ISO 23820:2023
(Main)Determination of the filtration efficiency of urea filter modules
Determination of the filtration efficiency of urea filter modules
This document specifies requirements relating to the testing method for AUS 32/diesel exhaust fluid (DEF) filters for the removal of suspended matter. This applies to urea filters dedicated to passenger vehicles as well as to commercial vehicles. This method applies to filters with flow rates from 3 l/h to 30 l/h depending on the application (by default 5 l/h for passenger vehicles and 25 l/h for commercial vehicles). This method can be used for other flow rates, provided the validation requirement can be met.
Détermination de l'efficacité de filtration des modules de filtres à urée
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INTERNATIONAL ISO
STANDARD 23820
First edition
2023-05
Determination of the filtration
efficiency of urea filter modules
Détermination de l'efficacité de filtration des modules de filtres à urée
Reference number
ISO 23820:2023(E)
© ISO 2023
---------------------- Page: 1 ----------------------
ISO 23820:2023(E)
COPYRIGHT PROTECTED DOCUMENT
© ISO 2023
All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication may
be reproduced or utilized otherwise in any form or by any means, electronic or mechanical, including photocopying, or posting on
the internet or an intranet, without prior written permission. Permission can be requested from either ISO at the address below
or ISO’s member body in the country of the requester.
ISO copyright office
CP 401 • Ch. de Blandonnet 8
CH-1214 Vernier, Geneva
Phone: +41 22 749 01 11
Email: copyright@iso.org
Website: www.iso.org
Published in Switzerland
ii
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ISO 23820:2023(E)
Contents Page
Foreword .iv
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Symbols . 2
5 Test procedures . 3
5.1 Principle . 3
5.2 Test equipment and materials . 4
5.2.1 Test rig . 4
5.2.2 Filter test circuit . 4
5.2.3 Contaminant injection circuits . 5
5.2.4 Automatic particle counting devices . 6
5.2.5 Test fluid . 6
5.2.6 Test contaminant . 6
5.2.7 Stop watch . 6
5.2.8 Ultra clean bottles . 6
5.2.9 Ultra-sonic bath . 6
5.3 Test rig validation . 6
5.3.1 General . 6
5.4 Procedure . 9
5.4.1 Operating conditions . 9
5.4.2 Preparation of the contaminant injection circuits . 10
5.4.3 Preparation of the test circuit . 11
5.4.4 Filter efficiency and retention capacity test . 11
5.5 Expression of results . .13
5.6 Test report . 13
Annex A (informative) Determination of the initial filtration efficiency as per this
document .15
Bibliography .21
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ISO 23820:2023(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 document 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).
ISO draws attention to the possibility that the implementation of this document may involve the use
of (a) patent(s). ISO takes no position concerning the evidence, validity or applicability of any claimed
patent rights in respect thereof. As of the date of publication of this document, ISO had not received
notice of (a) patent(s) which may be required to implement this document. However, implementers are
cautioned that this may not represent the latest information, which may be obtained from the patent
database available at www.iso.org/patents. ISO shall not be held responsible for identifying any or all
such patent rights.
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.
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.
iv
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---------------------- Page: 4 ----------------------
INTERNATIONAL STANDARD ISO 23820:2023(E)
Determination of the filtration efficiency of urea filter
modules
1 Scope
This document specifies requirements relating to the testing method for AUS 32/diesel exhaust fluid
(DEF) filters for the removal of suspended matter. This applies to urea filters dedicated to passenger
vehicles as well as to commercial vehicles. This method applies to filters with flow rates from 3 l/h to
30 l/h depending on the application (by default 5 l/h for passenger vehicles and 25 l/h for commercial
vehicles). This method can be used for other flow rates, provided the validation requirement can be
met.
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 11218, Aerospace — Cleanliness classification for hydraulic fluids
ISO 11923, Water quality — Determination of suspended solids by filtration through glass-fibre filters
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 following terms and definitions 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/
3.1
cumulative overall mean filtration efficiency
E
x
cumulative efficiency calculated from the total number of particles greater than size x [µm] counted
upstream and downstream of a filter during the initial 60 min counting period at 5 mg/l
Note 1 to entry: The efficiency is expressed in [%].
3.2
differential pressure
ΔP
pressure difference between the inlet and outlet of the complete filter unit measured under
predetermined conditions
Note 1 to entry: The differential pressure generated by the complete filter is equal to the sum of the differential
pressures generated by the housing and by the filter element (in case the filter element is removable from the
housing).
Note 2 to entry: The differential pressure is expressed in kPa.
1
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ISO 23820:2023(E)
3.3
ISO MTD
ISO medium test dust
siliceous test powder having a particle size distribution by volume in accordance with ISO 12103-1, A3
Note 1 to entry: It may also be referred as ISO 12103-1 A3 dust.
3.4
nominal flow rate
Q
flow rate for the filter specified by the manufacturer
Note 1 to entry: The flow rate is expressed in l/h.
3.5
reference filtration rating
S
dimension of the ISO MTD particles at which the overall mean cumulative filtration efficiency of
the integral filter (or the filter element) tested in accordance with the procedure described in this
document, is greater than or equal to 99 %
Note 1 to entry: The reference filtration rating is expressed in µm.
4 Symbols
The symbols used in this document are given in Table 1.
Table 1 — Symbols
Symbol Parameter Unit
C Test concentration mg/l
e
C Injection concentration mg/l
i
C Retention capacity g
R
C Concentration of the downstream fluid during the clogging
NR
mg/l
period
C Coefficient of variation %
ov
d Size of the particle μm
ΔP Loss of pressure due to the clean filter alone kPa
0
ΔP Loss of pressure at the end of the test kPa
F
E Cumulative efficiency at size greater than x µm %
x
M Mass of contaminant necessary for the test g
M Injected mass of contaminant in injection reservoir 1 g
i1
M Injected mass of contaminant in injection reservoir 2 g
i2
th
N > x µm i particle count upstream at size >x µm -/ml
i UP
th
N > x µm i particle count downstream at size >x µm -/ml
i DW
Q Flow rate l/h
Q Recirculation flow rate l/h
r
Q Injection flow rate circuit 1 (relative to the efficiency con-
C1
l/h
centration)
Q Injection flow rate circuit 2 (relative to the capacity con-
C2
l/h
centration)
S Suspended solid concentration mg/l
sc
V Injection circuit N°1 fluid volume l
i1
2
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ISO 23820:2023(E)
TTaabblle 1 e 1 ((ccoonnttiinnueuedd))
Symbol Parameter Unit
V Injection circuit N°2 fluid volume l
i2
V Injection circuit maximum fluid volume l
iM
V Recovered downstream volume during the clogging period l
CP
V Recovered downstream volume during the validation of
CPV
l
the clogging period
ΔT Time duration of the clogging period h
CP
5 Test procedures
5.1 Principle
The performance of the filter to be tested is determined by measuring its hydraulic and separative
properties when subjected to a constant flow rate of water conveying a known quantity of contaminant.
The test is performed with the water after passage through clean-up filters to produce a single pass
configuration. The test is conducted in two stages.
The first stage determines the initial efficiency of the test filter. It is conducted with a contaminant
concentration of 5 mg/l upstream to the test filter for 60 min. The second stage determines the mass of
contaminant needed to reach a specified differential pressure. This stage is conducted with an upstream
concentration of 800 mg/l, or as specified according to the customer specification. The retention
capacity shall be determined from the mass of contaminant required for obtaining a predetermined
differential pressure of 10 kPa or other value according to customer’s specifications. Several operating
parameters are specified as a function of the type of filter under test, e.g. the standard flow rate of
5 l/h is recommended for testing a standard urea filter module for passenger vehicles and 25 l/h for
commercial vehicles, unless otherwise specified.
