Aidan wrote:
On Dec 2, 9:45 pm, "Phil L" wrote:

Because the previous poster had made a typo, numpty.

No he hadn't, Phil. He had said, quite correctly, that it was "... at
20mbar pressure, i.e. 1/50th atmosphere pressure, or around 8" of
water".

You were wrong, Phil.

Gas is 2 bar at the meter,

No, you're wrong again there, Phil.

It is not 2 bar at the meter. It is 21mbar at the meter.
It is at a higher pressure at the governor/pressure reducing valve,
which is on the meter inlet. Even there, it's not usually anywhere
near 2 bar; more like 30" wg, 0.07 bar.

he didn't say where he'd connected the effing
manometer,

You're wrong, Phil. He had connected it to a test nipple, which is
usually the one on the meter outlet and so is at the reduced pressure,
21 mbar static.

He may have connected it to a test nipple on an appliance, but they're
all at 21 mbar static pressure too.

There are no test nipples on the high pressure/inlet side of the
governor because it would allow the users access to an unmetered gas
supply.

You should know that, having done the ACOPS course.
Why don't you just go and look at a meter? The usual arrangement is
service pipe, isolating valve, governor, meter ( with test nipple on
the meter outlet).

..did the few cc's of coloured water blow out of the straw or
not?

Yes, it did, because he opened the 1/4 turn gas isolating valve
quickly. The gas surged into the unpressurised manometer tube and the
water column had to stop the entire column of moving gas in the
service pipe. It causes a momentary pressure surge Water hammer
happens the same way.

If you open the valve slowly, it doesn't happen.
You should know that, having done 380,000 gas tests.


I didn't say I had performed 380,00 gas tests, and none on gas meters.

Which ones can operate safely in a sealed room?

The ones that can operate safely in a sealed room have a special name.
They are called "room sealed".

Like these;
http://www.google.co.uk/search?hl=en...UK%7CcountryGB

Now I know you are bull****ting, all those 'room sealed' gas fires have
balanced flues, they take air from outside, although I can't believe they
didn't teach you this at HVAC university.