ISO 19438:2023
(Main)Diesel fuel and petrol filters for internal combustion engines — Filtration efficiency using particle counting and contaminant retention capacity
Diesel fuel and petrol filters for internal combustion engines — Filtration efficiency using particle counting and contaminant retention capacity
This document specifies a multi-pass filtration test, with continuous contaminant injection and using the on line particle counting method, to evaluate the performance of diesel fuel and petrol filters for internal combustion engines submitted to a constant flow rate of test liquid. The test procedure determines the contaminant capacity of a filter, its particulate removal characteristics and differential pressure. This document is applicable to filter elements having a rated flow between 50 l/h and 800 l/h; however, by agreement between the filter manufacturer and customer, and with some modifications, the procedure is permitted for application to fuel filters with higher flow rates.
Filtres à carburant, essence ou diesel, pour moteurs à combustion interne — Efficacité de filtration par comptage des particules et capacité de rétention
General Information
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Standards Content (Sample)
INTERNATIONAL ISO
STANDARD 19438
Second edition
2023-02
Diesel fuel and petrol filters for
internal combustion engines —
Filtration efficiency using particle
counting and contaminant retention
capacity
Filtres à carburant, essence ou diesel, pour moteurs à combustion
interne — Efficacité de filtration par comptage des particules et
capacité de rétention
Reference number
ISO 19438:2023(E)
© ISO 2023
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ISO 19438:2023(E)
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© ISO 2023
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Published in Switzerland
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ISO 19438:2023(E)
Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Symbols . 2
5 Test apparatus and materials . 2
5.1 Test apparatus. 2
5.1.1 Test rig . 2
5.1.2 On line dilution and particle counting system . . 4
5.2 Test materials . 5
5.2.1 Test contaminant . 5
5.2.2 Test fluid . 5
6 Accuracy of measuring instruments and test conditions . 5
7 Test rig validation . .6
7.1 General . 6
7.2 Validation of the on line dilution and particle counting system . 6
7.3 Validation of filter test circuit . 6
7.4 Validation of contaminant injection circuit . 7
8 Preliminary preparation . 7
8.1 Test filter assembly . 7
8.2 Contaminant injection circuit . 7
8.3 Filter test circuit . 9
9 Test procedure .9
9.1 Initial procedure . 9
9.2 Filter test . . 11
10 Calculation and reporting of test results .12
10.1 Test report .12
10.2 Calculation .12
10.2.1 General .12
10.2.2 Gravimetric levels . 13
10.2.3 Filtration efficiencies . 13
10.2.4 Filter ratings. 14
10.2.5 Injected mass of contaminant . 14
10.2.6 Non-retained mass of contaminant . 14
10.2.7 Retained filter capacity . 15
Annex A (normative) Specification of test fluid for filter test .16
Annex B (informative) Typical filter test report, presentation of test results .17
Annex C (normative) Example filter efficiency calculations .22
Annex D (informative) Effect of dust cake filtration on filter capacity .26
Bibliography .28
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ISO 19438:2023(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.
The procedures used to develop this document and those intended for its further maintenance are
described in the ISO/IEC Directives, Part 1. In particular, the different approval criteria needed for the
different types of ISO documents should be noted. This document was drafted in accordance with the
editorial rules of the ISO/IEC Directives, Part 2 (see www.iso.org/directives).
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. Details of
any patent rights identified during the development of the document will be in the Introduction and/or
on the ISO list of patent declarations received (see www.iso.org/patents).
Any trade name used in this document is information given for the convenience of users and does not
constitute an endorsement.
For an explanation of the voluntary nature of standards, the meaning of ISO specific terms and
expressions related to conformity assessment, as well as information about ISO's adherence to
the World Trade Organization (WTO) principles in the Technical Barriers to Trade (TBT), see
www.iso.org/iso/foreword.html.
This document was prepared by Technical Committee ISO/TC 22, Road vehicles, Subcommittee SC 34,
Propulsion, powertrain and powertrain fluids.
This second edition cancels and replaces the first edition (ISO 19438:2003), which has been technically
revised.
