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ISO HYDRAULIC FLUID POWER – FILTERS – MULTI-PASS METHOD FOR EVALUATINGFILTRATION PERFORMANCE OF A FILTER ELEMENT. Introduction. The obsolescence of AC Fine test dust (ACFTD) has led to the adoption of a new test dust, ISO Medium Test. Dust (ISO MTD), and the impending. ISO Multi-Pass Test. The multi-pass test is a means of determining a filter’s performance; it measures the ability of the filter to remove particles of test dust.

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The Best Gets Better: More detailed information from the test has 168899 be published than previously required. In the s and s, a compromise was reached between what is desirable and what can be consistently achieved for the range of filters assessed by this test.

It is only when the ratings at higher Beta ratings are considered that the differences in performance are clearly seen. Current Issue Archive Advertise. About the Author Mike Day. Consequently, the number of different Beta ratings used has proliferated.

While primarily developed 116889 fluid power, the new standards are equally applicable to the lubricating oil sector. The Beta ratio is defined as: What value is most appropriate? However because of particle count statistics in the multi-pass test, the absolute rating cannot be measured with any degree of confidence. The need to remove particles consistently across a wide size range was recognized by the ISO Working Group responsible for updating the multi-pass filter test.


The changes in the ISO multi-pass test method and associated standards provide greater precision in measurement. Particles entering component working clearances will become work hardened and produce more wear particles.

Clarifying the New ISO Contamination Filtration Standards

The data that can be made available is as follows:. If the filter fails to provide the necessary control of damaging-sized particles, then their presence in the system will lead to a substantial increase in the number of particles generated within the system through a chain reaction of wear. Now, users can quickly see how the filter jso over a specified range of particle sizes and can compare the performance of candidate elements.

Therefore, the desired level of control will 16889 be achieved.

Clarifying the New ISO Contamination Filtration Standards

Strategies to Protect Grease Fittings from Contaminants. Most manufacturers published ratings at isi sizes but there was no consistency. The filter should control the fluid cleanliness to a level that is equal to the performance, life and reliability of the system required by the user.

The Role of the Filter To appreciate the importance of the filter in the management of the system, consider the primary function of the filter: Figure 2 shows the advantages of this approach.

The effectiveness of the hydraulic filter to control clearance-sized particles is 1889 if the desired level of reliability is to be realized in the hydraulic system concerned. It has to protect the components from the damaging, critical clearance-sized particles particles that can penetrate and interfere with the working clearances of components.


However, the multi-pass test jso carried out in a laboratory under steady-state conditions and does not represent strenuous operational conditions. It should allow fluid to pass through at the given flow with the minimum pressure drop DP to minimize stress and io losses. This article will focus on the impact the new standards have on selecting candidate filters based on performance criteria. Therefore, the highest Beta ratio that can be reliably measured should be selected.

The current data requirement is a substantial improvement.

The group also stipulated that detailing comprehensive performance data was necessary so users can make informed selections. The Beta ratio is defined as:. This will be through 1889 larger pores in the medium and any holes created by poor manufacturing techniques.

A filter must control the levels of all contaminant particles at and above the size critical to its operating system.

The more critical the system, the stronger 166889 filter element and the more frequent the monitoring required. Create your own user feedback survey. Toggle navigation Toggle search.