In an earlier contribution to this discussion,
Graham Jones wrote:


The reason for all this is that I am trying to determine whether this:

http://www.screwfix.com/app/sfd/cat/...12341&ts=05907

is the same as this:

http://www.screwfix.com/app/sfd/cat/...76620&ts=07117

but without the flexible hose. Do both items have the same diameters
and threads?

Yes, they both have a 15mm compression fitting one end and a 1/2" BSP female
thread at the other end.

However, I'm not sure whether the sealing arrangements of the 1/2" BSP bits
are the same as each other.

There are two different ways of sealing threaded joints. One uses parallel
threads and a washer - as in a tap fitting. The other uses a long parallel
female thread, and a slightly tapered male thread. The second sort actually
seals on the threads when the tapered bit is far enough in, using PTFE tape
or Boss White and hemp wound round the threads.

I suspect - but am not sure - that your first reference is designed to screw
onto a tapered thread. The second one (the flexible tap connector) is
definitely parallel, and seals against a face, using a fibre or neoprene
washer.

--
Cheers,
Set Square
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