Pressure rating of O-Rings

[vtmike]

Hi,

Normally when we see an O-Ring with a pressure rating, how are they actually tested to get that pressure rating?

 

[hydtools]

Installed per their gland dimensions.

Here is the Parker O-ring Handbook:

http://www.gulfcoastseal.com/downloads/ord5700.pdf

Ted

 

[Tmoose]

One way to reach the upper limit is to have gaps so large on the low pressure side that the 0-ring extrudes into them, and be cut or torn.

 

[eromlignod]

As far as I know there is no universal "pressure rating" for a given o-ring. If you see one, I wouldn't trust it to apply in any given application. As hydtools points out, you should take a good look at the Parker o-ring handbook.

The pressure rating depends on the size, material, duty and gland configuration. A Buna-n -101 o-ring in a static face seal might have a different maximum pressure rating than a silicone one used on the OD of a reciprocating piston.

For very high pressures, backup rings are needed to prevent the extrusion that Tmoose pointed out. This can greatly increase the pressure rating (and change gland dimensions).

Download the handbook that hydtools gives a link to and save it. It's actually fascinating as hell.

Don
Kansas City

 

[vtmike]

I know that an O-ring pressure rating will depend on the gland dimensions, configuration etc.
I wanted to know what testing procedure or what kind of testing equipment do the O-ring manufacturers use to find the pressure rating?

 

[btrueblood]

O-ring manufacturers DON'T provide pressure ratings. Equipment manufacturers might, and would do so (like Don said) if they know that different durometers or materials of the O-ring, or different groove configurations (e.g. to allow backup rings) affect the pressure limit for their equipment. They would probably establish such limits by hydrostatic or other testing. Read the handbook.

 

[hydtools]

Pose your question directly to Parker O-ring Division.

How do they determine extrusion vs. gap vs. durometer vs pressure?
How do they determine squeeze required for various applications?
How do they determine finish for dynamic applications?
How do they determine gland dimensions for dynamic and static applications?

I use their handbook and presume they have done their homework. When I had applications not specifically addressed in the handbook, I devised my own tests for my application.

http://www.parker.com/portal/site/P...toid=b126981ef31a0110VgnVCM10000048021dacRCRD

Ted