
proceeding to 6.2. If the threshold noise level has changed by more than 30 % since the last time it was
determined, this can be an indication that the calibration of the APC has changed and the APC is in need of
repair. Failure to check the threshold noise level before proceeding to 6.2 can result in lost time spent trying to
calibrate a defective APC and invalidation of particle count data.
6.2 Set the APC to the cumulative mode and, using at least six different channels, set the threshold voltage
as follows:
a) the lowest threshold setting shall be at least 1,5 times the threshold noise level of the APC; this
determines the minimum detectable particle size;
b) the highest threshold setting is limited by the working-voltage range of the APC (consult the APC
manufacturer to determine this), the particle size distribution and the volume of the calibration sample;
c) intermediate threshold settings shall be chosen to cover the size range of interest.
Prepare a calibration suspension sample for analysis. Shake the sample vigorously by hand. Agitate the
sample ultrasonically for at least 30 s and then shake it on a mechanical shaker for at least 1 min to disperse
the dust in the liquid. Continue shaking the sample until it is to be analysed.
The procedure described in 6.2 to 6.8 assumes manual calibration of an APC with a small number of
threshold settings. Alternatively, calibration can be performed using a multichannel analyser (MCA) or
software that follows the same procedure. If an MCA is used, it is essential that the relationship between the
measured voltage of the MCA and the APC threshold setting be first established. In general, software and
MCA methods tend to be faster and more accurate than manual methods.
6.3 Degas the sample under vacuum or ultrasonically until the bubbles rise to the surface and gently turn
the sample bottle over at least five times, taking care not to introduce air bubbles into the liquid. Obtain at
least five consecutive particle counts, each consisting of at least 10 ml and 10 000 particles at the smallest
threshold setting.
Calculate the total number, N, of particles counted for each channel using Equation (1):
NX= 5V (1)
where
X is the mean particle concentration, in particles per millilitre, for the five counts for a particular
channel;
V is the sample volume, in millilitres, for a single count.
The value of N shall be greater than or equal to 1 000 in order to ensure statistically significant results for that
particular channel.
Calculate D , which is the difference expressed as a percentage between the minimum, X , and maximum,
Q min
X , observed particle count for each channel, using Equation (2):
max
X−
X
max
min
= × 100 (2)
D
Q
X
Record in Table 2 the threshold voltage setting, particle concentration data, X , and D for each channel.
Q
Using Table C.2, find the maximum allowable difference expressed as a percentage corresponding to the
value of X for each channel. If the value of D is less than the maximum, then the value of X for that
Q
channel is acceptable for use. If there are at least six channels with acceptable data, proceed to 6.4. If not,
examine the results of any unacceptable channels as specified in the following.
Calculate D using Equation (3):
XX−
max min
D = (3)
XX−
0 N
where
X is the observed particle count of the suspected outlier (either X or X );
0 max min
X is the observed particle count closest in value to X .
N 0
If D for a particular channel is less than 1,44, discard the related outlier data point, X , recalculate X using
0 0
the remaining four data points, and use the recalculated value of X for calibration purposes. If D for a
particular channel is greater than 1,44, data from this channel are not acceptable and shall be discarded. If
there are at least six channels of acceptable data (using the D and D criteria), proceed to 6.4. If not, take
Q 0
appropriate corrective action and repeat 6.1 to 6.3.
If N is less than 1 000 for any channel, the data for that channel shall not be used. If sufficient numbers of
particles counted is the only quality criterion that is not met, change the threshold settings to correspond to
particle sizes that yield sufficient counts, or repeat 6.1 to 6.3 using a larger sample volume.
Primary and secondary calibration samples shall not be collected and reused.
NOTE Other failures to meet the quality criteria can arise from a number of sources, including contaminated dilution
fluid or glassware, volumetric errors, calculation errors, operating too close to the threshold noise level of the APC, or
bubbles in the samples. Flow rate variability due to counting while the sample chamber is being pressurized or due to
other sources also leads to problems. Particle settling can occur. If excessively high stirring rates are used, particles can
be centrifuged out or bubbles can be introduced.
10 © ISO 2010 – All rights reserved

Table 2 — APC particle sizing calibration worksheet (see 6.3, 6.8 and A.9)
APC Model Date
Serial number Operator
Sensor type Model Calibration sample
Serial number Lot number
Noise level Flow rate ml/min Concentration
First calibration suspension Calibration suspension identification number

Threshold setting
Count 1
Count 2
Count 3
Count 4
Count 5
X(particles/ml)
D
Q
Second calibration suspension Calibration suspension identification number

Threshold setting
Count 1
Count 2
Count 3
Count 4
Count 5
X(particles/ml)
D
Q
Third calibration suspension Calibration suspension identification number

Threshold setting
Count 1
Count 2
Count 3
Count 4
Count 5
X(particles/ml)
D
Q
6.4 Plot the particle concentrations (in particles larger than the indicated size per millilitre) versus the
corresponding threshold settings, in millivolts, on a log -log graph using only the acceptable data points (as
10 10
determined in 6.3). Use appropriate statistical regression techniques to define the relationship between
concentration and threshold setting.
6.5 Determine the expected particle concentrations for at least six different particle sizes using the
appropriate particle size distribution data for the calibration samples. Using the mathematical relationship
determined in 6.4, determine the threshold setting expected to yield these concentrations. Do not extrapolate
to sizes outside the range given in the particle size distribution data. If any of the threshold settings are less
than 1,5 times the threshold noise level of the APC, choose particle concentration data for a larger size that
yields an acceptable threshold setting. Set the threshold settings of the APC to these values.
NOTE Throughout this International Standard, reference to size distribution data refers either to particle size,
concentration, and standard deviation tables available for NIST calibration suspensions or to size, concentration, and
standard deviation data obtained in Annex F for secondary calibration suspensions.
6.6 Repeat 6.1 to 6.5 using at least six different threshold voltage settings, but use all acceptable data (as
determined in 6.3) from both samples to determine the relationship between particle concentration and
threshold setting in 6.4 and 6.5.
6.7 Repeat 6.1 to 6.5 once more using at least six different threshold voltage settings, but use all
acceptable data (as determined in 6.3) from all three samples to determine the final relationship between
particle concentration and threshold setting.
6.8 Construct a calibration curve using the relationship between particle concentration and the threshold
setting determined in 6.7. Choose at least 18 different particle sizes from the appropriate particle size
distribution data. Choose only particle sizes that fall within the size range actually observed in 6.3 to 6.7.
Record in Table 3 these 18 sizes and the corresponding concentrations and threshold settings (determined
using the concentration versus threshold setting plot constructed in 6.7). Plot the corresponding threshold
settings versus particle size. Use the statistical regression technique to define the calibration curve and for
interpolation. Do not extrapolate to sizes outside the size range used for calibration.
Some applications may require calibration at larger particle sizes than are reported in SRM 2806. To calibrate
APCs for counting particles larger than 50 µm(c), ISO 21501-3 should be used. In any case, the user is
cautioned that counting larger-sized particles is subject to many sources of error. Among the most likely
sources of error are: a) the settling of large particles during all phases of sample collection, handling and
analysis and b) the inherently poor particle-counting statistics resulting from the typically low concentrations of
large particles in hydraulic fluid samples.
ISO 21501-3 is a particle size calibration method that uses monodispersed polystyrene latex spheres. In
contrast, the calibration method described in this International Standard is a count calibration method using a
polydispersed test dust. Both methods determine the relationship between APC threshold voltage and particle
size. A particle size calibration method such as ISO 21501-3 can be used for particles larger than 50 µm(c)
because the NIST particle size distribution used in this International Standard is also based on the projected
area diameter of the particles. The signal detected by APCs for particles larger than 50 µm(c) is not strongly
dependent on the refractive index of either the particle or the liquid.
If a calibration method based on a polystyrene latex sphere suspension is used, the polystyrene latex spheres
shall have a size traceable to national or international standards and have a coefficient of variation of less
[11]
than 5 %. The polystyrene latex spheres shall be suspended in MIL-H-5606 hydraulic fluid using the
procedure described in Annex D (if the particles are supplied in aqueous suspension), or mixed directly into
[11]
MIL-H-5606 using ultrasound to disperse the particles (if the particles are supplied dry).
12 © ISO 2010 – All rights reserved

Table 3 — APC calibration summary
APC Model Date
Serial number Operator
Sensor Model Date
Serial number
Noise level Sample volume ml Flow rate ml/min
C % Flow rate limits ml/min
V,vol
Coincidence error limit particles/ml
s µm(c) R %
R R
s µm(c) R %
L L
d µm(c) R %
Sizing calibration
Calibration sample Lot number Concentration

Size Threshold setting
Observed particle concentration
µm(c) mV
Verification of particle-counting accuracy
Size Expected particle concentration
Observed particle concentration
µm(c) (see Table A.1)
7 Data presentation
7.1 Report all particle sizes obtained using an APC calibrated in accordance with this International
Standard, in one of the following ways:
a) as “µm” or “micrometres”, with the following statement: “The sizes quoted in this document were obtained
using an APC calibrated in accordance with ISO 11171:2010”;
b) as “µm(c)”, where (c) indicates that the APC was calibrated in accordance with ISO 11171:2010 (where
possible, this shall be defined in the text).
7.2 Retain completed Table 3 and Tables 2, B.1, C.1, and F.1 on file for inspection.
8 Identification statement
Use the following statement in test reports, catalogues and sales literature when electing to comply with this
International Standard:
“Calibration of liquid automatic particle counters conforms to ISO 11171:2010, Hydraulic fluid power —
Calibration of automatic particle counters for liquids.”
14 © ISO 2010 – All rights reserved

Annex A
(normative)
Preliminary APC check
A.1 Figure A.1 is a flow chart of the preliminary APC check procedure. Conduct the preliminary APC check
when a new APC is received, or following the repair or readjustment of an APC or sensor.

Figure A.1 — Preliminary APC check procedure
A.2 Determine the threshold noise level of the APC under no-flow conditions with clean dilution fluid (4.2) in
the sensor. Ensure that the noise levels do not differ significantly for all the channels of the APC. If significant
differences occur, readjust the APC. Record the APC and sensor model and serial number, the date and the
threshold noise level of the first channel in Tables 2, 3, B.1, C.1 and F.1.
For APCs that use pulse height analysers (as opposed to comparator circuits), determine only the
first-channel threshold noise level. Contact the APC manufacturer in order to determine the type of APC being
used (pulse height analyser or comparator circuit type).
NOTE The APC manufacturer can provide guidance on how to determine the threshold noise level described in A.2.
A.3 Determine the sample volume actually counted during a particle-counting run using a method with
traceability to a national or international standard. Record this value in Table 3 and use it to calculate particle
concentrations in all subsequent work.
NOTE Contact the APC manufacturer in order to determine an appropriate method of determining the sample volume.
A.4 Prepare an RM 8632 concentrate of about 100 mg/l as follows:
a) accurately weigh out the required amount of dry RM 8632 (±0,1 mg) and transfer it to a clean sample
bottle;
b) fill the bottle about three-quarters full with an accurately measured amount (±1 ml) of clean dilution fluid.
Calculate the mass concentration of dust, γ , in milligrams per litre, in the concentrate using Equation (A.1):
A
1000 m
γ = (A.1)
A
V
where
m is the mass, in milligrams, of RM 8632;
V is the volume, in millilitres, of clean dilution fluid.
The RM 8632 concentrate prepared in this annex is also used to determine the coincidence error limits
(Annex B) and flow rate limits (Annex C) of the APC, as well as to verify particle-counting accuracy (Annex E).
For this reason, special care shall be taken in determining the dust concentration of the concentrate and to
ensure that the concentrate is not contaminated. Failure to do so can cause an otherwise suitable APC to be
deemed unacceptable for use.
A.5 Cover the bottle with a clean closure and vigorously shake the concentrate by hand. Disperse the
RM 8632 concentrate ultrasonically for at least 30 s and then shake it on a mechanical shaker for at least 60 s
to disperse the dust.
A.6 Calculate the amount of concentrate required to prepare a dilution that is about 25 % of the
concentration limit for the sensor recommended by the manufacturer. The number concentration
corresponding to a particular mass concentration can be estimated from Table A.1. Add accurately the
required amount of concentrate and clean dilution fluid to a clean sample container in order to obtain the
correct total volume of diluted RM 8632 suspension. Put a particle-free closure on the sample container.
16 © ISO 2010 – All rights reserved

Table A.1 — Particle size distribution for sensor performance verification (see A.6 and B.4)
Particle concentration (particles/ml greater than indicated
Particle size
size for a 1 mg/l sample of RM 8632) shall be
µm(c) greater than or equal to less than or equal to
5 3 300 4 500
6 1 500 2 500
7 660 1 400
8 280 760
9 120 410
10 58 220
11 28 120
12 14 63
13 7,4 34
14 4,1 19
15 2,3 11
A.7 Set the APC to the cumulative mode. Set the lowest threshold setting of the APC to 1,5 times the
threshold noise level of the APC. Using clean dilution fluid, adjust the flow rate to the working flow rate.
Record the flow rate in Tables 2, 3, B.1, C.1, and F.1.
All of the procedures shall be conducted at the same flow rate. The flow rate limits of the APC are determined
in Annex C. Any data obtained at flow rates outside these limits shall be discarded and the corresponding part
of the procedure repeated using the proper flow rate.
A.8 Disperse the particles as described in A.5. Degas the diluted sample under vacuum or ultrasonically
until the bubbles rise to the surface. Obtain five consecutive particle counts of at least 10 000 particles in the
first channel for each measured sample volume. Calculate the coefficient of variation for volume measurement,
C , using Equation (A.2):
V,vol
NN
CC⎛⎞
⎜⎟
NX − X
C ii
∑∑
⎜⎟
100 ii==11
⎝⎠
C = (A.2)
V,vol
NN(1−)
X
CC
where
N is the number of consecutive particle counts performed (i.e. five);
C
X is the mean particle concentration, in particles per millilitre, for the five counts;
X is the mean particle concentration, in particles per millilitre, observed for count i.
i
A.9 The C shall be 3 % or less in order for the APC to be acceptable in accordance with this
V,vol
International Standard. Record the C in Table 3.
V,vol
Although the C is consider
...

