Gas release valve?

[Commander Kinsey]

What are those things you see in the middle of nowhere (in the UK at least), a 10 foot high white pole with an orange roof-shaped lid on top? I gather they're to release excess gas from the mains and burn it off, but why would that be necessary? Surely they wouldn't put more than the correct pressure in anyway? Any excess could be released at the source at the gas plant? I've never known of one actually operate. I can't find a picture of one on Google as I don't know what they're called. Searching for pressure release just shows domestic valves.

[Andy Burns]

Hi-viz poles to allow the chopper to follow the pipeline route easily.

[Commander Kinsey]

They're not just markers, I'm sure they can actually let off gas.

[Martin Brown]

They are simple makers for the helicopter that checks the pipeline to follow with its airborne leak checker. One of the high pressure pipelines runs close to me. They also mark the no dig zone at the roadside (permission required from the pipeline owner Ineos or Shell).

[Colonel Edmund J. Burke]

Everyone knows the tiny island nation is full of gas!

[Roger Hayter]

That seems unfair; after a boring day mashing up roadside culverts and the occasional fibre duct, a high pressure gas pipeline would be quite an exciting find for JCB operator.

[Commander Kinsey]

My local council once dug through a gas pipeline in my street. Unfortunately it didn't catch light and blow one of the dimwits to kingdom come, so there was just a smell of gas, some workmen running about hurriedly making phonecalls, and no gas for the afternoon.

What I like is when snowploughs destroy those stupid f****ng bollards on chicanes, as they can't see them in deep snow. I removed one myself once when I had an old Range Rover. They're plastic and smash up easily.

[Commander Kinsey]

Are you sure? I looked at one once and I'm sure it had some kind of valve in it to let gas out. When I asked someone at the time, I was told that if it had let off pressure and ignited it, the bright orange lid would have been blackened, signifying there had been a problem.

[Andy Burns]

You think they're going to allow gas at 1200 psi up a tiny pole at the side of the road for tom, dick and harry to crash into?

[Commander Kinsey]

A) I didn't know it was that high a pressure, in fact I thought it might just be the final house pressure.

B) It's better to let it off in a flame (and they're usually on quiet B roads) than to let it build up and cause an explosion.

[Brian Gaff]

Yes one round the back of my l place. They had to fiddle with the pressure though as everyone heard a throbbing from the thing at night. Brian

[Commander Kinsey]

If it makes a noise, it can't just be a marker.

[NY]

Shame the don't remove the whole chicane and return the road to a proper thoroughfare for traffic without causing it bunch up at each end waiting its turn to get into the chicaned-off part.

[Martin Brown]

The main pipelines run at some insane pressures & they don't vent. The estimate for the SPL at 100m if our pipeline was breached is 140dB.

[Commander Kinsey]

I did wonder how they could distribute all that gas at 1.1 bar. I guess there's a lot of complicated valves somewhere to change the "voltage" as it were? Do they ever fail and put high pressure into the final piping? I dread to think what would happen if the "insane" pressure got into your boiler.

[Scott Lurndal]

There are pressure reducing meters at pretty much every point-of-use which reduce the line pressure to a pressure compatible with standard appliances; you may notice that some meters have a much smaller inlet pipe than the outlet pipe (e.g. commercial premises) due to the need to for more volume at the lower pressure.

[Commander Kinsey]

So the meter outside my house reduces the pressure? I thought the pressure was lowered for the whole street, like a substation reduces the electricity to 240V.

I had noticed on older houses there's some kind of valve seperate from the meter (often exposed to the outdoor weather!), presumably nowadays it's inside the meter.

[Tim Watts]

Your meter has a regulator that drops from an already lowish pressure to

20mbar.

[Roger Hayter]

Do you often have a problem with people taking the piss?

[newshound]

+1.

In the old days, there were tall vent stacks for sewers. Cast iron with nice "petals" at the top, about the height of a telegraph pole. In urban areas.