Liquid fuel tank pressurised with compressed air?

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vhautaka
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Liquid fuel tank pressurised with compressed air?

Post by vhautaka » Wed Jan 21, 2004 11:53 pm

Hi again,

I know liquid fuels can be safely pressurised (given appropriate vessels / plumbing) with CO2 or nitrogen.

Would it be safe to pressurise a gasoline / diesel fuel tank with regular air compressor, or will it explode? (i.e. is compressed air in a fuel tank somehow more dangerous than ambient pressure air?)

Or, I could use a water pressure tank with a rubber bladder. These are as easy to pressurise as car tires, I only wonder if the bladder or some o-rings would melt with hydrocarbon fuel.

Fuel pumps just feel too complicated for a valveless machine that could've been invented by any alchemist who ever burned his face while distilling on an open flame. But the only middle ages pressure delivery method, boiling fuel in a closed vessel, doesn't attract me either. :)

Just asking, I think somebody must have thought of these, or used them if they're usable.

This would be just too easy?


- ville

Viv
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Post by Viv » Thu Jan 22, 2004 12:16 am

This has got to be my faverite pet hate subject, and I bite every time too:-(

No its a really bad idea and you are going to die horribly if you try it! there are just too many ways for it go wrong and they all involve a lot of highly combustible fuel being sprayed every were, probably over you too, sorry;-)

The failure mode just cant be made safe, and this is normally were somebody suggests a method that doesn't sound to dangerous as it just frys you gently instead of blowing you in to small bits and spreading them across the continent, but this time I would like to avoid that helpful suggestion if we can:-) ok;-)

A high pressure pump from a car is complex yes but a pressure switch in the high side of the circuit set to turn the pump off if the pressure fails when a pipe breaks is a lot safer than a few gallons of fuel in a pressurized tank, remember you will need to get it to latch up to run though.

And no you don't want to use air as the pressurizing gas as thats the other thing the fuel needs to ignite, and you really don't want to squeeze it in to a confined space with all that fuel:-)

Viv
PS rant over, we do need to get a FAQ written up some time!
"Sometimes the lies you tell are less frightening than the loneliness you might feel if you stopped telling them" Brock Clarke

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vhautaka
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Post by vhautaka » Thu Jan 22, 2004 10:24 am

Okay... the squeezing of air in with that fuel is what I was not sure of / what seemed the most suspicious.

I'm not worried about spraying, at least not any more than with propane. Any liquid gas is pretty dangerous in the way of freezing and peeling off human skin/eyes/whatever at the same time it turns into a cloud of flammable, toxic vapor.

The plumbing just needs to be made such that these things will not happen, no matter what fuel is used.

But, about the water pressure tanks? I'd think they would be safer than those plasmabag-inna-plastic-bottle tanks they use for RC jetplanes?

For one, they can be depressurised with a flick of a valve, and will not spray out anything but air. They're also as lightweight as any barbecue gas cylinder, if not lighter.

To find out about those rubber bladders and other suspicious parts, guess I could just fill one of those old tanks with some diesel and leave it there for a couple of weeks to see if the rubber turns into crap...


- ville

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