look here this will tell you just about everything you need to know.
I like using hunter valves. The spot where the selinoid screws in is a 1/4 inch npt thread. Because of this you don't need to drill and tap a new hole and you don't have to jb weld fill a hole. All you have to do is remove the selinoid. , then with the diaphragm out drill out. The metal pin hole, put
A little plumbers putty in the pass through hole and attach the blowgun where the selinoid used to be. It takes may ten minutes to do. Vs. 24 hours if you include cure time for the jb weld with the other valves.