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 data that can be made available is as follows:.
What value is most appropriate? This is essential to achieve the required system reliability and life.
The 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 current data requirement is a substantial improvement. Particles entering component working clearances will become work hardened and produce more wear particles.
The slope of the curve effectively defines the pore size distribution PSD of the filtration medium; the wider the PSD the less able the filter is to control those critically sized damaging 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.
The more critical the system, the stronger the filter element and the more frequent the monitoring required. Now, users can quickly see how the filter performs over a specified range of particle sizes and can compare the performance of candidate elements.
However because of particle count statistics in the multi-pass test, the absolute rating cannot be measured with any degree of confidence. This article will focus on the impact the new standards have on selecting candidate filters based on performance criteria.
Strategies to Protect Grease Fittings from Contaminants. The Best Gets Better: This will be through the larger pores in the medium and any holes created by poor manufacturing techniques. 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. This gives a series of Beta ratios for the filter as opposed to a percentage efficiency.
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 should allow fluid to pass through at the given flow with the minimum pressure drop DP to minimize stress and energy losses.
Hydrauliköl-Filtrationssysteme | Donaldson Hydraulik
It is a preselection requirement that provides the user and specifier of filter standards with more consistent information. Therefore, the desired level of control will not be achieved. Consequently, the number of different Beta ratings used has proliferated. 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: However, the multi-pass test is carried out in a laboratory under steady-state conditions and does not represent strenuous operational conditions.
The changes in the ISO multi-pass test method and associated standards provide greater precision in measurement. While primarily developed for fluid power, the new standards are equally applicable to the lubricating oil sector. 61889
The data that can be made available is as follows: A filter must control the levels of all contaminant particles at and above the size critical to its operating system. It also enables the user to discriminate between elements that achieve the desired control and those that do not.
To appreciate the importance of the filter in the management of the system, consider the primary function of the filter: About the Author Mike Day. This makes the capture of these particles, by the filter, essential to sustain the good health of the system. The group also isk that detailing comprehensive performance data was necessary so users can make informed selections.
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 has to protect the components from the damaging, critical clearance-sized particles particles that can penetrate and interfere with the working clearances of components.
It is able to control the critically sized particles better than Element B. More detailed information from the test has to be published than previously required. It is only when the ratings at higher Beta ratings are considered that the differences in performance are clearly seen. When the contaminated hydraulic fluid passes through the filtration medium, it takes the line of least resistance.
Users were often confused when comparing performance data of seemingly identical filters. These standards iwo been developed 1689 increase the precision in the measurement of contamination and filtration performance, and to extend the amount of information from the tests.
Therefore, the highest Beta ratio that can be reliably measured should be selected. Figure 2 shows the advantages of this approach.
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. Users of filters have historically liked the simplicity of a single point rating the size where a specified Beta ratio is attained.
Create your own user feedback survey. Current Issue Archive Advertise. The Beta ratio is defined as: The Beta ratio is defined as:. Most manufacturers published ratings at other sizes but there was no consistency.