I have undertaken some major surgery on a hedge in the front garden on on what is the boundary of the property have found an old and rusting cast iron plate informing me that there is a gas siphon 2'6" away. But what exactly is a gas siphon and is it likely to be 2'6" into the road or into the pavement. At a guess it dates from around 1948.
A quick Google turns up lots of references to them but most of these are American devices for removing petrol from cars.
Might you be on an old US military establishment that's been developed?
It could be from a land fill site that needed the methane gas drawn off every so often. Or it could be near an old air field with underground fuel tanks.
If you had asked that question a week ago, I couldn't have answered it. Today, I can!
We have just had the gas main replaced in our road - the old cast iron pipe being replaced by plastic. My house is at the lowest point, with the road rising slightly in either direction. Opposite my house was a gas syphon. This turned out to be a metal bomb-like object immediately underneath, and connected to the gas main - designed to collect any condensation forming in the pipe. A small vertical pipe comes from near the bottom of this chamber up to ground level. Apparently the idea is that when a tap on the top of this pipe is opened, gas pressure forces any collected water out through the pipe.
This device has been removed, and not replaced when replacing metal pipe with plastic. The explanation given by the contractors is that you don't get condensation in plastic pipes. My suspicion is that you don't get condensation in natural gas - whereas you did in towns gas, which was still (just) in use when the original pipes were put in around 1965.
I didn't know that the syphon was there until a few days ago, and have never seen anyone accessing it in the 27 years I have lived in this house!
I think ours was done in the late 60s but can't remember exactly the year. Certainly before 1970.
At the time, I'm sure they were still storing gas in the old fashioned holders, which used water as a seal, but presumably there must have either been some dryers after these before the distribution or something like that......
After a domestic meter? I don't remember seeing one of those. What did they look like?
I suspect that they still do.
.andy
To email, substitute .nospam with .gl
Surely BEFORE the meter, you wouldn't want to such all the crap through the meter nor would you want to force compressed air through a meter the wrong way ?
Its a connection point on a gas main from which water,MEG and other liquid substances can be extracted by use of a compressor,commonly called an Alan Taylor unit (ATU) presumably after the inventor. Even on modern plastic systems,there is still water and other liquids in mains which needs periodic extraction. It varies from area to area. Some areas have nothing others have plenty,sometimes to the point of loss of supply due to the mains filling up!!
joe
The water seals were impregnated with oil. They did not make any difference to the gas. It was stored at low pressure and pumped to high pressure in many cases.
Yep.
All the internal pipe had to fall back to the meter, so water would be collected at the trap. The lead outlets was in a U shape from the meter horn. It then went to copper or iron. A tee was inserted to take feed the house. the downward side off the tee had a short piece and a plug on it. In many installations the plug was under the floor. During the 1963 freeze, the Gas Boards were working 24 hours to unfreeze the siphons and empty them.
Better seals are now fited.
You will find that if water is in the gas main, it came from inside the pipe via a poor seal or whatever. Yes, you are right, even in modern systems the low point will have a syphon to collect debris and an water collected.
You know when there is too much water in a pipe. The gas supply is on-off as the gas disturbs the water in the pipe.
So now we know what a "Gas Syphon" is, how about, What's a ratchet ?
Excrement from a rodent?
Yeah !!! Got it in one.
So where is it likely to be. It's not by the meter because that is much more than 2'6" from the front hedge. But there is nothing else nearby excpet for a sewer cover. At least I had always assumed that it was for the sewers, perhaps its not.
Well, a reasonable approach might be to take a tape measure, and measure out a circle 2'6" in radius. This might take a while, as it's a lot of walking. Then look carefully round the edge.
It's directly *under* the gas main, with just a 1" pipe coming to the surface. Maybe there's a little square cover (about 5" x 5") with "Gas" embossed on it?
Open it up and have a look...
When natural gas is brought ashore the last stage before feeding the gas into the grid at around 1000 pounds, is to fed it into a Dew Point Train. all the way down the train glycol (PEG) is sprayed into the flow. At the end it then goes through a propane chiller and the glycol and most off the water drops out. the gas then is fed to the grid at around 0 degrees.
Hence no condensation in the grid.
Just so you know..
The Q (ex Bacton Gas terminal)(for a short time before we got taken over and half of us got made redundant)
OOps ERROR!!! the Peg Above should be MEG (Mono Eth...) The Q
>
Is this propane chiller where the propane and butane drops out?
AJH
Nope it's a wacking great fridge which cools the gas flow, ( to roughly 0 degrees for Transco to accept) propane is the refrigerant, compressed by a Huge V8 each cylinder is over a foot across and that powers two compressing cylinders of around half a ton each!! Oh and there are four V8s of these in the one building if required. The compressor is powered by waste gasses drawn mostly off of the small amounts (comparatively) of hydrocarbon liquids that come ashore with the gas. The hydrocarbon gases are drawn off of the liquids so they can be made stable enough for transportation for processing.
I hope that's a good explanation above, I've just been on the home brew again..
The Q
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