The main changes are as follows:
— revised validation procedure;
— added requirement to measure final test system conductivity;
— revised test report to include initial and final test system conductivity;
— Replaced Annex D “Summary of the International interlaboratory trial (round robin) to validate
ISO 19438 protocol” with “Effect of dust cake filtration on filter capacity”.
Any feedback or questions on this document should be directed to the user’s national standards body. A
complete listing of these bodies can be found at www.iso.org/members.html.
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ISO 19438:2023(E)
Introduction
This document establishes a standard test procedure for measuring the filtration efficiency, retention
capacities and resistance to flow of fuel filters. This test is intended to differentiate filters according to
their functional performance but is not intended to represent performance under actual field operating
conditions. Test conditions are steady-state and the dynamic characteristics of the fuel systems are not
represented. Other test protocols are in development to evaluate performance under cyclic flow and
vibration.
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INTERNATIONAL STANDARD ISO 19438:2023(E)
Diesel fuel and petrol filters for internal combustion
engines — Filtration efficiency using particle counting and
contaminant retention capacity
1 Scope
This document specifies a multi-pass filtration test, with continuous contaminant injection and using
the on line particle counting method, to evaluate the performance of diesel fuel and petrol filters
for internal combustion engines submitted to a constant flow rate of test liquid. The test procedure
determines the contaminant capacity of a filter, its particulate removal characteristics and differential
pressure. This document is applicable to filter elements having a rated flow between 50 l/h and 800 l/h;
however, by agreement between the filter manufacturer and customer, and with some modifications,
the procedure is permitted for application to fuel filters with higher flow rates.
2 Normative references
The following documents are referred to in the text in such a way that some or all of their content
constitutes requirements 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 2942, Hydraulic fluid power — Filter elements — Verification of fabrication integrity and determination
of the first bubble point
ISO 3968, Hydraulic fluid power — Filters — Evaluation of differential pressure versus flow
ISO 4021, Hydraulic fluid power — Particulate contamination analysis — Extraction of fluid samples from
lines of an operating system
ISO 4405, Hydraulic fluid power — Fluid contamination — Determination of particulate contamination by
the gravimetric method
ISO 11171, Hydraulic fluid power — Calibration of automatic particle counters for liquids
ISO 11841-1, Road vehicles and internal combustion engines — Filter vocabulary — Part 1: Definitions of
filters and filter components
ISO 11841-2, Road vehicles and internal combustion engines — Filter vocabulary — Part 2: Definitions of
characteristics of filters and their components
ISO 11943:2021, Hydraulic fluid power — Online automatic particle-counting systems for liquids —
Methods of calibration and validation
ISO 12103-1, Road vehicles — Test contaminants for filter evaluation — Part 1: Arizona test dust
3 Terms and definitions
For the purposes of this document, the terms and definitions given in ISO 11841-1, ISO 11841-2 and the
following apply.
ISO and IEC maintain terminology databases for use in standardization at the following addresses:
— ISO Online browsing platform: available at https:// www .iso .org/ obp
— IEC Electropedia: available at https:// www .electropedia .org/
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ISO 19438:2023(E)
3.1
multi-pass test
test which requires the recirculation of filtered fluid through the filter element
3.2
base upstream gravimetric level
upstream contaminant concentration if no contaminant is recirculated
3.3
filtration efficiency
ability of the filter to retain particles
Note 1 to entry: It is expressed as the percentage of particles of a given size retained by the filter under test.
3.4
overall efficiency
efficiency calculated from the average upstream and downstream particle counts obtained during the
entire test
3.5
filter rating
particle size corresponding to an initial efficiency (3.7) or cumulative overall efficiency (3.4) of a given
percentage
Note 1 to entry: It is expressed in micrometres(c) [µm(c)], which signifies throughout this document that
a particle size measurement is carried out using an automatic particle counter calibrated in accordance with
ISO 11171.
3.6
filter reference rating
filter rating (3.5) at 99 % efficiency
Note 1 to entry: It is expressed in micrometres(c) [µm(c)], which signifies throughout this document that
a particle size measurement is carried out using an automatic particle counter calibrated in accordance with
ISO 11171.
