No. The SU5/16 joins two sections of the same 5/16" (nominal 8 mm) outside-diameter tubing in a straight line; it is not a reducing union.

A union is for two tubing ends. Choose a male or female stud when the line must connect to a threaded component or port.

No. 5/16 in is 7.9375 mm, not precisely 8 mm. Some catalogues use a nominal cross-reference, but tube fit must be confirmed from approved outside-diameter tolerances and manufacturer guidance.

Pneuforce lists this stainless push-to-connect family for compressed air and vacuum. The completed connection must use compatible tubing with a clean, undamaged outside surface, and the system must be checked for leakage at its operating vacuum.

Do not assume potable-water approval. Pneuforce lists these push-in fittings for compressed air, vacuum and non-potable water; drinking-water or food-contact approvals would require separate documented certification.

FKM is the fluoroelastomer sealing material used in this fitting family. It is chosen for resistance to many oils, chemicals and elevated temperatures, but exact media compatibility depends on the fluid concentration, temperature and seal formulation.

Match the tube outside diameter and approved tubing material to the fitting. Cut squarely, remove burrs, insert fully and check retention and leaks before putting the system into service. Confirm the connection can be disconnected safely after depressurizing.