Freezing gas

[Big Steve]

That's the question, is gas freezing in cold weather a problem? If it is what can you do to stop it, if anything.

[denboy]

Haven`t had any problems in 9 years

[Pretty Funked Up]

I've not had a problem with it. (its compressed its always freezing) hehe

 

Does anyone know why, although always 'freezing', condensation doesnt form on the gas pipes yet it will on any other cold surface?

[twocvbloke]

That's the question, is gas freezing in cold weather a problem? If it is what can you do to stop it, if anything.

 

Use a Propane/Butane mix, Propane freezes at a much lower temperature than Butane, and the Butane provides a better flame, or something like that...

[OptedOut]

It' the boiling point you need to worry about.

 

Butane = -5 degrees C. Propane = -42 degrees C.

 

Butane may still work at minus 4 degrees C, propane will work to minus 40 degrees C.

 

Freezing points, propane = - 187, butane= -138.

 

Does anyone know why, although always 'freezing', condensation doesnt form on the gas pipes yet it will on any other cold surface?

 

It will depend on the humidity and dew point.

Edited November 29, 2008 by OptedOut

[Malarky]

The canal water temperature should stop the bottles freezing, Usually giving them a shake will break any icing on the surface of the gas in the bottle, unless it is nearly empty, where I'm guessing there is a higher perfume content sunk to the bottom, that reduces the freeing point slightly, as the hob sometimes smells of gas more just before it runs out. In extreme cold weather I suppose a hot water bottle chucked in the locker with the bottle would help squeeze the last two or three kettle boils out of it.

Once, when camping up in the moors of Derbyshire in realy cold weather I had the gas bottle sitting on a basting tray with a night light under it! There's no way it can get that cold so near to canal water though. I wouldn't recommend trying any such tricks in a boat, there is no escape for the gas to fall out, and something else could be causing the problem anyway.

[OptedOut]

The gas never freezes in the UK.

[twocvbloke]

The gas never freezes in the UK.

 

Neither do the prices...

[Malarky]

The gas never freezes in the UK.

I haven't had any problems of this nature in boats, so best check for faults if you do. But out of the water, in vehicles, I assure you I have!

[Gibbo]

Freezing points, propane = - 187, butane= -138.

 

But that's at atmospheric pressure. Doesn't it increase under pressure (which it is under in the bottle)?

 

Gibbo

[OptedOut]

Neither do the prices...

 

My autogas just went down to 50p litre in S.Wales, down to 40p litre in Wolves.

 

Makes it worth thinking about a refillable bottle for the boat. (5% less again).

 

But that's at atmospheric pressure. Doesn't it increase under pressure (which it is under in the bottle)?

 

Gibbo

 

I have not fully researched it yet but I know that when it's cold enough to prevent the gas vapourising it is below it's BOILING point.

 

http://encyclopedia.airliquide.com/Encyclo...=53#GeneralData

 

http://encyclopedia.airliquide.com/Encyclopedia.asp?GasID=8

 

Edit: As can be seen from the graphs the gas has no pressure when below it,s boiling point.

Edited November 30, 2008 by OptedOut

[Pretty Funked Up]

on occasional use i doubt it can ever be an issue, heavy/prolonged use possibly could do it. The more you draw then colder the bottle gets.

 

Condensation question was about my gas pipes inside the cabin, theyre noramlly the coldest thing in here but condensation forms on the metal (hull) that shows or windows. Something i havent managed to figure out yet.

[OptedOut]

Condensation question was about my gas pipes inside the cabin, theyre noramlly the coldest thing in here but condensation forms on the metal (hull) that shows or windows. Something i havent managed to figure out yet.

 

I would guess the gas pipework is above the dew point temp, the hull may be a lot colder at canal water temp and windows are good conductors of heat/cold from the hull/atmosphere.

 

http://en.wikipedia.org/wiki/Dew_point

 

Edit; The gas pipe may "feel" colder due to specific heat and thermal conductivity issues.

Edited November 30, 2008 by OptedOut

[Malarky]

But that's at atmospheric pressure. Doesn't it increase under pressure (which it is under in the bottle)?

 

Gibbo

 

Based on the workings of a pressure cooker, I think this must be so, as I reckon that I could hear ice knocking on the side of the bottle when shaken.

