ISO/TC 131/SC 6 - Contamination control

This document specifies procedures for the following: a) primary particle-sizing calibration for particle sizes 1 µm(c) and larger, sensor resolution and counting performance of liquid automatic particle counters that are capable of analysing bottle samples; b) secondary particle-sizing calibration using suspensions verified with a primary calibrated APC; c) establishing acceptable operation and performance limits; d) verifying particle sensor performance using a test dust; e) determining coincidence and flow rate limits. This document is applicable for use with hydraulic fluids, aviation and diesel fuels, engine oil and other petroleum-based fluids. This document is not applicable to particle-sizing calibration using NIST SRM 2806b primary calibration suspensions.

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) 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.

This document establishes methods for: — validating equipment used to prepare secondary calibration suspensions for automatic particle counters; — performing online secondary calibration of automatic particle counters; — matching two or more online particle counters, i.e. to count the same number of particles at a given size by two APCs associated online; — validating online particle counting systems with and without online dilution as used, for example, to measure the filtration efficiency of a hydraulic filter as described in the multi-pass filter test in ISO 16889.

This document describes a recommended method for the interpolation of particle concentration and filter Beta Ratio data when results are not otherwise available at the desired particle sizes. It is applicable for assessing conformance with existing fluid cleanliness and filter Beta Ratio specifications whereby the specification and actual test results are provided in different units of particle size, for example, the specification is in µm(c), but the particle counts or Beta Ratio data are in units of µm(b). This document is also applicable when particle sizes in specifications and available data use the same units of particle size, but do not correspond to exactly the same sizes, for example, when particle counts at 20 µm(c) are specified, but data was collected at 21 µm(c). This method allows interpolation to intermediate particle sizes within the range of existing data and does not permit extrapolation to particle sizes outside the range of available data.

This document provides the background for ISO 11171:2020 and the use of µm(c) as the sole means of reporting particle size for APC particle count data. It also summarizes results of the international inter-laboratory study (ILS) of its reproducibility using SRM 2806d candidate material and suspensions of Reference Material (RM) 8632a. The ILS results provided the basis for certification of SRM 2806d used for primary calibration of APC. Their implications with respect to particle counting and filter testing are discussed in this document.

This document specifies the code to be used in defining the quantity of solid particles in the fluid used in a given hydraulic fluid power system.

This document explains the use of the two acceptable methods of reporting particle size, µm(c) and µm(b), that are defined in ISO 11171:2016. It also explains the reasons for the existence of two alternative size reporting methods and its implications with respect to particle count and filter Beta Ratio data.

This document specifies a method for the determination of the particulate contamination level using the light extinction technique (also known as light blockage or light obscuration) either online or offline in containers. It also defines procedures for calibrating the instruments and verifying their correct operation both in the laboratory and in service. In general, the techniques described in this document are suitable for monitoring: — the general cleanliness level in hydraulic systems, — the progress in flushing operations, and — support equipment and test rigs. The use of this method is applicable to single-phase liquid systems only.

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 12669 specifies a method of determining the required cleanliness level of a hydraulic system, that is, the most appropriate fluid cleanliness level for an operating hydraulic system based upon the individual requirements of that system. It is applicable to systems where the level of fluid cleanliness is expressed in accordance with ISO 4406, although conversion to other contamination coding systems is possible. It is applicable to both high and low pressure fluid power systems and also lubrication systems. It does not include the effects of soft deformable particles that can be generated by thermal decomposition of the hydraulic fluid.

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 18413:2015 specifies the content of an inspection document that specifies both the cleanliness requirement for the specified hydraulic fluid power component and the inspection method to be used for evaluating its cleanliness level. In addition, guidelines for relevant extraction methods and analysis methods are given. Determination of what constitutes as an appropriate cleanliness level requirement for any particular component is beyond the scope of ISO 18413:2015. ISO 12669 provides a method of determining the required cleanliness of a hydraulic system. ISO TR 10686 provides a method of relating the required cleanliness of components to the required cleanliness of the hydraulic system. For the purposes of ISO 18413:2015, approved functional liquids are considered to be components. ISO 18413:2015 is applicable to the particulate contamination on the wetted surfaces and volumes of any hydraulic fluid power system component. Appearance defects and liquid or gaseous contamination are not covered by ISO 18413:2015. ISO 18413:2015 does not address safety problems that might arise from hazardous materials, operations, and equipment associated with its use. The user of ISO 18413:2015 is responsible for establishing appropriate safety and health practices and determining the applicability of regulatory limitations prior to use.

