OT/Propane freezing

[hwingo]

Guys,

This is way off topic. I live in Alaska. I began (late afternoon) smoking a pork shoulder with the outside temp being 21F. I nursed this project all night. Around 0600 hrs outside temp dropped to around 12F. The propane flame went out. This was a full tank of propane. Bottom line is, drop in temp with concomitant expansion of gas caused the regulator to freeze preventing gas flow to the burner. I was desperate to finish and I needed a flame. Using hot, wet towels I wrapped the regulator with these towels and covered with a dry blanket. Gas began to flow and I had a flame but not what I needed. Also, the towels lost heat quickly and I had to keep changing towels every 3 to 4 minutes. Finally I wrapped an electric heating pad around the regulator as well as a part of the hose (which goes to the burner). Still, the flame was not sufficient to get back to cooking temperature. When the sun came up around 1000 hrs, outside temp elevated and I barely managed to finish at 1400 hs (just as my guest arrived). I know WHY this occurred.

The question is, what tricks can I use to ensure this doesn't happen again while attempting to use the smoker in cold weather? Yea, I know. Cook only when it's warm outside. No, I am looking for a serious answer. I want to smoke meat or fish at an outside temp between -2F and above. There must be a way to keep the tank, regulator, and hose sufficiently warm to ensure a full, strong flame at low outside temps.

Harold

[YukonHam]

How big a burner / how small a tank are you running? I routinely run a 3 burner BBQ off a 20lb tank at -20F or so, never have a problem. However, one of my workmates has had problems with his propane pig (200 or so lbs) freezing the regulator, the propane guy figures he got some moisture built up over time. The fix recommended was same as for auto gas - a bit of methyl hydrate each refill for a while to take the water out.

[Evan]

Use a much bigger tank. The problem is caused by the propane cooling itself via expansion. Propane is used to heat houses at -30 and it doesn't go out because of the size of the tank. The amount of cooling below ambient is dependent on the amount of propane vaporized per unit time in proportion to the amount of propane in the tank. That also means you start with a full tank to avoid as much cooling.

[darryl]

Propane is pretty much useless below about -20F. Below about -40F it doesn't vaporize at all. At 0F, you can count on only about 1/10 the flow rate that you would get at 70F. Everything comes together against you when it's cold.

Chances are the regulator is where most of the cooling effect is coming from. If the tank is small, it will cool significantly also. Using a larger tank will help. Having a larger volume of propane in the tank will help. I doubt you will gain much by heating the hose since there's little expansion effect going on there, but it might be better for the valve on the smoker to have a bit warmer gas coming into it.

Since the cooling effect is related to the flow rate of the gas, and the ability of the tank and remaining liquid to absorb heat from the surroundings, part of the solution could be to increase the mass of the liquid and the mass of the regulator assembly. This could be done by adding a second tank and regulator, combining the outputs before the gas goes to the smoker. In use you would aim to have each tank supplying half the flow. I don't know the legalities of doing it this way, but the potential is obviously there for a gas leak if one tank is shut off and the hose removed while the other tank is still on.

Using some means to keep the regulator from freezing would help of course. It would not be recommended to use an electric heater, nor would it be fool-proof or easy to use the waste heat in some way. If you were to build a flange of sorts that could clamp around the regulator body and have a significant area of contact with it, you could mount a copper coil on the flange and pump a warmed fluid through it. Even a passive heat sink in significant contact with the regulator would help- it would provide a larger surface area to absorb heat from the surroundings to help keep the temperature from dropping into the low flow zone.

[Cuttings]

If you have snow on the ground, you can try burying the whole thing in snow to keep the tank and regulator warmer.
A LOT of years ago when I lived in northern BC we used to bury our oil tanks in snow to keep the fuel from gelling when it got very cold out. It worked well.

[Evan]

You could also just put the tank in a half barrel of water. Once the water has cooled to the triple point of 0 C it then must release the latent heat of crystallization in order to freeze. That is a lot of heat, 335,000 joules per litre. Until it all freezes solid the water will remain at 0 C regardless of the outside temperature or the temperature of the propane. This is not to be confused with the specific heat of water which is 4200 J/L. 4200 J/L is how much heat must be removed from a litre to lower temperature 1 degree C until it reaches 0 C. Then it must give up 335,000 more joules in order to freeze because of the phase change..

[tmc_31]

Redneck solution, put the tank and regulator inside the pit

Stand back...

[quasi]

I have had a few pickups that were Propane fueled, past -25 Celsius you need to plug in the block heater. A bit of heat tape is all you need with that small tank.

[Black_Moons]

Agreed, Considered trying those 'no freeze' pipe heater lines? wraped around the tank would do well... That, or maybe bungie cord a thermal banket to the side of the tank.

[MrFluffy]

LPG powered car's have a water heated lpg liquid->gas converter, heated off engine coolant heat. Without that they freeze up too on colder mornings. Maybe you could have a thermo controlled supply of hot water with a pumped loop off to a vapourizer.
Dont know if you could just use car lpg kit off the shelf for this, but worth looking into.

[Toolguy]

Maybe you could smoke with wood and not have to worry about propane at all?

[Black Forest]

Build a box and insulate with whatever you want. Put said propane bottle in box. Put shop light in box. Close lid on box. Just to be clear turn the light on before closing lid.. What time is dinner?

[hwingo]

Thanks to all for responding. I see I have many options from which to experiment. All suggestions have been appreciated.

Harold

[Willy]

It's all about the moisture in the fuel and how to control it.
A very interesting read below from Fisher Regulators.

http://www.documentation.emersonprocess.com/groups/public/documents/bulletins/d450146t012.pdf

[Jon Heron]

During my apprenticeship in northern Ontario -40c weather was a normal thing in winter, the propane tanks for the construction heaters came standard with an electric heating blanket, by keeping the tank and LPG warm the regulator wouldn't freeze either. At -40c the propane would not even come out of the tank without the heating blankets.
Brrrrr, I sure dont miss those days, freezing my ass off on a frozen slab of concrete for 12 hours a day @$7.00 an hour lol!
Cheers,
Jon