 

As for the gas pipe; is it not just conducting heat from warmer parts of the boat, and thus being warmer than its immediate surroundings?

[bottle]

SNIP>>>>>>>>>>>>

 

Makes it worth thinking about a refillable bottle for the boat. (5% less again).

 

<<<<<<<<<<<<<<<<<<<<<<<<SNIP

 

I don't think so.

 

http://www.boatsafetyscheme.com/downloads/...snostopfill.pdf

[David Schweizer]

Butane Gas (Blue Bottles) can, and will, freeze in this country. Wheras Propane Gas (orange/red) will not unless it gets as cold as Siberia.

 

It will take a prolonged period of sub zero weather for Butane Gas to freeze in the bottle, but the pressure regulatior will freeze up overnight. I can remember many a (happy?) time on the boat in the 1960's taking five minutes turns to hold our hands round the regulator in the morning to unfreeze it before we could make a cup of tea.

Edited November 30, 2008 by David Schweizer

[Gibbo]

My autogas just went down to 50p litre in S.Wales, down to 40p litre in Wolves.

 

Makes it worth thinking about a refillable bottle for the boat. (5% less again).

 

 

 

I have not fully researched it yet but I know that when it's cold enough to prevent the gas vapourising it is below it's BOILING point.

 

http://encyclopedia.airliquide.com/Encyclo...=53#GeneralData

 

http://encyclopedia.airliquide.com/Encyclopedia.asp?GasID=8

 

Edit: As can be seen from the graphs the gas has no pressure when below it,s boiling point.

 

Aye, but, surely, as it is in a sealed bottle, it IS under pressure. That's why it's liquid and not gas: because it's boiling point has been raised by the pressure.

 

So it's freezing point will raise as a result of the pressure. So it might freeze in UK weather.......

 

But then when it freezes, there's no pressure, so it's freezing point reduces, so it melts............. eh?

 

I'm just thinking out loud here.

 

I presume it finds an equilibrium with a higher freezing point than at atmospheric pressure?

 

Also, when it comes out of the bottle and goes through the pressure reducing valve it will cool substantially due to the huge expansion.

 

Gibbo

[John Orentas]

I don't think so.

 

http://www.boatsafetyscheme.com/downloads/...snostopfill.pdf

 

 

As usual in such matters the BSS have grossly over-reacted, probably through ignorance, if a system can be devised for safely using the equipment on motor-homes why should if not be applied to boats with equivalent safety regulation.

 

The point is why? Motor-homes have particular problems with weight, so aluminium gas bottles may well be a real advantage, but for use on boats I can't see the point of changing to a much more expensive system

 

For the reasons already expressed it is important in our climate to use only propane.

[ChrisPy]

as any mountaineer (not me!) will know, standard Camping Gaz stoves that use butane or butane/propane mix do not work in cold conditions because the gas freezes as it expands on leaving the container.

 

I found this out when using camping gaz containers to fire the boiler of a model steam engine. Even in average conditions the piping froze up below the valve because of the small diameter of the pipe compared with the huge demand of the blowlamp. I wrapped the steam exhaust round the valve piping to ensure pre-heat, and cured it immediately.

 

 

The freezing is the result of a combination of cold gas, cold ambient temperatures and high flow (such that the surrounding piping cannot replace the heat that is lost as the gas expands).

 

(For this reason you can buy camping stoves and containers that use 100% propane).

[Pretty Funked Up]

The refillable bottle i am looking at has an 80% safety valve and should be fine for the safety cert.

 

Is anyone using blue bottles on their boat?

Edited November 30, 2008 by Pretty Funked Up

[Boatgypsy]

LPG will not "freeze" in the normal range of temperatures in this country. What will happen is that Butane (the stuff in blue bottles) will not vapourise properly. Propane (in the red bottles) will vapourise perfectly in very low temperatures - about -40. Even LPG will not burn while it is still a liquid, it has to form a vapour so that it can mix in the right ratio with air.

 

You might think that freezing is happening because you see ice forming on the outside of the bottle. It is not. This is what happens when you vapourise a liquid into a gas. Energy is drawn from the surrounding environment, which creates low temperatures on the skin of the bottle. This then causes water from the air to freeze on the bottle, assuming the air temperature is already low. This is exactly the same as what happens in a refrigerator.

