ﺍﻟﻌﺭﺒﻴﺔ ﺍﻟﺨﻠﻴﺞ ﻟﺩﻭل ﺍﻟﺘﻌﺎﻭﻥ ﻤﺠﻠﺱ ﻟﺩﻭل ﺍﻟﺘﻘﻴﻴﺱ  ﻫﻴﺌﺔ 
GCC STANDARDIZATION ORGANIZATION (GSO) 
 
 
 
 
 
 ﻤﺸﺭﻭﻉ : ﻨﻬﺎﺌﻲ  
 
   
GSO2/FDS/ ISO TS 16332:2011 
ISO 16332:2006 
 
 
 
 ﺍﻟﺩﻴﺯل ﻤﺤﺭﻜﺎﺕ– ﺍﻟﻭﻗﻭﺩ ﻤﺭﺸﺤﺎﺕ -  ﺍﻟﻤﺎﺀ ﻓﺼل ﻜﻔﺎﺀﺓ ﺘﻘﻴﻴﻡ ﻁﺭﻴﻘﺔ 
ﺍﻟﻭﻗﻭﺩ ﻋﻥ 
 
 
Diesel engines – Fuel filter – Me thod for evaluating fuel/water 
separation efficiency 
 
إﻋﺪاد 
 
 ﺍﻟﻤﺭﻜﺒﺎﺕ  ﻤﻭﺍﺼﻔﺎﺕ  ﻟﻘﻁﺎﻉ ﺍﻟﻔﺭﻋﻴﺔ  ﺍﻟﺨﻠﻴﺠﻴﺔ  ﺍﻟﻔﻨﻴﺔ ﻭﺍﻹﻁﺎﺭﺍﺕﺍﻟﻠﺠﻨﺔ   
  
  
 ﻟﺫﻟﻙ ﺒﺸﺄﻨﻬﺎ، ﻭﺍﻟﻤﻼﺤﻅﺎﺕ  ﺍﻟﺭﺃﻱ ﻹﺒﺩﺍﺀ ﺘﻭﺯﻴﻌﻬﺎ  ﺘﻡ ﺨﻠﻴﺠﻴﺔ ﻗﻴﺎﺴﻴﺔ ﻟﻤﻭﺍﺼﻔﺔ  ﻤﺸﺭﻭﻉ  ﺍﻟﻭﺜﻴﻘﺔ ﻫﺫﻩ
ﻴ ﻭﻻ ﻭﺍﻟﺘﺒﺩﻴل،  ﻟﻠﺘﻐﻴﻴﺭ ﻋﺭﻀﺔ ﻓﺈﻨﻬﺎ  ﻤﻥ ﺍﻋﺘﻤﺎﺩﻫﺎ  ﺒﻌﺩ ﺇﻻ ﺨﻠﻴﺠﻴﺔ ﻗﻴﺎﺴﻴﺔ ﻜﻤﻭﺍﺼﻔﺔ  ﺇﻟﻴﻬﺎ ﺍﻟﺭﺠﻭﻉ  ﺠﻭﺯ
ﺍﻟﺨﻠﻴﺠﻴﺔ  ﺍﻟﻬﻴﺌﺔ ﺇﺩﺍﺭﺓ ﻤﺠﻠﺱ.   ﺁﻭ ﺇﺱ ﺠﻲ/ ﺁﻴﺯﻭﺇﺱ٢٣٣٦١ ﺘﻲ  : ١١٠٢  ﺧﻠﻴﺠﻴﺔ  ﻗﻴﺎﺳﻴﺔ  ﻣﻮاﺻﻔﺔ
GSO STANDARD GSO/ISO  TS 16332:2011  
 
1   
ﺘﻘﺩﻴﻡ  
 ﺍﻷﺠﻬﺯﺓ  ﻋﻀﻭﻴﺘﻬﺎ  ﻓﻲ ﺘﻀﻡ ﺇﻗﻠﻴﻤﻴﺔ ﻫﻴﺌﺔ ﺍﻟﻌﺭﺒﻴﺔ ﺍﻟﺨﻠﻴﺞ ﻟﺩﻭل ﺍﻟﺘﻌﺎﻭﻥ ﻤﺠﻠﺱ ﻟﺩﻭل ﺍﻟﺘﻘﻴﻴﺱ ﻫﻴﺌﺔ
 ﺇﻋﺩﺍﺩ ﺍﻟﻬﻴﺌﺔ ﻤﻬﺎﻡ ﻭﻤﻥ ، ﺍﻟﻌﺭﺒﻴﺔ ﺍﻟﺨﻠﻴﺞ ﺩﻭل ﻓﻲ ﻭﺍﻟﻤﻘﺎﻴﻴﺱ  ﻟﻠﻤﻭﺍﺼﻔﺎﺕ  ﺍﻟﻭﻁﻨﻴﺔ  ﺍﻟﻘﻴﺎﺴﻴﺔ ﺍﻟﻤﻭﺍﺼﻔﺎﺕ
 ﻤﺘﺨﺼﺼﺔ  ﻓﻨﻴﺔ ﻟﺠﺎﻥ ﺒﻭﺍﺴﻁﺔ ﺍﻟﺨﻠﻴﺠﻴﺔ  . 
 ﺍﻟﻔﻨﻴﺔ ﺍﻟﻠﺠﻨﺔ ﻋﻤل ﺒﺭﻨﺎﻤﺞ ﻀﻤﻥ ﺍﻟﻌﺭﺒﻴﺔ ﺍﻟﺨﻠﻴﺞ ﻟﺩﻭل ﺍﻟﺘﻌﺎﻭﻥ ﻤﺠﻠﺱ ﻟﺩﻭل ﺍﻟﺘﻘﻴﻴﺱ ﻫﻴﺌﺔ ﻗﺎﻤﺕ ﻭﻗﺩ  
 ٢ﺭﻗﻡ-١  " ﺍﻟﻤﺭﻜﺒﺎﺕ  ﻤﻭﺍﺼﻔﺎﺕ  ﻟﻘﻁﺎﻉ ﺍﻟﻔﺭﻋﻴﺔ ﺍﻟﺨﻠﻴﺠﻴﺔ  ﺍﻟﻔﻨﻴﺔ ﻭﺍﻹﻁﺎﺭﺍﺕﺍﻟﻠﺠﻨﺔ   "  ﺒﺘﺒﻨﻲ
ﺭﻗ ﺍﻟﺩﻭﻟﻴﺔ ﺍﻟﻘﻴﺎﺴﻴﺔ ﺁﻴﺯﻭﺍﻟﻤﻭﺍﺼﻔﺔ   ﺇﺱﻡ  ﺘﻲ  ٢٣٣٦١/٦٠٠٢  " ﺍﻟﺩﻴﺯل ﻤﺤﺭﻜﺎﺕ – ﻤﺭﺸﺤﺎﺕ  
ﺍﻟﻭﻗﻭﺩ-ﺍﻟﻭﻗﻭﺩ  ﻋﻥ ﺍﻟﻤﺎﺀ ﻓﺼل ﻜﻔﺎﺀﺓ ﺘﻘﻴﻴﻡ ﻁﺭﻴﻘﺔ“    – ﺃﺼﺩﺭﺘﻬﺎ  ﻭﺍﻟﺘﻲ" ﻟﻠﺘﻘﻴﻴﺱ ﺍﻟﺩﻭﻟﻴﺔ ﺍﻟﻤﻨﻅﻤﺔ"  
، ﺍﻟﻌﺭﺒﻴﺔ ﺒﺎﻟﻠﻐﺔ ﺘﺭﺠﻤﺘﻬﺎ  ﺍﻟﻤﻤﻠﻜﻭﺘﻤﺕ  ﻭﻗﺎﻤﺕ ﺍﻟﻤﻭﺍﺼﻔﺔﺔ  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 TS 16332:2006  “Diesel engi nes – Fuel filter 
– Method for evaluating fuel/water separation efficiency " issued by 
International Organization fo r Standardization which has been translated 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 number
ISO/TS 16332:2006(E)
© ISO 2006
  
