Bulkhead Unions require a 3/8" thru-hole to mount.
Bulkhead Manifolds require a 1/2" thru-hole to mount.
- Drill the appropriate sized hole in the bulkhead.
- Unscrew the nut and washer from the union / manifold body.
- Slide the union / manifold body through the mounting hole (see diagram below).
- Thread the lock washer and nut (in that order) onto the union / manifold.
- Finger tighten the nut until snug. Further tighten the nut 1/4" turn with the appropriate wrench:
Union: 3/8" wrench
Manifold: 1/2" wrench