3
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ISO 23820:2023(E)
5.2 Test equipment and materials
5.2.1 Test rig
Key
1A injection reservoir for efficiency period at 5 mg/l (N°1) 8 main recirculation pump
1B injection reservoir for clogging period at maximum 9 regulating level volume system
800 mg/l (N°2)
2 clean up filter 10 recirculation injection loop pump
3 main reservoir (6 l) 11A injection circuit (N°1) sampling valve
4 flow meter 11B injection circuit (N°2) sampling valve
5A upstream side particle counter 12 three-way valves
5B downstream side particle counter 13 heat exchanger
6 counter pressure control valve 14 temperature sensor
7 injection pump
Figure 1 — Diagram of filtration efficiency and retention capacity test rig
5.2.2 Filter test circuit
The filter test circuit is designed to permit the recycling of the fluid being filtered. Both return line
and recirculation loops are equipped with clean-up filters which retain all of the test particles that
have passed through the test filter or before going back to the main reservoir (a filtration efficiency of
99 % at 1 µm is suitable for such clean up filters). In case of multiple usage of the test liquid, the risk of
biological growth is given. Suitable control and countermeasures shall be implemented.
The test circuit comprises the following:
a) a conical bottom reservoir having a recommended cone angle less than or equal to 90°. Its volume
is of 6 l. The residence time inside the reservoir shall be of 30 s and the height shall be preferably
4
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ISO 23820:2023(E)
between twice and three times its diameter. Other type reservoir with other volumes can be used
if requirements of 5.3.1.2 are fulfilled. The recycled water return line penetrates beneath the free
face so as to avoid the risk of air entrainment;
b) a main circulation pump which ensures a constant, non-pulsed flow rate Q of at least twice the
r
volume unit (when expressed in l/min) (i.e. at least 12 l/min or 720 l/h) throughout the test
duration, particularly when the filter is clogged. It shall be resistant to the test contaminant by not
modifying the particle size distribution;
c) a bypass circuit from the main recirculation loop allowing to circulate through the urea filter under
test in a single pass way;
d) two clean-up filters dedicated to the main recirculation loop and the bypass filter test loop to
restore the level of the test fluid’s particulate contamination at less than 10 particles /ml >5 µm;
e) instruments for measuring the flow rate, the temperature, the differential pressures at the filter
connections;
f) two sampling devices in accordance with ISO 4021 put upstream and downstream of the filter in
order to ensure representative sampling of the water and contaminant and connected to automatic
particle counting devices (see 5.2.4);
g) interconnecting pipe and fittings, dimensioned and selected so as to ensure a turbulent flow
throughout the whole circuit, thereby preventing the formation of traps, segregation and quiescent
zones. The length of the piping shall be reduced to the minimum;
h) clean water level control device in the test reservoir, to regulate the level within 5 %;
i) temperature regulator to control the temperature at the specified value of (23 ± 2) °C;
j) all the pipes, connections, reservoirs shall be 316L INOX with the best polishing procedure available
to avoid the abrasive mix of sand and water.
5.2.3 Contaminant injection circuits
There are two injection circuits; one is allocated to 5 mg/l injection (injection circuit N° 1), the other
one to 800 mg/l injection (injection circuit N° 2).
Each injection circuit includes the following equipment:
a) conical bottom reservoir having a recommended cone angle less than or equal to 90°. Its height
is preferably between twice or three times its diameter. Other configured reservoir can be used
if requirements of 5.3.1.1 are fulfilled. It is equipped with a level indicator. The recycled water
returns beneath the free face;
b) recirculation pump which generates a flow rate to ensure sufficient mixing to meet the requirements
in 5.3. It shall be resistant to the test contaminant by not modifying the particle size distribution;
c) temperature regulation device to control the water temperature at 23 ± 2 °C;
d) clean-up filter, installed to by-pass the injection loop, capable of achieving a cleanliness level at less
than 40 particles/ml >5 µm;
e) contaminant injection pump which draws the concentrated contaminant into the recirculation
system at a point where the flow is turbulent and discharges it via a flexible pipe into the main
pump suction in case of injection circuit N°1 or upstream to the urea filter in case of injection
circuit N°2. There is a three-way valve to switch from injection circuit N°1 to injection circuit N°2.
It shall not generate any excessive flow rate pulsation and shall have no effect on the contaminant.
The injection flow rate shall be sufficient to prevent segregation of the test dust;
f) sampling device conforming to ISO 4021;
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ISO 23820:2023(E)
g) device for measuring the injection flow rate, insensitive to the contaminant and without effect on
its particle size distribution at the concentrations scheduled for the test.
5.2.4 Automatic particle counting devices
These devices comprise one or two counters and two optical units.
These devices operate on the light extinction principle; they shall be properly calibrated using certified
monosized latex spheres as per ISO 21501-3.
Ensure the concentration level of the particle sensors is capable of operating in the required system
concentration levels.
5.2.5 Test fluid
The test fluid shall be demineralized and filtered water with a cleanliness level of less than 10 particles
/ml >5 µm.
NOTE Using demineralized water will prevent a chemical reaction of the silica inside the injection and test
circuits.
5.2.6 Test contaminant
The test contaminant shall be silica test dust specified as ISO MTD.
5.2.7 Stop watch
5.2.8 Ultra clean bottles
Use thoroughly cleaned sample bottles when filled with micro-filtered water. The cleanliness level of
the bottle shall be CSC (0) as per ISO 11218.
5.2.9 Ultra-sonic bath
The characteristics should be the following one: power of 25 W/l with an ultra-sonic frequency varying
between 30 and 40 kHz.
5.3 Test rig validation
5.3.1 General
The purpose of the validation is to demonstrate that the test rig complies with the test requirements.
The validation shall be carried out again whenever a component of the installation is modified or
changed.
5.3.1.1 Validation of the injection circuits
The two injection circuits for attaining test concentrations of 5 mg/l and 800 mg/l shall be successively
validated.
The validation is conducted with the maximum volume (V ) in each tank and at the minimum flow
iM
rates for the injection circuits. Before starting, make sure that both injection reservoirs N°1 and N°2
are clean enough (initial cleanliness level of less than 40 particles /ml >5 µm).
a) Calculate the two injection circuit contamination concentrations so that the concentration in the
test circuit.
C = 5 mg/l (injection circuit N° 1) or C = 800 mg/l (injection circuit N° 2):
e e
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ISO 23820:2023(E)
QC
e
C = (1)
i
Q
i
where
Q is the flow rate expressed in l/h:
— (circulation loop flowrate Q of 720 l/h (or either) in case of injection circuit N°1);
r
or
— (urea/DEF filter test flowrate Q in case of injection circuit N°2);
Q is the minimum value of the injection flow rate, in l/h;
i
C is the injection circuit contaminant concentration, in mg/l.
i
b) Prepare a mass M of test dust ISO MTD, previously dried at a temperature between 110 °C to 150 °C
for at least 1 h and cooled to room temperature in a desiccator, to obtain the previously calculated
concentration Ci:
MV= C (2)
iM i
where
M is the mass of test dust, in mg;
V is the injection circuit maximum fluid volume, in l;
iM
C is the injection circuit contaminant concentration, in mg/l.
i
c) Disperse the contaminant in 200 ml of water taken from the injection reservoir ensuring complete
homogenization (e.g. by using ultra sonics and then mixing with a non-magnetic stirrer).
d) Introduce the fluid volume into the injection reservoir, start the recirculation pump (see Figure 1,
key 10), introduce the test contaminant prepared in b) and c) above, and allow to circulate for at
least 15 min.
e) Set the injection flow rate at the minimum Q value, continuously controlling the value displayed by
i
the flow rate meter and the height of the fluid in the injection reservoir. Start the injection into the
test reservoir.
NOTE It is preferable to inject the contaminant by means of a flexible pipe in order to facilitate the
sampling operations at the injection point.
f) Every 30 min, during a 6 h period, take a 200 ml sample via sampling valve (see Figure 1, key 11A or
11B) and at the injection point in the main circuit. Determine the suspended solids concentration in
accordance with ISO 11923.
g) The injection circuit is validated if the following conditions are satisfied:
— the injection flow recorded values does not differ by more than 5 % in terms of coefficient of
variation (see definition in 5.3.1.2 h) 1);
— suspended solids for each of the injection concentrations do not differ by more than 5 % of the
average measured concentration;
— real average measured concentration does not differ by more than 10 % of the theoretical
concentration.
