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

General Information

Status

Published

Publication Date

18-May-2023

ICS

43.060.40 - Fuel systems

Technical Committee

ISO/TC 22/SC 34 - Propulsion, powertrain and powertrain fluids

Drafting Committee

ISO/TC 22/SC 34/WG 1 - Fuel filters

Current Stage

6060 - International Standard published

Start Date

19-May-2023

Due Date

24-Feb-2023

Completion Date

19-May-2023

Ref Project

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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

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
© ISO 2023 – All rights reserved
---------------------- Page: 2 ----------------------
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

iii
© ISO 2023 – All rights reserved
---------------------- Page: 3 ----------------------
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.
© ISO 2023 – All rights reserved
---------------------- 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

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

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.
© ISO 2023 – All rights reserved
---------------------- Page: 5 ----------------------
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
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

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
C Injection concentration mg/l
C Retention capacity g
C Concentration of the downstream fluid during the clogging
mg/l
period
C Coefficient of variation %
d Size of the particle μm
ΔP Loss of pressure due to the clean filter alone kPa
ΔP Loss of pressure at the end of the test kPa
E Cumulative efficiency at size greater than x µm %
M Mass of contaminant necessary for the test g
M Injected mass of contaminant in injection reservoir 1 g
M Injected mass of contaminant in injection reservoir 2 g
N > x µm i particle count upstream at size >x µm -/ml
i UP
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
Q Injection flow rate circuit 1 (relative to the efficiency con-
l/h
centration)
Q Injection flow rate circuit 2 (relative to the capacity con-
l/h
centration)
S Suspended solid concentration mg/l
V Injection circuit N°1 fluid volume l
© ISO 2023 – All rights reserved
---------------------- Page: 6 ----------------------
ISO 23820:2023(E)
TTaabblle 1 e 1 ((ccoonnttiinnueuedd))
Symbol Parameter Unit
V Injection circuit N°2 fluid volume l
V Injection circuit maximum fluid volume l
V Recovered downstream volume during the clogging period l
V Recovered downstream volume during the validation of
CPV
the clogging period
ΔT Time duration of the clogging period h
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.
© ISO 2023 – All rights reserved
---------------------- Page: 7 ----------------------
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

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

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;
© ISO 2023 – All rights reserved
---------------------- Page: 9 ----------------------
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

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
© ISO 2023 – All rights reserved
---------------------- Page: 10 ----------------------
ISO 23820:2023(E)
C = (1)
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);

— (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;
C is the injection circuit contaminant concentration, in mg/l.

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;
C is the injection circuit contaminant concentration, in mg/l.

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

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.
© ISO 2023 – All rights reserved
---------------------- Page: 11 ----------------------
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

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.

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

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.
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

or equal to that given in Table 2. The coefficient of variation is calculated as per Formula (3):

C =×100 , (3)
n n
nx()− x ²
∑∑i ()i
i==1 i 1
σ = (4)
nn()−1
∑ i
i=1
x = (5)
NOTE C is expressed as a percentage [%].
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.
© ISO 2023 – All rights reserved
---------------------- Page: 12 ----------------------
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):
mV =× S (6)

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)

and downstream (sampling valve see Figure 1, key 5B) of the filter; and during C =800 mg/l (or

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;
© ISO 2023 – All rights reserved
---------------------- Page: 13 ----------------------
ISO 23820:2023(E)
f) duration of phases:
1) counting phase (C = 5 mg/l): 1 h;
2) clogging phase (C = 800 mg/l or other agreed concentration):6 h;

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
...

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
OF ANY RELEVANT PATENT RIGHTS OF WHICH
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:
COPYRIGHT PROTECTED DOCUMENT
© ISO 2023

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.
RECIPIENTS OF THIS DRAFT ARE INVITED TO
ISO copyright office
SUBMIT, WITH THEIR COMMENTS, NOTIFICATION
OF ANY RELEVANT PATENT RIGHTS OF WHICH
CP 401 • Ch. de Blandonnet 8
THEY ARE AWARE AND TO PROVIDE SUPPOR TING
CH-1214 Vernier, Geneva
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
© ISO 2023 – All rights reserved
NATIONAL REGULATIONS. © ISO 2023
---------------------- Page: 2 ----------------------
ISO/FDIS 23820:2023(E)
Contents Page