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Teflon Cap Seal spec?

Teflon Cap Seal spec?

Teflon Cap Seal spec?

Howdy all,

I have a small o-ring (-010) that uses a cap seal (see pic below). The cap seal P/N is part specific, and I was wondering if there was a standard for similar cap seals. I found a couple of websites that sell similar style O-ring cap seals such as Mykin inc and Gallagher fluid seals. But they don't reference a spec either. Does this part have a standard to conform to?



Kirby Wilkerson

Remember, first define the problem, then solve it.

RE: Teflon Cap Seal spec?

KW... materials nerd in me, having helped a good friend who is a hydraulics nerd...

Teflon is often used exactly as described/shown... but your configuration for usage and part 'nomenclature' are baffling… almost looks like a sliding V seal... but the term 'cap-seal' is inscrutable to me. Please advise more about this part.

Here are a couple of generic specs for Teflon used as parts in hydraulic and Pneumatic systems for backup rings, cups, spacers, retainers etc... plus deign and usage specs

Following [2] specs...
AS8791 Hydraulic and Pneumatic Retainers (Backup Rings), Polytetrafluoroethylene (PTFE) Resin [replaced MIL-R-8791]
AMS3678 Polytetrafluoroethylene (PTFE) Moldings and Extrusions Unfilled, Pigmented, and Filled [+Variations AMS3678/1-thru-AMS3678/16]
ASTM D 4745 Filled Compounds of Polytetrafluoroethylene (PTFE) Molding and Extrusion Materials
ASTM D 4894 Polytetrafluoroethylene (PTFE) Granular Molding and Ram Extrusion Materials
AS4716 Gland Design, O-Ring and Other Elastomeric Seals
AS5781 Retainers (Backup Rings), Hydraulic and Pneumatic, Polytetrafluoroethylene Resin, Single Turn, Scarf-Cut, For Use in AS4716 Glands
AS5857 Gland Design, O-Ring and Other Elastomeric Seals, Static Applications
AS5860 Retainers (Backup Rings), Hydraulic and Pneumatic, Polytetrafluoroethylene Resin, Single Turn, Static Gland
AS5861 Retainers, (Backup Rings), Hydraulic and Pneumatic, Polytetrafluoroethylene Resin, Solid, Static Gland
AS8791 Hydraulic and Pneumatic Retainers (Back-Up Rings), Polytetrafluoroethylene (PTFE) Resin


Regards, Wil Taylor
o Trust - But Verify!
o We believe to be true what we prefer to be true. [Unknown]
o For those who believe, no proof is required; for those who cannot believe, no proof is possible. [variation,Stuart Chase]
o Unfortunately, in science what You 'believe' is irrelevant. ["Orion", Homebuiltairplanes.com forum]

RE: Teflon Cap Seal spec?

I think that is more properly called a lip or cup seal, and they are usually sized to fit in standard o-ring groove sizes.

RE: Teflon Cap Seal spec?

Here's Gallahger's website describing them, https://www.gallagherseals.com/piston-channel-cap-..., and here's Mykin's page for them, https://mykin.com/mh7-oring-loaded-seals

They seem to work as a backup ring, well maybe not, since this is for a staging valve that doesn't see more than 300 psi normally. So seal extrusion isn't a problem, but it might prevent the o-ring from rolling. The picture below is for an indicator shaft that actuates a couple of switches outside of the pressurized section.


Kirby Wilkerson

Remember, first define the problem, then solve it.

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