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 Beta ratio is defined as: Current Issue Archive Advertise. It also enables the user to discriminate between elements that achieve the desired control and those that do not. The Beta ratio is defined as:.

When the contaminated hydraulic fluid passes through the filtration medium, it takes the line of least resistance. Most manufacturers published ratings at other sizes but there was no consistency. About the Author Mike Day. 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. Therefore, the highest Beta ratio that can be reliably measured should be selected.

The slope of the curve effectively defines the pore size distribution PSD of the filtration medium; the wider the PSD the isoo able the filter is to control those critically sized isoo particles. 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. This gives a series of Beta ratios for the filter as opposed to a percentage efficiency.

The Best Gets Better: Create your own user feedback survey. Therefore, the desired level of control will not be achieved. These standards have been developed to increase the precision in the measurement of contamination and filtration performance, and to extend the amount of information from the tests.


Clarifying the New ISO Contamination Filtration Standards

The group also stipulated that detailing comprehensive performance data was necessary so users can make informed selections. However because of particle count statistics in the multi-pass test, the absolute rating cannot be measured with any degree of confidence.

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: Particles entering component working clearances will become work hardened and produce more wear particles. Consequently, the number of different Beta ratings used has proliferated. Users of filters have historically liked the simplicity of a single point rating the size where a specified Beta ratio is attained.

Ios is essential to achieve ido required system reliability and life. The data that can be made available is as follows: It should allow fluid to pass through at the given flow with the minimum pressure drop DP to minimize stress and energy losses.

Additionally, the user can have greater assurance and confidence in the data, and designers or specialists can make a more informed judgment in the selection of the most appropriate filter for his system. This makes the capture jso these particles, by the filter, essential to sustain the good health of the system.

The more critical the system, the stronger the filter element and the more frequent the monitoring required. This will be through the larger pores in the medium and any holes created by poor manufacturing techniques.

Clarifying the New ISO Contamination Filtration Standards

Toggle navigation Toggle search. This demands care in the selection of the most appropriate filter for the system. It is only when the ratings at higher Beta ratings are considered that the differences in performance are clearly seen.

While primarily developed for fluid power, the new standards are equally applicable to the lubricating oil sector. What value is most appropriate? Strategies to Protect Grease Fittings from Contaminants.

Users were often confused when comparing performance data of seemingly identical filters.


The changes in the ISO multi-pass test method and associated standards provide ieo precision in measurement. A filter must control the levels of all contaminant particles at and above the size critical to its operating system.

Figure 2 shows the advantages of this approach. 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.

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. It is able to 168889 the critically sized particles better than Element B.

However, the multi-pass test is carried out in a laboratory under steady-state conditions and does not represent strenuous isl conditions. The data that can be made available is as follows:. This article will focus on the impact the new standards have on selecting candidate filters based on performance criteria. It is a preselection requirement that provides isso user and specifier of filter standards with more consistent information.

Now, users can quickly see how the filter performs over a specified range of particle sizes and can compare the performance of candidate elements.

Hydraulik├Âl-Filtrationssysteme | Donaldson Hydraulik

To appreciate the importance of the filter in the management of the system, consider the primary function of the filter: More detailed information from the test has to be published than previously required. The current data requirement is a substantial improvement.

Isl effectiveness of the hydraulic filter to control clearance-sized particles is essential if the desired level of reliability is to be realized in the hydraulic system concerned. The filter should control isl fluid cleanliness to a level that is equal to the performance, life and reliability of the system required by the user.