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Withdrawn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
Current Stage
9599 - Withdrawal of International Standard
Start Date
05-Oct-2016
Completion Date
05-Oct-2016

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Standards Content (sample)

SLOVENSKI STANDARD
SIST ISO 11171:2014
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
SIST ISO 11171:2014 en,fr

2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

---------------------- Page: 1 ----------------------
SIST ISO 11171:2014
---------------------- Page: 2 ----------------------
SIST ISO 11171:2014
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 11171:2010(E)
ISO 2010
---------------------- Page: 3 ----------------------
SIST ISO 11171:2014
ISO 11171:2010(E)
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.

COPYRIGHT PROTECTED DOCUMENT
© 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 copyright@iso.org
Web www.iso.org
Published in Switzerland
ii © ISO 2010 – All rights reserved
---------------------- Page: 4 ----------------------
SIST ISO 11171:2014
ISO 11171:2010(E)
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

© ISO 2010 – All rights reserved iii
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SIST ISO 11171:2014
ISO 11171:2010(E)
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
---------------------- Page: 6 ----------------------
SIST ISO 11171:2014
ISO 11171:2010(E)
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.
© ISO 2010 – All rights reserved v
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SIST ISO 11171:2014
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SIST ISO 11171:2014
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
© ISO 2010 – All rights reserved 1
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SIST ISO 11171:2014
ISO 11171:2010(E)

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
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SIST ISO 11171:2014
ISO 11171:2010(E)
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.
© ISO 2010 – All rights reserved 3
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SIST ISO 11171:2014
ISO 11171:2010(E)

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

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
---------------------- Page: 12 ----------------------
SIST ISO 11171:2014
ISO 11171:2010(E)

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.
© ISO 2010 – All rights reserved 5
---------------------- Page: 13 ----------------------
SIST ISO 11171:2014
ISO 11171:2010(E)
Figure 1 — Sequence of APC calibration procedures
6 © ISO 2010 – All rights reserved
---------------------- Page: 14 ----------------------
SIST ISO 11171:2014
ISO 11171:2010(E)
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 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

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

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.
© ISO 2010 – All rights reserved 7
---------------------- Page: 15 ----------------------
SIST ISO 11171:2014
ISO 11171:2010(E)
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
---------------------- Page: 16 ----------------------
SIST ISO 11171:2014
ISO 11171:2010(E)

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
...

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 11171:2010(E)
ISO 2010
---------------------- Page: 1 ----------------------
ISO 11171:2010(E)
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.

COPYRIGHT PROTECTED DOCUMENT
© 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 copyright@iso.org
Web www.iso.org
Published in Switzerland
ii © ISO 2010 – All rights reserved
---------------------- Page: 2 ----------------------
ISO 11171:2010(E)
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

© ISO 2010 – All rights reserved iii
---------------------- Page: 3 ----------------------
ISO 11171:2010(E)
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
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ISO 11171:2010(E)
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.
© ISO 2010 – All rights reserved v
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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
© ISO 2010 – All rights reserved 1
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ISO 11171:2010(E)

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.
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ISO 11171:2010(E)
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.
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ISO 11171:2010(E)

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

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
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ISO 11171:2010(E)

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.
© ISO 2010 – All rights reserved 5
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ISO 11171:2010(E)
Figure 1 — Sequence of APC calibration procedures
6 © ISO 2010 – All rights reserved
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ISO 11171:2010(E)
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 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

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

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.
© ISO 2010 – All rights reserved 7
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ISO 11171:2010(E)
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
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ISO 11171:2010(E)

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−
max
min
= × 100 (2)
Record in Table 2 the threshold voltage se
...

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

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© ISO 2010 – All rights reserved
oSIST ISO 11171:2014
ISO 11171:2010(E) © ISO 2010 – All rights reserved

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
ISO 11171:2010(E) iv

© ISO 2010 – All rights reserved 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. oSIST ISO 11171:2014

ISO 11171:2010(E) © ISO 2010 – All rights reserved

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

ISO 11171:2010(E) 2

© ISO 2010 – All rights reserved 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. oSIST ISO 11171:2014

ISO 11171:2010(E) © ISO 2010 – All rights reserved

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

ISO 11171:2010(E) 4

© ISO 2010 – All rights reserved 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. 4.11 Ultrasonic cleaner, with a power density of 3 000 W/m2 to 10 000 W/m2 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 DQ given 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, 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. oSIST ISO 11171:2014

ISO 11171:2010(E) © ISO 2010 – All rights reserved

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

ISO 11171:2010(E) 6
© ISO 2010 – All rights reserved
Figure 1 — Sequence of APC calibration procedures oSIST ISO 11171:2014
ISO 11171:2010(E) © ISO 2010 – All rights reserved

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

ISO 11171:2010(E) 8
© ISO 2010 – All rights reserved

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

ISO 11171:2010(E) © ISO 2010 – All rights reserved

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

...

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 11171:2010(F)
ISO 2010
---------------------- Page: 1 ----------------------
ISO 11171:2010(F)
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---------------------- Page: 2 ----------------------
ISO 11171:2010(F)
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

© ISO 2010 – Tous droits réservés iii
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ISO 11171:2010(F)
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
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ISO 11171:2010(F)
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.
© ISO 2010 – Tous droits réservés v
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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
© ISO 2010 – Tous droits réservés 1
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ISO 11171:2010(F)
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.

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ISO 11171:2010(F)
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.
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ISO 11171:2010(F)

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;
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ISO 11171:2010(F)

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

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.

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ISO 11171:2010(F)
Figure 1 — Succession des opérations d'étalonnage des CAP
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ISO 11171:2010(F)
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
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

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

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.
© ISO 2010 – Tous droits réservés 7
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ISO 11171:2010(F)

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.
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ISO 11171:2010(F)
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 opératoir
...

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