ISO 13357-1:2017

Petroleum products - Determination of the filterability of lubricating oils - Part 1: Procedure for oils in the presence of water

ISO 13357-1:2017 specifies a procedure for the evaluation of the filterability of lubricating oils, particularly those designed for hydraulic applications, in the presence of water. The procedure only applies to mineral-based oils, since fluids manufactured from other materials (e.g. fire-resistant fluids) may not be compatible with the specified test membranes. The range of application has been evaluated with oils of viscosity up to ISO viscosity grade (VG) 100, as defined in ISO 3448. Within the range described, the filterability as defined is not dependent on the viscosity of the oil. The procedure is not suitable for some hydraulic oils on which specific properties have been conferred by the use of insoluble/partially soluble additives, or by particularly large molecular species. NOTE Filterability is a prime requirement for lubricating oils used in hydraulic systems because of the fine filters used in this application. ISO 13357-1:2017 defines a method for assessing the filterability of oils in the presence of contaminating water. It is noted that some oils will exhibit poorer filterability characteristics in these conditions. ISO 13357‑2[1] is used to investigate the filterability of an oil which is used in applications where the presence of water in the oil is unlikely. An oil which has good filterability in the presence of contaminating water will not necessarily have equally good filterability in dry conditions. An oil having good filterability only when wet is unlikely to be generally acceptable.

Produits pétroliers — Détermination de la filtrabilité des huiles lubrifiantes — Partie 1: Méthode pour les huiles en présence d'eau

General Information

• Status: Published
• Publication Date: 08-May-2017
• ICS: 75.100 - Lubricants, industrial oils and related products
• Technical Committee: ISO/TC 28 - Petroleum and related products, fuels and lubricants from natural or synthetic sources
• Drafting Committee: ISO/TC 28/WG 12 - Test methods for hydraulic fluids and oils
• Current Stage: 9599 - Withdrawal of International Standard
• Start Date: 01-Apr-2025
• Completion Date: 13-Dec-2025

Relations

• Revised: ISO 13357-1:2025 - Petroleum products - Determination of the filterability of lubricating oils - Part 1: Procedure for oils in the presence of water
• Effective Date: 20-May-2023
• Revises: ISO 13357-1:2002 - Petroleum products - Determination of the filterability of lubricating oils - Part 1: Procedure for oils in the presence of water
• Effective Date: 05-Apr-2014

Overview

ISO 13357-1:2017 - Petroleum products - Determination of the filterability of lubricating oils - Part 1: Procedure for oils in the presence of water - specifies a laboratory test method to evaluate how mineral-based lubricating oils (especially hydraulic oils) pass through fine filters when contaminated with water. The standard defines a controlled procedure, required reagents and apparatus, and two stage measurements (Stage I and Stage II) to quantify filterability as a dimensionless percentage. The method has been evaluated for oils up to ISO viscosity grade (VG) 100 (ISO 3448).

Key topics and technical requirements

• Scope and limitations: Applies to mineral-based oils; not suitable for some fire‑resistant fluids or oils with insoluble/partially soluble additives or very large molecular species. Evaluated up to VG 100.
• Two-stage measurement:
  • Stage I compares filtered volume against an ideal, unblocked membrane benchmark.
  • Stage II compares early filtration flow rate with flow near 200–300 ml - more sensitive to gels and fine silts.
• Test principle: Oils are heat‑soaked with a defined amount of water, filtered under specified pressure through a membrane, and filtration times for set volumes recorded. Results are averages of three determinations.
• Apparatus and materials:
  • Mixed cellulose ester membrane filters, diameter 47 mm, mean pore size 0.8 µm.
  • Stainless-steel filtration assembly with an effective filtration area specified in the standard.
  • Reagents such as ISO Grade 3 water, isopropyl alcohol and a light aliphatic hydrocarbon wash solvent.
  • Oven (70 °C ± 2 °C), measuring cylinders, pressure regulator, timing device.
• Test report and validity: Specifies calculation methods, criteria for test validity and precision, and required report content.

Applications and practical value

• Product development: Evaluate new hydraulic lubricants for susceptibility to filter plugging when contaminated with water.
• Quality control and acceptance testing: Routine lab tests for manufacturers and suppliers to demonstrate filterability performance.
• Failure analysis and field assessment: Predict filtration behaviour in systems that use very fine filters (<5 µm) and assess risks from water ingress.
• Procurement and OEM specifications: Enables equipment manufacturers and end-users to set filterability requirements for hydraulic fluids.

