"Mungo" wrote in message
...
Hi Colin,
Ta for the reply (but)...


On 14 Mar, 08:48, "nightjar" cpb@insert my surname here.me.uk
wrote:
"Mungo Henning" wrote in message
Okay, what gives: someone educate me please?

A 3/8" washer fits a 3/8" tap.

Err... in these days of metric, the above (IMHO) is not that useful.

Steel and plastic pipes are still identified by the bore in inches, although
the standards now give their dimensions in mm, as are many fittings. Only
copper is properly identified by the OD in mm.

Tap sizes are based upon the bore of the feed
pipe.

I've got 15mm pipes feeding the taps, but they narrow down for the
monobloc tap thinggy.

The tap size is based upon the assumption that it has a British Standard
Pipe threaded connector, whether it actually has or not. That thread would
match the size of thread that could be cut on the oustide of a steel feed
pipe of the relevant size, in this case a 3/8" bore pipe. BSP is a metric
standard thread, even though it refers to inch sizes.

That will also be the size of the hole the water enters the tap body
through. The washer needs to seat onto a rim around that hole, so it has
to
be larger

Again (and also for the other kind repliers): what gives? How come the
caliper gauge measures the
old washer as 16mm diameter yet I have to go and buy a three-eighths
washer?

Measure the hole in the middle of the seat that the washer fits to. That
should be 3/8". You will find the same applies to 1/2" and 3/4" washers -
they are larger in diameter than the tap size marked on them.

Colin Bignell