 TECHNICAL 
SPECIFICATION  ISO/TS
16332
First edition
2006-09-15
Diesel engines — Fuel filters — Method 
for evaluating fuel/water separation efficiency 
Moteurs diesels — Filtres à carburant — Méthode d'évaluation de 
l'efficacité des séparateurs carburant-eau 
 ISO/TS 16332:2006(E) 
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Published in Switzerland 
 
ii  © ISO 2006 – All rights reserved
  ISO/TS 16332:2006(E) 
© ISO 2006 – All rights reserved   iii
 Contents Page 
Foreword....................................................................................................................... ..................................... iv  
Introduc tion ................................................................................................................... ..................................... v  
1 Scope .......................................................................................................................... ........................... 1  
2 Normative references ........................................................................................................... ................ 1  
3 Terms and de finiti ons.......................................................................................................... ................. 1  
4 Symbols ........................................................................................................................ ......................... 2  
5 Test equi pment ................................................................................................................. .................... 2  
5.1 Test fl uids .................................................................................................................... .......................... 2  
5.1.1 Test fuels ..................................................................................................................... .......................... 2  
5.1.2 Test water ..................................................................................................................... ......................... 3  
5.2 Laboratory e quipmen t........................................................................................................... ............... 3  
5.2.1 High-speed  mixer............................................................................................................... ................... 3  
5.3 Test stand ..................................................................................................................... ......................... 3  
5.3.1 Filter test circuit (see Figure 1) ............................................................................................. .............. 4  
6 Test c onditi ons ................................................................................................................ ..................... 6  
6.1 Volume of  fuel ................................................................................................................. ...................... 6  
6.2 Test temperature T............................................................................................................................... .6 
6.3 Test flow rate QT............................................................................................................................... .... 7 
6.4 Water concentration (undissolved  water) ........................................................................................ .. 7 
6.5 Differential pressure ∆pO across water emulsifying device (orifice plate) ..................................... 7  
6.6 Total test duration ttotal......................................................................................................................... 7  
7 Accuracy of measuring instru ments and test  conditions ................................................................ 7  
8 Validation pr ocedure ........................................................................................................... ................. 8  
8.1 Test stand ..................................................................................................................... ......................... 8  
8.2 Sampling pr ocedure ............................................................................................................. ................ 9  
8.2.1 Primary sampling procedure ..................................................................................................... .......... 9  
8.2.2 Secondary sampli ng proce dure ................................................................................................... ....... 9  
8.2.3 Secondary sampling pr ocedure va lidation ........................................................................................ 9 
9 Test procedure ................................................................................................................. ................... 10  
9.1 Pre-test pr eparation........................................................................................................... ................. 10  
9.2 Efficiency measure ment ......................................................................................................... ........... 10  
10 Calculation and reporti ng of test results...................................................................................... .... 11  
10.1 Calculation of water separation e fficiency..................................................................................... .. 11 
10.2 Test report .................................................................................................................... ....................... 12  
Annex A  (normative)   Water emulsifying device............................................................................................ 13  
Annex B  (normative)  Procedure to determine the water droplet size dist ribution (DSD) ........................ 16  
Annex C  (informative)  Typical filter test report ............................................................................................. 21  
Annex D  (informative)  Selection of the specified average water droplet sizes D50.................................. 23  
Bibliography ................................................................................................................... .................................. 24  
 ISO/TS 16332:2006(E) 
iv  © ISO 2006 – 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. 
In other circumstances, particularly when there is an urgent market requirement for such documents, a 
technical committee may decide to publish other types of normative document: 
— an ISO Publicly Available Specification (ISO/PAS) represents an agreement between technical experts in 
an ISO working group and is accepted for publication if it is approved by more than 50 % of the members 
of the parent committee casting a vote; 
— an ISO Technical Specification (ISO/TS) represents an agreement between the members of a technical 
committee and is accepted for publication if it is approved by 2/3 of the members of the committee casting a vote. 
An ISO/PAS or ISO/TS is reviewed after three years in order to decide whether it will be confirmed for a 
further three years, revised to become an International Standard, or withdrawn. If the ISO/PAS or ISO/TS is 
confirmed, it is reviewed again after a further three years, at which time it must either be transformed into an 
International Standard or be withdrawn. 
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/TS 16332 was prepared by Technical Committee ISO/TC 22, Road vehicles , Subcommittee SC 7, 
Injection equipment and filters for use on road vehicles . 
Annexes A and B form normative parts of this Technical Specification. Annexes C and D are for information 
only. ISO/TS 16332:2006(E) 
© ISO 2006 – All rights reserved   v
 Introduction 
Modern fuel injection systems, installed in passenger cars, as well as in heavy duty or off-road vehicle 
applications, require high and stable separation efficiencies for all insoluble contaminants in the fuel to ensure 
a prolonged life. Beside solid contamination, undissolved water, in finely or coarsely emulsified form, can also 
reduce the lifetime of injection systems. Suitable fuel filters, having a high level water separation efficiency, are an absolute necessity for system longevity. 
Factors found to affect the separation efficiency of undissolved water in the field are mainly due to the fuel 
quality, which is strongly influenced by the performance of additives in the fuel itself, as well as the actual characteristics of the fuel/water-emulsion, the specific flow rate of the system, the type of media in the filter 
element, as well as the size and design of the filter housing itself. To ensure laboratory test results are 
comparable, these various parameters have to be taken into account in the test method, in order to reduce their influence on the test results. 
NOTE A variety of tests were investigated prior and parallel to the preparation of this Technical Specification to 
specify the required test conditions. Additional work is underway to validate, confirm and if necessary to modify the 
following parameters: 
⎯ test fuel (5.1.1); 
⎯ water concentration of 1 500 ppm (6.4); 
⎯ volume of fuel (6.1); 
⎯ total test duration ttotal (6.6). 
At the time of publication of this Technical Specification, interlaboratory tests are being organized to establish the 
repeatability and reproducibility of the results. 
 TECHNICAL SPECIFICATION ISO/TS 16332:2006(E)
 
