The Truth About Hydraulic Suction Strainers

Given that particle contamination of hydraulic oil minimizes the service life of hydraulic elements, it’d seem reasonable that a hydraulic system can’t have too many filters. Very well, not exactly.


Some hydraulic types of filters can certainly do a lot more damage than good. And thus the addition of theirs in a hydraulic system is misguided. Pump inlet (suction) filters fall under this particular classification. Inlet filters generally take the type of a 140 micron, mesh strainer that is certainly screwed onto the pump intake penetration inside the hydraulic reservoir.

Suction strainers increase the odds of cavitation happening in the intake line and subsequent damage to, and failure of the hydraulic pump. Piston-type pumps are really predisposed.

If the tank commences out pristine and all oil returning to the tank is filtered, suction strainers usually are not required since the hydraulic oil will not contain particles large enough to be harnessed by a coarse mesh screen.

Therefore for the reasons reported above, I usually recommend taking away and discarding them where fitted. One of several typical counter contentions for this suggestion is that they are a’ rock-stopper’. This’s common from a suction strainer advocate:

“The something a strainer does that is worthwhile is keeping out the trash can which often gets dropped into the toilet’s water tank during service. Rexroth dealer in India were lost by us to things as bolts that we know weren’t in the tank when it got made. The means of adding hydraulic fluid on to the toilet tank typically doubles as the trash installation function. The screens which are usually set up on the fill neck normally get a hole poked through them so that oil go in faster.”

Two of years ago, I was in the middle of a situation where seals failed in the swivel on a hydraulic excavator. This permitted the automatic greasing system to spew grease into the hydraulic tank.

The grease clogged the suction strainers, which consequently failed. The wire mesh from the strainers destroyed all four hydraulic pumps and also many additional components. Had suction strainers not been fitted, it’s feasible that the grease will have ultimately dissolved in the hydraulic oil with minimal damage to the parts.

The point of mine about this story is, I don’t use this instance as an argument against connecting them. Because grease should not be inside the hydraulic reservoir. Moreover, I don’t think about trash exclusion being a legitimate argument for fitting them. Because nuts, bolts or maybe comparable waste should not experience the container.

The sloppy operators who enable trash to drop in to the tank are the same operators who never empty and clean the tank, then clean or perhaps replace the strainer. So it clogs eventually and additionally the pump fails through cavitation. And so with or perhaps without a suction strainer, the pump is destined to be unsuccessful prematurely.

The proper answer is not to allow scrap to reach the container. And this’s fundamental to my suggestion to remove and discard suction strainers, where fitted. There are some exceptions to this particular principle, but garbage exclusion is not among them.

Bottom line: excessive vacuum at the pump inlet caused by a strainer is a greater danger to pump everyday living in the very long run, than rubbish which often should not be inside the hydraulic reservoir in the first place.

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