We are told by the CFA that gas cylinders are safe and can't explode in bushfires. Have a look at this Video from Russia where many drivers have dash cams as an aid to proving fault/innocence in traffics situations and accidents. Are our gas cylinders made differently here in Australia?
Any gas, or liquid when heated far beyond its boiling point (-42C for LPG) in a sealed container can expand to a point where the container will rupture.
LP gas cylinders incorporate a pressure relief valve that is designed to allow excess pressure to escape to prevent rupture, but things can go wrong.
LPG is stored as a liquid and, when heated sufficiently, can readily rupture the cylinder if the relief valve either fails or can't release sufficient pressure in a timely fashion, this is called a Boiling Liquid Expanding Vapour Explosion, or BLEVE for short.
Even tap water heated in a sealed container can cause a BLEVE. There have been numerous incidents where normal hot water tanks have exploded violently due to the failure of the PT valve.
I would expect that if a bush fire can melt magnesium wheel rims which have a melting range between 400 and 600C, it can certainly provide enough heat to weaken the tank and to boil the LP in the cylinder, and then all you need is a stuck valve.
It is generally recognised that the steel cylinder will begin to weaken at 300C and will lose integrity at 450C whereupon the tank will rupture if the internal pressure is greater than atmospheric.
The pressure relief valve (PRV) is normally set at 1.93Mpa, therefore having a tank made from steel that can withstand that pressure is an advantage but it will still fail if the PRV remains closed.
As an aside, the bottles in that video appear to be Acetylene or similar industrial gases, not LPGs, and I would suggest that it all began with a valve or two being knocked off in the accident, a spark then igniting the escaping gas, leaking fuel from the truck would have fed the fire and the resultant heat then caused the later BLEVEs.
LPG bottles are safe and except in abnormal circumstances eg extreme heat and in this scenario you will be nowhere near the bottle anyway.
Cheers
David
Commercial carriers such as delivery people are prohibited from carrying above about 2Kg of LPG etc. (memory of DG rules have faded)within an enclosed vehicle. Yet people will quite happily throw a 9kg tank for the barbie in an enclosed and virtually leak proof boot.
Commercial carriers such as delivery people are prohibited from carrying above about 2Kg of LPG etc. (memory of DG rules have faded)within an enclosed vehicle. Yet people will quite happily throw a 9kg tank for the barbie in an enclosed and virtually leak proof boot.
If something goes wrong?
Mike.
I think that you will find the limit is 13.5Kg, must be carried with the relief valve to the top, and must have a bung in the outlet.
When my house burnt down in FNQ the 45kg gas bottles became flame throwers when the pressure relief valves did what they are meant to do, but the bottles did not lose their integrity. Also, I have driven LPG powered cars for many years and still firmly believe the LPG tank is safer than a tank full of petrol fumes. But really, by the time you need to worry about the integrity of your LPG tank you almost certainly have far bigger problems to worry about. And as to leaking gas, our LPG has added scent so that it is easy to detect. Take reasonable safety precautions and then forget about it. Most people die in bed
__________________
Cheers, Marianna.
The more I learn about people, the more I like my dogs (Mark Twain)
Plenty of cars have been burnt out but the bottles are intact .Way back in Vic I was a volunteer plumber at the Macedon fires and burnt out houses were evident but not a buggered bottle was seen . Mind you bounce one off a speeding truck and break the valve off and its not a happy camper !
__________________
Westy. Some people I know are like slinkies. They look really funny when you push them downstairs !