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ISO 23820:2023(E)
5.3.1.2 Validation of the test circuit
a) Adjust the volume of the fluid V in the main circuit to 6 l or the volume depending of reservoir
F
configuration.
b) After fitting a tubular sleeve in place of the filter to be tested, set up the temperature regulation
system and the main recirculation pump adjusting the recirculation flow rate Q to 720 l/h.
r
Operate until the conditions have stabilized and, if necessary, readjust the fluid volume in the circuit at
6 l.
c) To the upstream and downstream sample valves (see Figure 1, keys 5A and 5B), connect on-line
automatic counters previously calibrated, regulate the flow rate through the sensors to the values
recommended by the manufacturer of the automatic counters.
d) Introduce into the reservoir of each injection circuit, mass M and M of contaminant, previously
i1 i2
oven-dried and desiccated, to obtain the theoretical test concentrations of C = 5 mg/l and C =
e e
800 mg/l, respectively.
e) Start the validation with a 1 h phase at the test concentration C = 5 mg/l during which in-line
e
counts are carried out, via upstream and downstream sample valves (see Figure 1, keys 5A and
5B), for 30 s every minute, at the thresholds selected in Table 2.
f) Close the upstream sampling valve (see Figure 1, key 5A).
g) The downstream sensor having been previously disconnected, follow this by a 6 h phase with a
concentration C = 800 mg/l. Collect the entire volume V which has run off via downstream
e CPV
sampling valve (see Figure 1, key 5B) at the nominal counting flow rate and determine its suspended
solids concentration (S ) in accordance with ISO 11923.
SC
h) The test circuit is validated if the following four conditions are satisfied:
1) The coefficient of variation C [%] for each sensor during the phase e) of this clause is less than
OV
or equal to that given in Table 2. The coefficient of variation is calculated as per Formula (3):
σ
C =×100 , (3)
OV
x
n n
2
nx()− x ²
∑∑i ()i
i==1 i 1
σ = (4)
nn()−1
n
x
∑ i
i=1
x = (5)
n
NOTE C is expressed as a percentage [%].
OV
Table 2 — Percentage of variation in the number of particles per counter
Thresholds d > 5 d > 10 d > 15 d > 25 d > 40
[μm]
ISO MTD 5 7 10 32 55
[%]
2) The percentage difference at different thresholds in the counting results between the two
sensors during the phase e) is less than or equal to that given in Table 3.
8
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ISO 23820:2023(E)
Table 3 — Percentage difference in the number of particles between two counters
Thresholds > 5 > 7 > 10 > 12 > 15 > 20 > 30 > 40
[μm]
Difference 5,1 5,3 5,6 5,6 6,3 7 10 10
[%]
If the conditions of Table 3 are not met, repeat the phase e) and adjust the downstream sensor only
in order to reduce the variation at the corresponding sizes.
3) The mass of contaminant collected during the phase g) at downstream sampling valve (see
Figure 1, key 5B) does not deviate by more than 30 % from the injected masses.
This mass of contaminant is calculated by multiplying the collected volume V and the corresponding
suspended solids concentration S as per Formula (6):
SC
mV =× S (6)
sc
4) The particle size distribution of ISO MTD obtained at e) should comply with the Table 4.
Table 4 — Particle size distribution of ISO MTD (informative data)
Size Cumulative counts in 1 ml
of solution of ISO MTD at
[> µm]
1 mg/l
5 725 +/- 160
6 415 +/- 100
8 182 +/- 46
10 92 +/- 54
15 18,2 +/- 9
20 5,6 +/- 2,8
5.4 Procedure
5.4.1 Operating conditions
5.4.1.1 Fixed conditions
The following operating conditions shall be used:
a) test flow rate: manufacturer's specified flow rate as defined on the product label; (it should include
the upstream counting flowrate);
b) test contaminant: ISO MTD;
c) sampling method: during C = 5 mg/l phases both upstream (sampling valve see Figure 1, key 5A)
e
and downstream (sampling valve see Figure 1, key 5B) of the filter; and during C =800 mg/l (or
e
other value) phases only downstream of the filter;
d) counting method: on-line automatic particle counter using absorption of white light or laser beam
calibrated as per ISO 21501-3 with monosized latex beads;
e) level of initial cleanliness:
— injection circuit: less than 40 particles /ml >5 µm;
— main circuit: less than 10 particles /ml >5 µm;
9
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ISO 23820:2023(E)
f) duration of phases:
1) counting phase (C = 5 mg/l): 1 h;
e
2) clogging phase (C = 800 mg/l or other agreed concentration):6 h;
e
g) end of test: final differential pressure of 10 kPa or another agreed final differential pressure.
5.4.2 Preparation of the contaminant injection circuits
5.4.2.1 Calculatio
...
ISO/FDIS 23820:20222023(E)
ISO TC 22/SC 34/WG 1
Date: 2022-092023-01
Determination of the filtration efficiency of urea filter modules
---------------------- Page: 1 ----------------------
ISO/DISFDIS 23820:20222023(E)
© ISO 20222023
All rights reserved. Unless otherwise specified, or required in the context of its implementation, no
part of this publication may be reproduced or utilized otherwise in any form or by any means,
electronic or mechanical, including photocopying, or posting on the internet or an intranet, without
prior written permission. Permission can be requested from either ISO at the address below or ISO’s
member body in the country of the requester.
ISO copyright office
CP 401 • Ch. de Blandonnet 8
CH-1214 Vernier, Geneva
Phone: +41 22 749 01 11
Email: copyright@iso.org
Website: www.iso.org
Published in Switzerland
ii © ISO 20222023 – All rights reserved
---------------------- Page: 2 ----------------------
ISO/DISFDIS 23820:20222023(E)
Contents
Foreword . 4
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Symbols . 2
5 Test procedures . 3
5.1 Principle . 3
5.2 Test equipment and materials . 4
5.2.1 Test rig . 4
Annex A (informative) . 19
Bibliography . 28
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© ISO 20222023 – All rights reserved iii
---------------------- Page: 3 ----------------------
ISO/DISFDIS 23820:20222023(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.
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.
iv © ISO 20222023 – All rights reserved
---------------------- Page: 4 ----------------------
FINAL DRAFT INTERNATIONAL STANDARD ISO/DISFDIS 23820:20222023(E)
Determination of the filtration efficiency of urea filter modules
1 Scope
This document specifies requirements relating to the method of testing ofmethod for AUS 32/Diesel Exhaust
Fluiddiesel exhaust fluid (DEF) filters for the removal of suspended matter. This will applyapplies to urea
filters dedicated to passenger vehicles as well as to commercial vehicles. This method applies to filters with
flow rates from 3 l/h to 30 l/h depending on the application (by default 5 l/h for passenger vehicles and 25 l/h
for commercial vehicles). This method can be used for other flow rates, provided the validation requirement
can be met.
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 11218, Aerospace: cleanliness — Cleanliness classification for hydraulic fluidfluids
ISO 11923, Water quality — Determination of suspended solids by filtration through glass-fiberfibre filters
ISO 21501--3, Determination of particle size distribution — Single particle light interaction method:
partmethods — Part 3: Light extinction liquid-borne particle counter
ISO 22241, diesel engines – Nox reduction Agent AUS 32 – part 1 – Quality requirement
43 Terms and definitions
For the purposes of this document, the following terms and definitions 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
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3.1
cumulative overall mean filtration efficiency
E
x
cumulative efficiency calculated from the total number of particles greater than size x ([µm)] counted
upstream and downstream of a filter during the initial 60 min counting period at 5 mg/l
Note 1 to entry: The efficiency is expressed in (%)[%].
3.2
differential pressure (∆P)
ΔP
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ISO/DISFDIS 23820:20222023(E)
pressure difference between the inlet and outlet of the complete filter unit measured under predetermined
conditions.
Note 1 to entry: theThe differential pressure generated by the complete filter is equal to the sum of the differential
pressures generated by the housing and by the filter element (in case the filter element is removable from the housing)).
Note 2 to entry: theThe differential pressure is expressed in kPa.
3.3
ISO MTD
ISO medium test dust (ISO MTD)
siliceous test powder having a particle size distribution by volume in accordance with ISO 12103-1, A3
Note 1 to entry: It may also be referred as ISO 12103-1 A3 dust.
3.4
nominal flow rate
Q
Flowflow rate for the filter specified by the manufacturer
Note 1 to entry: The flow rate is expressed in Ll/h.
