piston ring low leakage in slow hyraulic service

[SteamBryan]

I would like to know the ring design used to reduce leakage in large slow moving hyraulic service. How do we calculate the leakage?
How many rings should be used for a pressure of 300 psi?
Is there a chart to know how many rings to use for a given pressure differential?

 

[MikeHalloran]

The piston ring that I usually use for hydraulics is called an o-ring. Go to parker.com for all the information you could ever want.

One is sufficient. Multiples are not better.

There is normally leakage amounting to a thin film on the rod. I'm not sure how to calculate it, or why anyone would need to.

Really slow motion can be a challenge; Balseals(r) can be a solution, but they fit in o-ring grooves, so start with o-rings.



Mike Halloran
Pembroke Pines, FL, USA

 

[EdDanzer]

If the working pressure is under 3000 psi and the seal does not have to pass over a port do not use cast iron piston rings. Never use more than 1 bidirectional seal when sealing fluid power pistons or rods. There will be pressure trapping between the seals and cause premature seal failure. There are several manufactures of single groove piston seals that work well at lower (3000 psi max.) pressures. We make a piston seal for 7,000 psi but cannot pass over a port. I have never seen a reliable method of having a seal of any type pass over a port.

Ed Danzer

http://www.danzcoinc.com