ISO/TC 131/SC 6/WG 2 - Filter and separator evaluation

This document describes the following: — a multi-pass filtration performance test with continuous contaminant injection for hydraulic fluid power filter elements; NOTE 1 For the background interlaboratory study used to verify the test methodology, see Annex D. — a procedure for determining the contaminant capacity, particulate removal and differential pressure characteristics; — a test currently applicable to hydraulic fluid power filter elements that exhibit an average filtration ratio greater than or equal to 75 for particle sizes ≥ 25 µm(c), and a final reservoir gravimetric level of less than 200 mg/L; NOTE 2 It is necessary to determine by validation the range of flow rates and the lower particle size limit that can be used in test facilities. — a test using ISO medium test dust (ISO MTD) contaminant and a test fluid in accordance with Annex A. This document is intended to provide a test procedure that yields reproducible test data for appraising the filtration performance of a hydraulic fluid power filter element without influence of electrostatic charge. This document applies to three test conditions: — test condition 1, with a base upstream gravimetric level of 3 mg/L; — test condition 2, with a base upstream gravimetric level of 10 mg/L; — test condition 3, with a base upstream gravimetric level of 15 mg/L.

This document specifies a bubble-point test method applicable to filter elements used in hydraulic fluid power systems. It can be used both to verify the fabrication integrity of a filter element (by checking the absence of bubbles) and to permit the localization of the largest pore of the filter element by determining the first bubble point. NOTE Verification of fabrication integrity is used to define the acceptability of the filter elements for further use or testing. The first bubble point is established through continuation of the fabrication integrity test. It is under no circumstances a functional characteristic of a filter element; in particular, it cannot be used to estimate filtration rating, efficiency or retention capacity and is intended to be used for information only. This document specifies a method to normalise fabrication integrity and bubble point data to a standard value of surface tension when test fluids other than 2-propanol are used.

ISO 18237:2017 specifies: - test equipment, test circuit and a procedure for the evaluation of the water separation capabilities of a dehydrator; - a procedure for preparing test fluid; - a procedure for obtaining and analysing the test fluid samples. ISO 18237:2017 applies only to those dehydration units that can dry a hydraulic fluid to less than 20 % of the hydraulic fluid's water saturation level at the test temperature. ISO 18237:2017 provides a test procedure that yields reproducible results for dehydrator water removal performance so that the performance of candidate units is compared on the same basis using the same test fluid. This procedure can be used to test the dehydrator's capabilities on different types of hydraulic fluids at different conditions. Parts of the procedure might need to be changed to suit the hydraulic fluid's characteristics. For example, the testing of hydraulic fluids with high water solubility (many synthetic and fire-resistant fluids) needs higher concentrations of water at the start of the test; the testing of hydraulic fluids with zinc-based additives needs modifications to the Karl Fischer analysis procedure. However, comparison of performance can be made under the conditions defined in ISO 18237:2017.

ISO 3668:2017 specifies a procedure for evaluating differential pressure versus flow characteristics of hydraulic filters and constitutes a basis for agreement between the filter manufacturer and user. It also specifies a method for measurement of the differential pressure generated at different flow rates and viscosities by the relevant parts of a filter assembly, spin-on and any valves contained within the filter which are in the flow stream. The typical types of filter to be tested are as follows: Type 1: which are spin-on filters in which the replaceable unit does not include a filter head (it might or might not include the element by-pass valve); Type 2: which are spin-on filters in which the replaceable element is tested together with a filter head (it might or might not include the element by-pass valve); Type 3: which are filter assembly, usually of the replacement element type, that is the housing (head and bowl) and element.

ISO 12829:2016 specifies methods for verifying the rated fatigue life and the rated static burst pressure of the pressure-containing envelope (i.e. the filter housing) of a spin-on hydraulic filter with a disposable filter element and a finite life. Because the service life of housings for these types of filters is relatively short, a rated fatigue life of 100 000 cycles is judged sufficient for typical industrial applications.

ISO 3723:2015 specifies a method for verifying the end load rating of a hydraulic fluid power filter element. It also verifies the ability of a hydraulic fluid power filter element to withstand the designated axial loading imposed by installation and use.

ISO 16908:2014 specifies a test procedure to thermally condition a hydraulic filter element and simulate cold start, such as that which can be encountered in mobile machinery applications. It is intended to provide a procedure that yields reproducible results and can be used prior to other filter element performance tests, such as those specified in ISO 11170.

ISO 11170:2013 defines a sequence of tests for verifying filter elements. It can be used to check their hydraulic, mechanical and separation characteristics. ISO 11170:2013 is not intended to qualify a filter for a particular duty or replicate conditions of service. This can only be done by a specific test protocol developed for the purpose, including actual conditions of use (e.g. the operating fluid). The procedure in ISO 11170:2013 is applicable to individual fluids or types of fluids that have similar chemistry.

ISO 27407:2010 specifies a means of marking filters to communicate filter performance characteristics of interest to users. This marking can be used with either the standards referenced in ISO 27407:2010 or with any standard that has been harmonized with any referenced standard. ISO 27407:2010 applies to the marking of information only on the filter; the customer can request that the same information be specified on the product drawing or as part of the product packaging.

