ISO 23820:2023

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

Standards Content (Sample)

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 2023
All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication may
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Published in Switzerland
ii
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
Foreword
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described in the ISO/IEC Directives, Part 1. In particular, the different approval criteria needed for the
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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
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.
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
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
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.
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
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;
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
...