 

Also, small camping style cookers can be prone to ice developing in the gas jet because unless it is designed with a preheated vapourisation tube, the vapourisation takes place at the jet, making the jet very cold and thus freezing water from the air. This is exacerbated by altitude.

[David Schweizer]

LPG will not "freeze" in the normal range of temperatures in this country. What will happen is that Butane (the stuff in blue bottles) will not vapourise properly. Propane (in the red bottles) will vapourise perfectly in very low temperatures - about -40. Even LPG will not burn while it is still a liquid, it has to form a vapour so that it can mix in the right ratio with air.

 

You might think that freezing is happening because you see ice forming on the outside of the bottle. It is not. This is what happens when you vapourise a liquid into a gas. Energy is drawn from the surrounding environment, which creates low temperatures on the skin of the bottle. This then causes water from the air to freeze on the bottle, assuming the air temperature is already low. This is exactly the same as what happens in a refrigerator.

 

Also, small camping style cookers can be prone to ice developing in the gas jet because unless it is designed with a preheated vapourisation tube, the vapourisation takes place at the jet, making the jet very cold and thus freezing water from the air. This is exacerbated by altitude.

Well how do you explain my experience in the 1960's?

 

Perhaps winters used to be colder in the past, but if we wanted to use the hob in sub zero temperatures, no gas would come out until we have warmed the regulator for about 15 minutes, what had happened if it had not frozen?

 

I am not talking about Capming Gaz burners, but a normal Butane Gas Hob connected to a 15kg bottle housed on the outside of a boat in a self contained steel locker let into the cabin side.

[Malarky]

Well how do you explain my experience in the 1960's?

 

Perhaps winters used to be colder in the past, but if we wanted to use the hob in sub zero temperatures, no gas would come out until we have warmed the regulator for about 15 minutes, what had happened if it had not frozen?

 

I am not talking about Capming Gaz burners, but a normal Butane Gas Hob connected to a 15kg bottle housed on the outside of a boat in a self contained steel locker let into the cabin side.

I have also referred to frozen butane, also based on experience!

[ChrisPy]

LPG will not "freeze" in the normal range of temperatures in this country. What will happen is that Butane (the stuff in blue bottles) will not vapourise properly. Propane (in the red bottles) will vapourise perfectly in very low temperatures - about -40. Even LPG will not burn while it is still a liquid, it has to form a vapour so that it can mix in the right ratio with air.

 

You might think that freezing is happening because you see ice forming on the outside of the bottle. It is not. This is what happens when you vapourise a liquid into a gas. Energy is drawn from the surrounding environment, which creates low temperatures on the skin of the bottle. This then causes water from the air to freeze on the bottle, assuming the air temperature is already low. This is exactly the same as what happens in a refrigerator.

 

Also, small camping style cookers can be prone to ice developing in the gas jet because unless it is designed with a preheated vapourisation tube, the vapourisation takes place at the jet, making the jet very cold and thus freezing water from the air. This is exacerbated by altitude.

correct. But effectively butane liquid will not vaporise at the low temperatures created as a result of the process. Once the free gas in the cylinder is used up there is no pressure left and the remaining liquid butane might as well be frozen. This is evident as the pressure at the flame drops off to nothing.

[Big Steve]

Fascinating. I ask because a friend of mine, who lives in a caravan, phoned last night for advice. His gas would not work, he's on propane. I told him to chuck a pot of boiling water over it. I've not heard from him since, don't know whether that's good or bad!

 

It's interesting that the boiling point of propane is 42C at 1 bar, but the critical pressure (the pressure at which propane becomes liquid at room temperature) is 42 bar, therefore the bottle is at 42 bar normally, what is the boiling point at 42 bar?

 

Thinks.... If ambient temperature is 0 C what will be the pressure in the bottle? What will be the boiling point at that pressure?

 

I've got it in my head that the lowest working temperature for propane is -4 C, but I don't know where that comes from. Of course it will be evaporating (boiling) as it's being used, so it'll cool down more.

 

So what is the minimum recommended working temp. of propane under a light load?