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cast iron piston ring leakage table

cast iron piston ring leakage table

cast iron piston ring leakage table

(OP)
Does anyone know where I can get leakage infromation for cast iron piston rings in large hydraulic service?

RE: cast iron piston ring leakage table

Try the "Designers Guide" and look at Piston Ringss under "Seals" at this site

www.fpweb.com

Some of the companies that make piston rings should have info on bypass.

I was told many years back that a Rule of Thumb was:

One Cubic Inch/Minute per Inch of bore per 1000 PSI.

There are several designs of piston rings that would appear to have lower bypass but I have had very little experience with Piston Ring cylinders.

Work with a couple of 50" bore hydraulic presses locally that appear to take about 20-25 GPM to keep them in the up position, at 850-900 PSI, between cycles. They were built id 1953 and have never had to be repaired.

Bud Trinkel, Fluid Power Consultant
HYDRA-PNEU CONSULTING, INC.
http://www.fluidpower1.us

RE: cast iron piston ring leakage table

(OP)
Thank you Bud for your response.
I think your hydraulic presses leakage is high but within reason.
When applying your rule of thumb to your presses I get a theoretical leakage of about 0.2 gal per min?
Am I missing something?
Bryan

RE: cast iron piston ring leakage table

No Bryan, I had never applied that formula to the presses.

I got my figure from knowing there are two 185 GPM Bi-directional Variable Volume Pumps that have a total stroke of approximately 5/8" either side of center and must be offset approximately 1/32" each to keep the Platen from drifting down when the oil is up to operating temperature.

From some old literature on the presses they state there is 5/8-3/4" end gap on the four piston rings when assembled and the presses operate 3 shifts per day 5 days per week about 50 weeks per year for a 60-70 second total cycle time .

You can figure the number of feet of piston travel for a 6' stroke during that length of time.

Bud Trinkel, Fluid Power Consultant
HYDRA-PNEU CONSULTING, INC.
http://www.fluidpower1.us

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