3.5
reference filtration rating
(S)
Dimensiondimension of the ISO MTD particles at which the overall mean cumulative filtration efficiency of the
integral filter (or the filter element) tested in accordance with the procedure described in this document, is
greater than or equal to 99 %
Note 1 to entry: The reference filtration rating is expressed in µm.
54 Symbols
The generic symbols used in this document are given in Table 1.
Table 1 — Symbols
Symbol or
Parameter Unit
Abbreviation
C Test concentration mg/l
e
Ci Injection concentration mg/l
C Retention capacity g
R
C Concentration of the downstream fluid during the clogging
NR
mg/l
period
Cov Coefficient of variation %
d Size of the particle μm
∆P ΔP Loss of pressure due to the clean filter alone kPa
0 0
∆P ΔP Loss of pressure at the end of the test kPa
F F
E Cumulative Efficiencyefficiency at size greater than x µm %
x
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ISO/DISFDIS 23820:20222023(E)
M Mass of contaminant necessary for the test g
Mi1 Injected mass of contaminant in injection reservoir 1 g
M Injected mass of contaminant in injection reservoir 2 g
i2
th
N > x µm i particle count upstream at x µm -/ml
i UP
th
N > x µm i particle count downstream at x µm -/ml
i DW
Q Flow rate l/h
Qr Recirculation flow rate l/h
Q Injection flow rate circuit 1 (relative to the efficiency
C1
l/h
concentration)
Q Injection flow rate circuit 2 (relative to the capacity
C2
l/h
concentration)
S Suspended Solid Concentrationsolid concentration mg/l
sc
V Injection circuit N°1 fluid volume l
i1
V Injection circuit N°2 fluid volume l
i2
ViM Injection circuit maximum fluid volume l
VCP Recovered downstream volume during the clogging period
l
VCPV Recovered downstream volume during the validation of
l
the clogging period
Time duration of the clogging period h
∆TCPΔTCP
65 Test procedures
6.15.1 Principle
The performance of the filter to be tested is determined by measuring its hydraulic and separative properties
when subjected to a constant flow rate of water conveying a known quantity of contaminant. The test is
performed with the water after passage through clean-up filters to produce a single pass configuration. The
test is conducted in two stages.
The first stage determines the initial efficiency of the test filter. It is conducted with a contaminant
concentration of 5 mg/l upstream to the test filter for 60 minutes min. The second stage determines the mass
of contaminant needed to reach a specified differential pressure. This stage is conducted with an upstream
concentration of 800 mg/Ll, or as specified according to the customer specification. The retention capacity
shall be determined from the mass of contaminant required for obtaining a predetermined differential
pressure of 10 kPa or other value according to customer’s specifications. Several operating parameters are
specified as a function of the type of filter under test, e.g. the standard flow rate of 5 l/h is recommended for
testing a standard urea filter module for passenger vehicles and 25 l/h for commercial vehicles, unless
otherwise specified.
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ISO/DISFDIS 23820:20222023(E)
6.25.2 Test equipment and materials
6.2.15.2.1 Test rig
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ISO/DISFDIS 23820:20222023(E)
Key
1A 8 main recirculation pump
injection reservoir for efficiency period at 5 mg/Ll (N°1)
1B 9 regulating level volume system
injection reservoir for clogging period at maximum 800 mg/Ll
(N°2)
2 clean up filter 10 recirculation injection loop pump
3 main reservoir (6 l) 11A injection circuit (N°1) sampling valveinjection
circuit (N°2) sampling valve
11B
4 flow meter 11B injection circuit (N°2) sampling valve
12 three-way valves
45A upstream side particle counterflow meter
upstream side particle counterdownstream side particle counter 13 heat exchanger
5A
5B
6 counter pressure control valve 14 temperature sensor
7 injection pump
Figure 1 — Diagram of filtration efficiency and retention capacity test rig
6.2.25.2.2 5.2.2 Filter test circuit
The filter test circuit is designed to permit the recycling of the fluid being filtered. Both return line and
recirculation loops are equipped with clean-up filters which retain all of the test particles that have passed
through the test filter or before going back to the main reservoir (Aa filtration efficiency of 99 % at 1 µm is
suitable for such clean up filters). In case of multiple usage of the test liquid, the risk of biological growth is
given. Suitable control and countermeasures mustshall be implemented.
The test circuit comprises the following:
a) A a conical bottom reservoir having a recommended cone angle less than or equal to 90°. Its volume is of 6 l.
The residence time inside the reservoir shall be of 30 s and the height shall be preferably between twice
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ISO/DISFDIS 23820:20222023(E)
and three times its diameter. Other type reservoir with other volumes couldcan be used if requirements
of clause 5.3.1.2 are fulfilled. The recycled water return line penetrates beneath the free face so as to avoid
the risk of air entrainment;
b) A a main circulation pump which ensures a constant, non-pulsed flow rate Q of at least twice the volume
r
unit (when expressed in l/min) (i.e. at least 12 l/min or 720 l/h) throughout the test duration, particularly
when the filter is clogged. It shall be resistant to the test contaminant by not modifying the particle size
distribution;
c) A a bypass circuit from the main recirculation loop allowing to circulate through the urea filter under test
in a single pass way;
d) 2 two clean-up filters dedicated to the main recirculation loop and the bypass filter test loop to restore the
level of the test fluid’s particulate contamination at less than 10 particles /ml >5 µm;
e) Instruments instruments for measuring the flow rate, the temperature, the differential pressures at the
filter connections;
f) Two two sampling devices in accordance with ISO 4021 are put upstream and downstream of the filter in
order to ensure representative sampling of the water and contaminant and connected to automatic
particle counting devices (see 5.2.4);
g) Interconnecting interconnecting pipe and fittings, dimensioned and selected so as to ensure a turbulent
flow throughout the whole circuit, thereby preventing the formation of traps, segregation and quiescent
zones. The length of the piping shall be reduced to the minimum;
h) Clean clean water level control device in the test reservoir, to regulate the level within 5 %;
i) Temperature temperature regulator to control the temperature at the specified value of (23 ± ± 2) °C;
j) All all the pipes, connections, reservoirs shall be 316L INOX with the best polishing procedure available
to avoid the abrasive mix of sand and water.
6.2.45.2.3 5.2.3 Contaminant injection circuits
There are two injection circuits; one is allocated to 5 mg/l injection (injection circuit N° 1), the other for
800 mg/l injection (injection circuit N° 2).
Each injection circuit includes the following equipment:
a) conical bottom reservoir having a recommended cone angle less than or equal to 90°. Its height is
preferably between twice or three times its diameter. Other configured reservoir can be used if
requirements of clause 5.3.1.1 are fulfilled. It is equipped with a level indicator. The recycled water returns
beneath the free face;
b) recirculation pump which generates a flow rate to ensure sufficient mixing to meet the requirements in
section 5.3. It shall be resistant to the test contaminant by not modifying the particle size distribution. ;
c) temperature regulation device to control the water temperature at 23 +/-± 2 °C;
d) clean-up filter, installed so as to by-pass the injection loop, capable of achieving a cleanliness level at less
than 40 particles/ml >5 µm;
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ISO/DISFDIS 23820:20222023(E)
e) contaminant injection pump which draws the concentrated contaminant into the recirculation system at
a point where the flow is turbulent and discharges it via a flexible pipe into the main pump suction in case
of injection circuit N°1 or upstream to the urea filter in case of injection circuit N°2. There is a three-way
valve to switch from injection circuit N°1 to injection circuit N°2. It shall not generate any excessive flow
rate pulsation and shall have no effect on the contaminant. The injection flow rate shall be sufficient to
prevent segregation of the test dust;
f) sampling device conforming to ISO 4021;
g) device for measuring the injection flow rate, insensitive to the contaminant and without effect on its
particle size distribution at the concentrations scheduled for the test.
6.2.65.2.4 5.2.4 Automatic particle counting devices
These devices comprise one or two counters and two optical units.
These devices operate on the light extinction principle; they shall be properly calibrated using certified
monosized latex spheres as per ISO 21501-3.
Note: InsureEnsure the concentration level of the particle sensors is capable of operating in the required
system concentration levels.
6.2.85.2.5 5.2.5 Test fluid
Demineralized The test fluid shall be demineralized and filtered water with a cleanliness level of less than 10
particles /ml >5 µm;.