2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.WHNRþLQDKTransmissions hydrauliques - Étalonnage des compteurs automatiques de particules en suspension dans les liquidesHydraulic fluid power - Calibration of automatic particle counters for liquids23.100.01Fluid power systems in general17.120.01VSORãQRMeasurement of fluid flow in generalICS:Ta slovenski standard je istoveten z:ISO 11171:2010oSIST ISO 11171:2014en,fr01-januar-2014oSIST ISO 11171:2014SLOVENSKI
STANDARD
oSIST ISO 11171:2014
Reference numberISO 11171:2010(E)© ISO 2010
INTERNATIONAL STANDARD ISO11171Second edition2010-11-01Hydraulic fluid power — Calibration of automatic particle counters for liquids Transmissions hydrauliques — Étalonnage des compteurs automatiques de particules en suspension dans les liquides
oSIST ISO 11171:2014
©
ISO 2010 All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized in any form or by any means, electronic or mechanical, including photocopying and microfilm, without permission in writing from either ISO at the address below or ISO's member body in the country of the requester. ISO copyright office Case postale 56 • CH-1211 Geneva 20 Tel.
+ 41 22 749 01 11 Fax
+ 41 22 749 09 47 E-mail
[e-mail] Web
www.iso.org Published in Switzerland
ii
oSIST ISO 11171:2014
iii Contents Page Foreword.iv Introduction.v 1 Scope.1 2 Normative references.1 3 Terms and definitions.1 4 Materials and equipment.3 5 Sequence of APC calibration procedures.4 6 Sizing calibration procedure.7 7 Data presentation.14 8 Identification statement.14 Annex A (normative)
Preliminary APC check.15 Annex B (normative)
Coincidence error procedure.18 Annex C (normative)
Flow rate limit determination.23 Annex D (normative)
Resolution determination.27 Annex E (normative)
Verification of particle-counting accuracy.32 Annex F (normative)
Preparation and verification of bottles of secondary calibration suspensions.34 Annex G (informative)
APC calibration round robin.37 Annex H (informative)
Sample calculations.42 Annex I (informative)
Verification of particle size distribution of calibration samples.48 Bibliography.50
oSIST ISO 11171:2014
v Introduction In hydraulic fluid power systems, power is transmitted and controlled through a liquid under pressure within an enclosed circuit. The fluid is both a lubricant and a power-transmitting medium. Reliable system performance requires control of the contaminants in the fluid. Qualitative and quantitative determination of the particulate contaminants in the fluid medium requires precision in obtaining the sample and in determining the contaminant particle size distribution and concentration. Liquid automatic particle counters (APCs) are an accepted means of determining the concentration and size distribution of the contaminant particles. Individual APC accuracy is established through calibration. This International Standard establishes a recommended standard calibration procedure for determining particle sizing and counting accuracy. The primary particle-sizing calibration is conducted using NIST SRM 2806 suspensions with particle size distribution certified by the United States' National Institute of Standards and Technology (NIST). A secondary calibration method with traceability to NIST uses suspensions of ISO MTD which are independently analysed using an APC calibrated by the primary method. Concentration limits are determined through the use of serial dilutions of a concentrated suspension. Operation and performance limits are also established using this International Standard.
oSIST ISO 11171:2014
oSIST ISO 11171:2014
INTERNATIONAL STANDARD ISO 11171:2010(E) © ISO 2010 – All rights reserved
1 Hydraulic fluid power — Calibration of automatic particle counters for liquids 1 Scope This International Standard specifies procedures for: a) primary particle-sizing calibration, sensor resolution and counting performance of automatic particle counters (APCs) for liquids capable of analysing bottle samples; b) secondary particle-sizing calibration using suspensions verified with a primary calibrated APC; c) establishing acceptable operation and performance limits; d) verifying particle sensor performance using a truncated test dust; e) determining coincidence and flow rate limits. 2 Normative references The following referenced documents are indispensable for the application of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies. ISO 3722, Hydraulic fluid power — Fluid sample containers — Qualifying and controlling cleaning methods ISO 5598, Fluid power systems and components — Vocabulary ISO 12103-1, Road vehicles — Test dust for filter evaluation — Part 1: Arizona test dust ISO 16889, Hydraulic fluid power — Filters — Multi-pass method for evaluating filtration performance of a filter element ISO 21501-3, Determination of particle size distribution — Single particle light interaction methods — Part 3: Light extinction liquid-borne particle counter 3 Terms and definitions For the purposes of this document, the terms and definitions given in ISO 5598 and the following apply. 3.1 automatic particle counter APC instrument that automatically counts and sizes individual particles suspended in a fluid, typically relying on optical light scattering or light extinction principles of particle sizing oSIST ISO 11171:2014

3 4 Materials and equipment 4.1 Polystyrene latex spheres, nearly monodispersed in aqueous suspension. Polystyrene latex spheres with a nominal diameter of 10 µm are required in Annex D for resolution determination, and polystyrene latex spheres with other nominal diameters larger than 50 µm are required in Clause 6 if size calibration for particle sizes of 50 µm and larger is performed. In certain situations, it may also be useful to use additional sphere sizes. Regardless, the coefficient of variation of each polystyrene latex sphere size shall be less than 5 %. The supplier of the polystyrene latex spheres shall provide a certificate of analysis with each batch, which indicates that the sphere particle size has been determined using techniques with traceability to national or international standards. Once opened, suspensions of polystyrene latex spheres shall be used within three months unless the size distribution and cleanliness of the suspension have been verified. NOTE 1 The size distribution and cleanliness of polystyrene latex spheres can be verified using the method described in D.13. NOTE 2 Polystyrene latex spheres in aqueous suspension have a limited shelf-life. Shelf-life is a function of a variety of factors including temperature and microbial contamination of the suspension. 4.2 Clean dilution fluid, consisting of the test fluid used in ISO 16889 and an antistatic additive that gives a conductivity of 2 500 pS/m ± 1 000 pS/m at room temperature. The fluid shall contain less than 0,5 % of the number of particles equal to or larger than the smallest particle size of interest expected to be observed in the samples. 4.3 Clean aerosol OT dilution fluid, to determine sensor resolution in Annex D (the clean dilution fluid specified in 4.2 is used for all other operations in this International Standard). It is prepared from a concentrate made by adding 120 g of aerosol OT to each litre of clean dilution fluid (4.2). Heat the concentrate to about 60 °C and stir until the aerosol OT has completely dissolved. Prepare the aerosol OT dilution fluid by diluting the concentrate with clean dilution fluid (4.2) to a final concentration of 12 g of aerosol OT per litre. The clean aerosol OT dilution fluid shall meet the same cleanliness levels as the dilution fluid specified in 4.2. CAUTION — Follow the precautions for safe handling and usage described in the materials safety data sheet (available from the supplier of the aerosol OT). Aerosol OT (dioctyl sulfosuccinate, sodium salt) is a waxy, hygroscopic solid. If it appears to be damp or have absorbed water prior to use, dry it first for at least 18 h at about 150 °C. 4.4 NIST standard reference material 2806x (SRM 2806x) primary calibration suspension, where x is the letter used by NIST to designate the batch number of the certified primary calibration suspension, available from NIST. Primary calibrations shall use SRM 2806. NOTE ISO/TR 16144[3] describes the procedures used to certify the standard reference material SRM 2806. 4.5 NIST reference material 8631 (RM 8631) dust, prepared by drying the dust for at least 18 h at a temperature between 110 °C and 150 °C, required if secondary calibration is to be performed (see 6.1). 4.6 ISO medium test dust (MTD) in accordance with ISO 12103-1, dried for at least 18 h at a temperature between 110 °C and 150 °C before use. 4.7 NIST reference material 8632 (RM 8632) dust, prepared by drying the dust for at least 18 h a temperature between 110 °C and 150 °C before use, if required for determination of coincidence error limit or in Annexes B, C and E. NOTE The reference materials specified in 4.4, 4.5, 4.6 and 4.7 are created using “living” documents that may change as new batches are produced. Users of this International Standard are advised to ensure that they are using the latest batch available. 4.8 Automatic particle counter (APC) for liquids, with bottle sampler. oSIST ISO 11171:2014

5 NOTE 2 For the purposes of this clause, repair or readjustment of an APC refers to service or repair procedures that affect the ability of the APC to accurately size and count particles. If the light source or any part of the optics is adjusted, repaired or replaced, the procedures of Clause 6 and Annexes A, B, D, and E shall be repeated. If the sensor or counting electronics is adjusted, repaired or replaced, the procedures of Clause 6 and Annexes A, B, C, D, and E shall be repeated. If the volume measurement system is repaired, replaced or readjusted, the procedures of Annex A shall be repeated. It is not necessary to repeat these procedures following normal cleaning procedures, the attachment of cables or peripheral equipment, the replacement of plumbing lines or connections, or following other operations that do not involve disassembly of the APC, sensor or volume measurement system. 5.2 Perform the preliminary APC check, which includes volume accuracy, in accordance with Annex A. 5.3 Determine the coincidence error limits of the APC in accordance with Annex B. 5.4 Perform the sizing calibration procedure in accordance with Clause 6. 5.5 Determine the flow rate limits of the APC in accordance with Annex C. 5.6 Determine the APC resolution in accordance with Annex D. 5.7 Verify the particle-counting accuracy in accordance with Annex E. 5.8 In order to conform to the requirements of this International Standard, the APC shall: a) be calibrated in accordance with 5.4; b) meet the volume accuracy, resolution and sensor performance specifications determined in 5.2, 5.6 and 5.7; c) be operated using the calibration curve determined in 5.4 within the coincidence error and flow rate limits determined in 5.3 and 5.5. oSIST ISO 11171:2014

Figure 1 — Sequence of APC calibration procedures oSIST ISO 11171:2014

7 Table 1 — Schedule of APC calibration procedures Relevant clause and annexes of this International Standard Clause 6 Annex A Annex B Annex C Annex D Annex E APC statusa Sizing calibration procedure Preliminary APC check Coincidence error limits Flow rate limits ResolutionAccuracyNew APC or existing APC not calibrated to this International Standard × × × × × × Last calibration was more than 6 to 12 months ago × — — — — — Suspicion that calibration has changed significantly × — — — — — Optics (including light source) repaired or readjusted × × × — × × Sensor or counting electronics repaired or readjusted × × × × × × Volume measurement components (e.g. flowmeter, burette, level detectors) repaired or readjusted — × — — — — Sensor cleaned No action necessary Cables or peripheral equipment attached No action necessary Plumbing lines and connections replaced No action necessary Operation performed that does not involve disassembly of APC, sensor or volume measurement system No action necessary a Repair or readjustment refers only to service or repair procedures that affect the ability of the APC to accurately size and count particles. In order to verify the ability of an APC to accurately size and count particles, analyse a primary or secondary calibration suspension in accordance with 6.2 and 6.3, then compare the resulting particle concentration data to the corresponding particle size distribution for the sample. If the results agree within the limits given for the maximum allowable DQ in Table C.2, the ability of the APC to size and count particles has not been significantly affected. If the results do not agree, proceed as indicated in this table.
6 Sizing calibration procedure 6.1 Refer to Figure 2 for a flow chart describing the sizing calibration procedure. Conduct the sizing calibration every three to six months, when a new APC is received, or after the repair or readjustment of an APC or sensor. For primary calibrations, use NIST calibration suspensions (see 4.4). For secondary calibrations, use calibration suspensions prepared in accordance with Annex F. oSIST ISO 11171:2014

Figure 2 — Sizing calibration procedure After a suitable calibration history for an APC and sensor has been developed, the frequency of calibration can gradually decrease, but the time interval between successive calibrations shall not exceed one year. All phases of the calibration shall be conducted at the same flow rate. The flow rate limits of the APC are determined in Annex C. Any data obtained at flow rates outside these limits shall be discarded and the corresponding part of the procedure repeated using the proper flow rate. Conduct the sizing calibration using the same sample volume used in 5.2. If a different volume is used, the procedure in 5.2 shall be repeated using the new sample volume to avoid volume measurement errors. oSIST ISO 11171:2014