3.7
initial efficiency
efficiency at first data points calculated from 4 min, 5 min and 6 min particle counts
4 Symbols
Graphical symbols used in this document for fluid power system components are in accordance with
ISO 1219-1.
5 Test apparatus and materials
5.1 Test apparatus
5.1.1 Test rig
The test rig, shown diagrammatically in Figure 1 (to which the numbers in parentheses throughout this
document refer), shall comprise the following.
5.1.1.1 Filter test circuit, including the components specified in 5.1.1.1.1 to 5.1.1.1.7.
5.1.1.1.1 Reservoir (1), constructed with a conical bottom having an included angle of not more than
90° and where the oil entering is diffused below the fluid surface.
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ISO 19438:2023(E)
5.1.1.1.2 Oil pump (2), which does not alter the contaminant particle size distribution and does not
exhibit pressure pulsation with an amplitude greater than 10 % of the average pressure at the filter
inlet.
5.1.1.1.3 Device, such as a filter head to accommodate spin-on filters, which connects the test filter
(6) and which can be bypassed or replaced by a straight section of pipe.
5.1.1.1.4 System clean-up filter (9), capable of providing an initial system contamination level of
less than 15 particles/ml having a size greater than 10 µm(c).
5.1.1.1.5 Sampling valves, in accordance with ISO 4021, for turbulent sampling upstream and
downstream of the test filter, for on line particle counting (18) and for gravimetric analysis (11).
5.1.1.1.6 Pressure tappings, in accordance with ISO 3968.
5.1.1.1.7 Piping, sized to ensure that turbulent mixing conditions exist throughout the filter test
circuit.
5.1.1.2 Contaminant injection circuit, including the components specified in 5.1.1.2.1 to 5.1.1.2.3.
5.1.1.2.1 Reservoir (12), constructed with a conical bottom having an included angle of not more
than 90° and where the oil entering is diffused below the fluid surface.
5.1.1.2.2 Oil pump (13), of centrifugal or other type, which does not alter the contaminant particle
size distribution.
5.1.1.2.3 System clean-up filter (14), capable of providing either of the following conditions:
a) an initial system contamination level of less than 1 000 particles/ml having a size greater than
10 µm(c);
b) a gravimetric level less than 2 % of the calculated level at which the test is being conducted,
measured using the double membrane gravimetric method in accordance with ISO 4405.
5.1.1.2.4 Piping, sized to ensure that turbulent mixing conditions exist throughout the contaminant
injection circuit.
While injection flows lower than 0,25 l/min may be used if validated, an injection flow of 0,25 l/min is
recommended.
Injection flows higher than 0,25 l/min shall not be used to minimize the effect of fluid extraction on
filter capacity.
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ISO 19438:2023(E)
Key
1 reservoir incorporating thermostatically 13 oil pump A contaminant injection circuit
controlled heater
2 oil pump 14 clean-up filter
3 three-way ball valve 15 heat exchanger B filter test circuit
4 pressure gauge 16 injection pump C dilution and counting system
5 differential pressure gauge 17 flow meter
6 test filter 18 sampling valve
7 throttle valve (for flow regulation) 19 dilution system
8 flow meter 20 optical particle
sensor
9 clean-up filter 21 particle counter
10 heat exchanger 22 sampling valve
11 sampling valve 23 by-pass flow
circuit
12 reservoir incorporating thermostatically
controlled heater
Figure 1 — Diagrammatic arrangement of test rig
5.1.2 On line dilution and particle counting system
The on line dilution and particle counting system shall be in accordance with ISO 11943 and include the
components specified in 5.1.2.1 to 5.1.2.4.
5.1.2.1 On line sample delivery pipework, sized to maintain a fluid velocity that prevents silting at
a flow rate of 0,125 l/min. For tests with sampling flows > 10 % of the total filter flow rate, the amount
of dust discarded in the sampling flow will be significant. This amount shall be evaluated and deducted
from the retained capacity. Lower flow rates may be used provided they are validated.
