Gallery, Projects and General > How do I??

Pumping gas

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Paul Barker:
Anyway Bates does mention an inflatable dinghy on top of the car, and this is not at all stupid. You could compress at much lower cost sufficient methane for a town car with say the range of a town electric car to a low pressure of perhaps 3 bar with a much cheaper compressor. Basically you just need a simple diaphragm gosvenor (which is all Bates' converter would be) to regulate the flow of gas when it can't get sufficient you are out of methane throw the petrol (which I think you across the pond call gas so this will get confusing) switch.

As far as anyone can see you have a boat which goes down a lot.

So what are the dangers?

The only risk you have with methane is that you must avoid it building up in an enclosed space to a ratio of 5 to 15% with air. More gas than that it will not explode, less gas it will not explode. It actually explodes at 12% every time ask anyone in the coal industry, they run tests all the time and it always explodes at 12% never anything different. I believe we in the gas industry are trained to the 5 to 15% knowledge so that we will be ever vigillant.

There is no poison it contains no carbon monoxide that is a product of incomplete combustion nowadays when we were on coal gas or town gas that did contain C0 which is why people used to put their head in a gas oven to kill themselves. If you did that today you would remain alive until a neighbour came in and switched on the light whence you would both be blown to smitherines. You could put your mouth over a gas supply pipe and breathe it in, you would lack oxygen but nothing in the gas (which is vertually neat methane with a little ethane butane and propane mixed in to ensure consistent calorific value).

So as long as your plant is outisde, zero risk.

We are not worried in the industry  in the slightest whatsoever about gas leaks outside. Methane oozes out of the cast iron mains all over this country.

Inside a dwelling gas is a very serious issue, there is never a minor outcome every so often there is a picture in the paper of a pile of rubble where a house used to be, allow methane to achieve combustible ratio, provide ignition (electrical switch) and it will take the whole house out without question. In the atmosphere it is impossible for it to explode. It might light and burn off but it won't explode.

The issue of monitoring your flow of gas from your supply is a big issue. There are many gas appliances without flame supervision, which in your property or your neighbours would become a bomb if you don't ensure sufficient gas is available to them inspight of what you are doing.

Bernd:
Spin,

Think of taking atmosphereic pressure of 14.5 psi up to 3000 psi. The larger the tank your pumping it in the longer it will take. The last piston that gives you the 3000 psi is very small. If I remember right it's about 5." to 1" in dia. Not much volume there only pressure. The pump needs to be saveral stages to get to that high pressure.

It's kind of tough to get your mind wraped around that. If I see the guy that does the diving I'll ask him about his pump and how long it takes.

One other consideration here when squeezing a gas into a more compack container is the heat generated. Get it hot enough and the gas could explode.

Bernd

Darren:
If I understand what you are saying it goes something like this.

1st pump moves a large volume at a relatively low pressure. 2nd pump has a smaller piston moving a smaller amount of gas but at a higher pressure. 3rd pump smaller piston and more pressure.

But all 3 pumps could run from the same power source thereby not having to increase the power required at each stage?

Bernd:
Darren,

Yes close. The pump is as one unit containing 3 or 4 pistons. The first cylinder would take a certain volume compress it into the next cylinder at a higher pressure and so on. Think of a triple expansion steam engine operating backwards. By that I mean take the steam after it has exited the exhust. Now take that steam and send it back through going from the largest cylinder back to the smallest. You'll, theoretically though, end up with the steam pressure that started out in the boiler. I used that example to see if you can grasp what I'm trying to explain.

I tred a Google search. To much info to look through. See if you can find something on high pressure pumps or cng pumps.

Bernd

Paul Barker:
it did occur to me that you could buy two 150 psi compressors and series them, but the components are only designed to withstand 150 psi.

I wonder what the multiplication factor is? If the first compressor liftes pressure by 150 times does the second lift 150 psi X 150? Absolutely not, surely not.

is it essential for the second compressor to be smaller? If you ran the pair off gearing you could simply half the speed of the second one to produce the same effect?

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