ISO/TR 16386:2014 discusses the impact of changes in International Standards for particle counting, contamination control, and filter testing. Liquid automatic particle counters (APCs) are used in monitoring contamination levels in hydraulic fluids, to establish component and assembly cleanliness level specifications, and in determining filter efficiencies and particle size ratings. As a result of the replacement of ISO 4402 with ISO 11171 (APC calibration), the replacement of ISO 4572 with ISO 16889 (multi-pass filter test), and the publication of ISO 11943 (online particle counter calibration), the quality and reliability of particle count and filter test data have improved, increasing their usefulness to industry. However, the resultant redefinition of particle sizes and the use of a new test dust affect how contamination levels and filter performance are reported and interpreted. NOTE The first editions of ISO 11171, ISO 16889 and ISO 11943 were published in 1999; all three of these International Standards either have been, or are in the process of being, revised.

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/TR 10686:2013 describes methods that can be used to: relate the cleanliness of a hydraulic system to the cleanliness of its components and the hydraulic fluid belonging to the system; estimate the final cleanliness level of an assembled hydraulic system filled with the hydraulic fluid, upon its release from the manufacturing area (the estimation of the final cleanliness level is based on the cleanliness level of each component in the system and on the cleanliness level of the filling fluid); calculate and manage cleanliness requirements of components and subassemblies that make up a system and of the fluid filling it so as to achieve a required cleanliness level (RCL) for the final system. These methods can apply whatever the particle size considered and can also be used for other types than hydraulic fluid power.

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.

ISO16431:2012 defines methods to measure the cleanliness of a fluid in an assembled hydraulic fluid power system, to verify a required system cleanliness upon release of the system from the production area, and if needed, to clean the system to the required cleanliness level. The clean-up procedure specified in ISO16431:2012 is not intended to replace proper system flushing procedures; see ISO 23309 for a system flushing procedure. Components and parts used in such systems should be clean prior to assembly; see ISO 18413 for guidance.

ISO/TR 15640:2011 is applicable to contamination control principles for hydraulic fluid power systems and includes guidelines for the selection and application of hydraulic filters. Although control of non-particulate contamination, e.g. air, water and chemicals, is important, and is briefly discussed, the primary focus of ISO/TR 15640:2011 is the control of particulate contamination and the selection and application of filters for that function.

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 11500:2008 specifies an automatic particle-counting procedure for determining the number and sizes of particles present in hydraulic-fluid bottle samples of clear, homogeneous, single-phase liquids using an automatic particle counter (APC) that works on the light-extinction principle. ISO 11500:2008 is applicable to the monitoring of the cleanliness level of fluids circulating in hydraulic systems, the progress of a flushing operation, the cleanliness level of support equipment and test rigs and the cleanliness level of packaged stock.

ISO 21018-1:2008 specifies methods and techniques that are applicable to the monitoring of particulate contamination levels in hydraulic systems. It also describes the relative merits of various techniques so that the correct monitor for a given application can be selected. The techniques described in ISO 21018-1:2008 are suitable for monitoring the general cleanliness level in hydraulic systems, the progress in flushing operations and support equipment and test rigs. ISO 21018-1:2008 can also be applicable for other liquids (e.g. lubricants, fuels and process liquids).

ISO 21018-3:2008 specifies a method for the semi-quantitative determination of the particulate contamination level using the filter blockage technique (also known as the mesh-obscuration method or the pore-blockage technique) either on-line or off-line in containers. ISO 21018-3:2008 also defines procedures for calibrating the instruments and verifying their correct operation both in the laboratory and in service. In general, the techniques are suitable for monitoring the general cleanliness level in hydraulic systems, the progress in flushing operations and support equipment and test rigs. The use of ISO 21018-3:2008 is applicable to all single- or multi-phase liquid systems.

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 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 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.

ISO/TR 10949:2002 gives guidelines for achieving, evaluating and controlling the cleanliness of hydraulic fluid power components from the time of their manufacture through to their installation in a hydraulic fluid power system.

This International Standard specifies methods for determining the level of particulate contamination in liquids used in hydraulic systems by counting the number of particles deposited on the surface of a membrane filter using an optical microscope. It includes particle counting by two manual methods and image analysis, using either transmitted or incident lighting systems. Particle sizes greater than or equal to 2 micrometres can be sized and counted by this method, but the resolution and accuracy of the results will depend upon the optical system used and the capabilities of the operator. All hydraulic fluids with a wide range of contamination levels can be analysed according to this International Standard. However, the counting uncertainty at the larger particle sizes increases if the volume filtered is reduced to allow smaller sized particles to be counted, where a fine precipitate or a high particle concentration is present.