9 It is recommended that the threshold noise level of the APC be determined using the method in A.2 before proceeding to 6.2. If the threshold noise level has changed by more than 30 % since the last time it was determined, this can be an indication that the calibration of the APC has changed and the APC is in need of repair. Failure to check the threshold noise level before proceeding to 6.2 can result in lost time spent trying to calibrate a defective APC and invalidation of particle count data. 6.2 Set the APC to the cumulative mode and, using at least six different channels, set the threshold voltage as follows: a) the lowest threshold setting shall be at least 1,5 times the threshold noise level of the APC; this determines the minimum detectable particle size; b) the highest threshold setting is limited by the working-voltage range of the APC (consult the APC manufacturer to determine this), the particle size distribution and the volume of the calibration sample; c) intermediate threshold settings shall be chosen to cover the size range of interest. Prepare a calibration suspension sample for analysis. Shake the sample vigorously by hand. Agitate the sample ultrasonically for at least 30 s and then shake it on a mechanical shaker for at least 1 min to disperse the dust in the liquid. Continue shaking the sample until it is to be analysed. The procedure described in 6.2 to 6.8 assumes manual calibration of an APC with a small number of threshold settings. Alternatively, calibration can be performed using a multichannel analyser (MCA) or software that follows the same procedure. If an MCA is used, it is essential that the relationship between the measured voltage of the MCA and the APC threshold setting be first established. In general, software and MCA methods tend to be faster and more accurate than manual methods. 6.3 Degas the sample under vacuum or ultrasonically until the bubbles rise to the surface and gently turn the sample bottle over at least five times, taking care not to introduce air bubbles into the liquid. Obtain at least five consecutive particle counts, each consisting of at least 10 ml and 10 000 particles at the smallest threshold setting. Calculate the total number, N, of particles counted for each channel using Equation (1): 5NX=V (1) where X is the mean particle concentration, in particles per millilitre, for the five counts for a particular channel; V is the sample volume, in millilitres, for a single count. The value of N shall be greater than or equal to 1 000 in order to ensure statistically significant results for that particular channel. Calculate DQ, which is the difference expressed as a percentage between the minimum, Xmin, and maximum, Xmax, observed particle count for each channel, using Equation (2): maxmin100Q XX = DX−× (2) Record in Table 2 the threshold voltage setting, particle concentration data, X, and DQ for each channel. Using Table C.2, find the maximum allowable difference expressed as a percentage corresponding to the value of X for each channel. If the value of DQ is less than the maximum, then the value of X for that channel is acceptable for use. If there are at least six channels with acceptable data, proceed to 6.4. If not, examine the results of any unacceptable channels as specified in the following. oSIST ISO 11171:2014

11 Table 2 — APC particle sizing calibration worksheet (see 6.3, 6.8 and A.9) APC
Model
Date
Serial number
Operator
Sensor type
Model
Calibration sample
Serial number
Lot number
Noise level
Flow rate ml/minConcentration
First calibration suspension
Calibration suspension identification number
Threshold setting
Count 1
Count 2
Count 3
Count 4
Count 5
X(particles/ml)
DQ
Second calibration suspension
Calibration suspension identification number
Threshold setting
Count 1
Count 2
Count 3
Count 4
Count 5
X(particles/ml)
DQ
Third calibration suspension
Calibration suspension identification number
Threshold setting
Count 1
Count 2
Count 3
Count 4
Count 5
X(particles/ml)
DQ
oSIST ISO 11171:2014
13 Table 3 — APC calibration summary APC
Model
Date
Serial number
Operator
Sensor
Model
Date
Serial number
Noise level
Sample volume mlFlow rate ml/minCV,vol %
Flow rate limits ml/minCoincidence error limit particles/mlsR µm(c)
RR %
sL µm(c)
RL %
d µm(c)
R %
Sizing calibration Calibration sample
Lot number
Concentration
Size µm(c) Threshold setting mV Observed particle concentration
Verification of particle-counting accuracy Size µm(c) Expected particle concentration (see Table A.1) Observed particle concentration
oSIST ISO 11171:2014
15 Annex A (normative)
Preliminary APC check A.1 Figure A.1 is a flow chart of the preliminary APC check procedure. Conduct the preliminary APC check when a new APC is received, or following the repair or readjustment of an APC or sensor.
Figure A.1 — Preliminary APC check procedure oSIST ISO 11171:2014

17 Table A.1 — Particle size distribution for sensor performance verification (see A.6 and B.4) Particle size Particle concentration (particles/ml greater than indicated size for a 1 mg/l sample of RM 8632) shall be µm(c) greater than or equal to less than or equal to 5 3 300 4 500 6 1 500 2 500 7 660 1 400 8 280 760 9 120 410 10 58 220 11 28 120 12 14 63 13 7,4 34 14 4,1 19 15 2,3 11
A.7 Set the APC to the cumulative mode. Set the lowest threshold setting of the APC to 1,5 times the threshold noise level of the APC. Using clean dilution fluid, adjust the flow rate to the working flow rate. Record the flow rate in Tables 2, 3, B.1, C.1, and F.1. All of the procedures shall be conducted at the same flow rate. The flow rate limits of the APC are determined in Annex C. Any data obtained at flow rates outside these limits shall be discarded and the corresponding part of the procedure repeated using the proper flow rate. A.8 Disperse the particles as described in A.5. Degas the diluted sample under vacuum or ultrasonically until the bubbles rise to the surface. Obtain five consecutive particle counts of at least 10 000 particles in the first channel for each measured sample volume. Calculate the coefficient of variation for volume measurement, CV,vol, using Equation (A.2): CC22C11,volCC100(1)NNiiiiVNXXCNNX==⎛⎞⎜⎟−⎜⎟⎝⎠=−∑∑ (A.2) where NC is the number of consecutive particle counts performed (i.e. five); X is the mean particle concentration, in particles per millilitre, for the five counts; Xi is the mean particle concentration, in particles per millilitre, observed for count i. A.9 The CV,vol shall be 3 % or less in order for the APC to be acceptable in accordance with this International Standard. Record the CV,vol in Table 3. Although the CV,vol is considered to be a measure of the ability of the bottle sampler to reproducibly deliver the indicated volume of fluid, other sources of variability, including sample handling and the counting accuracy of the APC, are also included. Regardless of the source of variability, the CV,vol shall be 3 % or less before proceeding with the calibration. oSIST ISO 11171:2014

Coincidence error procedure B.1 Figure B.1 is a flow chart of the coincidence error procedure. The coincidence error limit shall be determined when a new APC is received or after the repair or readjustment of an APC or sensor. The magnitude of the coincidence error at a given particle number concentration is governed by the physical dimensions of the sensing volume as well as the particle size distribution of the sample, including those particles too small to be counted. The coincidence error limit determined in this annex shall be regarded as a benchmark indicator that is useful for routine analyses. For other work, multiple dilutions of a sample shall be analysed to establish that the particle size distribution of the sample does not yi
...

SLOVENSKI STANDARD
01-marec-2014
1DGRPHãþD
SIST ISO 11171:2001
SIST ISO 11171:2001/TC 1:2002
)OXLGQDWHKQLND+LGUDYOLND8PHUMDQMHQDSUDY]DDYWRPDWVNRãWHWMHGHOFHYY
WHNRþLQDK
Hydraulic fluid power - Calibration of automatic particle counters for liquids
Transmissions hydrauliques - Étalonnage des compteurs automatiques de particules en
suspension dans les liquides
Ta slovenski standard je istoveten z: ISO 11171:2010
ICS:
17.120.01 0HUMHQMHSUHWRNDWHNRþLQQD Measurement of fluid flow in
VSORãQR general
23.100.01 +LGUDYOLþQLVLVWHPLQDVSORãQR Fluid power systems in
general
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

INTERNATIONAL ISO
STANDARD 11171
Second edition
2010-11-01
Hydraulic fluid power — Calibration of
automatic particle counters for liquids
Transmissions hydrauliques — Étalonnage des compteurs
automatiques de particules en suspension dans les liquides

Reference number
©
ISO 2010
PDF disclaimer
This PDF file may contain embedded typefaces. In accordance with Adobe's licensing policy, this file may be printed or viewed but
shall not be edited unless the typefaces which are embedded are licensed to and installed on the computer performing the editing. In
downloading this file, parties accept therein the responsibility of not infringing Adobe's licensing policy. The ISO Central Secretariat
accepts no liability in this area.
Adobe is a trademark of Adobe Systems Incorporated.
Details of the software products used to create this PDF file can be found in the General Info relative to the file; the PDF-creation
parameters were optimized for printing. Every care has been taken to ensure that the file is suitable for use by ISO member bodies. In
the unlikely event that a problem relating to it is found, please inform the Central Secretariat at the address given below.

©  ISO 2010
All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized in any form or by any means,
electronic or mechanical, including photocopying and microfilm, without permission in writing from either ISO at the address below or
ISO's member body in the country of the requester.
ISO copyright office
Case postale 56 • CH-1211 Geneva 20
Tel. + 41 22 749 01 11
Fax + 41 22 749 09 47
E-mail [e-mail]
Web www.iso.org
Published in Switzerland
ii © ISO 2010 – All rights reserved

Contents Page
Foreword .iv
Introduction.v
1 Scope.1
2 Normative references.1
3 Terms and definitions .1
4 Materials and equipment .3
5 Sequence of APC calibration procedures.4
6 Sizing calibration procedure .7
7 Data presentation .14
8 Identification statement .14
Annex A (normative) Preliminary APC check .15
Annex B (normative) Coincidence error procedure .18
Annex C (normative) Flow rate limit determination .23
Annex D (normative) Resolution determination .27
Annex E (normative) Verification of particle-counting accuracy.32
Annex F (normative) Preparation and verification of bottles of secondary calibration suspensions.34
Annex G (informative) APC calibration round robin .37
Annex H (informative) Sample calculations .42
Annex I (informative) Verification of particle size distribution of calibration samples.48
Bibliography.50

Foreword
ISO (the International Organization for Standardization) is a worldwide federation of national standards bodies
(ISO member bodies). The work of preparing International Standards is normally carried out through ISO
technical committees. Each member body interested in a subject for which a technical committee has been
established has the right to be represented on that committee. International organizations, governmental and
non-governmental, in liaison with ISO, also take part in the work. ISO collaborates closely with the
International Electrotechnical Commission (IEC) on all matters of electrotechnical standardization.
International Standards are drafted in accordance with the rules given in the ISO/IEC Directives, Part 2.
The main task of technical committees is to prepare International Standards. Draft International Standards
adopted by the technical committees are circulated to the member bodies for voting. Publication as an
International Standard requires approval by at least 75 % of the member bodies casting a vote.
Attention is drawn to the possibility that some of the elements of this document may be the subject of patent
rights. ISO shall not be held responsible for identifying any or all such patent rights.
ISO 11171 was prepared by Technical Committee ISO/TC 131, Fluid power systems, Subcommittee SC 6,
Contamination control.
This second edition of ISO 11171 cancels and replaces the first edition (ISO 11171:1999), of which it
constitutes a technical revision, including the following modifications to clarify the steps to be performed when
using this International Standard and to minimize several potential sources of variability. Specifically:
a) A definition of an automatic particle counter (APC) has been added as 3.1.
b) In 5.1, the specific sequence of steps to be followed in calibration is not longer mandated.
c) In 5.1, Note 2 has been added to provide guidance on how to detect a change in the calibration of an
APC.
d) 6.3 now explicitly requires that at least 5 000 particles be counted in order to have statistically valid data
for a particular channel setting.
e) B.4 no longer requires that a 0 % sample be prepared and analysed; instead, the regression equation for
coincidence error determined in B.7 is forced through the origin.
f) Annex C now distinguishes between fixed flow rate and adjustable flow rate bottle samplers. Fixed flow
rate instruments simply require verification of their ability to consistently deliver a constant flow rate within
3 %. For adjustable flow rate instruments, this International Standard requires that their working flow rate
and flow rate limits be determined, in addition to verification of their ability to consistently deliver a
constant flow rate within 3 %.
g) D.12 increases the acceptable resolution of an APC from 10 % to 15 %.
h) E.3 requires that NIST RM 8632 dust be used for verification of counting accuracy. Use of ISO UFTD is
no longer acceptable.
i) Annex H now includes an example of how to construct a calibration curve.
It also incorporates the Technical Corrigendum ISO 11171:1999/Cor.1:2001.
iv © ISO 2010 – All rights reserved

Introduction
In hydraulic fluid power systems, power is transmitted and controlled through a liquid under pressure within an
enclosed circuit. The fluid is both a lubricant and a power-transmitting medium. Reliable system performance
requires control of the contaminants in the fluid. Qualitative and quantitative determination of the particulate
contaminants in the fluid medium requires precision in obtaining the sample and in determining the
contaminant particle size distribution and concentration. Liquid automatic particle counters (APCs) are an
accepted means of determining the concentration and size distribution of the contaminant particles. Individual
APC accuracy is established through calibration.
This International Standard establishes a recommended standard calibration procedure for determining
particle sizing and counting accuracy. The primary particle-sizing calibration is conducted using
NIST SRM 2806 suspensions with particle size distribution certified by the United States' National Institute of
Standards and Technology (NIST). A secondary calibration method with traceability to NIST uses suspensions
of ISO MTD which are independently analysed using an APC calibrated by the primary method. Concentration
limits are determined through the use of serial dilutions of a concentrated suspension. Operation and
performance limits are also established using this International Standard.

