FAQs | Cummins Filtration


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Q: What is a micron?
A: A micron is a thousandth of a millimeter or a millionth of a meter or .000039 of an inch. Micron is the unit of measure used to determinate the size of particles in a fluid which are filtered out by the filter.

Q: What is the difference between Absolute and Nominal micron rating?
A: Micron rating is the size of particles which are filtered out by filters at a certain efficiency. When this efficiency is at least 98.6%, we speak about absolute micron rating/filtration. Nominal micron rating is just a commercial trick for all efficiencies lower than 98.6%, meaning that for the same micron rating (for ex. 10 µ) in the case of nominal rating, not all particles will be captured in the filter as in the case of absolute micron rating.

Q: Why doesn't Cummins Filtration publish micron ratings for all its filters?
A: Generally this is not necessary. Cummins Filtration filters are designed to meet or exceed OEM specifications.

Q: In your catalog, under Product Guide, you mention a by-pass setting for lube and hydraulic filters. What is this?
A: Each lube filter and hydraulic filter system is equipped with a by-pass valve to ensure that main components in the system are sufficiently lubricated independently-if oil is cold or the filter is blocked by excessive contamination. This by-pass valve can be located in the filter or filter head. Depending on the OEM manufacturer's specification, the setting of the by-pass valve can be different. So in the Cummins Filtration Master Filter Catalog, we mention the setting of this valve (14.7 PSI=1 bar). If no setting is mentioned, no by-pass valve is mounted in the filter.

Q: In your catalog, under Product Guide, you mention anti-drainback valve for lube and hydraulic filters. What is this?
A: An anti-drainback valve is fitted in filters for applications where there is risk that the filter is running empty. This situation should be avoided-otherwise wear will occur on the moving parts, as these parts are not yet lubricated by oil.