Oh great, an intermittent flame-thrower ;-)
Petrol vapour's explosive, petrol itself isn't, hollywood-style explosions don't really happen.
What protection has an LPG system got against a leak in the system, is there a rate-limiting valve on the tank's output feed? Can a leak at the wrong point make it vent the whole fuel load as explosive vapour?
In message , Derek writes
FLTs normally run on vapour take off - valve on the top.
One at work is liquid feed to a vapouriser, same as a car system. Badger.
Seems like an awful lot of messing about to try and stop the thing toasting the occupants, and you have to hope it's been fitted properly with a lot of high-pressure gas-tight joints needed....
Not much brake fluid in a car and it's under low pressure unless the brakes are on, loads of LPG under high pressure all the time though.
There just seems to be way too many danger signals with LPG systems to make it worth the hassle and savings.
No you are incorrect generally although the valve is at the top the feed pipe draws from the bottom and to one side ( turn the bottle over and you will see the arrow) a vapour feed drawing from the top is unable to supply sufficient fuel without icing which is why vapourisers are used on flts which are heated by the engine. In the case where somebody fits the bottle incorrectly you will see ice forming on the pipe and bottle. For less demanding applications a regulator is fitted at the valve ( lighting ,pikey heating systems) though these are frowned on the LPG bods don't like the idea of 7bar cylinders being used domestically and which are marked liquid take off . Part of the ADR course and forklift courses. Derek
Er, no -42C for propane. Butane is -0.5C under "normal" temp and pressure.
Derek uttered summat worrerz funny about:
This thread is a pisser :-)
Lee D
er yeah, after engaging brain. Doesn't altering the pressure instead of the temperature, as normally happens, make things so much harder to think through straight.
But will a cylinder be able to get enough energy from its surroundings to maintain the required vapour flow? It doesn't take much draw off of vapour for a healthy layer of frost to form on a normal cylinder. I have a feeling that the draw off for an engine is quite high.
20mpg about 5m/litre. At 60mph means evaporating a litre of LPG every 5 mins... at 30mph every 10mins thats a significant energy requirement.
So why do they make the tanks so hefty and then insist on sticking a plastic multivalve onto them!
So to transfer fuel from one car to the other without a pump i would need to park the full one at the top of the garden in the sun, empty one at the bottom in the shade, link em together then wait? :)
I think i may have hijacked it somewhat with talk of lpg transfers ;)
The flammable limits in air of LPG are significantly less than those of petrol. Several years as a career fireman taught me that LPG is nice and safe in vehicles - numerous calls to LPG vehicles in accidents and fires never gave me cause for concern.
How about Diesel? I have two diesels and one petrol, I don't intend to LPG the petrol one what with the costs and the low mileage, but have you seen much in the way of problems with diesel in crashes?
Hmmm.... dunno what cheap crud you've been looking at Tom, all the multivalves I've ever fitted or seen have been made of brass....... The vapour-box that fits around the multivalve tends to be of a plastic form however, is that what you mean? Badger.
I've seen Diesel cause lots of crashes.
Either on the road or on the drivers shoe and a wet brake pedal.
Lee D
I was thinking more along the lines of it catching fire after a crash to be honest... Dog shit can be dangerous too if looked at in that light, and I'll bet bikers hate horse shit ;-)
Why don't you go and read up a bit on the design of LPG systems for use on vehicles.
Yes and no are the answers to your two questions.
Well if you are comparing fuels you have to look at the whole risk spectrum - and the likelihood that spilt diesel in an accident will cause a 40 ton truck to smash into you is every bit as relevant as fire risk.
On or around Mon, 17 Sep 2007 20:40:12 +0100, hugh enlightened us thusly:
diesel has a much lower flammable-vapour risk (to the extent that if you toss a match into cold diesel it goes out). I believe it contains more specific energy though, and it can make flammable vapour if heated, for example by contact with a hot exhaust.
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