© ISO 2006 – All rights reserved   1
 Diesel engines — Fuel filters — Method for evaluating 
fuel/water separation efficiency 
1 Scope 
This Technical Specification specifies a fuel/water separation test with continuous water injection, using an 
offline water concentration measuring method, for evaluating the ability of a fuel filter to separate either finely 
or coarsely dispersed undissolved water out of fuel. This test is intended for application to filter elements 
which are installed upstream or downstream of the low pressure pump, having a rated flow (in litres per hour) between 50 l/h and 900 l/h. By agreement between customer and filter manufacturer, and with some modification, the procedure may be used for 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 760, Determination of water — Karl Fischer method (General method)  
ISO 1219-1, Fluid power systems and components — Graphic symbols and circuit diagrams — 
Part 1: Graphic symbols for conventional use and data-processing applications 
ISO 6889, Surface active agents — Determination of interfacial tension by drawing up liquid films   
ISO 13320-1, Particle size analysis — Laser diffraction methods — Part 1: General principles  
ASTM D 1401, Standard Test Method for Water Separability of Petroleum Oils and Synthetic Fluids 
CEC RF-06-03:2003 
1), CEC Legislative fuel RF-06-03 (reference fuel specification) 
3 Terms and definitions 
For the purposes of this document, the following terms and definitions apply. 
3.1 
interfacial tension IFT 
force required to increase the surface area of the interface between two liquids by a unit amount 
NOTE Interfacial tension is expressed in millinewtons per metre (mN/m). 
                                                      
1) The reference fuel specification is provided by CEC secretariat services: Interlynk Administrative Services Ltd., 
PO Box 6475, Earl Shilton, Leicester LE9 9ZB, UK; T +44(0)1455 21993; F +44(0)1455 821994. ISO/TS 16332:2006(E) 
2  © ISO 2006 – All rights reserved
 3.2 
droplet size distribution DSD 
curve of the percentage of the droplet population in different size ranges 
See Figure B.1. 
3.3 
base water concentration 
concentration of water in water saturated fuel  
3.4 
undissolved water 
difference between total and base water concentration 
3.5 
test time t 
“point of time” when a test or a measurement is started or running respectively 
NOTE In contrast to the total test duration ttotal, see 6.6. 
4 Symbols 
Graphical symbols used in this Technical Specification for fluid power system components are in accordance 
with ISO 1219-1. 
5 Test equipment 
5.1 Test fluids 
5.1.1 Test fuels 
The test fuel shall be according to CEC RF-06-03 2) and processed to achieve the following requirements by 
adding a multifunctional fuel additive (see Note 1): 
a) IFT 
15 mN/m ± 3 mN/m measured according to ISO 6889 after 60 s; 
b) water separability 
270 s ± 30 s, when 75 % of test fuel is separated (sedimentation test according to ASTM D 1401 at 
25 °C). Within this document, the water separability is defined through the point of time, when 75 % of the 
test fuel is separated. 
NOTE 1 Fundamental tests lead to a mass fraction of approximately 0,1 % of the multifunctional fuel additive 
HiTEC 4620 2) to reach the required values. 
The test fuel shall be stored protected from humidity, dust and light. 
The batch of test fuel shall be changed when the fuel no longer meets the specified requirements. 
                                                      
2) Suitable products are available commercially. Details may be obtained from the Secretariat of Technical Committee 
ISO/TC22 or from the ISO Central Secretariat. ISO/TS 16332:2006(E) 
© ISO 2006 – All rights reserved   3
 Optionally, if agreed between customer and filter manufacturer, the test can be performed with a fuel used in 
the application, but the deviations of the relevant fuel parameters shall be recorded in the test report. 
NOTE 2  By using  other fuel qualities (e.g. fuels used in application), the test results may not be comparable with the 
results obtained with the test fuel according to 5.1.1. 
5.1.2 Test water 
Clean, distilled, or deionized water with a surface tension of at least 70 mN/m, measured at 20 °C ± 1,5 °C.  
5.2 Laboratory equipment 
5.2.1 General 
All laboratory equipment and glassware, required to determine the water concentration, shall be according to 
ISO 760. 
5.2.2 Sampling bottles and glassware , 100 ml sampling bottles with 45 mm screw caps carefully rinsed 
with clean petroleum ether and dried in an oven. 
5.2.3 Karl Fischer titration system 3), as commercially available and validated according to 8.2.3. 
Recommended equipment should be composed of a coulometric, diaphragmless titration cell and a 
codistillation unit. 
Humidity is probably the largest source of error during the titration process. Special precautions should be 
taken during setup and testing. The recommended amount of water per sample should be W 50 µg to reach a 
good relation between titration time and accuracy. 
5.2.4 Analytical balance , with an accuracy of ± 1 mg.  
5.2.5 Sampling syringe , with a volume of 1 ml ± 0,1 ml.  
5.2.6 High-speed mixer 
Mixer of the ULTRA-TURRAX type 3) with 
⎯ a stator of 18 mm ± 1 mm, 
⎯ a rotor of 12,5 mm ± 1 mm, and 
⎯ a rotational speed of 15 000 min−1 ± 500 min−1. 
5.3 Test stand 
5.3.1 General 
The test stand, shown diagrammatically in Figure 1, shall comprise a filter test circuit as described in 5.3.2. 
                                                      
