ﺍﻟﻌﺭﺒﻴﺔ ﺍﻟﺨﻠﻴﺞ ﻟﺩﻭل ﺍﻟﺘﻌﺎﻭﻥ ﻤﺠﻠﺱ ﻟﺩﻭل ﺍﻟﺘﻘﻴﻴﺱ  ﻫﻴﺌﺔ 
GCC STANDARDIZATION ORGANIZATION (GSO) 
 
 
 
 
 
 ﻤﺸﺭﻭﻉ : ﻨﻬﺎﺌﻲ  
 
   
GSO2/FDS/ ISO 19438:2011 
ISO 19438:2003 
 
 
 
 ﻜﻔﺎﺀﺓ ـ ﺍﻟﺩﺍﺨﻠﻲ ﺍﻻﺤﺘﺭﺍﻕ  ﻟﻤﺤﺭﻜﺎﺕ  ﺍﻟﺩﻴﺯل ﻭﻭﻗﻭﺩ ﺍﻟﺒﻨﺯﻴﻥ ﻤﺭﺸﺤﺎﺕ
ﻭﺍﻟ ﺍﻟﺠﺴﻴﻤﺎﺕ  ﻋﺩ ﻁﺭﻴﻘﺔ ﺒﺎﺴﺘﺨﺩﺍﻡ  ﺍﻟﺘﺭﺸﻴﺢ  ﺍﻻﺤﺘﻔﺎﻅ  ﻋﻠﻰ ﻘﺩﺭﺓ
ﺍﻟﻤﻠﻭﺜﺔ ﺒﺎﻟﻤﺎﺩﺓ   
 
Diesel fuel and petrol filters fo r internal combustion engines – 
Filtration efficiency using pa rticle counting and contaminant 
retention capacity  
 
 إﻋﺪاد 
 ﺍﻟﻤﺭﻜﺒﺎﺕ  ﻤﻭﺍﺼﻔﺎﺕ  ﻟﻘﻁﺎﻉ ﺍﻟﻔﺭﻋﻴﺔ  ﺍﻟﺨﻠﻴﺠﻴﺔ  ﺍﻟﻔﻨﻴﺔ ﻭﺍﻹﻁﺎﺭﺍﺕﺍﻟﻠﺠﻨﺔ   
ﻫﺫ  ﻟﺫﻟﻙ ﺒﺸﺄﻨﻬﺎ، ﻭﺍﻟﻤﻼﺤﻅﺎﺕ  ﺍﻟﺭﺃﻱ ﻹﺒﺩﺍﺀ ﺘﻭﺯﻴﻌﻬﺎ  ﺘﻡ ﺨﻠﻴﺠﻴﺔ ﻗﻴﺎﺴﻴﺔ ﻟﻤﻭﺍﺼﻔﺔ  ﻤﺸﺭﻭﻉ  ﺍﻟﻭﺜﻴﻘﺔ ﻩ
 ﻤﻥ ﺍﻋﺘﻤﺎﺩﻫﺎ  ﺒﻌﺩ ﺇﻻ ﺨﻠﻴﺠﻴﺔ ﻗﻴﺎﺴﻴﺔ ﻜﻤﻭﺍﺼﻔﺔ  ﺇﻟﻴﻬﺎ ﺍﻟﺭﺠﻭﻉ  ﻴﺠﻭﺯ ﻭﻻ ﻭﺍﻟﺘﺒﺩﻴل،  ﻟﻠﺘﻐﻴﻴﺭ ﻋﺭﻀﺔ ﻓﺈﻨﻬﺎ
ﺍﻟﺨﻠﻴﺠﻴﺔ  ﺍﻟﻬﻴﺌﺔ ﺇﺩﺍﺭﺓ ﻤﺠﻠﺱ.   ﺁﻭ ﺇﺱ ﺠﻲ/ ﺁﻴﺯﻭ٨٣٤٩١ : ١١٠٢  ﺧﻠﻴﺠﻴﺔ  ﻗﻴﺎﺳﻴﺔ  ﻣﻮاﺻﻔﺔ
GSO STANDARD GSO/ISO 19438:2011  
 
1 ﺘﻘﺩﻴﻡ  
ﺍﻟﺨﻠﻴ ﻟﺩﻭل ﺍﻟﺘﻌﺎﻭﻥ ﻤﺠﻠﺱ ﻟﺩﻭل ﺍﻟﺘﻘﻴﻴﺱ ﻫﻴﺌﺔ  ﺍﻷﺠﻬﺯﺓ  ﻋﻀﻭﻴﺘﻬﺎ  ﻓﻲ ﺘﻀﻡ ﺇﻗﻠﻴﻤﻴﺔ ﻫﻴﺌﺔ ﺍﻟﻌﺭﺒﻴﺔ ﺞ
 ﺍﻟﻘﻴﺎﺴﻴﺔ ﺍﻟﻤﻭﺍﺼﻔﺎﺕ  ﺇﻋﺩﺍﺩ ﺍﻟﻬﻴﺌﺔ ﻤﻬﺎﻡ ﻭﻤﻥ ، ﺍﻟﻌﺭﺒﻴﺔ ﺍﻟﺨﻠﻴﺞ ﺩﻭل ﻓﻲ ﻭﺍﻟﻤﻘﺎﻴﻴﺱ  ﻟﻠﻤﻭﺍﺼﻔﺎﺕ  ﺍﻟﻭﻁﻨﻴﺔ
 ﻤﺘﺨﺼﺼﺔ  ﻓﻨﻴﺔ ﻟﺠﺎﻥ ﺒﻭﺍﺴﻁﺔ ﺍﻟﺨﻠﻴﺠﻴﺔ  . 
ﺍﻟﻠﺠﻨ ﻋﻤل ﺒﺭﻨﺎﻤﺞ ﻀﻤﻥ ﺍﻟﻌﺭﺒﻴﺔ ﺍﻟﺨﻠﻴﺞ ﻟﺩﻭل ﺍﻟﺘﻌﺎﻭﻥ ﻤﺠﻠﺱ ﻟﺩﻭل ﺍﻟﺘﻘﻴﻴﺱ ﻫﻴﺌﺔ ﻗﺎﻤﺕ ﻭﻗﺩ   ﺍﻟﻔﻨﻴﺔ ﺔ
 ٢ﺭﻗﻡ-١  " ﺍﻟﻤﺭﻜﺒﺎﺕ  ﻤﻭﺍﺼﻔﺎﺕ  ﻟﻘﻁﺎﻉ ﺍﻟﻔﺭﻋﻴﺔ ﺍﻟﺨﻠﻴﺠﻴﺔ  ﺍﻟﻔﻨﻴﺔ ﻭﺍﻹﻁﺎﺭﺍﺕﺍﻟﻠﺠﻨﺔ   "  ﺒﺘﺒﻨﻲ
 ﺁﻴﺯﻭ  ﺭﻗﻡ ﺍﻟﺩﻭﻟﻴﺔ ﺍﻟﻘﻴﺎﺴﻴﺔ ٨٣٤٩١ﺍﻟﻤﻭﺍﺼﻔﺔ /٣٠٠٢  " ﻟﻤﺤﺭﻜﺎﺕ  ﺍﻟﺩﻴﺯل ﻭﻭﻗﻭﺩ ﺍﻟﺒﻨﺯﻴﻥ ﻤﺭﺸﺤﺎﺕ
ﺍﻻﺤﺘﻔﺎ ﻋﻠﻰ ﻭﺍﻟﻘﺩﺭﺓ ﺍﻟﺠﺴﻴﻤﺎﺕ  ﻋﺩ ﻁﺭﻴﻘﺔ ﺒﺎﺴﺘﺨﺩﺍﻡ  ﺍﻟﺘﺭﺸﻴﺢ  ﻜﻔﺎﺀﺓ ـ ﺍﻟﺩﺍﺨﻠﻲ ﺍﻻﺤﺘﺭﺍﻕ  ﺒﺎﻟﻤﺎﺩﺓ ﻅ
ﺍﻟﻤﻠﻭﺜﺔ“   – ﺃﺼﺩﺭﺘﻬﺎ  ﻭﺍﻟﺘﻲ" ﻟﻠﺘﻘﻴﻴﺱ ﺍﻟﺩﻭﻟﻴﺔ ﺍﻟﻤﻨﻅﻤﺔ"  ، ﺍﻟﻌﺭﺒﻴﺔ ﺒﺎﻟﻠﻐﺔ ﺘﺭﺠﻤﺘﻬﺎ  ﻭﺘﻤﺕ  ﻭﻗﺎﻤﺕ 
ﺍﻟﻤﻭﺍﺼﻔﺔﺔﺍﻟﻤﻤﻠﻜ  ﻫﺫﻩ ﻤﺸﺭﻭﻉ  ﺒﺈﻋﺩﺍﺩ ﺍﻟﺴﻌﻭﺩﻴﺔ  ﺍﻟﻌﺭﺒﻴﺔ  . 
 ﺍﻟﻤﻭﺍﺼﻔﺔ  ﻫﺫﻩ ﺍﻋﺘﻤﺩﺕ  ﻭﻗﺩ  ﻋﻠﻴﻬﺎ ﻓﻨﻴﺔ ﺘﻌﺩﻴﻼﺕ  ﺃﻴﺔ ﺇﺩﺨﺎل ﺩﻭﻥ ﺨﻠﻴﺠﻴﺔ ﻗﻴﺎﺴﻴﺔ ﻜﻤﻭﺍﺼﻔﺔ  ﻓﻲ ﻭﺫﻟﻙ
 ﺭﻗﻡ ﺍﻟﻬﻴﺌﺔ ﺇﺩﺍﺭﺓ ﻤﺠﻠﺱ ﺍﺠﺘﻤﺎﻉ      )          (  ﺒﺘﺎﺭﻴﺦ         ﻋﻘﺩ ﺍﻟﺫﻱ ، /      /       ، ﻫـ
      ﺍﻟﻤﻭﺍﻓﻕ/      /       ﻡ  .
  
