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I don't understand LPG!

2K views 7 replies 7 participants last post by  Beefchief 
#1 ·
Sorry if this is a stupid question but I'm serious...

Me and my mate were discussing how stupid the name 'LPG' is, and i haven't got an awnser explaining why. It doesn't make sense. You have liquid, solid or gas. It can only be one. Although apparentely its a liquid gas, it's either a gas or a liquid. It can't be a liquid gas! LOL?? Anyone?
 
#2 ·
although i am not a chemist, i think you cannot categorise LPG as either a gas or liquid.. Due to LPG being a mix of butane and propane, it takes on special properties and characteristics that make it unique in the fact that it it can change between gas and liquid states when subjected to modest pressure or cooling
 
#3 ·
Hmm, digging up lost brain cells, I'm sure that LPG stands for 'Liquified Petroleum Gas'.

Like you, I really don't know how they came up with that, but for a guess I think it has something to do with the pressure & temperature involved.

All cylinders as far as I know, untill they have had the liquid component expelled will always contain a quantity of both liquid and gaseous LPG.

These ratios are dependant on the ambient temperature outside, and if it increases above the designed amount and when a cylinder is full to overfull, the pressure relief valve will vent the gas (and sometimes the liquid) to maintain the designed pressure.

When the temperature is reduced, the cylinder then will contain more liquid than gas.

Dunno if this helps you, but I'm having a bit of a blurb, so maybe someone more knowledgeable can help!!

Ed :)
 
#4 ·
Propane has a high pressure whereas Butane has a low pressure and is basically the crap that they mix in so they can burn it off.
Depending where they supply the gas from, PRA in Melbourne, Shell in Geelong or Long Island point at Hastings the finished product can have different pressures when loaded into a gas tanker.

In simple terms LPG is a gas (liquid petroleum gas) however, when compressed you can transform it into a liquid, hence the ease of transporting it. 40000 litres in a tanker in liquid form compared to say 2000 litres of gas vapour.

LPG stays a liquid until it reaches the engines internals.
As a liquid it has an expansion rate of 273 to 1, so one litre of liquid (LPG) will expand into 273 cubic litres of (LPG) vapour.
As a liquid, LPG is too rich to burn so it is quite safe to transport in bulk.

I’ve tried to keep this fairly brief, however, there is a lot to the story of how (LPG) is made, transported and stored, and the long version would only bore the crap out of everyone.

In summery, gases can be compressed to make liquids.

I nearly forgot to mention that I used to drive a gas tanker, otherwise I wouldn’t bother remembering all this useless info.

Cheers, Danny
 
#6 ·
T_Terror said:
Its a Petroleum Gas that has been compressed into liquid form for ease of transportation and storage.

Hence the name Liquefied (turned into liquid) Petroleum Gas
Spot on. Its not a liquid, its liquified. A fine distinction but an important one none the less.

The term 'LPG' has nothing to do with its mix, the only change when they make the butane/propane mix it's labeled as 'Auto LPG' where as pure propane is simply 'LPG'.

Hope this helps.
 
#8 ·
This may be a bit redundant, but here's a bit of info:

LPG is the generic name for commercial propane and commercial butane. There are hydrocarbon products produced by the oil and gas industries. Commercial Propane predominantly consists of hydrocarbons containing three carbon atoms, mainly propane (C3H8).

Commercial Butane predominantly consists of hydrocarbons containing four carbon atoms, mainly n- and iso - butanes (C4H10).

They have the special property of becoming liquid at atmospheric temperature if moderately compressed and reverting to gases when the pressure is sufficiently reduced. Advantage is take of this property to transport and store these products in the liquid state, in which they are roughly 250 times as dense as they are when gases.

Butane is usually supplied to customers in cylinders, propane can be supplied in cylinders or in bulk for storage in tanks at the customers premises.

Source: http://www.lpga.co.uk/LPGA.htm
 
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