3) This equipment has been found satisfactory. This information is given for the convenience of users of this Technical 
Specification and does not constitute an endorsement by ISO. Details may be obtained from the Secretariat of Technical 
Committee ISO/TC22 or from the ISO Central Secretariat. ISO/TS 16332:2006(E) 
4  © ISO 2006 – All rights reserved
 5.3.2 Filter test circuit (see Figure 1) 
5.3.2.1 Fuel sump  (1) 4) : conical bottom, stainless steel or corros ion resistant container with a fuel outlet 
at the bottom of the container. 
The container shall be able to contain the volume as specified in 6.1. The fuel sump has to be covered with a 
non transparent cover to protect the fuel from light. 
5.3.2.2 Water sump  (6): stainless steel or corrosion resistant container with approximate capacity of 30 l. 
NOTE Instead of the container, continuous water supply may be used. 
5.3.2.3 Test pump  (2) which does not exhibit pressure pulsation with an amplitude greater than 10 % of 
the average pressure at the inlet of the water emulsifying device.   
5.3.2.4 Adjustable water injection pump  (7) 5), capable of delivering a water flow between 0,15 % and 
2 % of the fuel flow. 
5.3.2.5 Fuel flow meter  (5a), capable of measuring with an accuracy as specified in Table 1. 
5.3.2.6 Water flow meter  (5b) 5), capable of measuring with an accuracy as specified in Table 1. 
5.3.2.7 Injection device  (8), with a maximum inner diameter of the injection pipe of 1 mm. 
5.3.2.8 Water emulsifying device  (9): fixture with an exchangeable orifice plate, as described in 
Annex A. 
5.3.2.9 Upstream  (12) and downstream  (17) sampling devices , as shown in Figure 3. 
5.3.2.10 Temperature indicator  (13) with an accuracy as specified in Table 1. 
5.3.2.11 Pressure gauge  (10) with an accuracy as specified in Table 1. 
5.3.2.12 Differential pressure gauges  (11) with an accuracy as specified in Table 1. 
5.3.2.13 Water drainage system  (15): closed collector (e.g. laboratory measuring cylinder), located 
directly below the test filter (water separator) (14) and capable to collect the injected amount of water; it is 
connected to the water outlet of the test filter with pressure-tight fittings. 
The internal diameter of the connecting pipe between the test filter and the closed collector shall be of at least 
10 mm. 
5.3.2.14 Test stand pipes  shall be made of stainless steel; painted or coated pipes are not allowed. 
For the adaptation of the test filter (14) to the test stand piping, flexible lines are allowed. 
The piping shall be designed with a minimum number of flanges or fittings and grounded upstream near the 
test filter (potential difference < 10 V between each point). 
The test stand pipes inner diameter di between injection device (8) and downstream sampling point (17) (see 
Figure 2) should allow a flow velocity W 0,75 m/s. 
The pipes, outside of Figure 2, shall be as short as possible. 
5.3.2.15 Inline static mixer  (16) to provide a representative sample at the downstream sampling 
point (17). 
NOTE Using a water emulsifying device (see 5.3.2.8 ) has been proven to be suitable as a static mixer. 
                                                      
4) The numbers in brackets refer to the key numbers in Figure 1. 
5) Suitable products are available commercially. Details may be obtained from the Secretariat of Technical Committee 
ISO/TC22 or from the ISO Central Secretariat. ISO/TS 16332:2006(E) 
© ISO 2006 – All rights reserved   5
 5.3.2.16  Optional: three-way ball valve  (18) and collecting sump  (19), if the test stand is used to run as 
a single pass system (open test circuit). 
5.3.2.17 Final water separator assembly  (20), 
⎯ with a suitable container in which to drain the water, and 
⎯ such that not more than 30 ppm by volume of undissolved water is recycled on an average basis under 
test conditions. 
5.3.2.18 Back pressure regulating valve (21) to ease test filter venting and optionally to control the test 
flow rate QT. 
5.3.2.19  Heat exchanger  (3), capable of maintaining the test temperature T within the tolerances given in 
Table 1. 
 
Key 
1 fuel sump 7 adjustable water injection pump 14 test filter (water separator) 
2 test pump 8 injection device 15 water drainage system 
3 heat exchanger 9 water emulsifying device 
 (orifice plate holder) 16 inline static mixer 
4 sampling point 
 (sampling valve) 10 pressure gauge 17 downstream sampling point 
 (downstream sampling device: see Figure 3)
5a fuel flow meter 11 differential pressure gauges (2) 18 three-way ball valve (optional) 
5b water flow meter 19 collecting sump (optional) 
6 water sump 12 upstream sampling point 
 (upstream sampling device: see Figure 3)20 final water separator assembly 
 13 temperature indicator 21 back pressure regulating valve 
a See Figure 2.  
Figure 1 — Filter test stand (diagrammatically) ISO/TS 16332:2006(E) 
6  © ISO 2006 – All rights reserved
  
Key 
Ødi inner pipe diameter  
Figure 2 — Length and inner diameter di of test stand pipes (detail X of Figure 1) 
Dimension in millimetres 
 