  
 
Foreword 
 
GCC Standardization Organization (GSO ) is a regional Organization which 
consists of the National Standards B odies of GCC member  States. One of 
GSO main functions is to issue Gulf Standards through specialized technical 
committees (TCs). GSO through the technical program of  committee TC No.2-1: " The Gulf 
technical Subcommittee for vehicles an d tyres standards” has adopted the 
International Standard No . : ISO 19438:2003  “Diesel fuel and petrol filters 
for internal combustion engines – Filtra tion efficiency using particle counting 
and contaminant retention capacity " is sued by International Organization for 
Standardization which has been translat ed into Arabic. The Draft Standard 
has been prepared by Kingdom of Saudi Arabia This standard has been approved as Gulf Standard without any technical 
modifications by GSO Board of Director s in its meeting No..../....  …….held 
on    /    /   /  H ,   /    /   G  
 
     
 Reference numbe r
ISO 19438:2003(E)
© ISO 2003
  
 INTERNATIONAL 
STANDARD  ISO
19438
First edition
2003-11-01
Corrected version
2004-06-15
Diesel fuel and petrol filters for internal 
combustion engines — Filtration efficiency using particle counting and contaminant retention capacity 
Filtres à carburant, essence ou diesel, pour moteurs à combustion 
interne — Efficacité de filtration par comptage des particules et capacité 
de rétention 
 ISO 19438:2003(E) 
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©   ISO 2003 
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ii  © ISO 2003 — All rights reserved
  ISO 19438:2003(E) 
© ISO 2003 — All rights reserved   iii
 Contents Page 
Foreword....................................................................................................................... ..................................... iv  
Introduction ................................................................................................................... ..................................... v  
1 Scope.......................................................................................................................... ............................ 1  
2 Normative references ........................................................................................................... ................ 1  
3 Terms and definitions.......................................................................................................... ................. 2  
4 Symbols ........................................................................................................................ ......................... 2  
5 Test equipment and materials ................................................................................................... .......... 2  
5.1 Test equipment................................................................................................................. ..................... 2  
5.2 Test materials ................................................................................................................. ....................... 5  
6 Accuracy of measuring instruments and test conditions ................................................................ 5  
7 Test rig validation ............................................................................................................ ..................... 6  
7.1 General........................................................................................................................ ........................... 6  
7.2 Validation of the on-line dilution and particle counting system ...................................................... 6  
7.3 Validation of filter test circuit .............................................................................................. ................ 6  
7.4 Validation of contaminant injection circuit .................................................................................... .... 7 
8 Preliminary preparation........................................................................................................ ................ 7  
8.1 Test filter assembly........................................................................................................... .................... 7  
8.2 Contaminant injection circuit .................................................................................................. ............ 7  
8.3 Filter test circuit ............................................................................................................ ........................ 9  
9 Test procedure ................................................................................................................. ..................... 9  
9.1 Initial procedure .............................................................................................................. ...................... 9  
9.2 Filter test .................................................................................................................... .......................... 11  
10 Calculation and reporting of test results...................................................................................... .... 12  
10.1 Test report .................................................................................................................... ....................... 12  
10.2 Calculation.................................................................................................................... ....................... 12  
Annex A (normative)   Specification of test fluid for filter test ...................................................................... 15  
Annex B (informative)   Typical filter test report, presentation of test results............................................. 17  
Annex C (informative)   Example filter efficiency calculations ...................................................................... 22  
Annex D (informative)   Summary of the International interlaboratory trial (“round robin”) to 
validate ISO 19438 protocol .................................................................................................... ........... 26  
Bibliography ................................................................................................................... .................................. 38  
 ISO 19438:2003(E) 
iv  © ISO 2003 — All rights reserved
 Foreword 
ISO (the International Organization for Standardization) is a worldwide federation of national standards bodies 
(ISO member bodies). The work of preparing International Standards is normally carried out through ISO 
technical committees. Each member body interested in a subject for which a technical committee has been 
established has the right to be represented on that committee. International organizations, governmental and non-governmental, in liaison with ISO, also take part in the work. ISO collaborates closely with the International Electrotechnical Commission (IEC) on all matters of electrotechnical standardization. 
International Standards are drafted in accordance with the rules given in the ISO/IEC Directives, Part 2. The main task of technical committees is to prepare International Standards. Draft International Standards 
adopted by the technical committees are circulated to the member bodies for voting. Publication as an 
International Standard requires approval by at least 75 % of the member bodies casting a vote. 
Attention is drawn to the possibility that some of the elements of this document may be the subject of patent 
rights. ISO shall not be held responsible for identifying any or all such patent rights. 
ISO 19438 was prepared by Technical Committee ISO/TC 22, Road vehicles , Subcommittee SC 7, Injection 
equipment and filters for use on road vehicles . 
It is intended that ISO 19438 replace ISO/TS 13353:2002 when that document is reviewed after three years. This corrected version of ISO 19438:2003 incorporates the following corrections: 
 in the test report in Annex B, under the headings “Presentation of test results…
 Initial filtration efficiency 
— Elapsed time: 6,00 min…” and “…  Initial filtration efficiency — Elapsed time: 15,00 min…”, the particle 
size “W 3 µm(c)” has been corrected to " W 13 µm(c)”; 
 in Figure D.4, the curve labelled at left of the legend as “LATOUR T2” has been corrected to read 
“LATOUR T1”; 
 an explanation that the barred values in the table are discarded outliers has been inserted in the title of 
Table D.2; 
 ISO/TS 13353 has been added to the bibliography; 
 typographical errors have been corrected. ISO 19438:2003(E) 
© ISO 2003 — All rights reserved   v
 Introduction 
An interlaboratory trial was conducted using ISO 19438 by six laboratories in 2002. Typical filters were 
evaluated and results for filtration efficiencies and retention capacities analysed to deduce repeatability, 
reproducibility and coefficient of variation of the method. Initial filtration efficiency results were found to closely 
correlate to those obtained through the method specified in ISO/TS 13353, thus making the method given in that Technical Specification redundant. 
A summary of the results is given in Annex D. INTERNATIONAL STANDARD ISO 19438:2003(E)
 