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.

The preferred method is to extract fluid samples from a main flowline in such a manner that the particulate contaminant in the sample is representative of the fluid flowing at the point of sampling. An alternative method is to extract a sample from the reservoir, but this method should only be used if a suitable sampler is not fitted.

Specifies a method, and establishes a means for ensuring that the accuracy of particulate contamination analyses in hydraulic systems is not degraded by a lack of sample container cleanliness. Gives definitions and tabulates the inspection ratios together with the AQQL values of concern.

This document specifies procedures for the following: a) primary particle-sizing calibration for particle sizes 1 µm(c) and larger, sensor resolution and counting performance of liquid automatic particle counters that are capable of analysing bottle samples; b) secondary particle-sizing calibration using suspensions verified with a primary calibrated APC; c) establishing acceptable operation and performance limits; d) verifying particle sensor performance using a test dust; e) determining coincidence and flow rate limits. This document is applicable for use with hydraulic fluids, aviation and diesel fuels, engine oil and other petroleum-based fluids. This document is not applicable to particle-sizing calibration using NIST SRM 2806b primary calibration suspensions.

This document establishes methods to: — validate equipment used to prepare secondary calibration suspensions for automatic particle counters; — perform online secondary calibration of automatic particle counters; — match two or more online particle counters, i.e. to count the same number of particles at a given size by two APCs associated on line; — validate online particle counting systems with and without online dilution as used, for example, to measure the filtration efficiency of a hydraulic filter as described in the multipass filter test in ISO 16889.

ISO 4406:2017 specifies the code to be used in defining the quantity of solid particles in the fluid used in a given hydraulic fluid power system.

ISO 21018-4:2016 specifies a method for the determination of the particulate contamination level using the light extinction technique (also known as light blockage or light obscuration) either online or off-line in containers. It also defines procedures for calibrating the instruments and verifying their correct operation both in the laboratory and in service. In general, the techniques described in ISO 21018-4:2016 are suitable for monitoring - the general cleanliness level in hydraulic systems, - the progress in flushing operations, and - support equipment and test rigs. The use of this method is applicable to single-phase liquid systems only.

ISO 11171:2016 specifies procedures for the following: a) primary particle-sizing calibration, sensor resolution and counting performance of automatic particle counters (APCs) for liquids capable of analysing bottle samples; b) secondary particle-sizing calibration using suspensions verified with a primary calibrated APC; c) establishing acceptable operation and performance limits; d) verifying particle sensor performance using a truncated test dust; e) determining coincidence and flow rate limits.

ISO 11171:2010 specifies procedures for: a) primary particle-sizing calibration, sensor resolution and counting performance of automatic particle counters (APCs) for liquids capable of analysing bottle samples; b) secondary particle-sizing calibration using suspensions verified with a primary calibrated APC; c) establishing acceptable operation and performance limits; d) verifying particle sensor performance using a truncated test dust; e) determining coincidence and flow rate limits.

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 23309:2007 specifies the procedures for flushing from the hydraulic lines of larger hydraulic fluid power systems solid particulate contamination that can be introduced during the initial build of a new hydraulic system or after maintenance or modification of an existing system. ISO 23309:2007 supplements, but does not replace, the requirements of the component supplier and customer, especially when those requirements are stricter than those specified by this International Standard.

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.

ISO/TR 16144:2002 describes the procedures used by the United States National Institute of Standards and Technology (NIST) for the certification of the calibration material SRM 2806, which is used in the primary calibration of liquid automatic particle counters. SRM 2806 is a suspension of ISO MTD in hydraulic fluid with a number size distribution certified using a scanning electron microscope (SEM) and image analysis techniques.

ISO 18413 specifies the content of an inspection document that includes both the cleanliness requirement for the specified part or component and the inspection method to be used for evaluating its cleanliness level. The cleanliness requirement and inspection method shall be established and agreed upon by the parties involved. ISO 18413 is applicable to the wetted surfaces of any fluid power system part or component. It does not cover appearance defects and contamination by liquid or gaseous materials. This International Standard does not address safety problems that may arise from hazardous materials, operations and equipment associated with its use. The user of ISO 18413 is responsible for establishing appropriate safety and health practices and determining the applicability of regulatory limitations prior to use.