A device used for mechanical separation of solid contaminants from a liquid or a gas. Fine mesh filters are used to remove the smallest particles of dirt from oil before the oil enters the finely machined engine parts. The filtering substance may be a natural or synthetic fibrous woolen felt or paper.
- By-pass filter – A filter, which provides an alternative unfiltered flow path around the filter element when a preset differential pressure is reached.
- Duplex filters – Duplex filters are similar to simplex filters except for the number of elements and provision for switching the flow through either element. A duplex filter may consist of a number of single element filters arranged for parallel operation, or it may consist of two or more filters arranged within a single housing. The full flow can be diverted, by operation of valves, through any single element.
- Full-flow filter – The term full-flow applied to a filter means that all the flow into the filter inlet port by-pass through the filtering element. In most full-flow filters, however, there is a bypass valve preset to open at a given pressure drop and divert the flow past the filter element. This prevents a dirty element from restricting flow excessively.
- Simplex filter – The simplex filter has one or more cylindrically-shaped fine mesh screens or perforated metal sheets. The size of the opening in the screens or the perforated metal sheets determines the size of particles filtered out of the fluid. The design of this type of filter is such that total flow must pass through a simplex filter.