INTERNATIONAL STANDARD ISO 11171:2010(E)

Hydraulic fluid power — Calibration of automatic particle
counters for liquids
1 Scope
This International Standard specifies procedures for:
a) primary particle-sizing calibration, sensor resolution and counting performance of automatic particle
counters (APCs) for liquids capable of analysing bottle samples;
b) secondary particle-sizing calibration using suspensions verified with a primary calibrated APC;
c) establishing acceptable operation and performance limits;
d) verifying particle sensor performance using a truncated test dust;
e) determining coincidence and flow rate limits.
2 Normative references
The following referenced documents are indispensable for the application of this document. For dated
references, only the edition cited applies. For undated references, the latest edition of the referenced
document (including any amendments) applies.
ISO 3722, Hydraulic fluid power — Fluid sample containers — Qualifying and controlling cleaning methods
ISO 5598, Fluid power systems and components — Vocabulary
ISO 12103-1, Road vehicles — Test dust for filter evaluation — Part 1: Arizona test dust
ISO 16889, Hydraulic fluid power — Filters — Multi-pass method for evaluating filtration performance of a filter
element
ISO 21501-3, Determination of particle size distribution — Single particle light interaction methods — Part 3:
Light extinction liquid-borne particle counter
3 Terms and definitions
For the purposes of this document, the terms and definitions given in ISO 5598 and the following apply.
3.1
automatic particle counter
APC
instrument that automatically counts and sizes individual particles suspended in a fluid, typically relying on
optical light scattering or light extinction principles of particle sizing
NOTE An APC consists of, at a minimum, a particle sensor, a means for delivering a known volume of sample to the
sensor at a controlled rate, a signal processor, an analyser that compiles the sensor output for the sizes of individual
particles into particle size distribution, and a means for outputting particle size distribution results for the sample.
3.2
threshold noise level
minimum voltage setting of an automatic particle counter at which the observed pulse-counting frequency
does not exceed 60 counts/min due to electrical noise in the absence of flow in the sensing volume
3.3
sensing volume
portion of the illuminated region of the sensor through which the fluid stream passes and from which the light
is collected by the optical system
3.4
resolution
measure of the ability of an automatic particle counter to distinguish between particles of similar, but different,
sizes
3.5
coincidence error limit
highest concentration of NIST RM 8632 that can be counted with an automatic particle counter with an error of
less than 5 % resulting from the presence of more than one particle in the sensing volume at one time
3.6
working flow rate
flow rate through the sensor used for sizing calibration and sample analysis
3.7
particle size
projected area equivalent diameter of particles as determined using scanning electron microscopy or as
determined using a calibrated liquid optical single particle automatic particle counter
NOTE 1 Unless otherwise stated, an APC used for particle size determination is calibrated in accordance with this
International Standard.
NOTE 2 NIST uses scanning electron microscopy to determine the projected area equivalent diameter of particles in its
reference materials.
3.8
particle size distribution
number concentration of particles, expressed as a function of particle size
3.9
primary calibration
sizing calibration conducted using NIST standard reference material 2806
NOTE 1 The procedure is specified in Clause 6.
NOTE 2 For details of NIST standard reference material 2806, see 4.4.
3.10
secondary calibration
sizing calibration conducted using calibration suspensions
NOTE The procedure is specified in Clause 6 and the calibration suspensions are prepared in accordance with
Annex F.
2 © ISO 2010 – All rights reserved

4 Materials and equipment
4.1 Polystyrene latex spheres, nearly monodispersed in aqueous suspension. Polystyrene latex spheres
with a nominal diameter of 10 µm are required in Annex D for resolution determination, and polystyrene latex
spheres with other nominal diameters larger than 50 µm are required in Clause 6 if size calibration for particle
sizes of 50 µm and larger is performed. In certain situations, it may also be useful to use additional sphere
sizes. Regardless, the coefficient of variation of each polystyrene latex sphere size shall be less than 5 %.
The supplier of the polystyrene latex spheres shall provide a certificate of analysis with each batch, which
indicates that the sphere particle size has been determined using techniques with traceability to national or
international standards.
Once opened, suspensions of polystyrene latex spheres shall be used within three months unless the size
distribution and cleanliness of the suspension have been verified.
NOTE 1 The size distribution and cleanliness of polystyrene latex spheres can be verified using the method described
in D.13.
NOTE 2 Polystyrene latex spheres in aqueous suspension have a limited shelf-life. Shelf-life is a function of a variety of
factors including temperature and microbial contamination of the suspension.
4.2 Clean dilution fluid, consisting of the test fluid used in ISO 16889 and an antistatic additive that gives
a conductivity of 2 500 pS/m ± 1 000 pS/m at room temperature. The fluid shall contain less than 0,5 % of the
number of particles equal to or larger than the smallest particle size of interest expected to be observed in the
samples.
4.3 Clean aerosol OT dilution fluid, to determine sensor resolution in Annex D (the clean dilution fluid
specified in 4.2 is used for all other operations in this International Standard). It is prepared from a concentrate
made by adding 120 g of aerosol OT to each litre of clean dilution fluid (4.2). Heat the concentrate to about
60 °C and stir until the aerosol OT has completely dissolved. Prepare the aerosol OT dilution fluid by diluting
the concentrate with clean dilution fluid (4.2) to a final concentration of 12 g of aerosol OT per litre. The clean
aerosol OT dilution fluid shall meet the same cleanliness levels as the dilution fluid specified in 4.2.
CAUTION — Follow the precautions for safe handling and usage described in the materials safety data
sheet (available from the supplier of the aerosol OT).
Aerosol OT (dioctyl sulfosuccinate, sodium salt) is a waxy, hygroscopic solid. If it appears to be damp or have
absorbed water prior to use, dry it first for at least 18 h at about 150 °C.
4.4 NIST standard reference material 2806x (SRM 2806x) primary calibration suspension, where x is
the letter used by NIST to designate the batch number of the certified primary calibration suspension,
available from NIST. Primary calibrations shall use SRM 2806.
[3]
NOTE ISO/TR 16144 describes the procedures used to certify the standard reference material SRM 2806.
4.5 NIST reference material 8631 (RM 8631) dust, prepared by drying the dust for at least 18 h at a
temperature between 110 °C and 150 °C, required if secondary calibration is to be performed (see 6.1).
4.6 ISO medium test dust (MTD) in accordance with ISO 12103-1, dried for at least 18 h at a
temperature between 110 °C and 150 °C before use.
4.7 NIST reference material 8632 (RM 8632) dust, prepared by drying the dust for at least 18 h a
temperature between 110 °C and 150 °C before use, if required for determination of coincidence error limit or
in Annexes B, C and E.
NOTE The reference materials specified in 4.4, 4.5, 4.6 and 4.7 are created using “living” documents that may
change as new batches are produced. Users of this International Standard are advised to ensure that they are using the
latest batch available.
4.8 Automatic particle counter (APC) for liquids, with bottle sampler.
4.9 Clean sample containers, with closures (appropriate bottle caps, for example), and volumetric
glassware of at least class B. The cleanliness levels of the sample containers, closures and glassware shall
be less than 0,5 % of the number of particles (larger than the smallest particle size of interest) expected to be
observed in the samples. The cleanliness levels shall be confirmed by ISO 3722.
4.10 Mechanical shaker, such as a paint or laboratory shaker, suitable for dispersing suspensions.
2 2
4.11 Ultrasonic cleaner, with a power density of 3 000 W/m to 10 000 W/m of bottom area.
4.12 Linear-linear graph paper or computer software for generating graphics.
4.13 Log-log graph paper or computer software for generating graphics.
4.14 Analytical or electronic balance with the following minimum specifications:
a) readability: 0,05 mg;
b) accuracy (agreement with true mass): ±0,05 mg;
c) precision (repeatability): ±0,05 mg;
d) front or side doors and a covered top to eliminate the effect of air currents.
5 Sequence of APC calibration procedures
5.1 See Figure 1 for a recommended sequence of steps to be followed when performing a full calibration on
a new APC. Conduct the procedures of this clause when a new APC is received or following the repair or
readjustment of an APC or sensor (see Table 1). Proceed to Clause 6 if neither the APC nor the sensor has
been repaired or readjusted, if no detectable change in the operating characteristics has occurred since the
last sizing calibration was performed, or if the APC has been subjected to the procedures in Annexes A, B, C,
D, and E and the results have been documented. The specific order of annexes and clauses specified in
Figure 1 and Table 1 are recommendations. The operator may follow a different order as long as all required
parts are performed.
NOTE 1 Annexes A, B, C, and D can be performed by an individual laboratory or by the manufacturer of the APC prior
to delivery.
A change in the operating characteristics of the APC can be detected by several different methods, including
but not limited to:
a) using particle data from control samples collected over time and a statistical process control chart, such
as an individuals moving range (IMR) chart, to detect significant changes in calibration;
b) comparing calibration curves over time to detect a significant change in calibration;
c) returning the APC to its manufacturer for evaluation and assessment of the change in calibration;
d) analysing a primary or secondary calibration suspension in accordance with 6.2 and 6.3, then comparing
the resulting particle concentration data to the corresponding particle size distribution for the sample. If
the results agree within the limits for the maximum allowable D given in Table C.2, the ability of the APC
Q
to size and count particles has not been significantly affected. If the results do not agree, a significant
change has occurred and the operator is instructed to proceed as indicated in Table 1; or
e) analysing a primary or secondary calibration suspension and resulting data as described in item d), then
analysing an ISO UFTD sample prepared in accordance with Annex A, then comparing the resulting
particle concentration data with the limits given in Table A.1. If the results agree within the limits given in
Table A.1, the ability of the APC to size and count particles has not been significantly affected. If the
results do not agree with the limits of Table A.1, the APC has experienced a significant change and the
operator is instructed to proceed as indicated in Table 1.
4 © ISO 2010 – All rights reserved

NOTE 2 For the purposes of this clause, repair or readjustment of an APC refers to service or repair procedures that
affect the ability of the APC to accurately size and count particles.
If the light source or any part of the optics is adjusted, repaired or replaced, the procedures of Clause 6 and
Annexes A, B, D, and E shall be repeated.
If the sensor or counting electronics is adjusted, repaired or replaced, the procedures of Clause 6 and
Annexes A, B, C, D, and E shall be repeated.
If the volume measurement system is repaired, replaced or readjusted, the procedures of Annex A shall be
repeated.
It is not necessary to repeat these procedures following normal cleaning procedures, the attachment of cables
or peripheral equipment, the replacement of plumbing lines or connections, or following other operations that
do not involve disassembly of the APC, sensor or volume measurement system.
5.2 Perform the preliminary APC check, which includes volume accuracy, in accordance with Annex A.
5.3 Determine the coincidence error limits of the APC in accordance with Annex B.
5.4 Perform the sizing calibration procedure in accordance with Clause 6.
5.5 Determine the flow rate limits of the APC in accordance with Annex C.
5.6 Determine the APC resolution in accordance with Annex D.
5.7 Verify the particle-counting accuracy in accordance with Annex E.
5.8 In order to conform to the requirements of this International Standard, the APC shall:
a) be calibrated in accordance with 5.4;
b) meet the volume accuracy, resolution and sensor performance specifications determined in 5.2, 5.6
and 5.7;
c) be operated using the calibration curve determined in 5.4 within the coincidence error and flow rate limits
determined in 5.3 and 5.5.
Figure 1 — Sequence of APC calibration procedures
6 © ISO 2010 – All rights reserved

Table 1 — Schedule of APC calibration procedures
Relevant clause and annexes
of this International Standard
Clause 6 Annex A Annex B Annex C Annex D Annex E
a
APC status
Sizing
Preliminary Coincidence Flow rate
calibration Resolution Accuracy
APC check error limits limits
procedure
New APC or existing APC not
calibrated to this International × × × × × ×
Standard
Last calibration was more than 6 to
× — — — — —
12 months ago
Suspicion that calibration has
× — — — — —
changed significantly
Optics (including light source)
× × × — × ×
repaired or readjusted
Sensor or counting electronics
× × × × × ×
repaired or readjusted
Volume measurement components
(e.g. flowmeter, burette, level — × — — — —
detectors) repaired or readjusted
Sensor cleaned No action necessary
Cables or peripheral equipment
No action necessary
attached
Plumbing lines and connections
No action necessary
replaced
Operation performed that does not
involve disassembly of APC, sensor No action necessary
or volume measurement system
a
Repair or readjustment refers only to service or repair procedures that affect the ability of the APC to accurately size and count
particles. In order to verify the ability of an APC to accurately size and count particles, analyse a primary or secondary calibration
suspension in accordance with 6.2 and 6.3, then compare the resulting particle concentration data to the corresponding particle size
distribution for the sample. If the results agree within the limits given for the maximum allowable D in Table C.2, the ability of the APC
Q
to size and count particles has not been significantly affected. If the results do not agree, proceed as indicated in this table.

