Life of an o-ring
Life of an o-ring
(OP)
How long should an o-ring last (silicone or PTFE) that will be around the OD of a 6" dia. 304 SS cylinder which will travel linearly 4" (bidirectional) once every 20 minutes? It is sealing 13 psi 250F clean air.





RE: Life of an o-ring
RE: Life of an o-ring
RE: Life of an o-ring
- O-rings generally require lubricant, even when used as static seals.
- PTFE and PTFE-coated o-rings won't seal against an imperfect surface, won't seal particularly well on a perfect surface, and don't wear very well.
- There's not enough pressure to 'energize' a PTFE o-ring.
- There's not enough pressure to energize a silicone o-ring, either, but that may be a blessing because silicone has poor abrasion resistance.
In my experience, one seal that has a chance of working in your application is the Bal-Seal.
Mike Halloran
Pembroke Pines, FL, USA
RE: Life of an o-ring
RE: Life of an o-ring
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RE: Life of an o-ring
RE: Life of an o-ring
RE: Life of an o-ring
RE: Life of an o-ring
RE: Life of an o-ring
What is the stretch and squeeze on your elastomer?
What is the surface finish on the bore of the cylinder?
No lubricant; what is the frictional coefficient rubber/steel? Use the textbook average?
What is the average piston velocity?
Does the elastomer have a backup ring? Flat or concave?
What is the rubber durometer? 70/75 or 90/95?
Is the thermal operating level static or variant?
The average lifetime of an o-ring is a couple of years. You have very low pressure, but your thermal is elevated which greatly effects the lifetime on the rubber.
I would probably GUESS you're looking at a single year.
Kenneth J Hueston, PEng
Principal
Sturni-Hueston Engineering Inc
Edmonton, Alberta Canada
RE: Life of an o-ring
RE: Life of an o-ring
RE: Life of an o-ring
RE: Life of an o-ring
RE: Life of an o-ring
There may also be plastic dust particles on the "piston" to deal with when sealing...
RE: Life of an o-ring
RE: Life of an o-ring
For a stroke of 2/3 the minor diameter, and a non- reversing pressure difference, you'd certainly do better than 10,000 cycles at room temperature. At 250F, I'm not so sure. Ask Bellofram for help.
Mike Halloran
Pembroke Pines, FL, USA