Howard a 1" gauge is usually plumbed in with 1/16" pipe which will fit INSIDE the brass nipple supplied
Some thing like this one from Macc Models
Here is one of mine, OK its sitting on a 1/16" drill bit but thats how they fit to copper pipe, if you want to run a larger pipe then you will have to make an adaptor

Edited By JasonB on 20/08/2015 13:45:23