6 Sizing calibration procedure
6.1 Refer to Figure 2 for a flow chart describing the sizing calibration procedure. Conduct the sizing
calibration every three to six months, when a new APC is received, or after the repair or readjustment of an
APC or sensor. For primary calibrations, use NIST calibration suspensions (see 4.4). For secondary
calibrations, use calibration suspensions prepared in accordance with Annex F.
Figure 2 — Sizing calibration procedure
After a suitable calibration history for an APC and sensor has been developed, the frequency of calibration
can gradually decrease, but the time interval between successive calibrations shall not exceed one year.
All phases of the calibration shall be conducted at the same flow rate. The flow rate limits of the APC are
determined in Annex C. Any data obtained at flow rates outside these limits shall be discarded and the
corresponding part of the procedure repeated using the proper flow rate.
Conduct the sizing calibration using the same sample volume used in 5.2. If a different volume is used, the
procedure in 5.2 shall be repeated using the new sample volume to avoid volume measurement errors.
8 © ISO 2010 – All rights reserved

It is recommended that the threshold noise level of the APC be determined using the method in A.2 before
proceeding to 6.2. If the threshold noise level has changed by more than 30 % since the last time it was
determined, this can be an indication that the calibration of the APC has changed and the APC is in need of
repair. Failure to check the threshold noise level before proceeding to 6.2 can result in lost time spent trying to
calibrate a defective APC and invalidation of particle count data.
6.2 Set the APC to the cumulative mode and, using at least six different channels, set the threshold voltage
as follows:
a) the lowest threshold setting shall be at least 1,5 times the threshold noise level of the APC; this
determines the minimum detectable particle size;
b) the highest threshold setting is limited by the working-voltage range of the APC (consult the APC
manufacturer to determine this), the particle size distribution and the volume of the calibration sample;
c) intermediate threshold settings shall be chosen to cover the size range of interest.
Prepare a calibration suspension sample for analysis. Shake the sample vigorously by hand. Agitate the
sample ultrasonically for at least 30 s and then shake it on a mechanical shaker for at least 1 min to disperse
the dust in the liquid. Continue shaking the sample until it is to be analysed.
The procedure described in 6.2 to 6.8 assumes manual calibration of an APC with a small number of
threshold settings. Alternatively, calibration can be performed using a multichannel analyser (MCA) or
software that follows the same procedure. If an MCA is used, it is essential that the relationship between the
measured voltage of the MCA and the APC threshold setting be first established. In general, software and
MCA methods tend to be faster and more accurate than manual methods.
6.3 Degas the sample under vacuum or ultrasonically until the bubbles rise to the surface and gently turn
the sample bottle over at least five times, taking care not to introduce air bubbles into the liquid. Obtain at
least five consecutive particle counts, each consisting of at least 10 ml and 10 000 particles at the smallest
threshold setting.
Calculate the total number, N, of particles counted for each channel using Equation (1):
NX= 5V (1)
where
X is the mean particle concentration, in particles per millilitre, for the five counts for a particular
channel;
V is the sample volume, in millilitres, for a single count.
The value of N shall be greater than or equal to 1 000 in order to ensure statistically significant results for that
particular channel.
Calculate D , which is the difference expressed as a percentage between the minimum, X , and maximum,
Q min
X , observed particle count for each channel, using Equation (2):
max
X−
X
max
min
= × 100 (2)
D
Q
X
Record in Table 2 the threshold voltage setting, particle concentration data, X , and D for each channel.
Q
Using Table C.2, find the maximum allowable difference expressed as a percentage corresponding to the
value of X for each channel. If the value of D is less than the maximum, then the value of X for that
Q
channel is acceptable for use. If there are at least six channels with acceptable data, proceed to 6.4. If not,
examine the results of any unacceptable channels as specified in the following.
Calculate D using Equation (3):
XX−
max min
D = (3)
XX−
0 N
where
X is the observed particle count of the suspected outlier (either X or X );
0 max min
X is the observed particle count closest in value to X .
N 0
If D for a particular channel is less than 1,44, discard the related outlier data point, X , recalculate X using
0 0
the remaining four data points, and use the recalculated value of X for calibration purposes. If D for a
particular channel is greater than 1,44, data from this channel are not acceptable and shall be discarded. If
there are at least six channels of acceptable data (using the D and D criteria), proceed to 6.4. If not, take
Q 0
appropriate corrective action and repeat 6.1 to 6.3.
If N is less than 1 000 for any channel, the data for that channel shall not be used. If sufficient numbers of
particles counted is the only quality criterion that is not met, change the threshold settings to correspond to
particle sizes that yield sufficient counts, or repeat 6.1 to 6.3 using a larger sample volume.
Primary and secondary calibration samples shall not be collected and reused.
NOTE Other failures to meet the quality criteria can arise from a number of sources, including contaminated dilution
fluid or glassware, volumetric errors, calculation errors, operating too close to the threshold noise level of the APC, or
bubbles in the samples. Flow rate variability due to counting while the sample chamber is being pressurized or due to
other sources also leads to problems. Particle settling can occur. If excessively high stirring rates are used, particles can
be centrifuged out or bubbles can be introduced.
10 © ISO 2010 – All rights reserved

Table 2 — APC particle sizing calibration worksheet (see 6.3, 6.8 and A.9)
APC Model Date
Serial number Operator
Sensor type Model Calibration sample
Serial number Lot number
Noise level Flow rate ml/min Concentration
First calibration suspension Calibration suspension identification number

Threshold setting
Count 1
Count 2
Count 3
Count 4
Count 5
X(particles/ml)
D
Q
Second calibration suspension Calibration suspension identification number

Threshold setting
Count 1
Count 2
Count 3
Count 4
Count 5
X(particles/ml)
D
Q
Third calibration suspension Calibration suspension identification number

Threshold setting
Count 1
Count 2
Count 3
Count 4
Count 5
X(particles/ml)
D
Q
6.4 Plot the particle concentrations (in particles larger than the indicated size per millilitre) versus the
corresponding threshold settings, in millivolts, on a log -log graph using only the acceptable data points (as
10 10
determined in 6.3). Use appropriate statistical regression techniques to define the relationship between
concentration and threshold setting.
6.5 Determine the expected particle concentrations for at least six different particle sizes using the
appropriate particle size distribution data for the calibration samples. Using the mathematical relationship
determined in 6.4, determine the threshold setting expected to yield these concentrations. Do not extrapolate
to sizes outside the range given in the particle size distribution data. If any of the threshold settings are less
than 1,5 times the threshold noise level of the APC, choose particle concentration data for a larger size that
yields an acceptable threshold setting. Set the threshold settings of the APC to these values.
NOTE Throughout this International Standard, reference to size distribution data refers either to particle size,
concentration, and standard deviation tables available for NIST calibration suspensions or to size, concentration, and
standard deviation data obtained in Annex F for secondary calibration suspensions.
6.6 Repeat 6.1 to 6.5 using at least six different threshold voltage settings, but use all acceptable data (as
determined in 6.3) from both samples to determine the relationship between particle concentration and
threshold setting in 6.4 and 6.5.
6.7 Repeat 6.1 to 6.5 once more using at least six different threshold voltage settings, but use all
acceptable data (as determined in 6.3) from all three samples to determine the final relationship between
particle concentration and threshold setting.
6.8 Construct a calibration curve using the relationship between particle concentration and the threshold
setting determined in 6.7. Choose at least 18 different particle sizes from the appropriate particle size
distribution data. Choose only particle sizes that fall within the size range actually observed in 6.3 to 6.7.
Record in Table 3 these 18 sizes and the corresponding concentrations and threshold settings (determined
using the concentration versus threshold setting plot constructed in 6.7). Plot the corresponding threshold
settings versus particle size. Use the statistical regression technique to define the calibration curve and for
interpolation. Do not extrapolate to sizes outside the size range used for calibration.
Some applications may require calibration at larger particle sizes than are reported in SRM 2806. To calibrate
APCs for counting particles larger than 50 µm(c), ISO 21501-3 should be used. In any case, the user is
cautioned that counting larger-sized particles is subject to many sources of error. Among the most likely
sources of error are: a) the settling of large particles during all phases of sample collection, handling and
analysis and b) the inherently poor particle-counting statistics resulting from the typically low concentrations of
large particles in hydraulic fluid samples.
ISO 21501-3 is a particle size calibration method that uses monodispersed polystyrene latex spheres. In
contrast, the calibration method described in this International Standard is a count calibration method using a
polydispersed test dust. Both methods determine the relationship between APC threshold voltage and particle
size. A particle size calibration method such as ISO 21501-3 can be used for particles larger than 50 µm(c)
because the NIST particle size distribution used in this International Standard is also based on the projected
area diameter of the particles. The signal detected by APCs for particles larger than 50 µm(c) is not strongly
dependent on the refractive index of either the particle or the liquid.
If a calibration method based on a polystyrene latex sphere suspension is used, the polystyrene latex spheres
shall have a size traceable to national or international standards and have a coefficient of variation of less
[11]
than 5 %. The polystyrene latex spheres shall be suspended in MIL-H-5606 hydraulic fluid using the
procedure described in Annex D (if the particles are supplied in aqueous suspension), or mixed directly into
[11]
MIL-H-5606 using ultrasound to disperse the particles (if the particles are supplied dry).
12 © ISO 2010 – All rights reserved

Table 3 — APC calibration summary
APC Model Date
Serial number Operator
Sensor Model Date
Serial number
Noise level Sample volume ml Flow rate ml/min
C % Flow rate limits ml/min
V,vol
Coincidence error limit particles/ml
s µm(c) R %
R R
s µm(c) R %
L L
d µm(c) R %
Sizing calibration
Calibration sample Lot number Concentration

Size Threshold setting
Observed particle concentration
µm(c) mV
Verification of particle-counting accuracy
Size Expected particle concentration
Observed particle concentration
µm(c) (see Table A.1)
7 Data presentation
7.1 Report all particle sizes obtained using an APC calibrated in accordance with this International
Standard, in one of the following ways:
a) as “µm” or “micrometres”, with the following statement: “The sizes quoted in this document were obtained
using an APC calibrated in accordance with ISO 11171:2010”;
b) as “µm(c)”, where (c) indicates that the APC was calibrated in accordance with ISO 11171:2010 (where
possible, this shall be defined in the text).
7.2 Retain completed Table 3 and Tables 2, B.1, C.1, and F.1 on file for inspection.
8 Identification statement
Use the following statement in test reports, catalogues and sales literature when electing to comply with this
International Standard:
“Calibration of liquid automatic particle counters conforms to ISO 11171:2010, Hydraulic fluid power —
Calibration of automatic particle counters for liquids.”
14 © ISO 2010 – All rights reserved

Annex A
(normative)
Preliminary APC check
A.1 Figure A.1 is a flow chart of the preliminary APC check procedure. Conduct the preliminary APC check
when a new APC is received, or following the repair or readjustment of an APC or sensor.

Figure A.1 — Preliminary APC check procedure
A.2 Determine the threshold noise level of the APC under no-flow conditions with clean dilution fluid (4.2) in
the sensor. Ensure that the noise levels do not differ significantly for all the channels of the APC. If significant
differences occur, readjust the APC. Record the APC and sensor model and serial number, the date and the
threshold noise level of the first channel in Tables 2, 3, B.1, C.1 and F.1.
For APCs that use pulse height analysers (as opposed to comparator circuits), determine only the
first-channel threshold noise level. Contact the APC manufacturer in order to determine the type of APC being
used (pulse height analyser or comparator circuit type).
NOTE The APC manufacturer can provide guidance on how to determine the threshold noise level described in A.2.
A.3 Determine the sample volume actually counted during a particle-counting run using a method with
traceability to a national or international standard. Record this value in Table 3 and use it to calculate particle
concentrations in all subsequent work.
NOTE Contact the APC manufacturer in order to determine an appropriate method of determining the sample volume.
A.4 Prepare an RM 8632 concentrate of about 100 mg/l as follows:
a) accurately weigh out the required amount of dry RM 8632 (±0,1 mg) and transfer it to a clean sample
bottle;
b) fill the bottle about three-quarters full with an accurately measured amount (±1 ml) of clean dilution fluid.
Calculate the mass concentration of dust, γ , in milligrams per litre, in the concentrate using Equation (A.1):
A
1000 m
γ = (A.1)
A
V
where
m is the mass, in milligrams, of RM 8632;
V is the volume, in millilitres, of clean dilution fluid.
The RM 8632 concentrate prepared in this annex is also used to determine the coincidence error limits
(Annex B) and flow rate limits (Annex C) of the APC, as well as to verify particle-counting accuracy (Annex E).
For this reason, special care shall be taken in determining the dust concentration of the concentrate and to
ensure that the concentrate is not contaminated. Failure to do so can cause an otherwise suitable APC to be
deemed unacceptable for use.
A.5 Cover the bottle with a clean closure and vigorously shake the concentrate by hand. Disperse the
RM 8632 concentrate ultrasonically for at least 30 s and then shake it on a mechanical shaker for at least 60 s
to disperse the dust.
A.6 Calculate the amount of concentrate required to prepare a dilution that is about 25 % of the
concentration limit for the sensor recommended by the manufacturer. The number concentration
corresponding to a particular mass concentration can be estimated from Table A.1. Add accurately the
required amount of concentrate and clean dilution fluid to a clean sample container in order to obtain the
correct total volume of diluted RM 8632 suspension. Put a particle-free closure on the sample container.
16 © ISO 2010 – All rights reserved

Table A.1 — Particle size distribution for sensor performance verification (see A.6 and B.4)
Particle concentration (particles/ml greater than indicated
Particle size
size for a 1 mg/l sample of RM 8632) shall be
µm(c) greater than or equal to less than or equal to
5 3 300 4 500
6 1 500 2 500
7 660 1 400
8 280 760
9 120 410
10 58 220
11 28 120
12 14 63
13 7,4 34
14 4,
...

