Nightjar wrote on 06/07/13 18:04:
On 06/07/2013 17:07, graham wrote:
I'm looking at buying a vacuum gauge, but they nearly all have BSPP
(male) threads - can anyone tell me how these are supposed to be sealed
when fitted to the BSPP female?
I've come across mention of copper crush washers and bonded washers, but
i've no idea if this is the standard technique.
Would the "crush washer" be sized to fit over the BSP thread, or inside
the female?

A bonded washer is intended to go over the male thread and to seal
between the faces of the two fittings. A crush washer is intended to fit
inside the female fitting and be crushed by the extended male thread
that pressure gauges have. That should allow you to get the gauge facing
the right way when tightening it down and still get a seal. I have no
idea whether vacuum gauges work the same way, as I have never needed
vacuum.

Colin Bignell



ahh, thanks. Does one need a special female fitting suitable for a small
crush washer or is t a standard shape of all female BSPP fittings?

graham