Could anyone explain how bulkhead sizing works?

[an411]

I need to get a bulkhead that I can use a 1 1/4 inch pipe with. So i just buy a 1 1/4 inch bulkhead cause they seem to be hard to find I only see 1 inch and 1 1/2 inch.

 

[Travis L. Stevens]

Yes, you buy the size of bulkhead that matches the size of PVC. Thus, .5" plumbing needs a .5" bulkhead, 2" plumbing needs a 2" bulkhead, and so on. Now, if you are drilling your own tank, make note that the size of the hole that the bulkhead fits into is larger than the said size of bulkhead. But that is just trivial information.

 

[an411]

Alright great thanks Travis yeah the hole size on the 1 1/4 inch bulkhead is a 2 3/8" so not I have to find out what the MM size is equivalent to this and purchase one on ebay to start drilling