Reducing Unions - Internal

stainless reducing union
Internal reducing union
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Internal reducing unions connect two sizes of tubing, using zero dead volume internal fittings on each end. In the bulkhead version, the bulkhead nut is on the side with smaller tubing. Standard material is 300 series stainless. Also available in Hastelloy C, gold-plated stainless, and titanium versions.

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
Internal 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.

Select a union type below to view product numbers:

Standard unions

Bulkhead unions

Standard internal reducing unions

Tubing OD Bore Product No.
1/16" to 1/32" 0.15 mm ZRU1.5XC
0.25 mm ZRU1.5
0.50 mm ZRU1.5L
1/32" ZRU1.5T
1/8" to 1/16" 0.25 mm ZRU21C
0.75 mm ZRU21
1/16" ZRU21T
1/4" to 1/16" 0.25 mm ZRU41C*
0.75 mm ZRU41*
1/16" ZRU41T

* Available as a special-order item.
  1/8" to 1/32" and 1/4" to 1/8" also available on special order.

Bulkhead internal reducing unions

The "Hole" heading in the table below refers to the size of the hole required for mounting the union through a bulkhead or panel.

Tubing OD Bore Hole Product No.
1/16" to 1/32" 0.25 mm 5/16" ZBRU1.5
0.50 mm 5/16" ZBRU1.5L*
1/32" 5/16" ZBRU1.5T*
1/8" to 1/16" 0.25 mm 5/16" ZBRU21C*
0.75 mm 5/16" ZBRU21
1/16" 5/16" ZBRU21T
1/4" to 1/8" 0.75 mm 5/8" ZBRU42*
2.0 mm 5/8" ZBRU42L
1/8" 5/8" ZBRU42T*

* Available as a special-order item.
  1/8" to 1/32" and 1/4" to 1/16" also available on special order.




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