Key 
l di /4 < l < di /3 
Ødi inner pipe diameter 
a Flow of test fluid. 
b Sampling flow.  
Figure 3 — Upstream and downstream sampling device 
6 Test conditions 
6.1 Volume of fuel 
The volume of the fuel [fuel sump (1)] shall be 15 times the test flow rate QT per minute. 
6.2 Test temperature T 
The test shall be conducted at a test temperature T of 23 °C ± 2 °C, measured at the test filter inlet. 
Alternatively, the test may be performed at a test temperature T as agreed between customer and filter 
manufacturer. This shall be recorded in the test report. ISO/TS 16332:2006(E) 
© ISO 2006 – All rights reserved   7
 6.3 Test flow rate QT 
The test flow rate QT is specified by the customer and is defined as the flow rate of fuel. 
6.4 Water concentration (undissolved water) 
One of the following two conditions for the undissolved water concentration (see 3.4) shall be used for the 
test: 
⎯ standard condition: 1 500 ppm volume fraction ± 75 ppm volume fraction (approx. 0,15 %); 
⎯ optional condition: 2 % volume fraction ± 0,1 % volume fraction. 
6.5 Differential pressure ∆pO across water emulsifying device (orifice plate) 
The following differential pressure ∆pO measured across the water emulsifying device shall be adjusted in 
order to achieve the required DSD. 
⎯ For coarse water droplets ( D50 of 300 µm), an orifice plate shall be installed with an orifice which creates 
a differential pressure ∆pO of 48 hPa ± 5 hPa; 
⎯ For fine water droplets ( D50 of 60 µm), an orifice plate shall be installed with an orifice which creates a 
differential pressure ∆pO of 260 hPa ± 10 hPa. 
⎯ For the definition of D50, see Annex B. 
⎯ For the selection of the specified average water droplet size ( D50), see Annex D. 
The choice of whether to use coarse or fine water droplets depends on the application and has to be specified 
by the customer. 
NOTE As agreed between customer and filter manufacturer, other D50 values may be used. These values shall be 
reported in the test report as a deviation to the standard operating conditions. 
6.6 Total test duration ttotal 
Depending on the concentration of undissolved water (see 6.4) the total test duration shall be  
a) ttotal = 90 min for 1 500 ppm (standard condition), and 
b) ttotal = 60 min for 2 % (optional condition). 
7 Accuracy of measuring inst ruments and test conditions 
The measuring instruments shall be capable of measuring to the levels of accuracy given in Table 1. In 
addition, Table 1 specifies the limits within which the test conditions shall be maintained. ISO/TS 16332:2006(E) 
8  © ISO 2006 – All rights reserved
 Table 1 — Instrument accuracy and test condition variation 
Test condition Units Measurement 
accuracy Allowed test condition variation 
Fuel flow rate ( Q, QC, QT) 
(fuel flow meter) l/h ± 1 % ± 2 % 
Water flow rate 
(water flow meter) ml/min ± 1 % ± 2 % a 
Pressure (gauge between injection 
device and water emulsifying device) hPa ± 2 % — 
Differential pressure ∆pO 
(gauge at orifice plate) hPa ± 0,5 % — 
Differential pressure ∆pF 
(gauge at test filter) hPa ± 2 % — 
Temperature 
(temperature indicator) °C ± 1 °C ± 2 °C  
Water concentration b % mass fraction ± 5 ppm  ± 5 % a 
a Undissolved water (see 3.4). 
b Upstream [at sample point (12) of Figure 1]. 
8 Validation procedure 
8.1 Test stand 
The validation of the test stand shall be performed at the minimum and maximum test stand design flow rates 
with a straight pipe in place of the test filter (14). 
For each of these two flow rates, perform the following procedure in the order given: a) commence operation of the final water separator (20); b) start the test pump (2) and adjust the flow rate to the required value; 
c) circulate the test liquid until the temperature reaches the required value; 
d) inject water at the required concentration (see 6.4); e) allow to stabilize for at least 10 min; f) for a 90 min test, take samples every 10 min according to the sampling procedure described in 8.2, 
1) at the sampling point (4), 
 [validation of final water separator assembly (20) and determination of base water concentration] 
2) at the upstream sampling point (12), and 
 [validation of the injection system (6), (7), (5b) and (8) and the water emulsifying device (9)] 
3) at the downstream sampling point (17); 
 [validation of the inline static mixer (16)] 
g) measure the water content of each sample. ISO/TS 16332:2006(E) 
© ISO 2006 – All rights reserved   9
 The validation shall be accepted only if 
⎯ at the sampling point (4), the variation between the total water concentration of each sample is less than 
30 ppm by volume, and 
⎯ at the sampling points (12) and (17), the actual concentration of water of each sample, reduced by the 
base water concentration, is equal to the injected water concentration, within the limits defined in Table 1. 
NOTE Many water in oil analytical devices will determine the water concentration in terms of micrograms. To convert 
micrograms to parts per million (ppm) by volume, use the following equation: 
Titration reading, in ppm volume fraction = titration reading, in ppm mass fraction × fuel/water densities correlation factor 
where the fuel/water densities correlation factor is (fuel density,  in grams per litre) / (water density, in grams per litre). 
8.2 Sampling procedure 
8.2.1 Primary sampling procedure 
The following procedure shall be executed for the upstream and downstream sampling points: 
a) open the sampling valves at sampling points (12) and (17); b) flush the volume between the sampling points (12) and (17) and discard in an appropriate repository; 
c) immediately open the sampling bottles (prepared as described in 5.2.2) and fill approximately 50 ml; 
d) close the sampling bottles directly after filling and identify the sample. If an automatic codistillation unit is used for Karl-Fisher titration, insert the bottles directly in the distillation unit. 
If an automatic sampling unit is used, flushing of the sampling pipes and exclusion of humidity inflow into the 
sample volume shall be assured, until final analysis in titration cells is completed. 