© ISO 2003 — All rights reserved   1
 Diesel fuel and petrol filters for internal combustion engines — 
Filtration efficiency using particle counting and contaminant 
retention capacity 
1 Scope 
This International Standard specifies a multi-pass filtration test, with continuous contaminant injection and 
using the on-line particle counting method, for evaluating the performance of diesel fuel and petrol filters for 
internal combustion engines submitted to a constant flow rate of test liquid. The test procedure determines the contaminant capacity of a filter, its particulate removal characteristics and differential pressure. This International Standard is applicable to filter elements having a rated flow of between 50 l/h and 800 l/h; however, by agreement between filter manufacturer and customer, and with some modification, the procedure is permitted for application to fuel filters with higher flow rates. 
2 Normative references 
The following referenced documents are indispensable for the application of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies. 
ISO 1219-1:1991, Fluid power systems and components — Graphic symbols and circuit diagrams — Part 1: 
Graphic symbols  
ISO 2942:1994, Hydraulic fluid power — Filter elements — Verification of fabrication integrity and 
determination of the first bubble point  
ISO 3968:2001, Hydraulic fluid power — Filters — Evaluation of differential pressure versus flow 
characteristics  
ISO 4021:1992,  Hydraulic fluid power — Particulate contamination analysis — Extraction of fluid samples from 
lines of an operating system  
ISO 11171:1999,  Hydraulic fluid power — Calibration of automatic particle counters for liquids  
ISO 4405:1991, Hydraulic fluid power — Fluid contamination — Determination of particulate contamination by 
the gravimetric method  
ISO 11841-1, Road vehicles and internal combustion engines — Filter vocabulary — Part 1: Definitions of 
filters and filter components  
ISO 11841-2, Road vehicles and internal combustion engines — Filter vocabulary — Part 2: Definitions of 
characteristics of filters and their components  
ISO 11943:1999, Hydraulic fluid power — On-line automatic particle-counting systems — Method of 
calibration and validation  
ISO 12103-1:1997, Road vehicles — Test dust for filter evaluation — Part 1: Arizona test dust  ISO 19438:2003(E) 
2  © ISO 2003 — All rights reserved
 3 Terms and definitions 
For the purposes of this document, the terms and definitions given in ISO 11841-1 and ISO 11841-2 and the 
following apply. 
3.1 
multipass test 
test which requires the recirculation of filtered fluid through the filter element 
3.2 
base upstream gravimetric level 
upstream contaminant concentration if no contaminant is recirculated 
3.3 
filtration efficiency 
ability of the filter to retain particles expressed as the percentage of particles of a given size retained by the 
filter under test 
3.4 
overall efficiency 
efficiency calculated from the average upstream and downstream particle counts obtained during the entire 
test 
3.5 
filter rating 
particle size corresponding to an initial efficiency or cumulative overall efficiency of a given percentage 
NOTE It is expressed in micrometres(c) [µm(c)], which signifies throughout this International Standard that a particle 
size measurement is carried out using an automatic particle counter calibrated in accordance with ISO 11171. 
3.6 
filter reference rating filter rating at 99 % efficiency 
NOTE It is expressed in micrometres(c) [µm(c)], which signifies throughout this International Standard that a particle 
size measurement is carried out using an automatic particle counter calibrated in accordance with ISO 11171. 
3.7 
initial efficiency 
efficiency at first data points calculated from 4 min, 5 min and 6 min particle counts 
4 Symbols 
Graphical symbols used in this International Standard for fluid power system components are in accordance 
with ISO 1219-1. 
5 Test equipment and materials 
5.1 Test equipment 
5.1.1 Test rig 
The test rig, shown diagrammatically in Figure 1 (to which the numbers in parentheses throughout this 
International Standard refer), shall comprise the following. ISO 19438:2003(E) 
© ISO 2003 — All rights reserved   3
 5.1.1.1 Filter test circuit , including the components specified in 5.1.1.1.1 to 5.1.1.1.7. 
5.1.1.1.1 Reservoir  (1), constructed with a conical bottom having an included angle of not more than 90 ° 
and where the oil entering is diffused below the fluid surface. 
5.1.1.1.2 Oil pump  (2), which does not alter the contaminant particle size distribution and does not exhibit 
pressure pulsation with an amplitude greater than 10 % of the average pressure at the filter inlet. 
5.1.1.1.3 Device , such as a filter head to accommodate spin-on filters, which connects the test filter (6) and 
which can be by-passed or replaced by a straight section of pipe. 
5.1.1.1.4 System clean-up filter  (9), capable of providing an initial system contamination level of less than 
15 particles/ml having a size greater than 10 µm(c). 
5.1.1.1.5 Sampling valves , in accordance with ISO 4021, for turbulent sampling upstream and 
downstream of the test filter, for on-line particle counting (18) and for gravimetric analysis (11). 
5.1.1.1.6 Pressure tappings , in accordance with ISO 3968. 
5.1.1.1.7 Piping , sized to ensure that turbulent mixing conditions exist throughout the filter test circuit. 
5.1.1.2 Contaminant injection circuit , including the components specified in 5.1.1.2.1 to 5.1.1.2.3. 
5.1.1.2.1 Reservoir  (12), constructed with a conical bottom having an included angle of not more than 90 ° 
and where the oil entering is diffused below the fluid surface. 
5.1.1.2.2 Oil pump  (13), of centrifugal or other type, which does not alter the contaminant particle size 
distribution. 
5.1.1.2.3 System clean-up filter  (14), capable of providing either of the following conditions: 
a) an initial system contamination level of less than 1 000 particles/ml having a size greater than 10 µm(c); 
b) a gravimetric level less than 2 % of the calculated level at which the test is being conducted, measured 
using the double membrane gravimetric method in accordance with ISO 4405. 
5.1.1.2.4 Piping , sized to ensure that turbulent mixing conditions exist throughout the contaminant injection 
circuit. 
While injection flows lower than 0,25 l/min may be used if validated, an injection flow of 0,25 l/min is 
recommended.  
Injection flows higher than 0,25 l/min shall not be used to minimize the effect of fluid extraction on filter 
capacity. ISO 19438:2003(E) 
4  © ISO 2003 — All rights reserved
  
