O-ring sizing for 3-in WTE

I am making a custom end-cap for the 3-in BR housings and wanted to duplicate the BR sealing scheme. However, when I double-checked the Parker O-ring handbook, it seems like the BR end flanges should be using a size 2-232 rather than 2-230. That is, the handbook’s listing for groove diameter, bore diameter, and plug diameter better match size 232 than 230, which BR calls out. Am I missing some other factor that went into the sizing?

Agreed, I posted a similar query under the Product section. They stretch the plug o-rings a bit more than we would. Seems to work though.

Hi @Zissou,

Its true the o-ring sizes we use do not quite match the nominal recommendations of the Parker O-ring Handbook, we use a size slightly smaller on all our enclosures radial seals.

Normally, o-rings should be installed with minimal stretch, but In larger piston bore sizes this can result in the o-ring sagging out of the groove, making installation challenging and pinching likely.

In this case, going down slightly in size is permissible to eliminate sag in order to ease installation and reduce the chances of damage.

You can find this information on page 3-8 of the Parker O-Ring Handbook.

We’ve thoroughly tested our enclosure o-ring seals in our hydrostatic pressure chamber, and are confident in their performance.



Thank you for the insight, Adam.

The seals do seem to work just fine, but I wondered about the ‘why’ behind the design.