NORME ISO
INTERNATIONALE 11171
Deuxième édition
2010-11-01
Transmissions hydrauliques —
Étalonnage des compteurs automatiques
de particules en suspension dans les
liquides
Hydraulic fluid power — Calibration of automatic particle counters for
liquids
Numéro de référence
©
ISO 2010
PDF – Exonération de responsabilité
Le présent fichier PDF peut contenir des polices de caractères intégrées. Conformément aux conditions de licence d'Adobe, ce fichier
peut être imprimé ou visualisé, mais ne doit pas être modifié à moins que l'ordinateur employé à cet effet ne bénéficie d'une licence
autorisant l'utilisation de ces polices et que celles-ci y soient installées. Lors du téléchargement de ce fichier, les parties concernées
acceptent de fait la responsabilité de ne pas enfreindre les conditions de licence d'Adobe. Le Secrétariat central de l'ISO décline toute
responsabilité en la matière.
Adobe est une marque déposée d'Adobe Systems Incorporated.
Les détails relatifs aux produits logiciels utilisés pour la création du présent fichier PDF sont disponibles dans la rubrique General Info
du fichier; les paramètres de création PDF ont été optimisés pour l'impression. Toutes les mesures ont été prises pour garantir
l'exploitation de ce fichier par les comités membres de l'ISO. Dans le cas peu probable où surviendrait un problème d'utilisation,
veuillez en informer le Secrétariat central à l'adresse donnée ci-dessous.

DOCUMENT PROTÉGÉ PAR COPYRIGHT

©  ISO 2010
Droits de reproduction réservés. Sauf prescription différente, aucune partie de cette publication ne peut être reproduite ni utilisée sous
quelque forme que ce soit et par aucun procédé, électronique ou mécanique, y compris la photocopie et les microfilms, sans l'accord écrit
de l'ISO à l'adresse ci-après ou du comité membre de l'ISO dans le pays du demandeur.
ISO copyright office
Case postale 56 • CH-1211 Geneva 20
Tel. + 41 22 749 01 11
Fax + 41 22 749 09 47
E-mail [e-mail]
Web www.iso.org
Publié en Suisse
ii © ISO 2010 – Tous droits réservés

Sommaire Page
Avant-propos .iv
Introduction.v
1 Domaine d'application .1
2 Références normatives.1
3 Termes et définitions .2
4 Matériaux et équipement .3
5 Succession des opérations d'étalonnage des CAP.4
6 Mode opératoire d'étalonnage dimensionnel .8
7 Présentation des données.15
8 Phrase d'identification .15
Annexe A (normative) Contrôle préliminaire du CAP .16
Annexe B (normative) Mode opératoire de détermination de l'erreur de coïncidence.19
Annexe C (normative) Détermination des débits limites .24
Annexe D (normative) Détermination de la résolution.28
Annexe E (normative) Vérification de la précision du comptage de particules.33
Annexe F (normative) Préparation et vérification des flacons de suspensions d'étalonnage
secondaire.36
Annexe G (informative) Essai interlaboratoires d'étalonnage de CAP.39
Annexe H (informative) Exemples de calculs.44
Annexe I (informative) Vérification de la distribution granulométrique des suspensions
d'étalonnage.50
Bibliographie.52

Avant-propos
L'ISO (Organisation internationale de normalisation) est une fédération mondiale d'organismes nationaux de
normalisation (comités membres de l'ISO). L'élaboration des Normes internationales est en général confiée
aux comités techniques de l'ISO. Chaque comité membre intéressé par une étude a le droit de faire partie du
comité technique créé à cet effet. Les organisations internationales, gouvernementales et non
gouvernementales, en liaison avec l'ISO participent également aux travaux. L'ISO collabore étroitement avec
la Commission électrotechnique internationale (CEI) en ce qui concerne la normalisation électrotechnique.
Les Normes internationales sont rédigées conformément aux règles données dans les Directives ISO/CEI,
Partie 2.
La tâche principale des comités techniques est d'élaborer les Normes internationales. Les projets de Normes
internationales adoptés par les comités techniques sont soumis aux comités membres pour vote. Leur
publication comme Normes internationales requiert l'approbation de 75 % au moins des comités membres
votants.
L'attention est appelée sur le fait que certains des éléments du présent document peuvent faire l'objet de
droits de propriété intellectuelle ou de droits analogues. L'ISO ne saurait être tenue pour responsable de ne
pas avoir identifié de tels droits de propriété et averti de leur existence.
L'ISO 11171 a été élaborée par le comité technique ISO/TC 131, Transmissions hydrauliques et
pneumatiques, sous-comité SC 6, Contrôle de la contamination.
Cette deuxième édition annule et remplace la première édition (ISO 11171:1999), qui a fait l'objet d'une
révision technique qui comporte les modifications suivantes visant à clarifier les étapes à suivre lors de
l'utilisation de la présente Norme internationale et à minimiser plusieurs sources de variabilité potentielles. En
particulier:
a) La définition d'un compteur automatique de particules (CAP) a été ajoutée en 3.1.
b) En 5.1, la séquence spécifique d'étapes à suivre lors de l'étalonnage n'est plus obligatoire.
c) En 5.1, la Note 2 a été ajoutée pour fournir un guide sur la méthode de détection d'un changement
d'étalonnage d'un CAP.
d) 6.3 exige désormais explicitement de compter au moins 5 000 particules pour obtenir des données
statistiquement valables pour un réglage de canal donné.
e) B.4 n'exige plus la préparation et l'analyse d'un échantillon de 0 %, mais permet l'extrapolation à l'origine
de l'équation de régression de l'erreur de coïncidence déterminée en B.7.
f) L'Annexe C fait désormais la distinction entre passeurs d'échantillon en flacon à débit fixe et à débit
réglable. Les instruments à débit fixe exigent simplement la vérification de leur aptitude à fournir en
permanence un débit constant à 3 % près. Pour les instruments à débit réglable, la présente Norme
internationale demande de déterminer le débit d'utilisation et les débits limites, en plus de la vérification
de leur aptitude à fournir en permanence un débit constant à 3 % près.
g) D.12 augmente de 10 % à 15 % la résolution acceptable d'un CAP.
h) E.3 exige l'emploi de poudre NIST RM 8632 pour vérifier la précision de comptage. L'utilisation
d'ISO UFTD n'est plus acceptée.
i) L'Annexe H donne désormais un exemple de tracé de courbe d'étalonnage.
Elle incorpore également le Rectificatif technique ISO 11171:1999/Cor.1:2001.
iv © ISO 2010 – Tous droits réservés

Introduction
Dans les systèmes de transmissions hydrauliques, l'énergie est transmise et commandée par l'intermédiaire
d'un liquide sous pression circulant en circuit fermé. Ce fluide est à la fois un lubrifiant et un milieu de
transmission de l'énergie. La fiabilité de fonctionnement d'un système exige un contrôle des contaminants
présents dans le fluide. La quantification et la qualification des contaminants particulaires d'un échantillon de
fluide requièrent que son prélèvement et la mesure de la distribution granulométrique et de la concentration
des contaminants soient réalisés avec soin et précision. Les compteurs automatiques de particules (CAP) en
suspension dans les liquides sont des moyens reconnus de détermination de la concentration et de la
distribution granulométrique des contaminants particulaires. La précision de chaque CAP est établie par
étalonnage.
La présente Norme internationale définit un mode opératoire d'étalonnage normalisé recommandé permettant
de déterminer la précision de l'analyse granulométrique et du comptage de particules. L'étalonnage
dimensionnel primaire est réalisé avec des suspensions NIST SRM 2806 ayant une distribution
granulométrique certifiée par le National Institute of Standards and Technology (NIST) des États-Unis. Une
méthode d'étalonnage secondaire, assurant la traçabilité au NIST, utilise des suspensions d'ISO MTD qui
sont soumises à une analyse séparée au moyen d'un CAP étalonné selon la méthode primaire. Les
concentrations limites sont déterminées en effectuant une série de dilutions d'une suspension concentrée.
Les limites de fonctionnement et de performances sont également établies à l'aide de la présente Norme
internationale.
NORME INTERNATIONALE ISO 11171:2010(F)

Transmissions hydrauliques — Étalonnage des compteurs
automatiques de particules en suspension dans les liquides
1 Domaine d'application
La présente Norme internationale spécifie des modes opératoires portant sur les aspects suivants:
a) l'étalonnage dimensionnel primaire, la résolution des capteurs et les performances de comptage des
compteurs automatiques de particules (CAP) en suspension dans les liquides capables d'analyser des
échantillons en flacon;
b) l'étalonnage dimensionnel secondaire avec des suspensions vérifiées au moyen d'un CAP ayant fait
l'objet d'un étalonnage primaire;
c) l'établissement de limites acceptables de fonctionnement et de performances;
d) la vérification des performances du détecteur de particules en utilisant de la poudre d'essai tronquée;
e) la détermination des limites de coïncidence et de débit.
2 Références normatives
Les documents de référence suivants sont indispensables pour l'application du présent document. Pour les
références datées, seule l'édition citée s'applique. Pour les références non datées, la dernière édition du
document de référence s'applique (y compris les éventuels amendements).
ISO 3722, Transmissions hydrauliques — Flacons de prélèvement — Homologation et contrôle des méthodes
de nettoyage
ISO 5598, Transmissions hydrauliques et pneumatiques — Vocabulaire
ISO 12103-1, Véhicules routiers — Poussière pour l'essai des filtres — Partie 1: Poussière d'essai d'Arizona
ISO 16889, Transmissions hydrauliques — Filtres — Évaluation des performances par la méthode de filtration
en circuit fermé
ISO 21501-3, Détermination de la distribution granulométrique — Méthodes d'interaction lumineuse de
particules uniques — Partie 3: Compteur de particules en suspension dans un liquide par extinction de la
lumière
3 Termes et définitions
Pour les besoins du présent document, les termes et définitions donnés dans l'ISO 5598 ainsi que les
suivants s'appliquent.
3.1
compteur automatique de particules
CAP
instrument qui compte automatiquement et dimensionne les particules individuelles en suspension dans un
fluide, reposant généralement sur les principes de la diffusion ou de l'absorption de lumière
NOTE Un CAP est constitué, au minimum, d'un détecteur de particules, d'un dispositif permettant de fournir un
volume connu d'échantillon au capteur à un débit régulé, d'un processeur de signal, d'un analyseur qui transforme les
tailles des particules individuelles fournies par le capteur en une distribution granulométrique, et d'un afficheur des
résultats de distribution granulométrique de l'échantillon.
3.2
niveau de bruit de fond
réglage minimum de la tension du CAP pour lequel la fréquence observée de comptage des impulsions ne
dépasse pas 60 comptages/min du fait de parasites en l'absence de débit dans le volume de détection
3.3
volume de détection
partie de la zone éclairée du capteur traversée par le flux de fluide et d'où le système optique capte la lumière
3.4
résolution
mesure de l'aptitude d'un CAP à différencier des particules de tailles similaires mais différentes
3.5
limite d'erreur de coïncidence
concentration maximale en NIST RM 8632 qu'un CAP peut compter avec moins de 5 % d'erreur due à la
présence simultanée de plusieurs particules dans le volume de détection
3.6
débit d'utilisation
débit traversant le capteur pendant l'étalonnage dimensionnel et l'analyse des échantillons
3.7
taille des particules
diamètre des particules de surface projetée équivalente, déterminé par microscopie électronique à balayage
ou déterminé avec un compteur optique de particules en suspension dans les liquides étalonné
NOTE 1 Sauf indication différente, un CAP utilisé pour déterminer la taille des particules est étalonné conformément à
la présente Norme internationale.
NOTE 2 Le NIST utilise la microscopie électronique à balayage afin de déterminer le diamètre des particules de
surface projetée équivalente dans ses matériaux de référence.
3.8
distribution granulométrique
concentration en nombre de particules, exprimée en fonction de la taille des particules
3.9
étalonnage primaire
étalonnage dimensionnel réalisé en utilisant le matériau de référence normalisé NIST 2806
NOTE 1 Le mode opératoire est spécifié à l'Article 6.
NOTE 2 Des détails sur le matériau de référence normalisé NIST 2806 sont donnés en 4.4.
2 © ISO 2010 – Tous droits réservés

