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Whilst
it is often possible to reduce air-line sizes by inserting
a larger air-line into a smaller one, this is not reliable;
instead, the use of a plug-in reducer is preferable.
Fittings
will need to be attached to threaded ports on valves, regulators,
and other parts. Threads come in many different shapes, and
this can pose severe problems. The most obvious difference
between methods of threading joints is the sealing. Either
the thread is parallel and the seal is made by a bonded washer
at the body end of the thread, or the thread is tapered and
sealant ,typically PTFE tape, is applied along the thread
to seal it.
However, some threads are parallel but sealed along the thread!.
In the UK, the threads are historically BSP or BSPT (modern
thread is specified as G), which is at a 55° angle;
In America, thread is to the American NPT and NPTF standards,
which is at a 60° angle. Trying to mix BSP and NPT results
in stripped thread and frustration. Threaded parts are specified
by the type of thread (BSP, BSPT, NPT, NPTF, G, ...) which
includes whether the thread is tapered or parallel, and the
diameter (1/4, 3/8, 1/2, 1/8, ...).
Thread
types and sizes are indicated on all relevent fittings and
valves supplied here.
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