Down here, we use LPG referred to as butane, up north it is called propane. I suspect that both are butane/propane mixes and the difference is the % of ea gas used, but cannot verify that. Butane boils at a higher temperature than propane:
Boiling Point butane = 30.2°F (-1°C)
Boiling Point propane-43.6°F (-42°C)
I do know I took a travel trailer to Ks. after filling the LPG tanks in S.Tx. @ around 60*. It was -3* in Wichita IIRC and my furnace wouldn't work because the S. Tx. "butane" remained in liquid state in the tanks. Once refilled tanks up north, no problem due to boiling point of the different gasses.
Quote:Butane vs Propane: Differences
Now that we have looked at the similarities, we will look at the differences in butane and propane. We will start off by looking at the properties of butane.
Although propane is more popular, butane continues to be used as a fuel source. It is used as a fuel in stoves, cigarette lighters and even in aerosol sprays as a propellant. Besides, butane is cheaper than propane, but comparatively, it is more difficult to use, so it is not very commonly available and not many gadgets, devices are designed to be used with butane as fuel source.
But you should know that butane is more efficient than propane when used as fuel. If same volume of butane and propane is burned at temperature above freezing, butane will end up providing 12% more energy than propane. Thus, butane can be the preferred choice when it is available in adequate amounts since it is energy-efficient and also has an advantage of cheaper price.
Unlike butane, propane is available more easily in small portable tanks and is used widely for heating houses. It is used as a fuel in gas barbeques, lanterns and camping stoves. Automobiles run on liquefied petroleum gas or LPG which is made by mixing propane with other fuels like butylene, propylene or butane.
When the fuel needs to be stored for a long time, propane is a better choice than butane. It stores well in variable weather conditions and even below freezing temperature will not affect the storage conditions of propane because of its propetries.
When people need to go camping, hiking or mountain climbing, especially in cold weather, propane is preferred over butane as a fuel for cooking. Since propane gas is odorless, leaks are harder to detect. For this reason, ethanethiol is mixed with propane so that leaks can be easily detected.
http://www.enkivillage.com/butane-vs-propane.html
Probably a lot more information than you wanted to know, but both are similar in that they boil at low temperatures and can increase pressure as the tank warms up. If the tank temp. increases sufficiently the relief valve can open and discharge flammable gas (which, by the way is heavier than air and can accumulate as explosive mixture in low places.)
Learned that the hard way trying to light a furnace that the main supply valve, unbeknown to me, had leaked through enough to form the explosive mix in the furnace. The resulting explosion was sufficient to blow the furnace vent cap about 30' in the air and resulted in 2nd degree burns on my hand. Needless to say, I have a great respect for butane or propane.
Regards,
hm