Bulkhead hole sizing

[RedSeareefkeeper]

Hello, I recently ordered this bulkhead off Amazon:

I checked on Lifegard"s website and they recommend a hole size of 11/4" for all of their 1/2" bulkheads, that seems a bit large, I know that the hole diameter needs to be larger than the stated size of 1/2" which is referring to the bulkhead's I.D. but when I looked at other brands of bulkheads for the same size they had much smaller recommended hole sizes (1.06-1.72" for BRS ABS bulkheads, 1.25-2" for BRS Sch 80 bulkheads and 11/8" for Aquarium co-op bulkheads.
Does anybody have experience with the brand and size of bulkhead I ordered and could they tell me what hole size they ended up going with, or could someone tell me if the size on Lifegard's website sounds reasonable?
Thanks!

 

[Formulator]

It sounds reasonable to me. You do know that 1 1/4 = 1.25 right? The ranges for the other bulk head brands you mentioned cover 1.25, so they are the same… and you can always just measure the bulkhead to be sure.

 

[theatrus]

Also sounds reasonable. You do need to accommodate the inner threads, the wall, and the outer threads into the hole which adds up quickly. Most of the hole recommendations are slightly big, as the mounting flanges are large giving a lot of tolerance to over-sized holes, but you can't easily make the bulkhead bigger in glass if its too tight/small.

Also remember nominal pipe sizes (e.g. 1/2" PVC pipe) are not the OD. Nor the ID. A 1/2" nominal pipe is actually 0.84in OD.

 

[RedSeareefkeeper]

It sounds reasonable to me. You do know that 1 1/4 = 1.25 right? The ranges for the other bulk head brands you mentioned cover 1.25, so they are the same… and you can always just measure the bulkhead to be sure.

Oh... I was reading it as 11/4 inches instead of 1 1/4 because the formating on the websites didn't have a space, didn't occur to me that's what they meant, sorry I am not very used to Imperial measurements. Thanks!

 

[RedSeareefkeeper]

Also sounds reasonable. You do need to accommodate the inner threads, the wall, and the outer threads into the hole which adds up quickly. Most of the hole recommendations are slightly big, as the mounting flanges are large giving a lot of tolerance to over-sized holes, but you can't easily make the bulkhead bigger in glass if its too tight/small.

Also remember nominal pipe sizes (e.g. 1/2" PVC pipe) are not the OD. Nor the ID. A 1/2" nominal pipe is actually 0.84in OD.

Interesting I didn't know that's how pipe sizes are defined in the US of A.
Well it's 0-1 for me vs the Imperial system of measurement but another win for Metric vs Imperial