Who should use this standard

• Lubricant manufacturers and formulators
• Independent testing laboratories
• Hydraulic system OEMs and maintenance engineers
• Quality assurance and product compliance teams

Related standards

• ISO 13357-2 - Filterability testing in dry conditions (complementary method)
• ISO 3448 - ISO viscosity classification (viscosity grades)
• ISO 3696, ISO 4788, ISO 6614 - referenced for laboratory water quality, glassware and separability/test equipment

Keywords: ISO 13357-1:2017, filterability, lubricating oils, hydraulic oils, water contamination, membrane filtration, ISO viscosity grade, test procedure.

Standards Content (Sample)

INTERNATIONAL ISO
STANDARD 13357-1
Second edition
2017-05
Petroleum products — Determination
of the filterability of lubricating oils —
Part 1:
Procedure for oils in the presence of
water
Produits pétroliers — Détermination de la filtrabilité des huiles
lubrifiantes —
Partie 1: Méthode pour les huiles en présence d’eau
Reference number
©
ISO 2017
© ISO 2017, Published in Switzerland
All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized otherwise in any form
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written permission. Permission can be requested from either ISO at the address below or ISO’s member body in the country of
the requester.
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ii © ISO 2017 – All rights reserved

Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 2
4 Principle . 2
5 Reagents and materials . 2
6 Apparatus . 3
7 Samples and sampling . 5
8 Preparation of apparatus . 5
9 Procedure. 6
10 Calculations. 8
10.1 Stage I filterability . 8
10.2 Stage II filterability . 8
11 Expression of results . 8
11.1 General . 8
11.2 Assessment of validity . 8
12 Precision . 9
13 Test report . 9
Annex A (informative) Suitable procedure for the addition of graduations to a
measuring cylinder .10
Bibliography .12
Foreword
ISO (the International Organization for Standardization) is a worldwide federation of national standards
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described in the ISO/IEC Directives, Part 1. In particular the different approval criteria needed for the
different types of ISO documents should be noted. This document was drafted in accordance with the
editorial rules of the ISO/IEC Directives, Part 2 (see www .iso .org/ directives).
Attention is drawn to the possibility that some of the elements of this document may be the subject of
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on the ISO list of patent declarations received (see www .iso .org/ patents).
Any trade name used in this document is information given for the convenience of users and does not
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For an explanation on the voluntary nature of standards, the meaning of ISO specific terms and
expressions related to conformity assessment, as well as information about ISO’s adherence to the
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URL: w w w . i s o .org/ iso/ foreword .html.
The committee responsible for this document is ISO/TC 28, Petroleum and related products: fuels and
lubricants from natural or synthetic sources.
This second edition cancels and replaces the first edition (ISO 13357-1:2002), of which it constitutes a
minor revision including alternative membranes in order to enable the continued use of this document.
A list of all parts in the ISO 13357 series can be found on the ISO website.
iv © ISO 2017 – All rights reserved

