Freezing gas

[alan_fincher]

There's a lot of getting hung up on whether people really mean "freeze" or not.

 

The OP probably doesn't care, and just needs to know if it will work in all UK climates.

 

The simple answer to that is exactly as David has described.

 

Propane cylinders stored outside will continue to deliver gas after temperatures go sub zero.

 

Butane cylinders will not.

 

I know this to be true, because I've tried living on a butane equipped bat when it was very icy.

 

You can usually maybe boil a small kettle in the morning, before no more gas flows. The unwise person uses that to make tea, and is then strapped for any more gas. However the wise person pours their hot water over the cylinder, and therefore gets a lot more gas.

 

Butane is only for fair-weather boaters. Propane is the only gas to choose for being aboard at any time.

 

Alan

[Boatgypsy]

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.

Exactly, but I thought we needed to be clear that the gas is not frozen, just not able to vapourise, as one of the previous posters seemed to be suggesting he could hear chunks of frozen ice knocking around in his bottle. The freezing point of even butane is well below any normal environmental temperature.

 

Call me a pedant if you wish, but saying that because the gas does not come out it might as well be frozen is akin to saying that because the moon looks like it might be made of cheese it may as well be.

[Malarky]

Exactly, but I thought we needed to be clear that the gas is not frozen, just not able to vapourise, as one of the previous posters seemed to be suggesting he could hear chunks of frozen ice knocking around in his bottle. The freezing point of even butane is well below any normal environmental temperature.

 

Call me a pedant if you wish, but saying that because the gas does not come out it might as well be frozen is akin to saying that because the moon looks like it might be made of cheese it may as well be.

I was also confused by what was rattling in the bottle, as I assumed it would'nt be frozen into any solid form; but that's what I heard! Could the butane be turning to cheese?

[ChrisPy]

mature brie probably

[ditchcrawler]

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?

Is this any help http://en.wikipedia.org/wiki/Vapor_pressure

[OptedOut]

I don't think so.

 

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

 

No problem, I already fill my 13Kg boat and 3.9 Kg campervan bottles from a 47Kg bottle anyway. (much cheaper per Kg).

[ditchcrawler]

No problem, I already fill my 13Kg boat and 3.9 Kg campervan bottles from a 47Kg bottle anyway. (much cheaper per Kg).

I use to do that many years ago when I worked at a camping site, but I don't think its recommended.

[OptedOut]

but I don't think its recommended.

 

No, not in this PC age, plus there are the equipment costs of a bit of hose and a bathroom scales.

[dor]

Propane and butane will not freeze in our temperatures, as has already been stated. However what can happen is water trapped in the cylinders, which can build up over time, can and does freeze.

 

Butane will be very prone to failing to vaporise from the liquid, but liquid it still is. Warming up the cylinder will allow it to vaporise, not melt!

 

If propane "freezes" anywhere south of the north pole in the middle of January, then look elsewhere - it is not the propane that is freezing.

[Big Steve]

I've been searching frantically for the min. temp. that a propane tank can still be used at. I've discovered that my earlier post re. critical pressure was rubbish, I had misunderstood what critical pressure was.

 

The gist of the info. is that there will be no trouble down to at least -20, and only then if you're using a lot of gas.

 

So why did my pal's gas refuse to work 'til he poured hot water on it? He'd been out all night so no gas had been used, so it wasn't cooling caused by evaporation.

 

Does water collect in the regulators and freeze? Or what?

 

Thanks for all your comments so far, by the way. that link to vapor pressure was very good.

 

Cheers

 

Steve PS This is just out of interest, nothing depends on it.

[OptedOut]

So why did my pal's gas refuse to work 'til he poured hot water on it? He'd been out all night so no gas had been used, so it wasn't cooling caused by evaporation.

 

Does water collect in the regulators and freeze? Or what?

 

Several years ago I fitted a new set of bottle to regulator hoses, all was OK for some time until the regulator seemed to be failing on "lock-up" pressure, (surge of gas on initial lighting of cooker).

On investigation the regulator was soaked internally with an oily yellow liquid which I assumed was either a "heavy fraction" or compressor oil from part of the refining process.

Later research seemed to suggest hose polymer leaching out of the rubber.

Anyway cleaned reg and no problem since?

 

Anyone else come across this situation, if so is it a factor in lack of gas at low temp?

[ChrisPy]

..... very mature brie probably

[OptedOut]

..... very mature brie probably

 

 

[cotswoldsman]

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?

 

Not to sure about the condensation in pipes thing, it was minus 7 here this morning and at 06:30 went to boil the water for my moring tea and had no gas (red bootle) I knew I had plenty of gas as only fitted it 4 weeks ago. By 11:00 after the sun had been out for a couple of hours hey presto gas, can only imagine this was condensation in the pipes or somewhere that caused this. Has happened to me twice before and this is my third winter

[Nickhlx]

Not to sure about the condensation in pipes thing, it was minus 7 here this morning and at 06:30 went to boil the water for my moring tea and had no gas (red bootle) I knew I had plenty of gas as only fitted it 4 weeks ago. By 11:00 after the sun had been out for a couple of hours hey presto gas, can only imagine this was condensation in the pipes or somewhere that caused this. Has happened to me twice before and this is my third winter

 

 

or the regulator itself freezing in a closed position from small amounts of water vapour present within ? As has been said above, propane ( and butane) will not turn solid in UK-encountered temperatures.

 

Nick

[cotswoldsman]

or the regulator itself freezing in a closed position from small amounts of water vapour present within ? As has been said above, propane ( and butane) will not turn solid in UK-encountered temperatures.

