gas card meter

[CES]

Even if it equals out there will be no movement either in or out of the pipe if the pressures are equal. The remaining gas in the pipe would remain.
For movement there needs to be an imbalance of pressure.

 

[GrahamM]

Air pressures are not exact here. Gas air and natural is in a fluid state. Gas is lighter than air Regulators don't shut down in microseconds.
You are thinking too precise.
Unless the regulator in meter and gas valve shut down at the exact microsecond of each and you have the slightest bit of space within that pipework for just a fraction of a second air can work its way in. Remember the gas has a fluid movement through the pipework as it is consumed by the boiler. This movement is not stopped dead in it's tracks as soon as the meter shuts down.

 

[CES]

what you have described is the pipe being put under negative pressure, by the actions of the gas meter / gas valve closing. I think what was being said is that if the pipe is found "full of air" then there would be a considerable leak on the gas pipework in the first place.

 

[GrahamM]

what you have described is the pipe being put under negative pressure, by the actions of the gas meter / gas valve closing. I think what was being said is that if the pipe is found "full of air" then there would be a considerable leak on the gas pipework in the first place.

What I believed was being discussed is how could a gas card meter have/get air in when it shuts down. As was mentioned air is under neutral pressure which is not the case.
Maybe went a bit sciency on it though.

Obviously if an enclosed gas pipe was full of air there maybe some fault in the system.

 

[CES]

Way too sciency for a sunday morning hangover!! :ack2:

 

[Dotty]

What I believed was being discussed is how could a gas card meter have/get air in when it shuts down. As was mentioned air is under neutral pressure which is not the case.
Maybe went a bit sciency on it though.

Obviously if an enclosed gas pipe was full of air there maybe some fault in the system.

Aye a wee bit sciencey for a Sunday! We quibble over terminology. My entire point was based on the statement made that appliances have to be bled each and every time a Meyer's reset or loaded up. I accept what you say about the meter and regulator not shutting down instantaneously. However the pressure of the medium in the pipework can only equalise itself to match the medium outside the pipework. In an extremely rare occurrence atmospheric pressure may, only may, be higher than that in the pipe and a minute amount of air may, only may, bey drawn in through the pipework. I would call this exceptional and extremely rare rather than the norm. For an installation to draw in so much air that it needs every appliance purged every time the meter knocks off suggests a much larger issue to me.

I'm enjoying this one mate!

 

[Dotty]

Meter, not Meyer! Bloody autocorrect!

 

[mountainman]

I'm with you on this one meyte.

 

[marsaday]

She has reset the boiler and all working ok so no need to panic. Thanks for replies.

 

[mightymark]

Thank god for that

 

[stevetheplumber]

i cant agree as ive had a lot of instances where card running out has resulted in purging being necessary to get the boiler to light sureley air can enter when gas runs out and the cooker and fire are alight ?since gas is lighter than air it will continue to drift up through the jets on the cooker which could give negative preasure on the fire jet drawing air in

 

[mightymark]

Lets face it, it was a purge job from the first post, just got a bit long winded lol

 

[mightymark]

As soon as I saw Flame Failure, I looked at my mate and said it needs purging. Can't believe it got dragged out for so long

 

[Barry98]

Lets face it, it was a purge job from the first post, just got a bit long winded lol

Didnt I say that , I tell ya sometimes it's like I know what I'm on about , only sometimes though hehehe

 

[linksman]

really??? are you being serious ? i think you need to go an have a little think about what your saying..