gas conversion ?

hehe :)

I meant hugh! ;) I know what youve got! :p spotted it parked up outside your offices the other day i think.

will send my mate on a mission to find it. if i tell him its cheaper than GT it wont take him long to find! ;)

Bingo!

You need to tip the bottle upside down to get the Liquid LPG to come out first in to your tank, though once the pressure equalises then your stuffed and as you say you end up with two semi full tanks. This is where the pump comes in to pump the gas in to the receiving tank out of the other.

I'm sure someone will pop up with a theoretical correction in a mo but thats how I understand it in simple terms. There was a web site of a guy in USA who carried a 4.5kg type bottle to refill if he ran out... dammed if I can find it now. Sort of like having a spare gallon of petrol.

Lee D

thats exaclty what i want to do now that my car is LPG only.. a 4.5kg bottle would be ideal infact! wonder why you can just get a 12v pump to transfer it?

Though i notice that you can get 10L and 20L normal LPG tanks. Might be just as easy to get one of them. Wonder if i can get away without an expensive multivalve thingy on a small tank? a 10 L tank would hold 8L of gas i guess which in the car would give me a 25-30 mile reserve.

I just moved the exhaust in my car and got rid of some silencers. wonder if i can fit an lpg tank in the new space? :)

ouch!!!

-- "For those who are missing Blair - aim more carefully."

To reply direct rot13 me

bURRt the 101 Camper

my lambda probe was playing up. Just managed to fix it again (the traditional leaving it unplugged all day did the job!). I was almost dissapointed i didnt manage 1km/litre... It was running at about 10:1 to get 5.3... its back at 14.5/15:1 now

Once vapourised it's a gas not a liquid. Roughly the liquid takes up

Slightly. Liquid propane is stored under about 7 bar (100psi), butane 2 bar (30psi) at 15C ambient temp.

Yes.

The pressure is there to keep the "gas" a liquid at ambient temp and will be pretty much the same in both cylinders. Thus there would only be little transfer of *gas* to equalise the pressures. I don't know enough about automotive systems but words such as "vapouriser" associated with "freezing" indicate that liquid gas is drawn off from the storage and fed to the vapouriser that provides the energy (waste engine heat?) to boil that liquid into gas.

In an ordinary propane cylinder the vaporisation occurs in the cylinder(*1) and high pressure gas is drawn off the top into the pressure regulator before being fed to the appliance at about 28mBar.

This means an ordinary cyclinder would have to be used inverted to draw off the liquid. I can't see any (technical *2) reason why a manual change over valve could not be fitted into the liquid feed to the vapouriser to switch between the vechical storage and a "reserve" from an ordinary, inverted, cylinder.

(*1) Which is why propane cylinders when get covered in frost when there is a significant draw off of gas. The latent heat of vapouristation is being taken from the enviroment.

(*2) There maybe legal issues with road fuel duty and the plumbing of ordinary LPG cylinders into the car systems (Venting of leaks, crash resistance etc).

thx for the effort. preciate it.

Sorry ZoNeHeaD, I've hunted high and low for the pictures but simply can't find them. I know they were on a CD but we've recently moved house and there's lots of stuff I can't find :-( I think SWMBO had a "sort out" before we moved ...

All the various parts were sourced from the Internet so a few Google searches should find what you're looking for.

On or around Sat, 15 Sep 2007 23:11:51 +0100, Tom Woods enlightened us thusly:

at normal temperatures, in a sealed tank, it exists at something around 7 bar pressure, with liquid gas at the bottom and saturated vapour at the top, plus any other gas (e.g. air) which hasn't got itself purged from the tank also at about 7 bar.

Given that your supply tank is higher than the liquid level in the receiving tank, it will (eventually) flow there of it's own accord. It'd do that better if it had a vapour return line from the top of the receiving tank to the supply tank, but that's uncommon on automotive systems these days.

If the sun's been shining, some gas will flow by itself into the (shaded) one on the vehicle, here. but not much and to get it "full" (i.e. to 80% liquid level) you have to pump the liquid in.

Yeah, and if a small leak develops in the fuel system, your whole fuel load comes out as explosive vapour, no thanks! I'm nervous enough with petrol, let alone a pressurised gas bomb.

Maybe not the ones we use on the forklifts have a liquid take off from the bottom edge so they can be stood up or on the side ( they have an arrow to say which side).

Derek

Whereas diesel is pretty hard to light, even with a match. There are some pix around somewhere of a Rangie that went on fire after a crash and the tank went up. There wasn't a lot of it left. I know the LPG fans will say how safe the tanks are. It's a bit like flying. It's 100% safe 99% of the time, but when things go wrong, it's curtains. I'll stick to diesel, TYVM.

Not really Nige, the wall thickness of a gas tank is designed to take a 20g impact (if memory serves me right) without damage. Those tanks are thick stuff, ever tried picking an empty one up? You'll see what I mean! (useful for chucking at unfriendly campers.... ;-) ) A larger impact may dent or distort it, but that's an awful lot safer than a paper-thin sheet steel petrol tank that simply splits wide open on impact spewing highly flammable liquid and explosive vapour out uncontrollably! Also, most gas tanks tend to be installed in places that won't get hit in an initial impact (with the exception of sill tanks on landies, of course, but even at that most impacts tend to be frontal or corner, not pure side-on). IF an over-pressure situation occurs (say, in the heat of a fire caused by a petrol tank splitting open in a crash) then the gas tank, if properly installed, will vent gas out in a controlled manner. Yes, this fuels the fire and makes it worse, but it's better than another kaboom! Badger.

Pump as in transfer, rather than up the pressure to 7 bar to get it in. Both tanks are more or less at the same pressure so you just need to have a pump able to transfer the liquid at a static pressure of 7 bar. It may have to cope with the increase in pressure of the recipient tank as it fills unless there is some means of releasing the vapour back to the sending tank or venting it (not good...).

IIRC in the UK LPG used for automotive propulsion must be permanently fixed to the vehicle's structure.

Having said that there's no need to turn it upside down, vapour will pass straight through.

Propane boils at -20C. To keep it liquefied it is stored under pressure

- hence the big heavy steel tanks. It's the pressure in the tank that pushes the LPG along the pipe to the vaporiser/regulator without the need for a pump.

Not as big as a petrol tank.

The tanks have excess pressure relief valves so in a fire the gas is vented in bursts.

The tanks themselves are subject to impact tests including testing to destruction in order to gain standards approval.

That's why in a correctly installed system all pipes in the vehicle e.g. the boot are surrounded and vented to the outside.

If you are worried about fires in your car then start with the brake fluid which I believe is the commonest cause of vehicle fires.

The vapour recondenses in the recipient tank as the pressure increases thus restoring the equilibrium.