Key 
1 reservoir incorporating thermostatically controlled heater 13 circulation pump 
2 test pump 14 clean-up filter A contaminant injection 
circuit 
3 three-way ball valve 15 heat exchanger B filter test circuit 
4 pressure gauge 16 injection pump 
5 differential pressure gauge 17 flow meter C dilution and counting 
system 
6 test filter 18 sampling valve  
7 throttle valve (for flow regulation) 19 dilution system  
8 flow meter 20 particle counter sensor  
9 clean-up filter 21 particle counter  
10 heat exchanger 22 sampling valve  
11 sampling valve 23 by-pass flow circuit  
12 reservoir incorporating thermostatically controlled heater   
Figure 1 — Diagrammatic arrangement of test rig 
5.1.2 On-line dilution and particle counting system  
The on-line dilution and particle counting system shall be in accordance with ISO 11943 and include the 
components specified in 5.1.2.1 to 5.1.2.4. 
5.1.2.1 On-line sample delivery pipework , sized to maintain a fluid velocity that prevents silting at a 
flow rate of 0,125 l/min. For tests with sampling flows > 10 % of the total filter flow rate, the amount of dust 
discarded in the sampling flow will be significant. This amount shall be evaluated and deducted from the 
retained capacity. Lower flow rates may be used provided they are validated. 
5.1.2.2 Dilution system  (19), comprising appropriate reservoir, pump, clean-up filters, flow meters and 
flow regulation valves. ISO 19438:2003(E) 
© ISO 2003 — All rights reserved   5
 5.1.2.3 Two optical particle sensors  (20), connected to a particle counter (21) having a minimum of five 
channels. 
5.1.2.4 Timer , capable of measuring minutes and seconds. 
5.2 Test materials 
5.2.1 Test contaminant 
5.2.1.1 Contaminant grade 
The contaminant shall be in accordance with the specification of ISO 12103-A3 medium grade test dust. 
5.2.1.2 Contaminant preparation 
The test dust shall be pre-dried in quantities no larger than 200 g for at least 1 h at (105 ± 5) °C and cooled to 
room temperature. Maintain in a desiccator until required for use. 
5.2.2 Test fluid 
The test fluid shall have a petroleum base and conform to the specifications given in Annex A. 
6 Accuracy of measuring instruments and test conditions 
The measuring instruments shall be capable of measuring to the levels of accuracy given in Table 1. The last 
column in the table gives the limits within which the test conditions shall be maintained. 
Table 1 — Instrument accuracy and test condition variation 
Test condition  Unit Measurement accuracy Allowed test condition variation
Flow    
 Filter Test Flow l/min ± 2 % ± 5 % 
 Sampling Flow ml/min ± 1,5 % ± 3 % 
 Injection Flow ml/min ± 2 % ± 5 % 
Pressure Pa ± 5 % — 
Temperature °C ± 1 °C  2 °C 
Volume l ± 5 % ± 10 % 
Base upstream gravimetric level mg/l — ± 10 % 
Conductivity pS/m ± 10 % See 8.3.4 
Viscosity a   mm2/s ± 5 % — 
a The viscosity of the test liquid should be checked at regular intervals to ensure that the test is conducted at a liquid tempe rature 
which corresponds to a viscosity of 15 ± 1 mm2/s. 
 ISO 19438:2003(E) 
6  © ISO 2003 — All rights reserved
 7 Test rig validation 
7.1 General 
These validation procedures reveal the effectiveness of the test rig in maintaining contaminant entrainment or 
preventing contaminant size modification or both. 
7.2 Validation of the on-line dilution and particle counting system 
Proceed in accordance with ISO 11943 to validate the on-line dilution system and in accordance with ISO 11171 to validate the particle counter. 
7.3 Validation of filter test circuit 
7.3.1 Validate the filter test circuit at the minimum flow rate at which the circuit will be operated. 
7.3.2 Install a straight section of pipe in place of a test filter during the validation procedure. 
7.3.3 Adjust the total circuit volume so that it is numerically equal to half the value of the minimum flow 
volume per minute through the filter, with a minimum of 6 l. The total circuit volume should include sump, 
piping and filter. A by-pass flow loop should be utilized for low flow test conditions. 
7.3.4 Contaminate the fluid to the calculated gravimetric level of 5 mg/l using ISO 12103-A3 test dust. 
NOTE This contamination level is below the coincidence limit of automatic particle counters. 
7.3.5 Circulate the fluid in the test system for 1 h while obtaining downstream cumulative counts at 5 µm(c), 
10 µm(c) and 20 µm(c), without on-line dilution, at 10 min sample intervals. 
7.3.6 Calculate and record the on-line count ( Co) in particles per millilitre, using the equation: 
c
oNCV=  
where 
Nc is the cumulative count for the selected sample period, in number of particles; 
V is the volume of fluid, in millilitres, passed through the particle counter sensor during the sample 
period. 
7.3.7 The validation shall be accepted only if 
a) each particle count obtained at 5 µm(c), 10 µm(c) and 20 µm(c) does not deviate by more than 10 % from 
the average particle count for these sizes, 
b) the average for all particles per millilitre at channels W 5 µm(c) is not less than 6 000 and not greater than 
7 300, 
c) the average for all particles per millilitre at channels W 10 µm(c) is not less than 815 and not greater than 
1 015, and 
d) the average for all particles per millilitre at channel W 20 µm(c) is not less than 77 and not greater than 
106. 
7.3.8 Contaminate the fluid to the maximum gravimetric level to be tested using ISO 12103-A3 test dust. ISO 19438:2003(E) 
© ISO 2003 — All rights reserved   7
 7.3.9 Circulate the fluid in the test system for 1 h while obtaining downstream cumulative counts at 5 µm(c), 
10 µm(c) and 20 µm(c), with on-line dilution, at 10 min sample intervals. 
7.3.10 The validation test shall be accepted only if each particle count obtained at 5 µm(c), 10 µm(c) and 
20 µm(c) does not deviate by more than 10 % from the average particle count for these sizes. 
7.4 Validation of contaminant injection circuit 
7.4.1 Validate the contaminant injection circuit at the maximum volume and the maximum gravimetric level 
to be used. 
7.4.2 Add the required quantity of contaminant in slurry form to the injection circuit fluid and circulate for a 
time sufficient to completely disperse the contaminant. 
NOTE All systems might not disperse contaminant at the same rate. A period of 10 min to 20 min could be necessary 
for complete dispersion. 
7.4.3 Extract fluid samples at the point where the injection fluid is discharged into the filter test circuit 
reservoir at 30 min intervals over 2 h and analyse each sample gravimetrically. These samples should be 
taken at the intended test injection flow rate. 
7.4.4 The validation test shall be accepted only if the gravimetric level of each sample is within ± 5 % of the 
average of the four samples and if this average is within ± 5 % of the gravimetric value selected in 7.3.1. 
8 Preliminary preparation 
8.1 Test filter assembly 
8.1.1 Ensure that the test fluid cannot by pass the filter element to be evaluated. 
8.1.2 Subject the test filter element to a fabrication integrity test in accordance with ISO 2942:1994 using 
MIL-H-5606 fluid prior to the multi-pass test or following it, if the element is not readily accessible as in the 
spin-on configuration. 
8.1.3 If the integrity test has been made prior to the multi-pass test and if the test filter element fails to meet 
the test pressure agreed between the purchaser and the manufacturer, the element shall be disqualified from 
further testing. If the integrity test has been made after the multi-pass test and if the element fails, the test result shall be disqualified. 
8.2 Contaminant injection circuit 
8.2.1 Using 50 mg/l as the base upstream gravimetric level, calculate the predicted test time, Te, in minutes, 
from the equation: 
cc
e50FFTGQ Q==×× 
where 
Fc is the estimated capacity of the filter element, in milligrams; 
G is the base upstream gravimetric level, in milligrams per litre; 
Q is the test flow rate, in litres per minute. ISO 19438:2003(E) 
8  © ISO 2003 — All rights reserved
 The test duration should be > 30 min. The base upstream gravimetric level of 50 mg/l should be adhered to 
unless otherwise agreed upon by purchaser and manufacturer. Base upstream gravimetric levels up to 
100 mg/l may be used to shorten test times, while base upstream gravimetric levels down to 25 mg/l may be used to lengthen test times, but only the results of filter tests using the same base upstream gravimetric level may be compared. 
NOTE If the estimated capacity of the filter element ( Fc) is not supplied by the manufacturer, it might be necessary to 
determine the capacity by testing an element. 
8.2.2 Calculate the minimum volume of fluid, Vm, in litres, required for the operation of the injection circuit, 
compatible with the predicted test time and an injection flow rate of 0,25 l/min, using the equation: 
Vm = 1,2Te × Qi + Vo 
where 
Te is the predicted test time, in minutes, in accordance with 8.2.1; 
Qi is the injection flow rate, in litres per minute; 
Vo is the minimum volume of fluid in the injection circuit necessary to avoid air entrainment. 
The calculated minimum volume should ensure a quantity of contaminant fluid sufficient to load the element, 
plus 20 % for adequate circulation throughout the test and to avoid entrainment. Larger injection volumes may be used. 
8.2.3 Calculate the gravimetric level, G
i, in milligrams per litre of the injection fluid, from the equation: 
i
ii50 QQGQQρ×==  
where 
G is the base upstream gravimetric level, in milligrams per litre, in accordance with 8.2.1; 
Q is the test flow rate, in litres per minute; 
Qi is the injection flow rate, in litres per minute. 
8.2.4 Calculate the quantity of contaminant, W, in grams, needed for the contaminant injection circuit, using 
the equation: 
ii
1 000GVW×=  
where 
Gi is the gravimetric level, in milligrams per litre, in accordance with 8.2.3; 
Vi is the volume of fluid contained in the injection circuit, in litres. 
8.2.5 Adjust the injection flow rate at stabilized temperature to within ± 5 % of the value selected in 8.2.2 
and maintain throughout the test. 
8.2.6 Circulate the fluid in the contaminant injection circuit through the clean-up filter (14) until either of the 
following conditions are attained: 
a) a contamination level of less than 1 000 particles per millilitre having a size greater than 10 µm(c); ISO 19438:2003(E) 
© ISO 2003 — All rights reserved   9
 b) a gravimetric level of less than 2 % of the value calculated in accordance with 8.2.3. 
8.2.7 By pass the system clean-up filter (14) after the required initial contamination has been achieved. 
8.2.8 Adjust the total volume of the contaminant injection system to the value determined in 8.2.2. 
8.2.9 Ensure that the conductivity of the test fluid and the injection fluid is at least 1 000 pS/m by measuring 
fluid conductivity prior to each test. A level of 1 500 pS/m ± 500 pS/m should be used. An initial level of 
100 ppm of an antistatic agent has been shown to produce conductivity within this range. 
8.2.10 Add in slurry form to the contaminant injection circuit reservoir (12) the quantity of contaminant ( W) 
determined in 8.2.4, and circulate until the contaminant is completely dispersed. 
NOTE Complete dispersal of the contaminant can take between 10 min and 20 min. 
8.3 Filter test circuit 
8.3.1 Install a straight section of pipe in place of the test filter. 
8.3.2 Circulate the fluid in the filter test circuit through the clean-up filter (9) until a contamination level of 
less than 15 particles per millilitre having a size greater than 10 µm(c) is attained. Record this value as the 
initial cleanliness level of the system. 
The contamination level should be checked with the on-line particle counting system, which will at the same 
time clean the sampling lines. 
8.3.3 Adjust the fluid volume of the filter test circuit to the value determined in 7.2.3 and record this value. 
8.3.4 Ensure that the conductivity of the test fluid is at least 1 000 pS/m by measuring fluid conductivity prior 
to each test. A level of 1 500 pS/m ± 500 pS/m should be used. An initial level of 100 ppm of an antistatic 
agent has been shown to produce conductivity within this range. 
8.3.5 Install the filter housing, without the test element, in the filter test circuit. For a spin-on type filter, 
install this spin-on filter body without an element inside. 
8.3.6 Circulate the fluid in the filter test circuit at the rated flow and at the stabilized test temperature 
specified in 9.1.1 ± 2 °C. Measure and record the differential pressure, ∆p3, of the empty filter housing. 
8.3.7 Adjust the channels on the particle counter to read the following particle sizes, in micrometres(c). 
 5 [6] channel counter: [4], 5, 10, 15, 20, 30. 
 16 channel counter: 4, 5, 6, 7, 8, 9, 10, 11, 13, 15, 17, 20, 25, 30, 40, 50. 
9 Test procedure 
9.1 Initial procedure 
9.1.1 Install the test filter element (6) in its housing and subject the assembly to the flow rate required  by the 
purchaser and to the temperature required to maintain an oil viscosity of 15 mm2/s ± 1 mm2/s. Recheck the 
fluid level. 
9.1.2 Measure and record the clean assembly differential pressure, ∆p1. ISO 19438:2003(E) 
10  © ISO 2003 — All rights reserved
 9.1.3 Calculate and record the clean element differential pressure, ∆p2, from the equation: 
∆p2 = ∆p1 − ∆p3 
where 
∆p1 is the clean assembly differential pressure measured at 9.1.2; 
∆p3 is the empty filter housing differential pressure measured at 8.3.6. 
9.1.4 Calculate the differential pressure, ∆p5, corresponding to increases of 80 % and 100 % of the net 
differential pressure, using the equation: 
∆p5 = ∆p4 − ∆p2 
where 
∆p4 is the element final differential pressure; 
∆p2 is the clean element differential pressure obtained from 9.1.3. 
For clarity, ∆p1 to ∆p6 are shown in Figure 2. 
In the absence of manufacturer specification, use 30 kPa as the final differential pressure of the element. 
 