3.10
étalonnage secondaire
étalonnage dimensionnel réalisé en utilisant des suspensions d'étalonnage
NOTE Le mode opératoire est spécifié à l'Article 6 et des suspensions d'étalonnage sont préparées conformément à
l'Annexe F.
4 Matériaux et équipement
4.1 Billes de latex de polystyrène, presque monodispersées, en suspension aqueuse. Les billes de latex
de polystyrène d'un diamètre nominal de 10 µm sont requises dans l'Annexe D pour la détermination de la
résolution, et les billes de latex de polystyrène d'autres diamètres nominaux, supérieurs à 50 µm, sont
requises à l'Article 6 si l'étalonnage dimensionnel concerne des particules de 50 µm et plus. Dans certains cas,
il peut également être utile d'ajouter des billes de latex d'autres tailles. Néanmoins, le coefficient de variation
de chaque taille de bille de latex de polystyrène doit être inférieur à 5 %. Le fournisseur des billes de latex de
polystyrène doit fournir avec chaque lot un certificat d'analyse indiquant que la taille de particules des billes a
été déterminée en utilisant des techniques raccordées à des étalons nationaux ou internationaux.
Après ouverture, les suspensions de billes de latex de polystyrène doivent être utilisées dans un délai de trois
mois, à moins que la distribution granulométrique et la propreté de la suspension aient été vérifiées.
NOTE 1 La distribution granulométrique et la propreté des billes de latex de polystyrène peuvent être vérifiées en
appliquant la méthode décrite en D.13.
NOTE 2 La durée de conservation des billes de latex de polystyrène en suspension aqueuse est limitée. Elle dépend
d'un certain nombre de facteurs, notamment la température et la contamination microbienne de la suspension.
4.2 Fluide de dilution propre, se composant du fluide d'essai utilisé dans l'ISO 16889 et d'un additif
antistatique donnant une conductivité de 2 500 pS/m ± 1 000 pS/m à température ambiante. Le fluide doit
contenir moins de 0,5 % de particules de tailles égales ou supérieures aux plus petites tailles d'intérêt que l'on
s'attend à trouver dans les échantillons.
4.3 Fluide de dilution propre aérosol OT, pour déterminer la résolution du capteur à l'Annexe D (le fluide
de dilution propre décrit en 4.2 étant utilisé pour toutes les autres opérations de la présente Norme
internationale). Il est préparé à partir d'un concentré réalisé en ajoutant 120 g d'aérosol OT à chaque litre de
fluide de dilution propre (4.2). Chauffer le concentré à environ 60 °C et le remuer jusqu'à dissolution complète
de l'aérosol OT. Préparer le fluide de dilution aérosol OT en diluant le concentré avec le fluide de dilution
propre (4.2) pour obtenir une concentration finale de 12 g d'aérosol OT par litre. Les niveaux de propreté du
fluide de dilution propre aérosol OT doivent être identiques à ceux du fluide de dilution décrit en 4.2.
ATTENTION — Prendre les précautions de sécurité de manipulation et d'utilisation décrites sur la
fiche de sécurité des matériaux (fiche disponible auprès du fournisseur d'aérosol OT).
L'aérosol OT (dioctylsulfosuccinate, sel de sodium) est une substance solide paraffineuse hygroscopique. S'il
est humide ou a absorbé de l'eau avant utilisation, le sécher pendant au moins 18 h à environ 150 °C.
4.4 Suspension d'étalonnage primaire de matériau de référence normalisé NIST 2806x (SRM 2806x),
où x est la lettre utilisée par le NIST pour désigner le numéro de lot de la suspension d'étalonnage primaire
certifiée, disponible auprès du NIST. Pour les étalonnages primaires, on doit utiliser le SRM 2806.
[3]
NOTE L'ISO/TR 16144 décrit les modes opératoires utilisés afin de certifier le matériau de référence normalisé
SRM 2806.
4.5 Poudre de référence NIST 8631 (RM 8631), préparée par séchage pendant au moins 18 h à une
température comprise entre 110 °C et 150 °C, nécessaire si on doit procéder à un étalonnage secondaire
(voir 6.1).
4.6 Poudre d'essai moyenne ISO (MTD) conforme à l'ISO 12103-1, séchée pendant au moins 18 h à
une température comprise entre 110 °C et 150 °C avant emploi.
4.7 Poudre de référence NIST 8632 (RM 8632), préparée par séchage pendant au moins 18 h à une
température comprise entre 110 °C et 150 °C avant emploi, si nécessaire à la détermination de la limite
d'erreur de coïncidence ou dans les Annexes B, C et E.
NOTE Les matériaux de référence spécifiés en 4.4, 4.5, 4.6 et 4.7 sont créés à l'aide de documents «vivants»
modifiables pendant la production de nouveaux lots. Les utilisateurs de la présente Norme internationale sont encouragés
à s'assurer d'utiliser le dernier lot disponible.
4.8 Compteur automatique de particules (CAP) en suspension dans les liquides, avec passeur
d'échantillon en flacon.
4.9 Flacons de prélèvement propres, qui ferment (bouchons de flacon appropriés, par exemple), et
verrerie volumétrique, au moins de classe B. Les niveaux de propreté des flacons, des bouchons et de la
verrerie doivent être inférieurs à 0,5 % du nombre de particules (plus grand que la plus petite taille d'intérêt)
que l'on s'attend à trouver dans les échantillons. Les niveaux de propreté doivent être vérifiés selon
l'ISO 3722.
4.10 Agitateur mécanique, tel qu'agitateur à peintures ou de laboratoire, à même de disperser les
suspensions.
2 2
4.11 Bain à ultrasons, ayant une puissance volumique comprise entre 3 000 W/m et 10 000 W/m de
surface de fond.
4.12 Papier graphique arithmétique ou logiciel informatique de tracé graphique.
4.13 Papier graphique logarithmique ou logiciel informatique de tracé graphique.
4.14 Balance d'analyse ou électronique répondant au minimum aux spécifications suivantes:
a) lisibilité: 0,05 mg;
b) précision (concordance avec la masse réelle): ±0,05 mg;
c) fidélité (répétabilité): ±0,05 mg;
d) portes avant et latérales et couvercle pour éliminer l'effet des courants d'air.
5 Succession des opérations d'étalonnage des CAP
5.1 La Figure 1 donne la séquence recommandée d'étapes à suivre pour effectuer l'étalonnage complet
d'un nouveau CAP. Appliquer les modes opératoires du présent article à réception d'un nouveau CAP ou à la
suite de la réparation ou d'un nouveau réglage d'un CAP ou d'un capteur (voir Tableau 1). Passer à l'Article 6
si aucune réparation ou aucun nouveau réglage du CAP ou du capteur n'ont été effectués, si aucune
modification perceptible des caractéristiques de fonctionnement ne s'est produite depuis le dernier étalonnage
dimensionnel et si les modes opératoires des Annexes A, B, C, D et E ont déjà été réalisés sur le CAP et que
les résultats ont été documentés. L'ordre précis des annexes et articles spécifiés à la Figure 1 et dans le
Tableau 1 est une recommandation. L'opérateur peut suivre un ordre différent, tant que toutes les étapes
requises sont réalisées.
NOTE 1 Les Annexes A, B, C et D peuvent être réalisées par un laboratoire individuel ou par le fabricant du CAP avant
livraison.
Une modification des caractéristiques de fonctionnement du CAP peut être détectée par plusieurs méthodes
distinctes, notamment (liste non exhaustive):
a) étude des résultats de comptage de particules sur des échantillons de contrôle prélevés dans le temps et
d'une carte de contrôle de processus, par exemple une carte de plage de mouvements d'individus (IMR),
pour détecter les modifications significatives de l'étalonnage;
4 © ISO 2010 – Tous droits réservés

b) comparaison des courbes d'étalonnage dans le temps pour détecter une modification significative de
l'étalonnage;
c) retour du CAP au fabricant pour évaluation et analyse de la modification de l'étalonnage;
d) analyse d'une suspension d'étalonnage primaire ou secondaire conformément à 6.2 et 6.3, puis
comparaison des données de concentration en particules ainsi obtenues à la distribution granulométrique
de l'échantillon. Si les résultats concordent avec les limites de D maximale admissible données dans le
Q
Tableau C.2, l'aptitude du CAP à dimensionner et compter les particules n'a pas été affectée de manière
significative. En cas de non-concordance des résultats, une modification significative s'est produite et
l'opérateur doit procéder comme indiqué dans le Tableau 1; ou
e) analyse d'une suspension d'étalonnage primaire ou secondaire et des données obtenues tel que décrit
en d), puis en analysant un échantillon d'ISO UFTD préparé conformément à l'Annexe A et en comparant
les données de concentration en particules ainsi obtenues aux limites indiquées dans le Tableau A.1. Si
les résultats sont dans les limites du Tableau A.1, l'aptitude du CAP à dimensionner et compter les
particules n'a pas été affectée de manière significative. En cas de non-conformité des résultats avec les
limites du Tableau A.1, le CAP a subi une modification significative et l'opérateur doit procéder comme
indiqué dans le Tableau 1.
NOTE 2 Pour les besoins du présent article, la réparation et le nouveau réglage d'un CAP font référence aux
opérations d'entretien courant ou de réparation affectant l'aptitude du CAP à dimensionner et compter les particules avec
précision.
En cas de réglage, réparation ou remplacement de la source lumineuse ou d'une partie du système optique,
les modes opératoires de l'Article 6 et des Annexes A, B, D et E doivent être répétés.
En cas de réglage, réparation ou remplacement du capteur ou de l'électronique de comptage, les modes
opératoires de l'Article 6 et des Annexes A, B, C, D et E doivent être répétés.
En cas de réparation, remplacement ou nouveau réglage du système de mesure du volume, les modes
opératoires de l'Annexe A doivent être répétés.
Il est inutile de répéter ces modes opératoires à la suite d'un nettoyage normal, de la fixation de câbles ou
d'un équipement périphérique, du remplacement de tuyauteries ou de raccords ou de toute autre opération
n'entraînant pas le démontage du CAP, du capteur ou du système de mesure de volume.
Figure 1 — Succession des opérations d'étalonnage des CAP
6 © ISO 2010 – Tous droits réservés

Tableau 1 — Planning des opérations d'étalonnage des CAP
Appliquer les dispositions des articles et annexes
de la présente Norme internationale
Article 6 Annexe A Annexe B Annexe C Annexe D Annexe E
a
État du CAP
Contrôle Limites
Étalonnage Débits
préliminaire d'erreur de Résolution Précision
dimensionnel limites
du CAP coïncidence
Nouveau CAP ou CAP existant
non étalonné conformément à la X X X X X X
présente Norme internationale
Dernier étalonnage effectué il y a
X — — — — —
plus de 6 mois à 12 mois
Étalonnage soupçonné d'avoir
X — — — — —
changé de manière significative
Réparation ou nouveau réglage
du système optique (y compris la X X X — X X
source lumineuse)
Réparation ou nouveau réglage
du capteur ou de l'électronique de X X X X X X
comptage
Réparation ou nouveau réglage
des organes de mesure de
— X — — — —
volume (par exemple débitmètre,
burette, détecteurs de niveau)
Nettoyage du capteur Aucune action nécessaire
Fixation de câbles ou
Aucune action nécessaire
d'équipements périphériques
Remplacement de tuyauteries ou
Aucune action nécessaire
de raccords
Opération n'entraînant pas le
démontage du CAP, du capteur
Aucune action nécessaire
ou du système de mesure du
volume
a
La réparation ou le nouveau réglage font uniquement référence aux opérations d'entretien courant ou de réparation affectant
l'aptitude du CAP à dimensionner et compter les particules avec précision. Pour vérifier l'aptitude d'un CAP à dimensionner et compter
les particules avec précision, analyser une suspension d'étalonnage primaire ou secondaire conformément à 6.2 et 6.3, puis comparer
les données de concentration en particules ainsi obtenues à la distribution granulométrique de l'échantillon. Si les résultats sont dans
les limites de D maximale admissible données dans le Tableau C.2, l'aptitude du CAP à dimensionner et compter les particules n'a pas
Q
été affectée de manière significative. En cas de non-concordance des résultats, procéder comme indiqué dans ce tableau.

5.2 Effectuer le contrôle préliminaire du CAP, y compris la précision du volume, conformément à l'Annexe A.
5.3 Déterminer les limites d'erreur de coïncidence du CAP conformément à l'Annexe B.
5.4 Effectuer l'étalonnage dimensionnel conformément à l'Article 6.
5.5 Déterminer les débits limites du CAP conformément à l'Annexe C.
5.6 Déterminer la résolution du CAP conformément à l'Annexe D.
5.7 Vérifier la précision du comptage de particules conformément à l'Annexe E.
5.8 Pour satisfaire aux exigences de la présente Norme internationale, le CAP doit
a) être étalonné conformément à 5.4;
b) être conforme aux spécifications de précision de volume, de résolution et de performances du capteur
déterminées en 5.2, 5.6 et 5.7;
c) fonctionner en utilisant la courbe d'étalonnage déterminée en 5.4 dans les limites d'erreurs de
coïncidence et de débit déterminées en 5.3 et 5.5.
6 Mode opératoire d'étalonnage dimensionnel
6.1 La Figure 2 donne le diagramme du mode opératoire d'étalonnage dimensionnel. Effectuer l'étalonnage
dimensionnel tous les trois à six mois, à réception d'un nouveau CAP ou à la suite d'une réparation ou d'un
nouveau réglage d'un CAP ou d'un capteur. Pour les étalonnages primaires, utiliser des suspensions
d'étalonnage NIST (voir 4.4). Pour les étalonnages secondaires, utiliser des suspensions d'étalonnage
préparées conformément à l'Annexe F.
8 © ISO 2010 – Tous droits réservés

