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[tunnie]

I understand most of the LPG install, what does what, and how most of it works. One thing still confuses me (not hard  )

The LPG comes from the tank, in liquid form, heads to the vaporisor, which uses hot water from the cooling system to turn the LPG into vapor so it can be injected into the pots.

How does the vaporisor do this? Even at full temp (85 degrees) i would have thought it would be difficult to turn the liquid into vapour? So how can it do it from as little as 25 degrees? Also why does it get cold, and not hot?  :-/

[hotel21]

Why does a butane lighter have liquid LPG in it but comes out as a gas?

[hotel21]

The boiling point of LPG is much much lower than water, even when its under pressure....

[tunnie]

Why does a butane lighter have liquid LPG in it but comes out as a gas?

But that has a spark to ignite it, with the straw to feed once lit....

[tunnie]

The boiling point of LPG is much much lower than water, even when its under pressure....

That makes sense, was struggling to see how 20 degrees can vaporise a liquid 

[hotel21]

Why does a butane lighter have liquid LPG in it but comes out as a gas?

But that has a spark to ignite it, with the straw to feed once lit....

butane, not petrol.  It emerges as a gas, not a liquid...

[tunnie]

Why does a butane lighter have liquid LPG in it but comes out as a gas?

But that has a spark to ignite it, with the straw to feed once lit....

butane, not petrol.  It emerges as a gas, not a liquid...

Talking about standard ciggy lighters? Is that because its compressed before emerging?

[Kevin Wood]

Boiling point of propane is -42 Degrees C at atmospheric pressure. It only stays liquid because it's under 7 or 8 BAR of pressure. Drop the pressure to 1 bar in the vapouriser and it boils pretty quickly.

However, it still absorbs heat energy whil boiling due to its' latent heat of vapourisation so if the vapouriser were not heated it would steadily cool until it was no longer able to boil the liquid.

It needs about a kilowatt of heat energy to boil enough LPG to run the engine during motorway cruising.

Next time you're at a market (or wherever), especially this time of year, have a look round the back of the burger van and you'll see a layer of frost on the propane cylinder if they're using gas at a reasonable rate.

The gas in the cylinder is boiling off as they draw vapour out of the top and it has to cool down to absorb heat. This causes water vapour to condense and eventually freeze on the cylinder.

Butane gas boils at a much higher temperature (only just below freezing point IIRC) which makes it ideal for camping in the summer but no use outside in winter because it doesn't boil off in the cylinder. It's often mixed with Propane to improve its' performance. Or the cylinder is placed on a burner of the stove for a while to liven it up.

Kevin

[tunnie]

Boiling point of propane is -42 Degrees C at atmospheric pressure. It only stays liquid because it's under 7 or 8 BAR of pressure. Drop the pressure to 1 bar in the vapouriser and it boils pretty quickly.

However, it still absorbs heat energy whil boiling due to its' latent heat of vapourisation so if the vapouriser were not heated it would steadily cool until it was no longer able to boil the liquid.

It needs about a kilowatt of heat energy to boil enough LPG to run the engine during motorway cruising.

Next time you're at a market (or wherever), especially this time of year, have a look round the back of the burger van and you'll see a layer of frost on the propane cylinder if they're using gas at a reasonable rate.

The gas in the cylinder is boiling off as they draw vapour out of the top and it has to cool down to absorb heat. This causes water vapour to condense and eventually freeze on the cylinder.

Butane gas boils at a much higher temperature (only just below freezing point IIRC) which makes it ideal for camping in the summer but no use outside in winter because it doesn't boil off in the cylinder. It's often mixed with Propane to improve its' performance. Or the cylinder is placed on a burner of the stove for a while to liven it up.

Kevin

Thanks Kev, it all becomes clear   

[davethediver]

Boiling point of propane is -42 Degrees C at atmospheric pressure. It only stays liquid because it's under 7 or 8 BAR of pressure. Drop the pressure to 1 bar in the vapouriser and it boils pretty quickly.

However, it still absorbs heat energy whil boiling due to its' latent heat of vapourisation so if the vapouriser were not heated it would steadily cool until it was no longer able to boil the liquid.

It needs about a kilowatt of heat energy to boil enough LPG to run the engine during motorway cruising.

Next time you're at a market (or wherever), especially this time of year, have a look round the back of the burger van and you'll see a layer of frost on the propane cylinder if they're using gas at a reasonable rate.

The gas in the cylinder is boiling off as they draw vapour out of the top and it has to cool down to absorb heat. This causes water vapour to condense and eventually freeze on the cylinder.

Butane gas boils at a much higher temperature (only just below freezing point IIRC) which makes it ideal for camping in the summer but no use outside in winter because it doesn't boil off in the cylinder. It's often mixed with Propane to improve its' performance. Or the cylinder is placed on a burner of the stove for a while to liven it up.

Kevin

Thanks Kev, it all becomes clear   

And there was me thinking after schooling i could forget all that, just goes to show you never know when it comes in usefull. Very interesting read and does make more sense now, nice one Kev

[mathewst]

Tunnie if you want to see live experiment, take a gas lighter and open it
Afterwards you wont need any more explanations