∆p1 clean assembly differential pressure 
∆p2 clean element differential pressure 
∆p3 housing differential pressure 
∆p4 element final differential pressure 
∆p5 net differential pressure 
∆p6 final differential pressure across filter assembly = differential pressure at end of test 
∆p measured differential pressure 
Figure 2 — Diagrammatic representation of filter differential pressures ISO 19438:2003(E) 
© ISO 2003 — All rights reserved   11
 9.1.5 Obtain a fluid sample from the contaminant injection circuit, at the point where the fluid return pipe 
discharges into the reservoir (12). 
9.1.6 Measure and record the injection flow rate. 
9.1.7 Adjust the dilution at the start of the test to the anticipated maximum dilution required during the test 
to avoid particle counter saturation. 
9.2 Filter test 
9.2.1 By-pass the clean-up filter (9). 
9.2.2 Allow the injection flow to enter the filter test circuit reservoir. 
9.2.3 Start the timer. 
9.2.4 Start the upstream and downstream sample flows. 
9.2.5 Record the differential pressure, and count particles upstream and downstream during 50 s every 
minute at the specified flow within the sensor. 
9.2.6 Calculate and record the on-line count ( Co) (number of particles per millilitre) using the equation: 
c
oNDCV×=  
where 
Nc is the cumulative count for the sample interval, in number of particles; 
D is the dilution factor; 
V is the volume of fluid passed through the particle counter sensor during the sample interval, in 
millilitres. 
9.2.7 Record the test time, in minutes, required for the differential pressure across the filter assembly to 
increase the net differential pressure by 80 % and 100 %. 
9.2.8 Take an upstream sample at valve (11) for gravimetric analysis when the differential pressure across 
the filter assembly has increased by 80 % of the net differential pressure. 
NOTE The sample is taken at the 80 % point because it often overlaps the 100 % point. 
9.2.9 Stop the flow to the test filter and measure and record the exact final volume of test fluid, Vf. 
If 100 % net differential pressure is reached during sampling, complete sampling before stopping the flow to 
the test filter. 
9.2.10 The test shall be accepted if Vf is within ± 10 % of the initial volume. 
9.2.11 Obtain a final fluid sample from the contaminant injection circuit at the point where the injection fluid is 
discharged into the filter test circuit. 
9.2.12 Measure and record the final injection flow rate. 
9.2.13 Remove the element and check that there is no visual evidence of filter damage as a result of 
performing this test. ISO 19438:2003(E) 
12  © ISO 2003 — All rights reserved
 10 Calculation and reporting of test results 
10.1 Test report 
See Annex B for a typical test report sheet. The test report shall include a graph of overall efficiency with 
respect to particle size, as illustrated in Figure B.1, and a graph of differential pressure with respect to time and to mass of contaminant added, as shown in Figure B.2. If required by the purchaser, the manufacturer shall also include a graph of overall efficiency with respect to particle size, as shown in Figure B.3. 
10.2 Calculation 
10.2.1 General 
Carry out the following calculations and record the results in the test report. 
10.2.2 Gravimetric levels 
10.2.2.1 Conduct a gravimetric analysis according to ISO 4405 on the two samples extracted from the 
contaminant injection circuit (see 9.1.5 and 9.2.11) and on the upstream sample extracted from the filter test 
circuit at the 80 % sample point (see 9.2.8) 
10.2.2.2 Record the non-retained contaminant concentration, in milligrams per litre, at the 80 % sampling 
point as the final system gravimetric level, Gf. 
10.2.2.3 Calculate and record the average of the gravimetric levels, Gia, for the two samples taken from 
the contaminant injection circuit in 9.1.5 and 9.2.11. 
10.2.2.4 The test shall be accepted only if the gravimetric level of each sample is within ± 10 % of the 
average Gia calculated in 10.2.2.3. 
10.2.2.5 Calculate and record the injection flow rate, Qia, by averaging the measurements taken at 9.1.6 
and 9.2.12. 
10.2.2.6 The test shall be accepted only if the value of Qia is equal to the selected value ± 5 % (see 8.2.2). 
10.2.2.7 Calculate and record the actual base upstream gravimetric level, Ga, in milligrams per litre, using 
the equation: 
ia ia
aGQGQ×=  
where 
Gia is the average injection gravimetric level, in milligrams per litre, obtained at 10.2.2.3; 
Qia is the average injection flow rate, in litres per minute, obtained at 10.2.2.5; 
Q is the test flow rate, in litres per minute. 
10.2.2.8 The test shall be accepted only if Ga is equal to 50 mg/l or to some other acceptable value in 
accordance with 8.2.1 within the variation given in Table 1. ISO 19438:2003(E) 
© ISO 2003 — All rights reserved   13
 10.2.3 Filtration efficiencies 
10.2.3.1 Initial efficiency 
From the upstream and downstream particle counts recorded from each channel of the counter at 8.3.7, 
calculate the initial efficiency at each particle size, in accordance with Annex C (see C.1 and C.2). 
Record the initial efficiency for each particle size in the filtration efficiencies  section of the test report (see 
Annex B). 
10.2.3.2 Average intermediate efficiencies 
From the upstream and downstream particle counts, calculate the average intermediate efficiencies at each 
particle size, in accordance with Annex C (see C.1 and C.3). 
Identify the minimum calculated intermediate efficiency for each particle size and record it in the filtration 
efficiencies  section of the test report. 
10.2.3.3 Overall efficiencies 
Calculate the overall efficiency, at each particle size, in accordance with Annex C (see C.4). 
Record the calculated overall efficiency at each particle size in the filtration efficiencies  section of the test 
report. 
Prepare a graph of overall efficiency versus particle size as shown in Figure B.1 and, if required by the 
purchaser, also provide a graph as shown in Figure B.3. 
10.2.4 Filter ratings 
A graph of initial or overall efficiency versus particle size can highlight those particle sizes which correspond to 
efficiencies of 50 %, 90 %, 95 %, and 99 %, as shown in the example of Figure B.2. These particle sizes shall be recorded in the test report sheet.  
The particle sizes which correspond to overall efficiencies of 95 % and 99 % cannot be determined graphically 
with acceptable accuracy. These values should therefore be calculated by linear Interpolation. 
10.2.5 Injected mass of contaminant 
Calculate the mass of contaminant injected into the filter element, m
i, in grams, using the equation: 
ia ia
i1 000QGTm××=  
where 
Qia is the average injection flow rate, in litres per minute, obtained at 10.2.2.5; 
Gia is the average gravimetric level of the injection fluid, in milligrams per litre, obtained at 10.2.2.3; 
T is the time required to reach the terminal differential pressure, in minutes (see 9.2.7). 
Record the calculated value of mi in the test report. ISO 19438:2003(E) 
14  © ISO 2003 — All rights reserved
 10.2.6 Non-retained mass of contaminant 
Calculate the non-retained mass of contaminant, mnr, in grams, using the equation: 
()()fa
ff d f a u
nr2
10 0 0GGVG QT G G QT
m ++− + 
=  
where 
Vf is the final volume of test fluid, in litres, obtained at 9.2.9; 
Gf is the final system gravimetric level, in milligrams per litre, obtained at 10.2.2.2; 
Qd is the average flow rate through the downstream sampling system, in litres per minute; 
Qu is the average flow rate through the upstream sampling system, in litres per minute. 
Record the calculated value of mnr in the test report. 
NOTE The three terms in the above equation represent 
a) the weight of contaminant remaining in the test system at the end of the test, 
b) an estimate of the amount of contaminant permanently extracted from the system through the downstream sampling 
system [the term ( Gf – Ga) is a conservative estimate of the gravimetric level downstream of the filter], and  
c) an estimate of the amount of contaminant permanently extracted from the system through the upstream sampling 
system [the term ( Gf – Ga)/2 is an estimate of the gravimetric level upstream of the filter]. 
10.2.7 Retained filter capacity 
Calculate the retained filter capacity ( Cr), in grams, using the equation: 
Cr = mi − mnr 
where 
mi is the mass of contaminant injected into the filter element, in grams, obtained at 10.2.5; 
mnr is the non-retained mass of contaminant, in grams, obtained in 10.2.6. 
Record the calculated value of Cr in the test report. ISO 19438:2003(E) 
© ISO 2003 — All rights reserved   15
 Annex A  
(normative)  
 
