John Stumbles wrote:
On Tue, 05 Feb 2008 12:33:24 +0000, 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?

For pipework it's no observable drop, which IIRC is stated somewhere
to be less than 0.25mbar (over 2 minutes test).

If any appliance is connected then it depends on the type (and
volume) of the gas meter, but if your CORGI registered installer is
testing that his pipework is sound he should shut off appliances so
that he's testing only the pipework.

It wasn't so long ago that a gas fitter came and did the old "sucking of
teeth" bit when he saw our gas cooker didn't have an isolating valve (which
he then fitted).

It took us some time to realise that the odd smell in the kitchen was coming
from the back of the unit where he had fitted the valve, which was leaking.
;-)

Fortunately, it just took a bit of working the valve open & closed a few
times to get it to seal properly but it's made me a wee bit sceptical about
the benefits of all these valves.

If he's canny he'll have tested
the installation before he made any changes in which case if there
was a slight but acceptable drop beforehand *and no smell of gas* and
the drop is no greater afterwards he can probably put it down to
appliance drop and leave it like that.

We don't have a smell of gas (unlike the time another BG engineer who
supposedly had tested our system cocked up) but I've decided to invest in a
manometer to see if I can isolate the leak.

On several occasions, I have heard mention (from plumbers) of a figure
(something like 4mm or 4mbar over some period or other mentioned), hence my
question.

Tim