What size bulkhead fitting fits an 1-3/8 inch hole?
 

What size bulkhead fitting fits an 1-3/8 inch hole?

3/4 inch or 1 inch?

Sorry to rain on your parade but, thats a 1/2" bulkhead.

The 1/2" bulkheads I just used required a 1 1/8" hole. 1 1/2" for 3/4" and 1 3/4" for 1". These are standard double threaded bulkheads that I am referring to also.

Uh....1 1/8" = smaller than 1 3/8" = fit
and 1 1/2" = larger than 1 3/8" = no fit

:rolleyes:

heavy-duty 1/2" bulkheads require 1 3/8" holes , regular 1/2" bulkheads are 1 1/8", but I'm sure both holes are oversized. I measured my standard 1/2" bukheads and they are 1.09" and not 1.125".

I figured this out last week, as I need to order a diamond hole saw in mm. 1 1/8" is like 28.65.mm, but a 28mm holesaw is fine for a standard bulkhead that is only 27.65mm wide at the threads.