Specification of test fluid for filter test 
NOTE Suitable test fluids are aircraft hydraulic oils MIL-H-5606 and AIR 3520. 
A.1 Petroleum base stock 
The petroleum base stock shall have the following properties. 
 Pour point:     − 59,4 °C (min.) 
 Flash point:     93,3 °C (min.) 
 Acid or base number:   0,10 (max.) 
 Precipitation number:   0 
A.2 Additives 
The test fluid shall contain the following additive materials. 
 Viscosity-temperature coefficient improver:  10  % (max.) 
 Oxidation inhibitors:       2 % (max.) 
 Tricresyl phosphate anti-wear agent:   0,5 % ± 0,1 % 
The free phenol content of the tricresyl phosphate anti-wear agent should not exceed 0,05 %. 
A.3 Properties 
The test fluid shall have the following properties. 
 Viscosity1):     13,2 mm2/s at 40 °C min. 
 Viscosity:     500 mm2/s at − 40 °C min. 
 Pour point:      − 59,4 °C min. 
 Flash point:     93,3 °C min. 
 Precipitation number:   0 
 Acid or base number:   0,2 mg KOH/g max. 
                                                      
1) 1 mm2/s = 1 cSt. ISO 19438:2003(E) 
16  © ISO 2003 — All rights reserved
 A.4 Colour 
The test fluid shall be clear and transparent. For identification purposes, it shall contain a red dye in a 
proportion not greater than one part of dye per 10 000 parts of oil. ISO 19438:2003(E) 
© ISO 2003 — All rights reserved   17
 Annex B  
(informative) 
 
Typical filter test report, presentation of test results 
Test report: ISO 19438 
Test date: Test location: Test ID: 
Test time: Operator: Project: 
Filter identification 
Filter ID:  Fab. integrity:  hPa
Housing type:  Date const: 
Operating conditions  
Test fluid Type: Viscosity: mm2/s
 Conductivity: pS/m Temperature: °C
Test dust Type: Batch no. 
Injection system Dust added, W: g Injection grav. initial: mg/l
 Volume, Vi: l Injection grav. final: mg/l
 Injection flow rate, Qia: ml/min Injection grav. Average,  Gia: mg/l
Test system : Flow rate, Q: l/min Initial cleanliness: no. > 10 µm(c)/ml
 Volume: l Base gravimetric level, Ga: mg/l
 Final volume, Vf: lFinal gravimetric level, Gf: mg/l
Dilution system  Sensor type: Sample time: s
 Flow rate: ml/min Hold time: s
 Counting method: Sampling time: min
 Upstream dilution ratio: No records to average: 
 Downstream dilution ratio: Total record read: 
Test results  
∆p Clean assembly ∆p1: kPa Clean element ∆p2: kPa
 Housing ∆p3: kPa Final net ∆p5: kPa
% net ∆p 5 10 15 20 40 80 100 
Assembly ∆p:   kPa        
Test time, min        
Filtration efficiencies 
Particle size W 4 µm (c) W 5 µm (c) W 6 µm (c) W 7 µm (c) W 8 µm (c) W 9 µm (c) W 10 µm (c)W 11 µm (c)
Initial Eff. (%)         
Min. Eff. (%)         
Overall Eff. (%)         ISO 19438:2003(E) 
18  © ISO 2003 — All rights reserved
 Particle size W 13µm (c) W 15 µm (c) W 17 µm (c)W 20 µm (c)W 25 µm (c)W 30 µm (c)W 40 µm (c) W 50 µm(c)
Initial Eff. (%)         
Min. Eff. (%)         
Overall Eff. (%)         
 
Injected mass, mi: g Efficiency (%) 50 90 95 99 a 
Non-retained mass, mnr: g Initial filter rating [µm(c)]     
Retained capacity, Cr: g Overall filter rating [µm(c)]     
a Filter reference rating. 
 
Presentation of test results 
Test date: Test location: Test ID: 
Test time: Operator: Project: 
Initial filtration efficiency — Elapsed time: 6,00 min — Diff. pressure: 63,88 kPa 
Particle size W 4 µm(c) W 5 µm(c) W 6 µm(c) W 7 µm(c) W 8 µm(c) W 9 µm(c) W 10 µm(c) W 11 µm(c)
Upstream (cnts/ml) 25 530,67 18 282,82 13 346,41 9 839,04 7 295,43 5 463,28 3 040,80 1 810,17 
Downstream 
(cnts/ml) 8 819,81 5 101,95 2 986,96 1 799,02 1 051,93 637,18 215,72 77,71 
Efficiency  (%) 65,45 72,09 77,62 81,72 85,58 88,34 92,91 95,71 
Particle size W 13 µm(c) W 15 µm(c) W 17 µm(c) W 20 µm(c) W 25 µm(c) W 30 µm(c) W 40 µm(c) W 50 µm(c)
Upstream (cnts/ml) 1 108,04 723,27 492,52 233,32 113,00 67,59 36,62 14,02 
Downstream 
(cnts/ml) 28,62 9,17 3,76 0,56 0,18 0,18 0 0 
Efficiency  (%) 97,42 98,71 99,24 99,76 99,84 99,73 99,99 99,99 
Filtration efficiency — Elapsed time: 10,00 min — Diff. pressure: 64,56 kPa 
Particle size W 4 µm(c) W 5 µm(c) W 6 µm(c) W 7 µm(c) W 8 µm(c) W 9 µm(c) W 10 µm(c) W 11 µm(c)
Upstream (cnts/ml) 27 855,07 19 682,25 14 264,96 10 376,26 7 617,47 5 685,05 3 132,44 1 836,56 
Downstream 
(cnts/ml) 11 712,46 6 886,89 4 160,77 2 534,51 1 512,46 937,77 354,48 136,28 
Efficiency  (%) 57,95 65,01 70,83 75,57 80,14 83,50 88,68 92,58 
Particle size W 13 µm(c) W 15 µm(c) W 17 µm(c) W 20 µm(c) W 25 µm(c) W 30 µm(c) W 40 µm(c) W 50 µm(c)
Upstream (cnts/ml) 1 126,19 726,39 490,31 226,00 112,28 65,36 38,61 15,24 
Downstream 
(cnts/ml) 56,9 22,32 9,37 0,60 0 0 0 0 
Efficiency  (%) 94,99 96,93 98,09 99,74 99,99 99,99 99,99 99,99 
Filtration efficiency — Elapsed time: 15,00 min —  Diff. pressure: 60,25 kPa 
Particle size W 4 µm(c) W 5 µm(c) W 6 µm(c) W 7 µm(c) W 8 µm(c) W 9 µm(c) W 10 µm(c) W 11 µm(c)
Upstream (cnts/ml) 31 072,96 21 814,17 15 695,25 11 403,34 8 394,78 6 210,63 3 394,82 1 983,12 
Downstream 
(cnts/ml) 13 826,42 8 245,83 5 023,72 3 123,81 1 850,97 1 152,67 420,57 156,80 
Efficiency  (%) 55,50 62,20 67,99 72,61 77,95 81,44 87,61 92,09 ISO 19438:2003(E) 
© ISO 2003 — All rights reserved   19
 Particle size W 13 µm(c) W 15 µm(c) W 17 µm(c) W 20 µm(c) W 25 µm(c) W 30 µm(c) W 40 µm(c) W 50 µm(c)
Upstream (cnts/ml) 1 224,52 781,08 529,93 237,74 118,22 66,43 39,48 14,18 
Downstream 
(cnts/ml) 60,09 25,70 10,77 0,97 0,20 0 0 0 
Efficiency  (%) 95,09 96,71 97,97 99,59 99,83 99,99 99,99 99,99 
Filtration efficiency — Elapsed time: 20,00 min — Diff. pressure: 61,51 kPa  
Particle size W 4 µm(c) W 5 µm(c) W 6 µm(c) W 7 µm(c) W 8 µm(c) W 9 µm(c) W 10 µm(c) W 11 µm(c)
Upstream (cnts/ml) 32 759,21 22 855,29 16 421,83 11 831,78 8 654,75 6 347,78 3 479,81 2 036,89 
Downstream 
(cnts/ml) 15 691,99 9 290,40 5 698,19 3 506,52 2 106,79 1 310,74 479,40 183,56 
Efficiency  (%) 52,10 59,35 65,30 70,36 75,66 79,35 86,22 90,99 
Particle size W 13 µm(c) W 15 µm(c) W 17 µm(c) W 20 µm(c) W 25 µm(c) W 30 µm(c) W 40 µm(c) W 50 µm(c)
Upstream (cnts/ml) 1 249,57 793,43 531,29 233,19 118,66 66,30 30,66 11,75 
Downstream 
(cnts/ml) 67,25 23,28 8,28 1,36 0,20 0 0 0 
Efficiency  (%) 94,62 97,07 98,44 99,42 99,83 99,99 99,99 99,99 
 