Figure 2 — Mode opératoire d'étalonnage dimensionnel
Après avoir établi un historique de l'étalonnage d'un CAP et d'un capteur, il est possible de réduire
progressivement la fréquence d'étalonnage, mais l'intervalle entre des étalonnages successifs ne doit pas
dépasser un an.
Toutes les phases de l'étalonnage doivent être réalisées au même débit. L'Annexe C détermine les débits
limites du CAP. Toutes les valeurs obtenues à des débits se situant en dehors de ces limites doivent être
éliminées et la partie correspondante du mode opératoire doit être répétée en utilisant le bon débit.
Effectuer l'étalonnage dimensionnel en utilisant le même volume d'échantillon qu'en 5.2. En cas d'utilisation
d'un volume différent, le mode opératoire de 5.2 doit être répété en utilisant le nouveau volume d'échantillon
afin d'éviter des erreurs de mesurage du volume.
Il est recommandé de déterminer le niveau de bruit de fond du CAP à l'aide de la méthode indiquée en A.2
avant de passer à 6.2. Une variation éventuelle de plus de 30 % du niveau de bruit de fond depuis la dernière
détermination peut être une indication d'un changement d'étalonnage du CAP et de la nécessité de le réparer.
L'absence de contrôle du niveau de bruit de fond avant de passer à 6.2 peut entraîner une perte de temps en
essayant d'étalonner un CAP défectueux et la nullité des résultats de comptage de particules.
6.2 Mettre le CAP en mode cumulé et, en utilisant au moins six canaux différents, régler comme suit les
tensions de seuil:
a) le seuil le plus bas du CAP doit être réglé à 1,5 fois son niveau de bruit de fond, ce qui détermine la taille
minimale de particule détectable;
b) le réglage du seuil le plus élevé est limité par la plage de tension d'utilisation du CAP (consulter le
fabricant du CAP pour déterminer cette plage), la distribution granulométrique et le volume de la
suspension d'étalonnage;
c) des valeurs intermédiaires de seuils doivent être choisies afin de couvrir la plage de dimensions d'intérêt.
Préparer un échantillon de suspension d'étalonnage en vue de l'analyse. Agiter énergiquement l'échantillon à
la main. Disperser l'échantillon aux ultrasons pendant au moins 30 s, puis l'agiter sur un agitateur mécanique
pendant au moins 1 min afin de disperser la poudre dans le liquide. Continuer à agiter l'échantillon jusqu'à son
analyse.
Le mode opératoire décrit de 6.2 à 6.8 suppose un étalonnage manuel d'un CAP avec un petit nombre de
seuils. L'étalonnage peut également être effectué en utilisant un analyseur multicanal (AMC) ou un logiciel
utilisant le même mode opératoire. En cas d'utilisation d'un AMC, il est primordial d'établir d'abord la relation
entre la tension mesurée par l'AMC et les seuils de comptage du CAP. D'une manière générale, les méthodes
utilisant un logiciel ou un AMC tendent à être plus rapides et plus précises que les méthodes manuelles.
6.3 Dégazer sous vide ou aux ultrasons l'échantillon jusqu'à ce que les bulles atteignent la surface;
retourner doucement le flacon de prélèvement au moins cinq fois, en veillant à ne pas introduire de bulles
d'air dans le liquide. Effectuer successivement au moins cinq comptages de particules d'au moins 10 ml
chacun et 10 000 particules pour le réglage du seuil le plus bas.
Calculer le nombre total, N, de particules comptées pour chaque canal à l'aide de l'Équation (1):
NX= 5V (1)
où
X est la concentration moyenne, en particules par millilitre, en particules des cinq comptages pour un
canal donné;
V est le volume d'échantillon, en millilitres, pour un comptage individuel.
La valeur de N doit être supérieure ou égale à 1 000 afin d'obtenir des résultats statistiquement significatifs
pour le canal concerné.
Calculer D , qui est la différence en pourcentage entre les nombres minimal, X , et maximal, X , de
Q min max
particules observés dans chaque canal, à l'aide de l'Équation (2):
X−
X
max min
= × 100 (2)
D
Q
X
Reporter dans le Tableau 2 le réglage de la tension de seuil, la concentration en particules, X , et la valeur de
D pour chaque canal.
Q
10 © ISO 2010 – Tous droits réservés

À l'aide du Tableau C.2, relever la différence maximale admissible, en pourcentage, correspondant à la valeur
de X pour chaque canal. Si la valeur de D est inférieure à ce maximum, la valeur de X pour ce canal peut
Q
être utilisée. Si les valeurs d'au moins six canaux sont acceptables, passer à 6.4. Dans le cas contraire,
examiner les résultats de tous les canaux inacceptables de la manière suivante:
Calculer D à l'aide de l'Équation (3):
XX−
max min
D = (3)
XX−
0 N
où
X est le comptage de particules observé pour la valeur aberrante supposée (X ou X ); et
0 max min
X est le comptage de particules observé dont la valeur est la plus proche de X .
N 0
Si D est inférieure à 1,44 dans un canal donné, éliminer la valeur aberrante, X , recalculer X en utilisant les
0 0
quatre valeurs restantes, et prendre la valeur recalculée de X pour l'étalonnage. Si D est supérieure à 1,44
dans un canal donné, les valeurs de ce canal ne sont pas acceptables et doivent être éliminées. Si les valeurs
d'au moins six canaux sont acceptables (selon les critères D et D ), passer à 6.4. Dans le cas contraire,
Q 0
engager l'action corrective appropriée et répéter 6.1 à 6.3.
Si N est inférieur à 1 000 pour un canal quelconque, les données de ce canal ne doivent pas être utilisées. Si
le seul critère de qualité non respecté est le comptage d'un nombre insuffisant de particules, modifier les
réglages des seuils pour qu'ils correspondent aux tailles de particules donnant des nombres suffisants, ou
répéter 6.1 à 6.3 sur un plus gros volume d'échantillon.
On ne doit pas recueillir et réutiliser les suspensions d'étalonnage primaire et secondaire.
NOTE D'autres non-respects des critères de qualité peuvent être dus à un certain nombre de facteurs, notamment la
pollution du fluide de dilution ou de la verrerie, des erreurs volumétriques, des erreurs de calcul, un fonctionnement trop
proche du niveau de bruit de fond du CAP, ou la présence de bulles dans les échantillons. La variabilité du débit due au
comptage pendant la pressurisation de l'enceinte d'échantillonnage ou à d'autres causes peut également créer des
problèmes. Il peut se produire une décantation des particules. Une agitation à des vitesses excessives peut provoquer la
centrifugation des particules ou l'introduction de bulles.
Tableau 2 — Feuille de données d'étalonnage dimensionnel du CAP (voir 6.3, 6.8 et A.9)
CAP Modèle Date
Numéro de série Opérateur
Type de capteur Modèle Suspension étalon
Numéro de série Numéro de lot
Niveau de bruit Débit ml/min Concentration
Première suspension étalon Numéro d'identification de la suspension étalon

Valeur du seuil
Comptage 1
Comptage 2
Comptage 3
Comptage 4
Comptage 5
X (particules/ml)
D
Q
Deuxième suspension étalon Numéro d'identification de la suspension étalon

Valeur du seuil
Comptage 1
Comptage 2
Comptage 3
Comptage 4
Comptage 5
X (particules/ml)
D
Q
Troisième suspension étalon Numéro d'identification de la suspension étalon

Valeur du seuil
Comptage 1
Comptage 2
Comptage 3
Comptage 4
Comptage 5
X (particules/ml)
D
Q
12 © ISO 2010 – Tous droits réservés

Tableau 3 — Récapitulatif de l'étalonnage du CAP
CAP Modèle Date
Numéro de série Opérateur
Capteur Modèle Date
Numéro de série
Niveau de bruit Volume d'échantillon ml Débit ml/min
C % Débits limites ml/min
V,vol
Limite d'erreur de coïncidence particules/ml
s µm(c) R %
R R
s µm(c) R %
L L
d µm(c) R %
Étalonnage dimensionnel
Suspension étalon Numéro de lot Concentration

Taille Valeur du seuil Concentration en particules
µm(c) mV observée
Vérification de la précision du comptage de particules
Taille Concentration en particules Concentration en particules
µm(c) attendue (voir Tableau A.1) observée

6.4 Porter sur un papier graphique logarithmique les concentrations en particules (particules supérieures à
la taille indiquée par millilitre) en fonction des valeurs de seuil correspondantes, en millivolts, en utilisant
uniquement les valeurs acceptables (déterminées en 6.3). Appliquer des techniques statistiques de
régression appropriées pour définir la relation entre la concentration et le réglage du seuil.
6.5 Déterminer les concentrations en particules attendues pour au moins six tailles différentes en utilisant
les valeurs appropriées de la distribution granulométrique des suspensions d'étalonnage. En appliquant la
relation mathématique établie en 6.4, déterminer la valeur du seuil supposée donner ces concentrations. Il
n'est pas permis d'extrapoler les tailles se situant en dehors de la plage donnée par les valeurs de la
distribution granulométrique. Si l'une des valeurs de seuil est inférieure à 1,5 fois le niveau de bruit de fond du
CAP, choisir des valeurs de concentration en particules d'une plus grande taille donnant un réglage du seuil
acceptable. Régler le seuil du CAP sur ces valeurs.
NOTE Tout au long de la présente Norme internationale, la référence aux valeurs de la distribution granulométrique
renvoie à des tableaux de tailles de particules, de concentration et d'écart-type accompagnant les suspensions
d'étalonnage NIST, ou aux valeurs de tailles, de concentration et d'écart-type obtenues dans l'Annexe F pour les
suspensions d'étalonnage secondaire.
6.6 Répéter 6.1 à 6.5 en utilisant au moins six réglages différents de la tension de seuil, mais utiliser toutes
les valeurs acceptables (déterminées en 6.3) des deux échantillons pour déterminer la relation entre la
concentration en particules et la valeur du seuil en 6.4 et 6.5.
6.7 Répéter 6.1 à 6.5 une fois de plus en utilisant au moins six réglages différents de la tension de seuil,
mais utiliser toutes les valeurs acceptables (déterminées en 6.3) de l'ensemble des trois échantillons pour
déterminer la relation finale entre la concentration en particules et la valeur du seuil.
6.8 Établir une courbe d'étalonnage en utilisant la relation entre la concentration en particules et la valeur
du seuil déterminée en 6.7. Choisir au moins 18 tailles différentes de particules parmi les valeurs de
distribution granulométrique appropriées. Ne choisir que des tailles entrant dans la plage dimensionnelle
réellement observée de 6.3 à 6.7. Reporter sur le Tableau 3 ces 18 tailles ainsi que les concentrations et
valeurs de seuil correspondantes (déterminées en utilisant le graphique de concentration en fonction du seuil
établi en 6.7). Porter sur un graphique les tensions de seuil correspondantes en fonction des tailles des
particules. Utiliser la technique statistique de régression pour définir la courbe d'étalonnage et effectuer
l'interpolation. Ne pas extrapoler les tailles se situant en dehors de la plage utilisée pour l'étalonnage.
Certaines applications peuvent nécessiter un étalonnage à des tailles supérieures à celles reportées pour le
SRM 2806. Pour étalonner les CAP à des tailles de particules supérieures à 50 µm(c), il convient d'utiliser
l'ISO 21501-3. Dans tous les cas, l'utilisateur est averti que le comptage de particules de grande taille est
source de nombreuses erreurs. Les plus probables sont: a) la sédimentation des grosses particules au cours
de toutes les phases de prélèvement, de manipulation et d'analyse de l'échantillon et b) une qualité par
essence statistiquement médiocre du comptage des particules du fait de la concentration en général faible
des particules de grande taille dans les échantillons de fluide hydraulique.
L'ISO 21501-3 est une méthode d'étalonnage dimensionnel des particules qui utilise des billes de latex de
polystyrène monodispersées. En revanche, la méthode d'étalonnage décrite dans la présente Norme
internationale est une méthode de comptage utilisant de la poudre d'essai polydispersée. Les deux méthodes
déterminent le rapport existant entre la tension de seuil du CAP et la taille des particules. Il est possible
d'utiliser une méthode d'étalonnage dimensionnel telle que l'ISO 21501-3 pour des tailles de particules
supérieures à 50 µm(c) car la distribution granulométrique NIST utilisée dans la présente Norme
internationale est également fondée sur le diamètre de la surface projetée des particules. Le signal détecté
par le CAP pour des tailles de particules supérieures à 50 µm(c) n'est pas lié de manière significative à l'indice
de réfraction des particules ou du liquide.
Si une méthode d'étalonnage à la suspension de billes de latex de polystyrène est utilisée, les billes de latex
de polystyrène doivent avoir des tailles qui sont raccordées à des étalons nationaux ou internationaux et leur
coefficient de variation doit être inférieur à 5 %. Les billes de latex de polystyrène doivent être mises en
[11]
suspension dans le fluide hydraulique MIL-H-5606 suivant le mode opératoire décrit dans l'Annexe D (si
les particules sont fournies en suspension aqueuse), ou les billes de latex doivent être mélangées directement
[11]
dans le fluide MIL-H-5606 par technique ultrasonore afin de disperser les particules (si les particules sont
fournies sèches).
14 © ISO 2010 – Tous droits réservés

7 Présentation des données
7.1 Noter dans le rapport toutes les tailles de particules obtenues au moyen d'un CAP étalonné
conformément à la présente Norme internationale en exprimant la valeur obtenue soit:
a) en «µm» ou «micromètres», accompagnée de la mention suivante: «Les tailles indiquées dans le présent
document ont été obtenues au moyen d'un CAP étalonné conformément à l'ISO 11171:2010»;
b) en «µm(c)», où (c) indique que l'étalonnage du CAP a été réalisé conformément à l'ISO 11171:2010
(dans la mesure du possible, cet indicateur doit être explicité dans le texte).
7.2 Conserver sur fichier le Tableau 3 complété et les Tableaux 2, B.1, C.1 et F.1 remplis, de façon qu'ils
soient disponibles pour inspection.
8 Phrase d'identification
Utiliser la phrase d'identification suivante dans les rapports d'essai, les catalogues et la documentation
commerciale, en cas de décision de se conformer à la présente Norme internationale:
«Étalonnage des compteurs automatiques de particules en suspension dans les liquides conforme à
l'ISO 11171:2010, Transmissions hydrauliques — Étalonnage des compteurs automatiques de particules en
suspension dans les liquides».
Annexe A
(normative)
Contrôle préliminaire du CAP
A.1 La Figure A.1 donne le diagramme du mode opératoire de contrôle préliminaire du CAP. Effectuer un
contrôle
...