NOTE The fact usingUsing demineralized water will prevent froma chemical reaction of the silica inside the injection and
test circuits.
6.2.105.2.6 5.2.6 Test contaminant
SilicaThe test contaminant shall be silica test dust specified as ISO MTD.
6.2.125.2.7 5.2.7 Stop watch
6.2.145.2.8 5.2.8 Ultra clean bottles
Use thoroughly cleaned sample bottles when filled with micro-filtered water (. The cleanliness level of the
bottle has toshall be CSC (0) as per ISO 11218).
6.2.165.2.9 5.2.9 Ultra-sonic bath
The characteristics should be the following one: power of 25 W/l with an ultra-sonic frequency varying
between 30 and 40 kHz.
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ISO/DISFDIS 23820:20222023(E)
6.45.3 5.3 Test rig validation
6.4.25.3.1 5.3.1 General
The purpose of the validation is to demonstrate that the test rig complies with the test requirements. The
validation shall be carried out again whenever a component of the installation is modified or changed.
6.4.2.25.3.1.1 5.3.1.1 Validation of the injection circuits
The two injection circuits for attaining test concentrations of 5 mg/l and 800 mg/l shall be successively
validated.
The validation is conducted with the maximum volume (V V ) in each tank and at the minimum flow rates
im iM
for the injection circuits. Before starting, make sure that both injection reservoirs N°1 and N°2 are clean
enough (initial cleanliness level of less than 40 particles /mL > ml >5 µm)).
a) Calculate the two injection circuit contamination concentrations so that the concentration in the test
circuit.
C = 5 mg/l (injection circuit N° 1) or C = 800 mg/l (injection circuit N° 2):
e e
QC
e
C =
i
Q
i
𝑄𝑄𝐶𝐶
𝑒𝑒
𝐶𝐶 = (1)
𝑖𝑖
𝑄𝑄
𝑖𝑖
(1)
where
• Q expressed in l/h
o (circulation loop flowrate Q of 720 l/h (or either) in case of injection circuit N°1)
r
or
o (urea/DEF filter test flowrate Q in case of injection circuit N°2);
• Qi is the minimum value of the injection flow rate, in l/h;
• C expressed in mg/l.
i
Q is the flow rate expressed in l/h:
— (circulation loop flowrate Q of 720 l/h (or either) in case of injection circuit N°1);
r
or
— (urea/DEF filter test flowrate Q in case of injection circuit N°2);
Qi is the minimum value of the injection flow rate, in l/h;
C is the injection circuit contaminant concentration, in mg/l.
i
b) Prepare a mass M of test dust ISO MTD, previously dried at a temperature between 110 °C to 150 °C for at
least 1 h and cooled to room temperature in a desiccator, to obtain the previously calculated concentration
Ci:
M = VC
iM i
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ISO/DISFDIS 23820:20222023(E)
𝑀𝑀 =𝑉𝑉 𝐶𝐶 (2)
𝑖𝑖𝑖𝑖 𝑖𝑖
(2)
where
• M is the mass of test dust, in mg;
• V , in l;
iM
• C is the injection circuit contaminant concentration, in mg/l.
i
M is the mass of test dust, in mg;
V is the injection circuit maximum fluid volume, in l;
iM
C is the injection circuit contaminant concentration, in mg/l.
i
c) Disperse the contaminant in 200 ml of water taken from the injection reservoir ensuring complete
homogenization (e.g. by using ultra sonics and then mixing with a non-magnetic stirrer).
d) Introduce the fluid volume into the injection reservoir, start the recirculation pump (see Figure 1, itemkey
12), introduce the test contaminant prepared in b) and c) above, and allow to circulate for at least 15
minutes min.
e) Set the injection flow rate at the minimum Q value, continuously controlling the value displayed by the
i
flow rate meter and the height of the fluid in the injection reservoir. Start the injection into the test
reservoir.
NOTE : It is preferable to inject the contaminant by means of a flexible pipe in order to facilitate the sampling
operations at the injection point.
f) Every 30 min, during a 6 h period, take a 200 ml sample via sampling valve (see Figure 1, itemkey 13) and
at the injection point in the main circuit. Determine the suspended solids concentration in accordance
with ISO 11923.
g) The injection circuit is validated if the following conditions are satisfied:
— the injection flow recorded values does not differ by more than 5 % in terms of coefficient of variation
(see definition in §5.3.1.2.1 h.) 1);
— suspended solids for each of the injection concentrations do not differ by more than 5 % of the average
measured concentration.;
Real— real average measured concentration does not differ by more than 10 % of the theoretical
concentration.
6.4.2.45.3.1.2 5.3.1.2 Validation of the test circuit
a) Adjust the volume of the fluid VF in the main circuit to 6 l or the volume depending of reservoir
configuration;.
b) After fitting a tubular sleeve in place of the filter to be tested, set up the temperature regulation system
and the main recirculation pump adjusting the recirculation flow rate Q to 720 l/h.
r
Operate until the conditions have stabilized and, if necessary, readjust the fluid volume in the circuit at 6 l.
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ISO/DISFDIS 23820:20222023(E)
c) To the upstream and downstream sample valves (see Figure 1, itemskeys 6 and 7), connect on-line
automatic counters previously calibrated, regulating the flow rate through the sensors to the values
recommended by the manufacturer of the automatic counters.
d) Introduce into the reservoir of each injection circuit, mass M and M of contaminant, previously oven-
i1 i2
dried and desiccated, to obtain the theoretical test concentrations of C = 5 mg/l and C = 800 mg/l.
e e
e) Start the validation with a 1hour1 h phase at the test concentration C = 5 mg/l during which in-line
e
counts are carried out, via upstream and downstream sample valves (see Figure 1, itemskeys 6 and 7), for
30 s every minute, at the thresholds selected in Tables 2a. Table 2.
f) Close the upstream sampling valve (see Figure 1, itemkey 6).
g) The downstream sensor having been previously disconnected, follow this by a 6 hours h phase with a
concentration C = 800 mg/l. Collect the entire volume V which has run off via downstream sampling
e CPV
valve (see Figure 1, itemkey 7) at the nominal counting flow rate and determine its suspended solids
concentration (S ) in accordance with ISO 11923.
SC
h) The test circuit is validated, if the following four conditions are satisfied:
h.1/) The coefficient of variation C (%)[%] for each sensor during the phase e) of this clause is less
OV
than or equal to that given in Table 3 2. The coefficient of variation is calculated as per the following
formula Formula (3):
σ
C ×100
OV
x
𝜎𝜎
𝐶𝐶 = × 100 , (3)
𝑂𝑂𝑂𝑂
ẋ
n n
2
nx()− x ²
ii
∑∑( )
ii11
σ = (4)
nn( −1)
n
x
∑ i
i=1
x =
, (5)
n
NOTE C beingis expressed in (%)as a percentage [%].
OV
𝑛𝑛 2 𝑛𝑛
𝑛𝑛∑ (𝑥𝑥 )−(∑ 𝑥𝑥 )²
𝑖𝑖=1 𝑖𝑖 𝑖𝑖=1 𝑖𝑖
𝜎𝜎 = � (4)
𝑛𝑛(𝑛𝑛−1)
𝑛𝑛
∑ 𝑥𝑥
𝑖𝑖
𝑖𝑖=1
ẋ = (5)
𝑛𝑛
Table 3 2 — Percentage of variation in the number of particles per counter
Thresholds d > 5 d > 10 d > 15 d > 25 d > 40
([μm)]
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==
=
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ISO/DISFDIS 23820:20222023(E)
ISO MTD 5 7 10 32 55
(%)
[%]
h.2/) The %percentage difference at different thresholds in the counting results between the two
sensors during the phase e) is less than or equal to that given in Table 4. 3.
Table 4 3 — Percentage difference in the number of particles between two counters
Thresholds > 5 > 7 > 10 > 12 > 15 > 20 > 30 > 40
([μm) ]
Difference 5,1 5,3 5,6 5,6 6,3 7 10 10
(%) [%]
If the table 4 conditions of Table 3 are not met, repeat the phase e) and adjust the downstream sensor
only in order to reduce the variation at the corresponding sizes.
h.3/) The mass of contaminant collected during the phase g) at downstream sampling valve (see
Figure 1, itemskey 7) dodoes not deviate by more than 30 % from the injected masses.