ISO 2941:2009 specifies a method for verifying the collapse/burst pressure rating of a hydraulic fluid power filter element, i.e. the capability of a filter element to withstand a designated differential pressure at the normal (i.e., intended direction of) flow, by means of pumping contaminated fluid through the filter element until either collapse/burst occurs or the maximum expected differential pressure is reached without element failure.

ISO 3724:2007 specifies a method for determining the resistance of a hydraulic filter element to flow fatigue after it has been loaded with particulate contaminant and subjected to a uniform varying flow rate and predetermined terminal differential pressure. It establishes a uniform method for verifying the ability of a filter element to withstand the flexing caused by cyclic differential pressures induced by a variable flow rate.

ISO 23181:2007 specifies a method for determining the resistance of a hydraulic filter element to flow fatigue when subjected to high viscosity fluid, using a uniformly varying flow rate up to a predetermined terminal differential pressure and a controlled waveform. It establishes a method for verifying the ability of a filter element to withstand the flexing caused by cyclic differential pressures induced by a variable flow rate.

ISO 16860:2005 provides a standard method for determining the operating characteristics of a differential pressure or bypass valve condition-signalling device used as an accessory to a hydraulic fluid power filter.

This International Standard specifies a method of verifying the compatibility of materials comprising a hydraulic fluid power filter element with a designated fluid, by verifying the ability of the filter element to maintain its collapse burst rating after being subjected to the designated system fluid at a high and/or low temperature. The filter element mounting seal is not included as part of the element.

This document specifies: a) A multi-pass filtration performance test under cyclic flow conditions with continuous contaminant injection for hydraulic fluid power filter elements. b) A procedure for determining the contaminant capacity, particulate removal and differential pressure characteristics. c) A test currently applicable to hydraulic fluid power filter elements that exhibit an average filtration ratio greater than or equal to 75 for particle sizes ≤25 µm(c), and a final test system reservoir gravimetric level of less than 200 mg/L. It is necessary to determine by validation the range of flow rates and the lower particle size limit that can be used in test facilities. d) A test using ISO12103-1 A3 medium test dust contaminant and a test fluid. This document provides a test procedure that yields reproducible test data for appraising the filtration performance of a hydraulic fluid power filter element without influence of electrostatic charge. This document is applicable to three test conditions: 1) Base upstream gravimetric level of 3 mg/L. 2) Base upstream gravimetric level of 10 mg/L. 3) Base upstream gravimetric level of 15 mg/L.

ISO 16889:2008 describes a multi-pass filtration performance test with continuous contaminant injection for hydraulic fluid power filter elements; a procedure for determining the contaminant capacity, particulate removal and differential pressure characteristics; a test currently applicable to hydraulic fluid power filter elements that exhibit an average filtration ratio greater than or equal to 75 for particle sizes less than or equal to 25 µm(c), and a final reservoir gravimetric level of less than 200 mg/L; and a test using ISO medium test dust contaminant and a test fluid. ISO 16889:2008 is intended to provide a test procedure that yields reproducible test data for appraising the filtration performance of a hydraulic fluid power filter element without influence of electrostatic charge. ISO 16889:2008 applies to three test conditions: test condition 1, conducted with a base upstream gravimetric level of 3 mg/L; test condition 2, conducted with a base upstream gravimetric level of 10 mg/L; and test condition 3, conducted with a base upstream gravimetric level of 15 mg/L.

ISO 2942:2004 specifies a bubble-point test method applicable to filter elements used in hydraulic fluid power systems. It can be used either to verify the fabrication integrity of a filter element (by checking the absence of bubbles) or to permit the localization of the largest pore of the filter element by determining the first bubble point.

ISO 11170:2003 defines a sequence of tests for verifying filter elements. It can be used to check their hydraulic, mechanical and separation characteristics. ISO 11170:2003 is not intended to qualify a filter for a particular duty or replicate conditions of service. This can only be done by a specific test protocol developed for the purpose, including actual conditions of use (for example the operating fluid). The procedure in ISO 11170:2003 is applicable to individual fluids, or types of fluids having similar chemistry.

A statement of requirements (SOR) is defined as a document to be provided by a user to specify his requirements to a manufacturer. A model SOR is described to enable a user to define his requirements fully, without ambiguity and in standard form so that the supplier can meet the requirements as accurate as possible. Annex A contains a standard form for a SOR, annex B shows clearances.

Specifies a method for determining the characteristics of a filter element and establishes a uniform method for verifying the ability of an element to withstand the flexing caused by cyclic differential pressures without altering its collapse/burst rating. Gives definitions, test procedures, and criteria for acceptance. A figure shows the typical test stand.

Specifies a method for verifying the end load rating for a filter element, and verifies also the ability of an element to withstand the designated axial load imposed by installation and use. Gives definitions, test procedure, and criteria for acceptance.

Specifies a method for verifying the collapse/burst rating of a filter element, i. e. the capability of the filter to withstand a designated differential pressure at the normal (intended direction) of flow. The figure shows a sketch of a typical collapse/burst test stand.