On Tue, 05 Feb 2008 12:49:28 +0000, Roger Mills wrote:

In an earlier contribution to this discussion, Tim Downie
wrote:

I was recently told when a plumber cut off a dead leg in our gas
pipework that we had a small (but allowable) leak in our system.

Clearly he wasn't wild about chasing the leak but I'd rather there
wasn't one. Before I start hunting, what's the acceptable leak level
in mbar/min?
Tim

I don't know the answer, but is that the only way to measure leaks - in
mbar/min?

If so, surely that makes the max permissible *absolute* leak rate
(gms/min, or whatever) a function of the volume of your pipework. Is
that's what's intended?

Since the volume of the pipework+meter is to a first approximation is
similar for all ordinary domestic installations, then the pressure drop
and time equates to roughly similar amount of gas leakage.

If you reckoned that the volume of the pipe+meter is about 10 litres then
4 mbar/2min is about 20cm^3 per min. That's about about 1/2 an egg cup
per min, MAXIMUM when the old appliances are connected and there is NO
SMELL of gas.

If you have a smaller electronic meter (E6 type) or heavy domestic/light
commercial (R5) type then the times and pressures are different.

On large domestic installations and above then calculations are required
to work out the permitted leakage limits.

THE PERMITTED LEAKAGE FOR PIPEWORK (new or old) IS ZERO. I.e. less than
0.25mbar/2min on a normal installation. That's less than 1cm^3 per min.


--
Ed Sirett - Property maintainer and registered gas fitter.
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