 
Figure B.1 — Overall efficiency vs. particle size (linear presentation) graph — Example 
 ISO 19438:2003(E) 
20  © ISO 2003 — All rights reserved
  
Figure B.2 — Differential pressure vs. test time graph — Example ISO 19438:2003(E) 
© ISO 2003 — All rights reserved   21
  
Figure B.3 — Overall efficiency vs. particle size (probabilistic presentation) graph — Example ISO 19438:2003(E) 
22  © ISO 2003 — All rights reserved
 Annex C  
(informative) 
 
Example filter efficiency calculations 
C.1 General conditions 
For the purpose of these example calculations, it is assumed that particles were counted at one minute 
intervals, upstream and downstream, in 16 channels, for a test duration of 86 min. The calculations relate to 
one channel in which the particle size was > 20 µm(c) and the readings taken at one minute intervals were as 
shown in Table C.1. 
Table C.1 — Particle counter readings in one channel 
Time interval Particle count Time interval Particle count 
min upstream downstream min upstream downstream 
1 14,4 1,0 16 209,6 77,0 
2 171,4 35,3 17 217,8 73,1 
3 191,7 53,8 18 193,3 68,9 
4 163,7 47,3 19 204,2 84,3 
5 190,9 51,5 20 224,4 85,5 
6 182,8 54,9 — — — 
7 165,2 41,8 — — — 
8 191,5 66,7 — — — 
9 186,4 57,5 80 382,6 207,8 
10 218,4 49,4 81 350,9 198,2 
11 190,7 54,9 82 347,7 208,3 
12 174,8 59,1 83 308,3 165,2 
13 210,6 55,0 84 309,0 157,7 
14 242,3 66,9 85 297,5 162,0 
15 188,0 82,8 86 295,7 147,4 
NOTE The readings taken at time intervals 21 min to 79 min have been omitted from the table since they are not relevant to the 
example calculations. 
C.2 Calculation of filter initial efficiency 
The filter initial efficiency, E6, is calculated from the average particle counts, upstream and downstream, at the 
6 min interval, using the equation: 
u6 d6
6
u6100CCEC−=×  ISO 19438:2003(E) 
© ISO 2003 — All rights reserved   23
 where 
Cu6 is the average of the upstream counts taken at the 4 min, 5 min and 6 min intervals, i.e. 
163,7 190,9 182,8179,133++=  
Cd6 is the average of the downstream counts taken at the 4 min, 5 min and 6 min intervals, i.e. 
47,3 51 ,5 54,951 ,233++=  
therefore, 
6179,13 51 ,23100 71 ,40179,13E−=× =  
in percent. 
C.3 Calculation of filter intermediate efficiencies 
C.3.1 General 
Intermediate efficiencies are calculated from the average particle counts, upstream and downstream, at either 
of the following time intervals. 
a) 5 min: if the duration of the test did not exceed one hour. 
b) 10 min: if the duration of the test exceeded one hour. In the present example, the duration of the test was 86 min. Therefore, the intermediate efficiencies are 
calculated for each 10 min interval. 
C.3.2 First 10 min interval 
In order to eliminate potentially erroneous particle counts obtained prior to stabilization of the system, the first 3 min of the test are disregarded. 
The intermediate efficiency of the filter at the 10 min interval, E
10, is calculated using the equation: 
u10 d10
10
u10100CCEC−=×  
where 
Cu10 is the average of the upstream counts taken at the 4 min to 10 min intervals, i.e. 
163,7 190,9 ... 218,4185,567++ +=  
Cd10 is the average of the downstream counts taken at the 4 min to 10 min intervals, i.e. 
47,3 51 ,5 ... 49,452,737++ +=  ISO 19438:2003(E) 
24  © ISO 2003 — All rights reserved
 therefore, 
10185,56 52,73100 71 ,58185,56E−=× =  
in percent. 
C.3.1 Subsequent 10 min intervals 
The intermediate efficiency is calculated for each of the subsequent 10 min intervals in accordance with the 
following example, E20, which corresponds to the 20 min interval. 
u20 d20
20
u20100CCEC−=×  
where 
Cu20 is the average of the upstream counts taken at the 11 min to 20 min intervals, i.e. 
190,7 174,8 ... 224,4205,5710++ +=  
Cd20 is the average of the downstream counts taken at the 11 min to 20 min intervals, i.e. 
54,9 59,1 ... 85,570,7510++ +=  
therefore, 
20205,57 70,75100 65,58205,57E−=× =  
in percent. 
C.3.2 Final interval 
The intermediate efficiency for the final interval of 6 min (i.e. the period from 81 min to 86 min) is calculated 
using the equation: 
u86 d86
86
u86100CCEC−=×  
where 
Cu86 is the average of the upstream counts taken at the 81 min to 86 min intervals, i.e. 
350,9 347,7 ... 295,7318,186++ +=  
Cd86 is the average of the downstream counts taken at the 81 min to 86 min intervals, i.e. 
198,2 208,3 ... 147,4173,136++ +=  ISO 19438:2003(E) 
© ISO 2003 — All rights reserved   25
 therefore, 
86318,18 173,13100 45,59318,18E−=× =  
in percent. 
C.4 Calculation of filter overall efficiencies 
The overall efficiency of the filter at the > 20 µm(c) particle size, selected for this example, is calculated using 
the equation: 
u020 d020
020
u020100CCEC−=×  
where 
Cu020  is the average of the upstream counts taken at 1 min intervals from 4 min to 86 min, i.e., 
163,7 190,9 ... 295,7287,3583++ +=  
Cd020  is the average of the downstream counts taken at 1 min intervals from 4 min to 86 min, i.e., 
47,3 51 ,5 ... 147,4142,583++ +=  
therefore, 
020287,35 142,5100 50,41287,35E−=× =  
in percent. ISO 19438:2003(E) 
26  © ISO 2003 — All rights reserved
 Annex D  
(informative) 
 
