Filter

[joewilshire]

What's it mean when the filter on my hydraulic system starts to expand? It's on the suction side of the valve leading back to the reservoir.

 

[Farmerford]

Are you sure it is on the suction side? Most filters are in the return line to the reservoir. If it is expanding it may be clogged up and pressure is building in the cannister. Most, but not all, filter mounts have a bypass valve set at from 10 to 45 psi so that fluid will flow around the filter if it becomes clogged. The typical spin on filter element is rated for 100 to 150 psi, and if there is no bypass valve, the pressure could easily get that high as the filter begins to clog up. I would replace the filter and see if the new one does the same thing.

 

[RonMar]

What's it mean when the filter on my hydraulic system starts to expand? It's on the suction side of the valve leading back to the reservoir.

There is no "suction" side on the valve. There is a suction line that runs from resovoir to pump... There is a "return" line comming off the valve going back to the resovoir. Is that what you were refering to?

What does it mean when the filter canister starts to swell? It has been over-pressurized. As Farmerford said, the return line filter usually has a bypass to allow fluid to start flowing around the filter element somewhere around 30 PSI typically. This to keep fluid flowing when the filter clogs or fluid is really cold/thick. Some filter bases have this spring loaded bypass built into the base, some setups have the bypass valve built into the spin on filter cartrige itself. If you happen to have a non bypass cartridge on a non bypass valve base, or your bypass valve is not working and the filter starts to clog, the filter cartridge will expand and ultimatly rupture when the flow is restricted enough to raise the pressure high enough.

At the least you probably need a new filter and to check operation(or presence) of a bypass valve either in the filter base or the cartrige.

 

[joewilshire]

The filter is mounted on the return line to the reservoir. It does have a bypass valve in the filter base. I did notice before that fluid was leaking from two set screws mounted on the sides of the base. I tightened them somewhat but it did seem they were going in deeper than before.

Are the set screws used to somehow adjust the bypass pressure? Maybe I should back them out a little more?

Thanks for all you help.

Joe

 

[Farmerford]

The screws are probably pipe plugs in the ports for a pressure guage. The bypass valve is usually non-adjustable, though some designs let you adjust by moving a circlip on the shaft that connects the spring to the valve.

The bypass valve could be stuck closed, but that is unlikely because they are so simple: just a spring holding a flap over a hole.

Could there be an obstruction between the filter and the reservoir?

I suggest you buy a cheap 0-50psi guage (probably with a 1/8" npt male base) and install it into the filter bracket to see what is happening. Use the port on the upstream side of the bracket so you are measuring pressure coming into the filter. Then install a new filter and try it out.

 

[joewilshire]

I removed the filter and it's base. The filter did not seem to be clogged and the bypass in the base is working ok.

I think instead of having a pressure problem, that somehow the filter got bumped or wacked by a log while I was splitting wood yesterday.

Anyway...I'll get a new filter and install it just in case and let you know if problem occurs again.

Thanks a ton for all your help and suggestions.

L8R

Joe

P.S. The screws are exactly what Farmerford said. Ports for pressure gauge.