Internal reducing unions connect two tubing sizes, using zero-dead-volume internal fittings at 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 that matches the smaller tube's bore.
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.