8.2.2 Secondary sampling procedure 
If a manually served cell is used, homogenize the sample using the same mixer (see 5.2.6) to assure that the 
water is completely and uniformly dispersed. Use a hypodermic syringe and extract an adequate sample 
volume as described in 5.2.3. 
This secondary sampling procedure shall be validated according to 8.2.3. 
8.2.3 Secondary sampling procedure validation 
a) Take 51 g ± 0,05 g sample of test fuel; 
b) take 1 g ± 0,01 g secondary sample by using a micro-syringe; 
c) measure the water content c
1; 
d) add 0,075 g ± 0,005 g water into remaining 50 g sample and mix by using an ULTRA-TURRAX mixer; 
e) take another 1 g ± 0,01 g sample using a micro-syringe; 
f) measure the water content c2; 
g) c2 – c1 shall be 1 500 ppm ± 75 ppm.  ISO/TS 16332:2006(E) 
10  © ISO 2006 – All rights reserved
 9 Test procedure 
9.1 Pre-test preparation 
Perform the pre-test preparation procedure in the following order: 
a) install the test filter (14) and water drainage system (15) for testing; 
b) choose an orifice plate with a suitable orifice for the required DSD ( D50 = 60 µm or D50 = 300 µm) and 
fuel flow rate QC according to Annex B; 
c) install the orifice plate into the holder [water emulsifying device (9)]; 
d) start circulation at the specified test flow rate QT (see 6.3) and test temperature T (see 6.2). Bleed air from 
the system including water drainage system (15). Record an initial pressure drop reading at the orifice (9) and at the test filter (14) immediately after the start; 
e) record the resulting DSD as described in Annex B; f) circulate the clean test fluid at the specified test flow rate Q
T (see 6.3) through the test filter (14) for at 
least 30 min. 
9.2 Efficiency measurement  
Perform the following procedure in the order given: 
a) commence water injection at the specified test flow rate QT (see 6.3) and start the timing clock at the 
same time water begins to flow. This point is test time t = 0. Record the differential pressure ∆pO across 
the orifice (9) and test filter (water separator) (14); 
b) after 10 min: 
1) take an initial sample at sampling point (4) and measure the water content; this is to determine the 
base water concentration of the fuel; 
2) take an initial upstream sample according to the sampling procedure described in 8.2; analyse the 
sample immediately to confirm that the specified water concentration is being injected into the fuel stream; 
3) take an initial downstream sample according to the sampling procedure described in 8.2; repeat this 
sampling procedure every 10 min thereafter until termination of the test; 
The volume of the samples analysed shall be sufficient to dose at least 50 µg of water into the titration cell. 
c) record the differential pressure ∆p
O (11) across the orifice (9) and the test filter (14) at each downstream 
sampling interval; 
d) terminate the test if one or more of the following conditions are met: 
1) the undissolved water concentration in the downstream sample is above the acceptable level 
specified by customer or filter manufacturer, or 
2) an equilibrium pressure drop across the test filter (14) has been reached and a minimum of 90 min of 
total test duration ttotal has been attained, or 
3) the differential pressure ∆pF across the test filter (14) exceeds an upper limit specified by customer or 
filter manufacturer; ISO/TS 16332:2006(E) 
© ISO 2006 – All rights reserved   11
 e) take a final sample at sampling point (4) to verify that the base water concentration did not change [i.e. 
check of the final water separator (20)]; 
f) if the base water concentration has not changed, record the volume of water drained from the test 
filter (14); 
g) if the base water concentration has changed by more than 30 ppm, cancel the test; check the final water 
separator (20) and repeat the steps a) to e). 
10 Calculation and repo rting of test results 
10.1 Calculation of water separation efficiency 
Perform the following procedures in the order given: 
a) determine and record the concentration of undissolved water of the downstream samples with respect to 
test time t: 
undissolved water = total water − base water 
b) plot the concentration of undissolved water in the downstream samples (ppm by volume) versus test 
time t, in min; 
NOTE All following water concentrations ( c, ic, avc) refer to undissolved water.  
c) calculate, report and plot (see Figure C.1) the instantaneous water separation efficiency iη, in %, versus 
test time t, in min, by the following equation: 
iη=)(100i cc
c−
×  
 where 
c is the specified test water concentration, in ppm by volume; 
ic is the downstream water concentration, in ppm by volume, of sample i; 
d) calculate and report the average downstream water concentration avc, in ppm by volume, by the following 
equation: 
avc=ic
n∑ 
 where 
ic is the downstream water concentration, in ppm by volume, of the sample i; 
n is the number of samples (see 9.2); ISO/TS 16332:2006(E) 
12  © ISO 2006 – All rights reserved
 e) calculate and report the average water separation efficiency avη, in %,  by the following equation: 
avη=)( av cc
c−
100×  
 where 
c is the specified test water concentration, in ppm by volume; 
avc is the average downstream water concentration, in ppm by volume. 
10.2 Test report 
The test report shall include: 
a) test fluid(s) characteristics;  
b) test flow rate QT; 
c) water concentration (undissolved water);  d) calibrated orifice diameter 
d; 
e) differential pressure ∆pO at orifice plate and corresponding average droplet size D50; 
f) differential pressure ∆pF at test filter; 
g) test temperature T; 
h) total test duration ttotal; 
i) base water concentration of the fuel at test temperature T; 
j) total volume of water drained from the test filter; k) a graph showing the water separation efficiency versus test time 
t as shown in Figure C.1; and 
l) an explanation of reason(s) for test termination. 
See Annex C for a typical filter test report. ISO/TS 16332:2006(E) 
© ISO 2006 – All rights reserved   13
 Annex A 
(normative)  
 
