To Strain or Not to Strain?

Over the years I have listened to many opinions about hydraulic strainers. Some schools say that they should be fitted whilst others say they shouldn't.
To get behind these differing views lets look at what strainers are and the reasons they are fitted.
The strainer is a tube of wire mesh with perforations of around 125 microns. This is no way near the rating of a return line filter at 25micron nor the fine filtration of the pressure filter at 25micron down to 1 micron absolute.
Strainers are fitted to the suction pipe to stop big lumps being sucked into the pump.
The problem we have with these tubes of wire is that customers do not always know that they are fitted. Even if you do know, they are often difficult to remove and replace. I have seen strainers that have never been changed and have been sat undetected in a tank for more than ten years. During this time the strainer has become coated with silt and hairy contamination. The consequence is a starved and damage pump caused by cavitation.
On balance I think strainers should be fitted to stop that lump of weld splatter or large flake of paint entering the pump. Signs should be placed on the pack to indicate that they are fitted and must be changed (not cleaned) within a suitable period of time.
You may have differing views and I certainly would not take up the argument , its too close to call!

Bob Jackson

Hydraulics over 40 years

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