 

Nick

 

Nick thanks for the suggestion but never have my regulator in the closed position so it is still a mystry

[tidal]

My understanding is that Propane, because it drops below a vaporization temperature, does not always have sufficient pressure to activate the regulator so no gas passes through. Warming the cylinder or the regulator /pipes allows vaporization and increases the pressure allowing the regulator to work.

 

From experience of both boats in the UK and Norway during winter, and helping to stock mountain refuges in the Cairngorms I personally cannot recommend anything but butane for winter weather.

 

Having just talked to my butane supplier about the "ice" clanging about inside both butane and propane cylinders during winter, he says (if my spanish translates correctly) that this is due to the small amounts of water that collect within the cylinders over time freezing.

 

*written at a height of 3250ft above sea-level in the snow in southern Spain*

[OptedOut]

My understanding is that Propane, because it drops below a vaporization temperature, does not always have sufficient pressure to activate the regulator so no gas passes through. Warming the cylinder or the regulator /pipes allows vaporization and increases the pressure allowing the regulator to work.

 

From experience of both boats in the UK and Norway during winter, and helping to stock mountain refuges in the Cairngorms I personally cannot recommend anything but butane for winter weather.

 

Having just talked to my butane supplier about the "ice" clanging about inside both butane and propane cylinders during winter, he says (if my spanish translates correctly) that this is due to the small amounts of water that collect within the cylinders over time freezing.

 

*written at a height of 3250ft above sea-level in the snow in southern Spain*

 

You sure you got that the right way around?

Also looking at the properties for the gases concerned the water would freeze in a layer at the bottom?

Edited December 1, 2008 by OptedOut

[alan_fincher]

From experience of both boats in the UK and Norway during winter, and helping to stock mountain refuges in the Cairngorms I personally cannot recommend anything but butane for winter weather.

I'm completely intrigued, particularly as you obviously have experience of using these gases in fairly extreme conditions.

 

I know from personal experience that Butane becomes just about unusable if stored outside when subjected to temperatures much below zero.

 

Every mobile home or accommodation caravan I have ever seen uses the red (propane) cylinders stored outside, and I've always believed this to be because they continue to work when it gets very cold.

 

Back when I boated in the 1970s use of Butane on boats was common, and it did stop working if it got too cold. Now one hardly ever sees a boat equipped with anything but Propane.

 

I've never had the issues with Propane that I used to suffer with Butane.

 

I can't explain the problems reported by others in this thread, but also wonder if it is something like water trapped in the regulator, causing a valve to freeze stuck.

 

You certainly can get liquids in pipes and regulators that in an idea world should not be there. Calor recommend that any high pressure changeover valves and regulator should be higher than the cylinder connections, to allow anything unwanted to drain back into the cylinders. The depth of a typical narrowbaot gas locker usually conspires against this, and the regulator ends up lower than the cylinder connection, meaning it can get contaminated with anything that collects in the pigtails.

[tidal]

You sure you got that the right way around?

Also looking at the properties for the gases concerned the water would freeze in a layer at the bottom?

 

Well duh!

What the heck was I thinking of..... yes I got it wrong.....I blame early onset of senility and trying to do 3 things at once.

As for the ice yes it does form at the bottom, usually the coldest place on land but even at -15C I have never got a solid lump just bits which move around (by sound) in the bottom layers when you shake the bottle

[Malarky]

Well duh!

What the heck was I thinking of..... yes I got it wrong.....I blame early onset of senility and trying to do 3 things at once.

As for the ice yes it does form at the bottom, usually the coldest place on land but even at -15C I have never got a solid lump just bits which move around (by sound) in the bottom layers when you shake the bottle

Why is the ice not sticking to the bottom? Is the gas leaving a "greasy" film on the interior, or does the ice float to the top of the liquid when dislodged by movement?

[Big Steve]

Why is the ice not sticking to the bottom? Is the gas leaving a "greasy" film on the interior, or does the ice float to the top of the liquid when dislodged by movement?

 

It won't float to the top because water is a lot denser than liquid propane. I've just found a site which says water dissolves in liquid propane, as the propane gets colder the water can condense out and freeze. It's is most likely to do this as it goes through the regulator apparently, so methanol is added to mop up the water.

 

So that looks like the answer, dissolved water blocking the pipes, not freezing or too cold propane. Here's the link

 

http://64.233.169.132/search?q=cache:GOkuI...;cd=2&gl=uk

Edited December 1, 2008 by Big Steve

[alan_fincher]

Many, many moons ago I had a Saturday job with a hire firm, and changing empty cylinders was one of my tasks on the boats being turned around.

 

Nearly all "empties" had something slopping around in them, but it wasn't gas, because if you opened a valve with it the right way up nothing came out, but the liquid remained.

 

I've often wondered why no apparent attempt is made to get this residue out when they refill them, (and whether it's weight forms part of the gas you are supposed to be paying for!).

 

When I have emptied the gloop out of an old cylinder though, it has been an oily black sludge that looks unlikely to freeze. I've never seen anything that looks water based - it's usually much too viscous.

[OptedOut]

Many, many moons ago I had a Saturday job with a hire firm, and changing empty cylinders was one of my tasks on the boats being turned around.

 

Nearly all "empties" had something slopping around in them, but it wasn't gas, because if you opened a valve with it the right way up nothing came out, but the liquid remained.

 

I've often wondered why no apparent attempt is made to get this residue out when they refill them, (and whether it's weight forms part of the gas you are supposed to be paying for!).

 

When I have emptied the gloop out of an old cylinder though, it has been an oily black sludge that looks unlikely to freeze. I've never seen anything that looks water based - it's usually much too viscous.

 

I think they probably empty the sludge out during the refill procedure.

My campervan has a plug on the vaporizer to drain said gloop.

[Malarky]

I cut one up once to make a burner(initially with a hacksaw to avoid sparks!), no exesively ripe black castello, but about an egg cup of what was possibly water drained out.