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How to properly install the PTFE Bulkhead fittings?

PTFE Bulkhead fitting

Tank Wall Hole: The diameter of the hole through the tank should be equal to, or up to 1/32" larger than the nominal Body O.D. Do not exceed this size, or the o-ring may not seal properly.

Inserting the Fitting: The fitting, together with the o-ring, should be installed from the inside of the tank.

Sealing Surface: The o-ring sealing surface should be smooth and free from sharp edges, burrs, and deep scratches. Ideally, it should have a 20 micro-inch or smoother finish, although depending upon the characteristics of the surface, the o-ring will often achieve a seal against rough surfaces.

Tighten Nut: When tightening the nut, bring it to the point at which the O-ring seal is just in contact with the tank wall. Then tighten it approximately as shown in the following table:

Nominal Pipe Size Tighten Unit
1/4" – 1/2"2/3 of a turn
3/4" – 2-1/2"1/2 of a turn
3" – 4"1/3 of a turn

Achieving the Seal: Sealing to a less-than-smooth surface with Teflon® PFA encapsulated o-rings is different than sealing with rubber o-rings. A rubber o-ring will immediately deform into surface imperfections; Teflon® takes time. Thus, the o-ring may leak when installed. To correct this situation, allow the o-ring to settle in place overnight. This allows the Teflon® to cold-flow into the voids. Alternatively, you can heat the o-ring, allowing it to flow more quickly. If a seal is not achieved, it may help to take up a little more on the nut.

Title: How to properly install the PTFE Bulkhead fittings?
Description: Installation instructions for the PTFE Bulkhead fittings.
Published: 1/27/2010
Last Edited: 1/17/2023
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