Introduction
As the fluid in a hydraulic system acts as a lubricant to minimize wear of the components, it is
important to reduce the concentrations of circulating hard contaminant particles. This is particularly
necessary when the performance of the system depends on the maintenance of small clearances and
orifices. Removal of these contaminants is effected by the use of filters. The ability of a hydraulic fluid
to pass through fine filters, without plugging them, is called its “filterability”. This document describes
a laboratory test procedure for assessing the filterability of mineral oils which have been heat-soaked
in the presence of water. Filterability so determined is not a physical characteristic of the oil, but
represents an estimation of its behaviour in service.
This document describes two measurements, referred to as “stages”. The Stage I determination is based
on a comparison of the mean flow rate of a fluid through a test membrane with its initial flow rate. Oils
having good Stage I filterability, but only a poor Stage II performance (see below), would be unlikely to
give performance problems in use, unless extremely fine system filters are utilized.
The Stage II determination is based upon the ratio between the initial flow rate of fluid through the
test membrane and the rate at the end of the test. It is considered that this part of the procedure is a
more severe test, and is more sensitive to the presence of gels and fine silts in the oil. Silts and gels may
be present in an oil when it is produced, or could be formed as an oil ages, especially when hot. An oil
with good Stage II filterability would be unlikely to give filtration problems even in the most extreme
conditions, and with fine (less than 5 µm) filtration present. It would thus be suitable for use in more
critical hydraulic and lubrication systems.
The procedure has been evaluated with mineral oils up to ISO viscosity grade 100. There would appear
to be no reason why it should not be used with oils of higher viscosity grade (ISO viscosity grade 220 is
a practical maximum), but the data obtained could not be claimed to be completely in accordance with
this method. Similarly, it should be possible to extend the test procedure to fluids other than mineral
oils. However, some fluids, e.g. fire-resistant fluids, will not be compatible with the specified test
membranes, and the test could only be used for comparison purposes even when suitable membranes,
with similar pore size/pore density characteristics to those specified in this procedure, have been
identified.
INTERNATIONAL STANDARD ISO 13357-1:2017(E)
Petroleum products — Determination of the filterability of
lubricating oils —
Part 1:
Procedure for oils in the presence of water
WARNING — The use of this document can involve hazardous materials, operations and
equipment. This document does not purport to address all of the safety problems associated
with its use. It is the responsibility of the user of this document to establish appropriate safety
and health practices and determine the applicability of regulatory limitations prior to use.
1 Scope
This document specifies a procedure for the evaluation of the filterability of lubricating oils, particularly
those designed for hydraulic applications, in the presence of water. The procedure only applies to
mineral-based oils, since fluids manufactured from other materials (e.g. fire-resistant fluids) may not
be compatible with the specified test membranes. The range of application has been evaluated with
oils of viscosity up to ISO viscosity grade (VG) 100, as defined in ISO 3448. Within the range described,
the filterability as defined is not dependent on the viscosity of the oil. The procedure is not suitable for
some hydraulic oils on which specific properties have been conferred by the use of insoluble/partially
soluble additives, or by particularly large molecular species.
NOTE Filterability is a prime requirement for lubricating oils used in hydraulic systems because of the fine
filters used in this application.
This document defines a method for assessing the filterability of oils in the presence of contaminating
water. It is noted that some oils will exhibit poorer filterability characteristics in these conditions.
[1]
ISO 13357-2 is used to investigate the filterability of an oil which is used in applications where
the presence of water in the oil is unlikely. An oil which has good filterability in the presence of
contaminating water will not necessarily have equally good filterability in dry conditions. An oil having
good filterability only when wet is unlikely to be generally acceptable.
2 Normative references
The following documents are referred to in the text in such a way that some or all of their content
constitutes requirements of this document. For dated references, only the edition cited applies. For
undated references, the latest edition of the referenced document (including any amendments) applies.
ISO 1219-1, Fluid power systems and components — Graphical symbols and circuit diagrams — Part 1:
Graphical symbols for conventional use and data-processing applications
ISO 3170, Petroleum liquids — Manual sampling
ISO 3448, Industrial liquid lubricants — ISO viscosity classification
ISO 3696, Water for analytical laboratory use — Specification and test methods
ISO 4788, Laboratory glassware — Graduated measuring cylinders
ISO 6614:1994, Petroleum products — Determination of water separability of petroleum oils and
synthetic fluids
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
ISO and IEC maintain terminological databases for use in standardization at the following addresses:
— IEC Electropedia: available at http:// www .electropedia .org/
— ISO Online browsing platform: available at http:// www .iso .org/ obp
3.1
filterability
dimensionless number which is the ratio, expressed as a percentage, between volumes (Stage I) or flow
rates (Stage II) at specified intervals in the test procedure
3.2
stage I filterability
ratio, expressed as a percentage, between 240 ml and the volume of oil actually filtered in the time that
240 ml would have theoretically taken, assuming no plugging of the membrane
3.3
stage II filterability
ratio, expressed as a percentage, between the flow rate near the start of the filtration, and the flow rate
between 200 ml and 300 ml of filtered volume
4 Principle
The test fluid is treated with water at an elevated temperature, filtered under specified conditions
through a membrane of 0,8 µm mean pore diameter, and the times for the specified filtrate volumes
are recorded. Filterabilities are calculated from ratios of the filtration rate near the start of filtration
to the filtration rate at specified higher filtered volumes. The result of the test is the
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