Water emulsifying device 
Details of the water emulsifying device (9) are shown in Figures A.1 to A.4. 
The orifice itself (calibrated diameter d) shall be produced by laser cutting and shall be free from any burrs.  
Dimensions in millimetres 
  
a)   Simple orifice plate  b)   Double orifice plate  
Key 
Ød calibrated orifice diameter d of orifice plate 
Figure A.1 — Orifice plates with calibrated orifice diameters d ISO/TS 16332:2006(E) 
14  © ISO 2006 – All rights reserved
  
Key 
A–A see Figure A.3 
Figure A.2 — Water emulsifying device (orifice plat e holder) with double orifice plate and pressure 
taps (measurement of differential pressure ∆pO) 
 
Key 
X see Figure A.4 
Figure A.3 — Water emulsifying device (orifice plate holder) 
(cut A – A of Figure A.2) ISO/TS 16332:2006(E) 
© ISO 2006 – All rights reserved   15
 Dimensions in millimetres 
 
Key 
1 pressure transmitting bores (to pressure tap connections for differential pressure ∆pO measurement) 
2 orifice plate holder 
3 orifice plate 
Ød calibrated orifice diameter of orifice plate 
Ødi inner pipe diameter 
Øj diameter of pressure transmitting bores and of pressure tap bores 
a Flow of fuel/water mixture. 
Figure A.4 — Detail X of Figure A.3: 
Measurement of differential pressure ∆pO at the orifice plate ISO/TS 16332:2006(E) 
16  © ISO 2006 – All rights reserved
 Annex B  
(normative) 
 
Procedure to determine the water droplet size distribution (DSD) 
B.1 Water droplet size dist ribution (DSD) — Definition 
The water droplets are generated by dissipating a known energy within the fuel/water mixture by flowing it 
through a calibrated orifice diameter d (see Figure B.2). 
Droplet sizes D are polydispersed, generally according to the model shown in Figure B.1, when measured 
using the laser diffraction technique according to ISO 13320-1. 
 
Key 
D droplet size, in micrometres (µm) 
DSDdiff differential droplet size distribution (curve A), in percent (%) 
DSDcum cumulative droplet size distribution (curve B), in percent (%) 
A typical size distribution curve of water droplets after passing through an orifice  (DSDdiff) 
B typical droplet size distribution curve for the determination of D10, D50 and D90 (DSDcum) 
Figure B.1 — Typical distribution curves of polydispersed droplet sizes D ISO/TS 16332:2006(E) 
© ISO 2006 – All rights reserved   17
 Curve A represents the differential distribution of droplet sizes DSDdiff (i.e. percentage of droplets within a size 
range) and curve B the cumulative one DSDcum (i.e. percentage of droplets smaller than the indicated droplet 
size D). The cumulative distribution DSDcum can be represented by three droplet sizes: 
⎯ D10 is the droplet size D that only 10 % of the droplets underpass. 
⎯ D50 is the droplet size D which separates the droplets in two identical populations, 50 % larger and 50 % 
smaller; i.e., D50 is the average diameter of the droplet size distribution DSD. 
⎯ D90 is the droplet size D that only 10 % of the droplet population overpass (90 % underpass). 
Since it has been shown by studies performed to develop this Technical Specification that water droplets in 
fuel have similar Gaussian distributions whatever their average sizes, it has been agreed to characterize this distribution by the D
50 figure, only. 
B.2 Calibrated orifices 
Because of their simplicity, orifice plates with calibrated orifice diameters d have been used to mix, under 
known and repeatable conditions, the water with fuel to generate droplets of known size D. The orifice plates 
are made of 0,5 mm thick stainless steel discs with  a central hole of variable inside diameter d (orifice 
diameter). Typical stainless steel orifice plates with calibrated orifice diameters d (simple and double orifice 
plates) are shown in Figure A.1. 
The energy dissipated by a liquid flowing through the calibrated orifice diameter d is quantified by its pressure 
drop (or differential pressure ∆pO measured across the orifice plate) provided measured adequately, e.g. as 
shown on Figure B.2. 
 
Key 
p+, p− differential pressure ∆pO measuring points at the orifice plate (see Figure A.4, detail X) 
Ødi inner pipe diameter 
Ød calibrated orifice diameter of orifice plate 
Figure B.2 — Energy dissipated by a liquid fl owing through the calibrated orifice diameter d of an 
orifice plate 
Typical curves representing differential pressure ∆pO versus fuel flow rate QC have been measured on 
calibrated orifices of various diameters d with a given fuel (CEC RF-06-99; ν = 7 mm2/s at 24 °C). These 
curves are shown in Figure B.3. ISO/TS 16332:2006(E) 
18  © ISO 2006 – All rights reserved
  
Key 
QC fuel flow rate (for calibration of orifice plates), in litres per hour (l/h) 
∆pO orifice differential pressure, in hectoPascals (hPa) 
Ød calibrated orifice diameter of orifice plate, in millimetres (mm) 
NOTE The curves of Figure B.3 are given for information only, since they strongly depend on the actual 
characteristics of the test fuel used. 
Figure B.3 — Typical curves of differential pressure ∆pO through calibrated orifice diameter d 
B.3 DSD generated by orifices 
It has been shown with various fuel/water mixtures in a number of conditions that the average droplet size D50, 
in µm, of the DSD was linked to the differential pressure ∆pO, in hPa, across an orifice plate by the following 
equation: 
D50 = ()2
O ln
10 1339 ep∆−
×  where r2 = 0,96 (B.1) 
As a reciprocal, the equation used to determine the differential pressure ∆pO, in hPa, across an orifice plate to 
generate a known average droplet size D50, in µm, is: 
∆pO = 5010 ln1339eD⎛⎞−×⎜⎟
⎝⎠ where r2 = 0,96 (B.2) 
NOTE r2 is the linear regression coefficient for fitting the equat ion to actual experimental data measured on 92 points. 
These equations lead to the curve shown on Figure B.4. ISO/TS 16332:2006(E) 
© ISO 2006 – All rights reserved   19
  
Key 
∆pO orifice differential pressure, in hectoPascals (hPa) 
D50 average droplet size, in micrometres (µm) 
Figure B.4 — Standard curve of average droplet size D50 vs orifice differential pressure ∆pO 
Figure B.5 can be used as a help in choosing the appropriate calibrated orifice diameter d from the type of 
filter to be tested (i.e. pressure or suction system) and the test flow rate QT. 
 
