Reducing Unions - External

stainless reducing union
External reducing union
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External reducing unions connect two sizes of tubing, using external fittings on each end. Standard material is 300 series stainless.

Select the union with the bore that matches the ID of the tubing. If the IDs are different, choose the union with a bore which matches the smaller tube bore.

stainless bulkhead reducing union
External bulkhead reducing union
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Bulkhead versions are designed to be mounted through an instrument panel or on a bracket. The fitting body is undercut so that it bites into the panel when the mounting nut is tightened, eliminating the need for a lock washer.

Note: Because 1/16" external fittings have very thin, easily distorted walls, they are not as durable as 1/16" internal fittings. We recommend the use of external/internal reducing unions when connecting to an installed external nut.

Standard External Reducing Unions

Tubing OD Bore Product No.
1/8" to 1/16" 0.75 mm ERU21
1/16" ERU21T

Other sizes, bores, and bulkhead versions available as special-order items.



With a bulkhead union, an O-ring can be installed between the body and the panel to allow operation in purged environments.