This mass of contaminant is calculated by multiplying the collected volume V and the corresponding
suspended solids concentration SSC as per the following formula:Formula (6):
mV × S
sc
𝑚𝑚 =𝑉𝑉 ×𝑆𝑆 (6)
𝑠𝑠𝑠𝑠
h.4/) The particle size distribution of ISO MTD obtained at e) should comply with the table 5
Table 5 4.
Table 4 — Particle size distribution of ISO MTD (informative data)
Size (> Cumulative counts
[> µm)] in 1 ml of solution of ISO
MTD at 1 mg/l
5 725 +/- 160
6 415 +/- 100
8 182 +/- 46
10 92 +/- 54
15 18.,2 +/- 9
20 5.,6 +/- 2.,8
6.85.4 5.4 Procedure
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=
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ISO/DISFDIS 23820:20222023(E)
6.8.35.4.1 5.4.1 Operating conditions
6.8.3.25.4.1.1 5.4.1.1 Fixed conditions
The following operating conditions shall be used:
a) test flow rate: manufacturer's specified flow rate as defined on the product label;(; (it should include the
upstream counting flowrate));
b) test contaminant: ISO MTD;
c) sampling method: during C = 5 mg/l phases both upstream (sampling valve see Figure 1, itemkey 6) and
e
downstream (sampling valve see Figure 1, itemkey 7) of the filter; and during C =800 mg/l (or other
e
value) phases only downstream of the filter;
d) counting method: on-line automatic particle counter using absorption of white light or laser beam
calibrated as per ISO 2350121501-3 with monosized latex beads;
e) level of initial cleanliness:
— injection circuit: less than 40 particles /ml >5 µm;
— main circuit: less than 10 particles /ml >5 µm;
f) duration of phases:
1) counting phase (C = 5 mg/l): 1 hour h;
e
2) clogging phase (C = 800 mg/l or other agreed concentration):6 hours h;
e
g) end of test: final differential pressure of 10 kPa or another agreed final differential pressure.
6.8.55.4.2 5.4.2 Preparation of the contaminant injection circuits
6.8.5.25.4.2.1 5.4.2.1 Calculation of the test conditions for injection circuit N° 1 (5 mg/l test
concentration)
a) Select the injection flow rate value (Q ) as a function of the sampling flow rates upstream and
i1
downstream of the filter under test and of a possible additional draw-off flow rate in order to guarantee
the stability of the fluid volume in the main circuit throughout the test. The sampling flow rates are set to
the flow rates required for the particle counters.
b) Calculate the total volume Vi1 in literslitres of fluid required for injecting the contaminant during the
scheduled hour for the test, from the injection flow rate Q ([l/h)] and with adding a safety margin of
i1
20 %:
VQ = 1,2
i1 i1
( )
𝑉𝑉 = 1,2 𝑄𝑄 7
𝑖𝑖1 𝑖𝑖1
(7)
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ISO/DISFDIS 23820:20222023(E)
c) Calculate the concentration C ([mg/l)] of the contaminant in injection circuit N° 1:
i1
CQ ×
( )
er
C =
i1
Q
i1
( )
𝐶𝐶𝐶𝐶 ×𝑄𝑄𝑄𝑄
( )
𝐶𝐶 = 8
𝑖𝑖1
𝑄𝑄
𝑖𝑖1
(8)
where C = 5 mg/l and Q (recirculation flow rate) = 720 l/h (by default)).
e r
d) Calculate the quantity M in grams of contaminant required to be introduced into the injection water in
i1
order to conform to the previously calculated test conditions, according to the following equation:Formula
(9):
(C ×V )
i1 i1
M =
i1
1 000
( )
𝐶𝐶 ×𝑂𝑂
𝑖𝑖1 𝑖𝑖1
𝑀𝑀 = (9).
𝑖𝑖1
1000
5.4.2.2 (9)
6.8.5.35.4.2.2 Calculation of the test conditions for injection circuit N° 2 (800 mg/l test concentration
or other concentration according with the customer)
a) Select the
...
FINAL
INTERNATIONAL ISO/FDIS
DRAFT
STANDARD 23820
ISO/TC 22/SC 34
Determination of the filtration
Secretariat: ANSI
efficiency of urea filter modules
Voting begins on:
2023-01-31
Détermination de l'efficacité de filtration des modules de filtres à urée
Voting terminates on:
2023-03-28
RECIPIENTS OF THIS DRAFT ARE INVITED TO
SUBMIT, WITH THEIR COMMENTS, NOTIFICATION
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THEY ARE AWARE AND TO PROVIDE SUPPOR TING
DOCUMENTATION.
IN ADDITION TO THEIR EVALUATION AS
Reference number
BEING ACCEPTABLE FOR INDUSTRIAL, TECHNO-
ISO/FDIS 23820:2023(E)
LOGICAL, COMMERCIAL AND USER PURPOSES,
DRAFT INTERNATIONAL STANDARDS MAY ON
OCCASION HAVE TO BE CONSIDERED IN THE
LIGHT OF THEIR POTENTIAL TO BECOME STAN-
DARDS TO WHICH REFERENCE MAY BE MADE IN
NATIONAL REGULATIONS. © ISO 2023
---------------------- Page: 1 ----------------------
ISO/FDIS 23820:2023(E)
FINAL
INTERNATIONAL ISO/FDIS
DRAFT
STANDARD 23820
ISO/TC 22/SC 34
Determination of the filtration
Secretariat: ANSI
efficiency of urea filter modules
Voting begins on:
Détermination de l'efficacité de filtration des modules de filtres à urée
Voting terminates on:
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DOCUMENTATION.
Phone: +41 22 749 01 11
IN ADDITION TO THEIR EVALUATION AS
Reference number
Email: copyright@iso.org
BEING ACCEPTABLE FOR INDUSTRIAL, TECHNO
ISO/FDIS 23820:2023(E)
Website: www.iso.org
LOGICAL, COMMERCIAL AND USER PURPOSES,
DRAFT INTERNATIONAL STANDARDS MAY ON
Published in Switzerland
OCCASION HAVE TO BE CONSIDERED IN THE
LIGHT OF THEIR POTENTIAL TO BECOME STAN
DARDS TO WHICH REFERENCE MAY BE MADE IN
ii
© ISO 2023 – All rights reserved
NATIONAL REGULATIONS. © ISO 2023
---------------------- Page: 2 ----------------------
ISO/FDIS 23820:2023(E)
Contents Page
Foreword .iv
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Symbols . 2
5 Test procedures . 3
5.1 Principle . 3
5.2 Test equipment and materials . 4
5.2.1 Test rig . 4
5.2.2 Filter test circuit . 4
5.2.3 Contaminant injection circuits . 5
5.2.4 Automatic particle counting devices . 6
5.2.5 Test fluid . 6
5.2.6 Test contaminant . 6
5.2.7 Stop watch . 6
5.2.8 Ultra clean bottles . 6
5.2.9 Ultrasonic bath . 6
5.3 Test rig validation . 6
5.3.1 General . 6
5.4 Procedure . 9
5.4.1 Operating conditions . 9
5.4.2 Preparation of the contaminant injection circuits . 10
5.4.3 Preparation of the test circuit . 11
5.4.4 Filter efficiency and retention capacity test . 11
5.5 Expression of results . .13
5.6 Test report . 13
Annex A (informative) Determination of the initial filtration efficiency as per this document .15
Bibliography .21
iii
© ISO 2023 – All rights reserved
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ISO/FDIS 23820:2023(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 nongovernmental, 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).
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This document was prepared by Technical Committee ISO/TC 22, Road vehicles, Subcommittee SC 34,
Propulsion, powertrain and powertrain fluids.
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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FINAL DRAFT INTERNATIONAL STANDARD ISO/FDIS 23820:2023(E)
Determination of the filtration efficiency of urea filter
modules
1 Scope
This document specifies requirements relating to the testing method for AUS 32/diesel exhaust fluid
(DEF) filters for the removal of suspended matter. This applies to urea filters dedicated to passenger
vehicles as well as to commercial vehicles. This method applies to filters with flow rates from 3 l/h to
30 l/h depending on the application (by default 5 l/h for passenger vehicles and 25 l/h for commercial
vehicles). This method can be used for other flow rates, provided the validation requirement can be
met.
