O/T(ish) - BSP threads

[David WE Roberts]

Our local allotment has piped water, but the male tap connectors are larger than the standard hose connector - about as large as the outside of the connector.

Having established that the standard connector is 3/4" BSP I got out my trusty Powerfix caliper and started mesasuring up to try and work out what the larger thread was.

I was a little confused to find that I couldn't find anything on the 3/4" BSP connector which measured 0.75".

Visiting

showed me that I was indeed dealing with a 3/4" BSP connector and that the one I wanted was a 1" connector.

Apparently the size is the bore size of the tube to which the thread is appropriate, which is why the nominal thread size bears no relation to the measurements.

Had I not been able to work back from a known size fitting I would have been well confused.

Cheers

Dave R

[Grimly Curmudgeon]

We were somewhere around Barstow, on the edge of the desert, when the drugs began to take hold. I remember "David WE Roberts" saying something like:

Welcome to the whacky world of plumbing threads. And then you find that some manufacturer breaks with the convention and uses some other weird and wonderful thread.

[Dave Osborne]

Funny you should say that. I also have a "trusty Powerfix caliper", which I bought from Lidl. It's by far the best "cheap" one I've ever used. Much better than the one I bought from Aldi.

[Dave Plowman (News)]

Swings and roundabouts. The pipe could have been steel, copper, lead or plastic. All with different OD. You're not really concerned with the outside dimensions of electrical cable, but what it can carry, current wise. So the same sort of thing.

[John]

This shows a 3/4 BSP to have an outside diameter of 1.04 inches.