Summary of international interlaboratory trial (“round robin”) to validate 
ISO 19438 protocol 
D.1 Historical 
ISO 19438 has been developed to measure the variations of the filtration efficiency of fuel filters when they 
are clogged by a mineral standard particulate contaminant, up to a given differential pressure, and to calculate the retention capacity of the filter. 
The efficiency is determined by comparing particle counts measured at various sizes upstream and 
downstream of the filter, counting being by optical automatic particle counters (APCs) using the light extraction principle. 
The international “round robin” organized by ISO TC22/SC7 had two goals: a) quantify the overall variations of results both within and between laboratories, including the effects of 
APCs calibration, test stand validation and operating conditions variations; 
b) compare the initial filtration efficiency measured during the first 6 min of the test with those measured 
using the ISO/TS 13353 method during 60 min. 
The six laboratories involved were asked to proceed according to a detailed protocol including four steps: a) calibration of particle counters per ISO 11171; b) validation of on-line counting and dilution system per ISO 11943; c) validation of the test stand according to ISO 19438 and, when agreed, ISO/TS 13353; 
d) fuel filter tests according to  ISO 19438 and ISO/TS 13353. 
A step could be passed only if the previous one had been fully validated. Test results were processed according to ISO 5725-2 and ISO 5725-6 to calculate statistical parameters. 
Each participant tested two fuel filters of two grades with close mean pore sizes. 
D.2 Preliminary calibration/validation tests 
D.2.1 Particle counting system calibration 
Each lab calibrated one particle counter with its sensor according to either ISO 11171:1999, Clause 6, using NIST SRM 2806 (primary calibration) or ISO 11943:1999, Clause 9, using an ISO MTD suspension certified with a primary APC and circulating in a validated loop (secondary calibration). The second APC was matched 
to the first according to Clause 10 of this International Standard. ISO 19438:2003(E) 
© ISO 2003 — All rights reserved   27
 D.2.2 On-line counting and dilution system validation 
The contaminant concentration specified for the test (50 mg/l) was higher than the saturation concentration of 
the APC sensors. For that reason, the test fluid had to be continuously diluted before being counted. The 
dilution system of each participant was validated according to Clause 11. 
D.2.3 Test stand validation 
Each test stand, including filter test circuit and contaminant injection system, was validated according to Clause 7 of this International Standard and ISO/TS 13353:2002, Clause 6. 
Validation criteria are summarized in Table D.1, which was completed in by each participant. 
Table D.1 — Validation data sheet 
 ISO 19438:2003(E) 
28  © ISO 2003 — All rights reserved
 D.3 Test conditions 
D.3.1 Test filters 
Two samples of two grades of fuel filters were tested: 
 2 filters “A”, MFP2) = 5 µm, CR ≈ 10 to 12 g; 
 2 filters “B”, MFP = 15 µm, CR ≈ 10 to 15 g 
D.3.2 Test parameters 
D.3.2.1 Filtration efficiency and retention capacity per ISO  19438 
Fluid: type MIL H 5606 (AIR 3520) — Viscosity: 15 mm2/s 
Volume: 6 l — Conductivity: 1500 ± 500 pS/m 
Test flowrate: Filter A: 180 l/h; Filter B: 50 l/h 
Contaminant: ISO 12103-A3, batch No. 4961F Concentration: 50 mg/l 
Final differential pressure: ∆P
F = ∆Po + 30 kPa 
D.3.2.2 Initial filtration efficiency per ISO/TS 13353 
Same operating conditions as above but for 
Test concentration: 5 mg/l 
Test time: 60 min 
D.4 Interlaboratory trial test results 
D.4.1 Differential pressure, concentration, capacities 
Table D.2 presents results obtained on Filters A and B tested twice and the corresponding average, coefficient 
of variation, repeatability ( r) and reproducibility ( R). 
                                                      
2) MFP = mean flow pore size. ISO 19438:2003(E) 
© ISO 2003 — All rights reserved   29
 Table D.2 — Differential pressures, contaminant concentrations and filter capacities measured by five 
laboratories on two grades of fuel filters (barred values represent discarded outliers)  
 
D.4.2 Average filtration efficiencies 
D.4.2.1 ISO 19438 
Filtration efficiency of the test filter is calculated every minute from online upstream and downstream particle 
counts. 
The overall efficiencies measured twice on Filter A and Filter B by each lab are reported on Figures D.1 and 
D.2. ISO 19438:2003(E) 
30  © ISO 2003 — All rights reserved
  
Figure D.1 — Plot of average filtration efficiency curves measured by 5 laboratories on Filter A 
 
Figure D.2 — Plot of average filtration efficiency curves measured by 5 laboratories on Filter B 
The overall, initial and minimum filtration efficiencies as well as the corresponding average, coefficient of 
variation, repeatability and reproducibility are reported in Table D, for Filter A and Filter B. ISO 19438:2003(E) 
© ISO 2003 — All rights reserved   31
 Table D.3 — Overall, initial and minimum efficiency vs. particle size for Filter A and Filter B  
— Average, COV, repeatability and reproducibility 
 ISO 19438:2003(E) 
32  © ISO 2003 — All rights reserved
 From the average, minimum and maximum filtration efficiencies given in Table D.3, Figure D.3 illustrates the 
difference between Filters A and B and thus the sensitivity of the method. 
 
Figure D.3 — Plot of average, minimal and maximal data for overall filtration efficiency vs. particle 
size — Method sensitivity 
D.4.2.2 ISO/TS 13353 
Initial filtration efficiency is calculated from counts measured upstream and downstream the test filter every 
minute. 
According to ISO/TS 13353, efficiency results have to be expressed versus differential counts. In order to compare ISO/TS 13353 and ISO 19438 results, they are also given versus cumulative counts. The initial efficiencies determined twice on Filter A and Filter B by each lab are gathered in Figures D.4 to D.7, 
both in term of “differential” and “cumulative” average initial efficiency. ISO 19438:2003(E) 
© ISO 2003 — All rights reserved   33
   
Figure D.4 — Plot of cumulative  average initial 
efficiency curves measured by 3 laboratories on 
Filter A Figure D.5 — Plot of differential  average initial 
efficiency curves measured by 3 laboratories on 
Filter A 
  
Figure D.6 — Plot of cumulative  average initial 
efficiency curves measured by 3 laboratories on 
Filter B Figure D.7 — Plot of differential  average initial 
efficiency curves measured by 3 laboratories on 
Filter B 
 ISO 19438:2003(E) 
34  © ISO 2003 — All rights reserved
 The average, minimum and maximum efficiency values of all the data obtained from all the labs are reported 
for both Filters A and B in Figures D.8 and D.9. 
  
Figure D.8 — Plot of cumulative  average initial 
efficiency for Filter A and Filter B 
(Average/Minimum/Maximum based on all data) Figure D.9 — Plot of differential  average initial 
efficiency for Filter A and Filter B 
(Average/Minimum/Maximum based on all data) 
 
These plots exhibit no overlap between the Filter A and Filter B characteristics measured with ISO/TS 13353 
method in all labs, showing the sensitivity of this method. 
D.4.2.3 Comparison of initial filtration efficiencies upon ISO 19438 and ISO/TS 13353 
To illustrate a difference, if any, between filter ratings as determined by initial single pass efficiency test 
according to ISO/TS 13353 and by multipass test according to ISO 19438, one reports the efficiencies 
 measured during the first 6 min of the ISO 19438 test (50 mg/l), and 
 measured during the first 60 min of the ISO/TS 13353 test (5 mg/l). 
Table D.4 below shows mean results obtained on Filter B tested twice by all the participating labs. ISO 19438:2003(E) 
© ISO 2003 — All rights reserved   35
 Table D.4 — Initial average efficiencies of Filter B measured in accordance with ISO 19438 
and ISO/TS 13353 
 
Results are illustrated for both Filter A and Filter B in Figures D.10 and D.11, which show the similarity 
between the results obtained by either ISO/TS 13353 or ISO 19438. 
 
Figure D.10 — Comparison of average initial efficiency measured on Filter A with the two methods ISO 19438:2003(E) 
36  © ISO 2003 — All rights reserved
  
Figure D.11 — Comparison of average initial efficiency measured on Filter B with the two methods 
D.4.3 Filter rating 
From Table D.4, it is possible to determine for each filter the particle size corresponding to various preset 
efficiencies from which the filter rating is defined. These values are reported in Table D.5. 
Table D.5 — Filter ratings at various efficiencies for Filter A and Filter B 
 ISO 19438:2003(E) 
© ISO 2003 — All rights reserved   37
 D.5 Conclusion 
The limited number of participants reduces the significance of the “round robin” test. However, some 
conclusions have been able to be drawn by the ISO TC22/SC7 expert group. 
a) ISO 19438 provides industry with a good test method with high repeatability, which makes it a very 
precise tool to follow-up a manufacturing process. It allows a precise determination of the test filter rating 
and retention capacity. 
b) ISO 19438 has good reproducibility (variation between labs) on fine filters and a lower one on coarse 
filters. 
c) ISO 19438 leads to similar initial filtration efficiencies measured during the first 6 min of test as the one 
obtained during 60 min using ISO/TS 13353. 
Thus, initial filter ratings measured using ISO/TS 13353 and ISO 19438 are the same. 
 ISO 19438:2003(E) 
38  © ISO 2003 — All rights reserved
 Bibliography 
[1] ASTM3) D4308-95, Standard test method for electrical conductivity of liquid hydrocarbons  by precision 
meter  
[2] ISO/TS 13353:2002, Diesel fuel and petrol filters for internal combustion engines — Initial efficiency by 
particule counting  
 
                                                      
3) American Society for Testing and Materials. ISO 19438:2003(E) 
ICS  43.060.40 
Price based on 38 pages 
© ISO 2003 — All rights reserved