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ISO 19438:2023(E)
5.1.2.2 Dilution system (19), comprising appropriate reservoir, pump, clean-up filters, flow meters
and flow regulation valves.
5.1.2.3 Two optical particle sensors (20), connected to a particle counter (21) having a minimum of
five channels.
5.1.2.4 Timer, capable of measuring minutes and seconds.
5.2 Test materials
5.2.1 Test contaminant
5.2.1.1 Contaminant grade
The contaminant shall be in accordance with the specification of ISO 12103-1 A.3 medium grade test
dust.
5.2.1.2 Contaminant preparation
The test dust shall be pre-dried in quantities no larger than 200 g for at least 1 h at (105 ± 5) °C and
cooled to room temperature. Maintain it in a desiccator until required for use.
5.2.2 Test fluid
The test fluid shall have a petroleum base and conform to the specifications given in Annex A.
6 Accuracy of measuring instruments and test conditions
The measuring instruments shall be capable of measuring to the levels of accuracy given in Table 1. The
last column in the table gives the limits within which the test conditions shall be maintained.
Table 1 — Instrument accuracy and test condition variation
Allowed test condition vari-
Test condition Unit Measurement accuracy
ation
Flow
Filter test flow l/min ±2 % ±5 %
Sampling flow ml/min ±1,5 % ±3 %
Injection flow ml/min ±2 % ±5 %
Pressure Pa ±5 % —
Temperature °C ±1 °C 2 °C
Volume l ±5 % ±10 %
Base upstream gravimetric level mg/l — ±10 %
Conductivity pS/m ±10 % See 8.3.4
a 2
Viscosity mm /s ±5 % —
a
The viscosity of the test liquid should be checked at regular intervals to ensure that the test is conducted at a liquid
2
temperature which corresponds to a viscosity of (15 ± 1) mm /s.
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ISO 19438:2023(E)
7 Test rig validation
7.1 General
These validation procedures reveal the effectiveness of the test rig in maintaining contaminant
entrainment or preventing contaminant size modification or both.
7.2 Validation of the on line dilution and particle counting system
Proceed in accordance with ISO 11943 to validate the on line dilution system and in accordance with
ISO 11171 to validate the particle counter.
7.3 Validation of filter test circuit
7.3.1 Validate the filter test circuit at the minimum flow rate at which the circuit will be operated.
7.3.2 Install a straight section of pipe instead of a test filter during the validation procedure.
7.3.3 Adjust the total circuit volume so that it is numerically equal to half the value of the minimum
flow volume per minute through the filter, with a minimum of 6 l. The total circuit volume should
include sump, piping and filter. A by-pass flow loop should be utilized for low flow test conditions.
7.3.4 Contaminate the fluid to the calculated gravimetric level of 5 mg/l using ISO 12103-1 A.3
medium test dust.
NOTE This contamination level is below the coincidence limit of automatic particle counters.
7.3.5 Circulate the fluid in the test system for 1 h while obtaining downstream cumulative counts at
5 µm(c), 10 µm(c) and 18 µm(c), without on line dilution, at 10 min sample intervals.
7.3.6 Calculate and record the on line count (C ) in particles per millilitre, using the formula:
o
N
c
C =
o
V
where
N is the cumulative count for the selected sample period, in number of particles;
c
V is the volume of fluid, in millilitres, passed through the particle counter sensor during the sample
period.
7.3.7 The validation shall be accepted only if:
a) the particle count obtained for a given size at each sample interval does not deviate more than
15 % from the average particle count from all sample intervals for that size, and
b) the average of all cumulative particle counts per millilitre is within the range of acceptable counts
in accordance with ISO 11943:2021, Table C.2.
7.3.8 Contaminate the fluid to the maximum gravimetric level to be tested using ISO 12103-1 A.3
medium test dust.
7.3.9 Circulate the fluid in the test system for 1 h while obtaining downstream cumulative counts at
5 µm(c), 10 µm(c) and 18 µm(c), with online dilution, at 10 min sample intervals.
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ISO 19438:2023(E)
7.3.10 The validation test shall be accepted only if each particle count obtained at 5 µm(c), 10 µm(c)
and 18 µm(c) does not deviate by more than 10 % from the average particle count for these sizes.