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 11218, Aerospace — Cleanliness classification for hydraulic fluids
ISO 11923, Water quality — Determination of suspended solids by filtration through glass-fibre filters
ISO 215013, 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 following terms and definitions 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/
3.1
cumulative overall mean filtration efficiency
E
x
cumulative efficiency calculated from the total number of particles greater than size x [µm] counted
upstream and downstream of a filter during the initial 60 min counting period at 5 mg/l
Note 1 to entry: The efficiency is expressed in [%].
3.2
differential pressure
ΔP
pressure difference between the inlet and outlet of the complete filter unit measured under
predetermined conditions
Note 1 to entry: The differential pressure generated by the complete filter is equal to the sum of the differential
pressures generated by the housing and by the filter element (in case the filter element is removable from the
housing).
Note 2 to entry: The differential pressure is expressed in kPa.
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ISO/FDIS 23820:2023(E)
3.3
ISO MTD
ISO medium test dust
siliceous test powder having a particle size distribution by volume in accordance with ISO 12103-1, A3
Note 1 to entry: It may also be referred as ISO 12103-1 A3 dust.
3.4
nominal flow rate
Q
flow rate for the filter specified by the manufacturer
Note 1 to entry: The flow rate is expressed in l/h.
3.5
reference filtration rating
S
dimension of the ISO MTD particles at which the overall mean cumulative filtration efficiency of
the integral filter (or the filter element) tested in accordance with the procedure described in this
document, is greater than or equal to 99 %
Note 1 to entry: The reference filtration rating is expressed in µm.
4 Symbols
The symbols used in this document are given in Table 1.
Table 1 — Symbols
Symbol Parameter Unit
C Test concentration mg/l
e
C Injection concentration mg/l
i
C Retention capacity g
R
C Concentration of the downstream fluid during the clogging
NR
mg/l
period
C Coefficient of variation %
ov
d Size of the particle μm
ΔP Loss of pressure due to the clean filter alone kPa
0
ΔP Loss of pressure at the end of the test kPa
F
E Cumulative efficiency at size greater than x µm %
x
M Mass of contaminant necessary for the test g
M Injected mass of contaminant in injection reservoir 1 g
i1
M Injected mass of contaminant in injection reservoir 2 g
i2
th
N > x µm i particle count upstream at x µm /ml
i UP
th
N > x µm i particle count downstream at x µm /ml
i DW
Q Flow rate l/h
Q Recirculation flow rate l/h
r
Q Injection flow rate circuit 1 (relative to the efficiency con
C1
l/h
centration)
Q Injection flow rate circuit 2 (relative to the capacity con
C2
l/h
centration)
S Suspended solid concentration mg/l
sc
V Injection circuit N°1 fluid volume l
i1
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ISO/FDIS 23820:2023(E)
TTaabblle 1 e 1 ((ccoonnttiinnueuedd))
Symbol Parameter Unit
V Injection circuit N°2 fluid volume l
i2
V Injection circuit maximum fluid volume l
iM
V Recovered downstream volume during the clogging period l
CP
V Recovered downstream volume during the validation of
CPV
l
the clogging period
ΔT Time duration of the clogging period h
CP
5 Test procedures
5.1 Principle
The performance of the filter to be tested is determined by measuring its hydraulic and separative
properties when subjected to a constant flow rate of water conveying a known quantity of contaminant.
The test is performed with the water after passage through clean-up filters to produce a single pass
configuration. The test is conducted in two stages.
The first stage determines the initial efficiency of the test filter. It is conducted with a contaminant
concentration of 5 mg/l upstream to the test filter for 60 min. The second stage determines the mass of
contaminant needed to reach a specified differential pressure. This stage is conducted with an upstream
concentration of 800 mg/l, or as specified according to the customer specification. The retention
capacity shall be determined from the mass of contaminant required for obtaining a predetermined
differential pressure of 10 kPa or other value according to customer’s specifications. Several operating
parameters are specified as a function of the type of filter under test, e.g. the standard flow rate of
5 l/h is recommended for testing a standard urea filter module for passenger vehicles and 25 l/h for
commercial vehicles, unless otherwise specified.
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ISO/FDIS 23820:2023(E)
5.2 Test equipment and materials
5.2.1 Test rig
Key
1A injection reservoir for efficiency period at 5 mg/l (N°1) 8 main recirculation pump
1B injection reservoir for clogging period at maximum 9 regulating level volume system
800 mg/l (N°2)
2 clean up filter 10 recirculation injection loop pump
3 main reservoir (6 l) 11A injection circuit (N°1) sampling valve
4 flow meter 11B injection circuit (N°2) sampling valve
5A upstream side particle counter 12 three-way valves
5B downstream side particle counter 13 heat exchanger
6 counter pressure control valve 14 temperature sensor
7 injection pump
Figure 1 — Diagram of filtration efficiency and retention capacity test rig
5.2.2 Filter test circuit
The filter test circuit is designed to permit the recycling of the fluid being filtered. Both return line
and recirculation loops are equipped with clean-up filters which retain all of the test particles that
have passed through the test filter or before going back to the main reservoir (a filtration efficiency of
99 % at 1 µm is suitable for such clean up filters). In case of multiple usage of the test liquid, the risk of
biological growth is given. Suitable control and countermeasures shall be implemented.
The test circuit comprises the following:
a) a conical bottom reservoir having a recommended cone angle less than or equal to 90°. Its volume
is of 6 l. The residence time inside the reservoir shall be of 30 s and the height shall be preferably
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ISO/FDIS 23820:2023(E)
between twice and three times its diameter. Other type reservoir with other volumes can be used
if requirements of 5.3.1.2 are fulfilled. The recycled water return line penetrates beneath the free
face so as to avoid the risk of air entrainment;
b) a main circulation pump which ensures a constant, non-pulsed flow rate Q of at least twice the
r
volume unit (when expressed in l/min) (i.e. at least 12 l/min or 720 l/h) throughout the test
duration, particularly when the filter is clogged. It shall be resistant to the test contaminant by not
modifying the particle size distribution;
c) a bypass circuit from the main recirculation loop allowing to circulate through the urea filter under
test in a single pass way;
d) two clean-up filters dedicated to the main recirculation loop and the bypass filter test loop to
restore the level of the test fluid’s particulate contamination at less than 10 particles /ml >5 µm;
e) instruments for measuring the flow rate, the temperature, the differential pressures at the filter
connections;
f) two sampling devices in accordance with ISO 4021 put upstream and downstream of the filter in
order to ensure representative sampling of the water and contaminant and connected to automatic
particle counting devices (see 5.2.4);
g) interconnecting pipe and fittings, dimensioned and selected so as to ensure a turbulent flow
throughout the whole circuit, thereby preventing the formation of traps, segregation and quiescent
zones. The length of the piping shall be reduced to the minimum;
h) clean water level control device in the test reservoir, to regulate the level within 5 %;
i) temperature regulator to control the temperature at the specified value of (23 ± 2) °C;
j) all the pipes, connections, reservoirs shall be 316L INOX with the best polishing procedure available
to avoid the abrasive mix of sand and water.
5.2.3 Contaminant injection circuits
There are two injection circuits; one is allocated to 5 mg/l injection (injection circuit N° 1), the other for
800 mg/l injection (injection circuit N° 2).
Each injection circuit includes the following equipment:
a) conical bottom reservoir having a recommended cone angle less than or equal to 90°. Its height
is preferably between twice or three times its diameter. Other configured reservoir can be used
if requirements of 5.3.1.1 are fulfilled. It is equipped with a level indicator. The recycled water
returns beneath the free face;
b) recirculation pump which generates a flow rate to ensure sufficient mixing to meet the requirements
in 5.3. It shall be resistant to the test contaminant by not modifying the particle size distribution;
c) temperature regulation device to control the water temperature at 23 ± 2 °C;
d) clean-up filter, installed to by-pass the injection loop, capable of achieving a cleanliness level at less
than 40 particles/ml >5 µm;
e) contaminant injection pump which draws the concentrated contaminant into the recirculation
system at a point where the flow is turbulent and discharges it via a flexible pipe into the main
pump suction in case of injection circuit N°1 or upstream to the urea filter in case of injection
circuit N°2. There is a three-way valve to switch from injection circuit N°1 to injection circuit N°2.
