Filter. tätningar och föroreningar av fluider

This document 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.

This document is applicable to the monitoring of:

a)      the cleanliness level of fluids circulating in hydraulic systems;

b)      the progress of a flushing operation;

c)       the cleanliness level of support equipment and test rigs;

d)      the cleanliness level of packaged stock fluid.

NOTE           Measurements can be made with particles suspended in the original liquid or in a sample of the liquid diluted with a compatible liquid when APC coincidence error limits are exceeded.

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.

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.