Gas Towers

[nebodeuk]

My son asked me this the other day and I could not give him an answer.  The huge big gas towers that appear to move telescopically up and down when filed with gas or when they are getting low on gas they shrink. Why do they do that? Why do they not just have a solid cylinder that they fill up when someone looks at a guage. Why do they have to move up and down? I would love to know the answer!

[dilligaf]

Simple. You can put air/gas into a deflated balloon and it will inflate. If its already full (inflated) you can not put any more in without it bursting.

[v64paul]

i think the point is that they deflate as the gas is used, thus maintaining a constant mains gas pressure.

[muna]

I am not an expert on these matters but I have often wondered as to why the gasometers behave like that.On several occasions it was noticed that  they had water line marks,as if they had been submerged upside down in water( like when my school days we used to capture gasses in the lab).

in my opinion,this serves two purposes( I may be wrong)? 1. the gas is pumped below the water level and into the gas holder therefore it deosnt need eloberate sealing round the rims,and secondly, both the weight of the "bell" and pumped gas is  mentained at a constant  supply pressure without the gas holder bursting at the seams,Not forgetting that gases can be compressed but not liquids!

i will be most greatful if any of the gas "BODS" can enlighten me on this subject. 

.

[Skids]

Aparantly, they're called manometers.

[goofyone]

Oddly, manometer is for gauging man like a blood pressure gauge. 
    Anyway, gas is combustible so to be safe.

[nebodeuk]

Fantastic! Thanks to every one for your answers, what a great site this is, thank you all once again.

[peanut]

Just a guess here but i would have to say the reason for that would be to eliminate the buildup of fumes. If youre speaking of liquid (gasoline) that is.

[chakka35]

The real answer is that the gas-holder must always contain gas and nothing else. If the cylinder were fixed then air would have to be drawn in as gas was pumped out; otherwise there would be a vacuum which would either stop the pumps or suck in the sides of the holder.But gas and air form an explosive mixture.  Not a good idea.

[JudgeJ]

The bottom of these structures actually sit in a pond of water. As has been said, it is important to prevent anything else (especially air) from mixing with the gas and the water seal helps with this.

There is another type of of gasholder which does not appear to shrink and grow. These have a solid shell with a piston inside which accommodates the changing volume of gas as it is emptied or filled. A fine example of this type can be seen when leaving Victoria railway station.

[Jane Grove]

The most elaborate gasholder's in the UK were at the back of Kings Cross Station and are pictured here .

[Gef]

Sorry skids but they are called gasometers. A manometer is an instrument used to measure gas pressure.