It shall not generate any excessive flow rate pulsation and shall have no effect on the contaminant.
The injection flow rate shall be sufficient to prevent segregation of the test dust;
f) sampling device conforming to ISO 4021;
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ISO/FDIS 23820:2023(E)
g) device for measuring the injection flow rate, insensitive to the contaminant and without effect on
its particle size distribution at the concentrations scheduled for the test.
5.2.4 Automatic particle counting devices
These devices comprise one or two counters and two optical units.
These devices operate on the light extinction principle; they shall be properly calibrated using certified
monosized latex spheres as per ISO 21501-3.
Ensure the concentration level of the particle sensors is capable of operating in the required system
concentration levels.
5.2.5 Test fluid
The test fluid shall be demineralized and filtered water with a cleanliness level of less than 10 particles
/ml >5 µm.
NOTE Using demineralized water will prevent a chemical reaction of the silica inside the injection and test
circuits.
5.2.6 Test contaminant
The test contaminant shall be silica test dust specified as ISO MTD.
5.2.7 Stop watch
5.2.8 Ultra clean bottles
Use thoroughly cleaned sample bottles when filled with micro-filtered water. The cleanliness level of
the bottle shall be CSC (0) as per ISO 11218.
5.2.9 Ultra-sonic bath
The characteristics should be the following one: power of 25 W/l with an ultra-sonic frequency varying
between 30 and 40 kHz.
5.3 Test rig validation
5.3.1 General
The purpose of the validation is to demonstrate that the test rig complies with the test requirements.
The validation shall be carried out again whenever a component of the installation is modified or
changed.
5.3.1.1 Validation of the injection circuits
The two injection circuits for attaining test concentrations of 5 mg/l and 800 mg/l shall be successively
validated.
The validation is conducted with the maximum volume (V ) in each tank and at the minimum flow
iM
rates for the injection circuits. Before starting, make sure that both injection reservoirs N°1 and N°2
are clean enough (initial cleanliness level of less than 40 particles /ml >5 µm).
a) Calculate the two injection circuit contamination concentrations so that the concentration in the
test circuit.
C = 5 mg/l (injection circuit N° 1) or C = 800 mg/l (injection circuit N° 2):
e e
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ISO/FDIS 23820:2023(E)
QC
e
C = (1)
i
Q
i
where
Q is the flow rate expressed in l/h:
— (circulation loop flowrate Q of 720 l/h (or either) in case of injection circuit N°1);
r
or
— (urea/DEF filter test flowrate Q in case of injection circuit N°2);
Q is the minimum value of the injection flow rate, in l/h;
i
C is the injection circuit contaminant concentration, in mg/l.
i
b) Prepare a mass M of test dust ISO MTD, previously dried at a temperature between 110 °C to 150 °C
for at least 1 h and cooled to room temperature in a desiccator, to obtain the previously calculated
concentration Ci:
MV= C (2)
iM i
where
M is the mass of test dust, in mg;
V is the injection circuit maximum fluid volume, in l;
iM
C is the injection circuit contaminant concentration, in mg/l.
i
c) Disperse the contaminant in 200 ml of water taken from the injection reservoir ensuring complete
homogenization (e.g. by using ultra sonics and then mixing with a non-magnetic stirrer).
d) Introduce the fluid volume into the injection reservoir, start the recirculation pump (see Figure 1,
key 12), introduce the test contaminant prepared in b) and c) above, and allow to circulate for at
least 15 min.
e) Set the injection flow rate at the minimum Q value, continuously controlling the value displayed by
i
the flow rate meter and the height of the fluid in the injection reservoir. Start the injection into the
test reservoir.
NOTE It is preferable to inject the contaminant by means of a flexible pipe in order to facilitate the
sampling operations at the injection point.
f) Every 30 min, during a 6 h period, take a 200 ml sample via sampling valve (see Figure 1, key 13)
and at the injection point in the main circuit. Determine the suspended solids concentration in
accordance with ISO 11923.
g) The injection circuit is validated if the following conditions are satisfied:
— the injection flow recorded values does not differ by more than 5 % in terms of coefficient of
variation (see definition in 5.3.1.2 h) 1);
— suspended solids for each of the injection concentrations do not differ by more than 5 % of the
average measured concentration;
— real average measured concentration does not differ by more than 10 % of the theoretical
concentration.
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ISO/FDIS 23820:2023(E)
5.3.1.2 Validation of the test circuit
a) Adjust the volume of the fluid V in the main circuit to 6 l or the volume depending of reservoir
F
configuration.
b) After fitting a tubular sleeve in place of the filter to be tested, set up the temperature regulation
system and the main recirculation pump adjusting the recirculation flow rate Q to 720 l/h.
r
Operate until the conditions have stabilized and, if necessary, readjust the fluid volume in the circuit at
6 l.
c) To the upstream and downstream sample valves (see Figure 1, keys 6 and 7), connect on-line
automatic counters previously calibrated, regulating the flow rate through the sensors to the
values recommended by the manufacturer of the automatic counters.
d) Introduce into the reservoir of each injection circuit, mass M and M of contaminant, previously
i1 i2
ovendried and desiccated, to obtain the theoretical test concentrations of C = 5 mg/l and C =
e e
800 mg/l.
e) Start the validation with a 1 h phase at the test concentration C = 5 mg/l during which inline
e
counts are carried out, via upstream and downstream sample valves (see Figure 1, keys 6 and 7),
for 30 s every minute, at the thresholds selected in Table 2.
f) Close the upstream sampling valve (see Figure 1, key 6).
g) The downstream sensor having been previously disconnected, follow this by a 6 h phase with a
concentration C = 800 mg/l. Collect the entire volume V which has run off via downstream
e CPV
sampling valve (see Figure 1, key 7) at the nominal counting flow rate and determine its suspended
solids concentration (S ) in accordance with ISO 11923.
SC
h) The test circuit is validated if the following four conditions are satisfied:
1) The coefficient of variation C [%] for each sensor during the phase e) of this clause is less than
OV
or equal to that given in Table 2. The coefficient of variation is calculated as per Formula (3):
σ
C =×100, (3)
OV
x
n n
2
nx()− x ²
∑∑i ()i
i==1 i 1
σ = (4)
nn()−1
n
x
∑ i
i=1
x = (5)
n
NOTE C is expressed as a percentage [%].
OV
Table 2 — Percentage of variation in the number of particles per counter
Thresholds d > 5 d > 10 d > 15 d > 25 d > 40
[μm]
ISO MTD 5 7 10 32 55
[%]
2) The percentage difference at different thresholds in the counting results between the two
sensors during the phase e) is less than or equal to that given in Table 3.
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ISO/FDIS 23820:2023(E)
Table 3 — Percentage difference in the number of particles between two counters
Thresholds > 5 > 7 > 10 > 12 > 15 > 20 > 30 > 40
[μm]
Difference 5,1 5,3 5,6 5,6 6,3 7 10 10
[%]
If the conditions of Table 3 are not met, repeat the phase e) and adjust the downstream sensor only
in order to reduce the variation at the corresponding sizes.
3) The mass of contaminant collected during the phase g) at downstream sampling valve (see
Figure 1, key 7) does not deviate by more than 30 % from the injected masses.
This mass of contaminant is calculated by multiplying the collected volume V and the corresponding
suspended solids concentration S as per Formula (6):
SC
mV =× S (6)
sc
4) The particle size distribution of ISO MTD obtained at e) should comply with the Table 4.
Table 4 — Particle size distribution of ISO MTD (informative data)
Size Cumulative counts
[> µm] in 1 ml of solution of ISO
MTD at 1 mg/l
5 725 +/ 160
6 415 +/ 100
8 182 +/ 46
10 92 +/ 54
15 18,2 +/ 9
20 5,6 +/ 2,8
5.4 Procedure
5.4.1 Operating conditions
5.4.1.1 Fixed conditions
The following operating conditions shall be used:
a) test flow rate: manufacturer's specified flow rate as defined on the product label; (it should include
the upstream counting flowrate);
b) test contaminant: ISO MTD;
...
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