Key 
QT test flow rate, in litres per hour (l/h) 
Ød calibrated orifice diameter of orifice plate, in millimetres (mm) 
1 suction system ( D50 = 300 µm) 
2 pressure system ( D50 = 60 µm) 
NOTE The curves of Figure B.5 are given for information only, since they strongly depend on actual fuel 
characteristics. 
Figure B.5 — Curves relating diameter d of calibrated orifices and fuel test flow rate QT 
for filters of pressure and suction systems ISO/TS 16332:2006(E) 
20  © ISO 2006 – All rights reserved
 B.4 Procedure for determining actual average test DSD 
Perform the following procedure in the order given: 
a) select the test DSD depending on the type of fuel filter to be tested: 
1) for “pressure side” filters, generate fine droplets with a D50 of 60 µm, 
2) for “suction side” filters, generate coarse droplets with a D50 of 300 µm; 
NOTE Based on the tolerances given in 6.5 on the differential pressure ∆pO at the orifice plates, tolerances on the 
D50 can be calculated as follows: ± 2 µm on the 60 µm droplets and ± 25 µm on the 300 µm droplets. 
b) using Equation (B.2) of B.3 or Figure B.4, determine the corresponding differential pressure ∆pO to be 
generated through the water emulsifying device; 
c) using Figures B.3 or B.4, determine the calibrated orifice diameter d which generates the differential 
pressure ∆pO determined above, at the test flow rate QT (see 6.3); 
d) select and install an available orifice plate with the calibrated orifice  diameter d closest to the one 
calculated in B.4 c); 
e) during the test (see 9.2), record the actual differential pressure ∆pO at the installed orifice plate for the test 
flow rate QT and calculate its average value throughout the test; 
f) using Equation (B.1) of B.3 or Figure B.4, determine the actual average test D50 of the DSD and report 
this in the test report. ISO/TS 16332:2006(E) 
© ISO 2006 – All rights reserved   21
 Annex C  
(informative) 
 
Typical filter test report 
A typical test report sheet is formed and composed as follows. 
The test report should include additional information presented in graphical form, as illustrated in Figure C.1. 
Fuel filter water efficiency test report according to ISO 16332 
TEST IDENTIFICATION  
TEST DATE: TEST LOCATION: TEST IDENTIFICATION: 
TEST TIME: OPERATOR: PROJECT: 
FILTER IDENTIFICATION 
FILTER IDENTIFICATION: FABRICATION INTEGRITY (ISO 2942) : hPa
HOUSING TYPE: MANUFACTURING DATE: 
OPERATING CONDITIONS 
Test performed under standard conditions YES  NO  
STANDARD OPERATING CONDITIONS  
TEST FUEL Type:  CEC RF-06-03 Batch-No: 
 Water separability: 
(duration, when 75 % of test 
fuel is separated)  s IFT (fuel/water): 
Base water concentration: 
 15 mN/m
ppm
TEST WATER Surface tension: 72 mN/m ± 2 mN/m  
TEST SYSTEM Test flow rate QT:  l/h Volume: l
 Calibrated orifice diameter d:  mm Test temperature T: 23 °C ± 2 °C
 Average droplet size D50:       300 (µm)    
         60 (µm)  (∆pO = 48 hPa) 
(∆pO = 260 hPa) 
INJECTION SYSTEM: Injection flow rate Qia:  ml/min Water concentration (calc.): 1 500 ppm
   Water concentration  
(initial upstream sample): ppm
DEVIATIONS FROM STANDARD OPERATING CONDITIONS  
TEST FUEL Type:  Batch-No:  
 Density: 
Kinematc viscosity: 
Water separability:   
(duration, when 75 % of test 
fuel is separated)  kg/m³ 
 mm²/s 
 s  IFT (fuel/water): 
Base water concentration: 
  mN/m 
 ppm 
 
TEST WATER Surface tension:   mN/m   
TEST SYSTEM Test temperature T:    °C   
 Average droplet size D50:       µm  ∆pO:  hPa 
INJECTION SYSTEM: Injection flow rate Qia:  ml/min Water concentration (calc.):  ppm 
   Water concentration 
(initial upstream sample):  
 ppm ISO/TS 16332:2006(E) 
22  © ISO 2006 – All rights reserved
 TEST RESULTS  
Test time t  (min) 0 10 20 30 40 50 60 70 80 90 
Differential pressure ∆pF 
at test filter ( h P a )            
Differential pressure ∆pO 
at orifice plate ( h P a )            
Downstream water 
concentration ci ( p p m )            
Water separation 
efficiency ηi ( % )            
Total test duration ttotal: min 
Average downstream water concentration ( cav): ppm 
Average water separation efficiency (avη): % 
Total volume of water drained from test filter: l 
ISO/TS 16332 Water separation efficiency η 
 
Key 
t test time, in minutes (min) 
η water separation efficiency, in percent (%) 
Figure C.1 — Typical test diagram ISO/TS 16332:2006(E) 
© ISO 2006 – All rights reserved   23
 Annex D  
(informative) 
 
Selection of the specified average water droplet sizes D50 
Characterization of emulsions transferred to fuel filters 
The laser diffraction technique has been applied to measure the size D50 of the droplets generated by various 
fuel transfer systems under single pass operating condition. Suction side systems are characterized by a fuel 
filter located upstream the fuel supply pump; these also include the so-called jet pumps. Pressure side systems have the fuel filter downstream the fuel supply pump. The D
50 figures have been measured in various 
conditions of water concentration, fuel temperature and flow rate. Experimental results are reported on Figure D.1. 
Based on these experimental results, ISO/TC22/SC7/WG1 has adopted an average D
50 of 300 µm to 
represent suction systems and an average D50 of 60 µm to represent pressure ones. 
 
Key 
Q fuel flow rate, in litres per hour (l/h) 
D50 average droplet size, in micrometres (µm) 
Fuel transfer systems: 
   roller vane pump 1 
  external gear pump 1 
  strainer 1 
 roller vane pump 2 
  external gear pump 2 
  strainer 2 
 roller vane pump 3 
  jet pump 
  strainer 3 
Figure D.1 — Average size D50 of water droplets measured in fuels downstream 
various fuel transfer systems ISO/TS 16332:2006(E) 
24  © ISO 2006 – All rights reserved
 Bibliography  
[1] ISO 2942, Hydraulic fluid power — Filter elements — Verification of fabrication integrity and 
determination of the first bubble point  
[2] ISO 3722, Hydraulic fluid power — Fluid sample containers — Qualifying and controlling cleaning 
methods  
[3] ISO 3968, Hydraulic fluid power — Filters — Evaluation of differential pressure versus flow 
characteristics  
 ISO/TS 16332:2006(E) 
ICS  43.060.40 
Price based on 24 pages 
© ISO 2006 – All rights reserved