7.4 Validation of contaminant injection circuit
7.4.1 Validate the contaminant injection circuit at the maximum volume and the maximum
gravimetric level to be used.
7.4.2 Add the required quantity of contaminant in slurry form to the injection circuit fluid and
circulate for a time sufficient to completely disperse the contaminant.
NOTE It is possible that all systems do not disperse contaminant at the same rate. A period of 10 min to
20 min can be necessary for complete dispersion.
7.4.3 Extract fluid samples at the point where the injection fluid is discharged into the filter test
circuit reservoir at 30 min intervals over 2 h and analyse each sample gravimetrically. These samples
should be taken at the intended test injection flow rate.
7.4.4 The validation test shall be accepted only if the gravimetric level of each sample is within ± 5 %
of the average of the four samples and if this average is within ± 5 % of the gravimetric value selected in
7.4.1.
8 Preliminary preparation
8.1 Test filter assembly
8.1.1 Ensure that the test fluid cannot bypass the filter element to be evaluated.
8.1.2 Subject the test filter element to a fabrication integrity test in accordance with ISO 2942 using
MIL-H-5606 fluid prior to the multi-pass test or following it, if the element is not readily accessible as in
the spin-on configuration.
8.1.3 If the integrity test has been made prior to the multi-pass test and if the test filter element fails
to meet the test pressure agreed between the purchaser and the manufacturer, the element shall be
disqualified from further testing. If the integrity test has been made after the multi-pass test and if the
element fails, the test result shall be disqualified.
8.2 Contaminant injection circuit
8.2.1 Using 50 mg/l as the base upstream gravimetric level, calculate the predicted test time, T , in
e
minutes, from the formula:
F F
cc
T = =
e
GQ× 50×Q
where
F is the estimated capacity of the filter element, in milligrams;
c
G is the base upstream gravimetric level, in milligrams per litre;
Q is the test flow rate, in litres per minute.
The test duration should be > 30 min. The base upstream gravimetric level of 50 mg/l should be adhered
to unless otherwise agreed upon by purchaser and manufacturer. Base upstream gravimetric levels up
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ISO 19438:2023(E)
to 100 mg/l may be used to shorten test times, while base upstream gravimetric levels down to 25 mg/l
may be used to lengthen test times, but only the results of filter tests using the same base upstream
gravimetric level may be compared.
NOTE If the estimated capacity of the filter element (F ) is not supplied by the manufacturer, it can be
c
necessary to determine the capacity by testing an element.
8.2.2 Calculate the minimum volume of fluid, V , in litres, required for the operation of the injection
m
circuit, compatible with the predicted test time and an injection flow rate of 0,25 l/min, using the
formula:
V = 1,2T × Q + V
m e i o
where
T is the predicted test time, in minutes, in accordance with 8.2.1;
e
Q is the injection flow rate, in litres per minute;
i
V is the minimum volume of fluid in the injection circuit necessary to avoid air entrainment.
o
The calculated minimum volume should ensure a quantity of contaminant fluid sufficient to load the
element, plus 20 % for adequate circulation throughout the test and to avoid entrainment. Larger
injection volumes may be used.
8.2.3 Calculate the gravimetric level, G , in milligrams per litre of the injection fluid, from the formula:
i
ρ×Q 50Q
G = =
i
Q Q
ii
where
G is the base upstream gravimetric level, in milligrams per litre, in accordance with 8.2.1;
ρ is the pressure;
Q is the test flow rate, in litres per minute;
Q is the injection flow rate, in litres per minute.
i
8.2.4 Calculate the quantity of contaminant, W, in grams, needed for the contaminant injection
circuit, using the formula:
GV×
ii
W =
1000
where
G is the gravimetric level, in milligrams per litre, in accordance with 8.2.3;
i
V is the volume of fluid contained in the injection circuit, in litres.
i
8.2.5 Adjust the injection flow rate at stabilized temperature to within ± 5 % of the value selected in
8.2.2 and maintain throughout the test.
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