What temperature does propane stop flowing?

Tomorrow is supposed to be the coldest before it warms up. If the furnace survives the night I should be ok, But I will pick up a heating pad tomorrow.

I wonder if a battery blanket would do the trick....

Whats a magnetic heater?

pianotuna wrote:
Hi Bob,

Propane boils at -42 C. However at -40 it doesn't boil too fast at all.

As it boils it cools the tank. When it is -35 there is not much heat that the tank can extract from the ambient, so it is quite possible for the tank to below the temperature it is being stored in.

I agree that the tank contents will be a lot colder than the outside air. I was in Laughlin NV around Thanksgiving in 1987, and the propane tank was about 30' long and 5 or 6' diameter. The bottom half of the tank was solid ice about 2" thick. I would guess the Riverside Hotel was using propane pretty quickly. Probably would help to have a electric heater inside the commercial sized tank to improve the tank pressure.

Fred.

Hi Bob,

Propane boils at -42 C. However at -40 it doesn't boil too fast at all.

As it boils it cools the tank. When it is -35 there is not much heat that the tank can extract from the ambient, so it is quite possible for the tank to below the temperature it is being stored in. When that happens gas production drops down. If it drops enough, then there won't be a sufficient volume of propane to operate the burner in the furnace.

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

Just tuck a heating pad between the two tanks. If you don't wish to do that then use one of the chemical type hand warmers.

I have a 200 watt magnetic heater that I use to warm up my generator. It doubles as a tank warmer for me.

I know when I skin deer in the shop when its down close to 0 I have to set the propane tank in front of the heater or the tank freezes up and the heater stops working. And skinning deer with cold finger tips is no fun!

What temperature are you at? Yep that is cold enough, just your luck.

There is a propane pressure temperature chart, it is R-290. Yes a refrigerant.

Here is a place to find it's pressure at various temperatures.

http://www.engineeringtoolbox.com/propane-butane-mix-d_1043.html


So it looks like -44 and the pressure will be 0 PSI. However recall that you will be boiling the propane inside a tank, so if it is -20 outside, then the tank can reach -44, depending on the speed that you are using the propane from the tank. The slower that you are going to consume propane, the closer you can get to -44 and still have it boil faster than the tank gets cold.

If you can rotate tanks, and keep one inside for a while, you will be able to increase it's pressure, and thus have one ready to take outside and hook it up around midnight. (yes thanks for knowing that).

If you are collecting a lot of ice on the tank, the ice will help insulate the tank from the heat outside, and make the pressure even lower. Putting the tank into a warm sink full of water is what I have to do when I empty a R-22 freon tank as a vapor into a air conditioner. It will also increase the tank pressure in your case. You would need a bucket slightly larger in diameter than the 30# tank, and then fill it with some hot water, let it soak a while (inside the RV where it will not freeze or lose to much more heat to the outside.)

Fred.

Thats what I get for going to Calgary to work at this time of year! Yuk yuk!

Coulda got a motel, but wheres the fun and challenge in that?

"Why do the sides of my propane tank freeze up?"

"As you use the vapor propane (that resides in the top of the tank), the liquid (in the bottom of the tank) begins to release replacement vapors. The liquid propane inside your tank must absorb warmth from the steel walls of your tank in order to convert the liquid to a vapor.

If your vapor withdrawal rate is larger than the liquid conversion rate, the steel will begin to freeze and ice up as the liquid propane is demanding
more and more warmth."

Propane boils at about -50C. However, vapor pressure drops as temperature drops. So... what happens is the max BTU/hr you can draw drops with temperature and with the size of tank, and how much is left in the tank.

What your experiencing is probably a combination of all three. low temp, bottle to small capacity, bottle partially filled.

I did a web search a while ago, and my memory may be bad but what I recalled was that for a 100lb tank, with 20lbs left, at 0F BTU/hr capacity was around 30KBTU/hr. you've got a smaller tank and lower temps!!!

Add to that the oven, furnace, stove..... Ug... hope the WH doesn't decide to turn on!!

time to put the tanks to bed with a electric blanket!!

BTW my folks, further south than you hit -30F last night and they think it will be colder tonight. Reminds me of Xmas weather in the 60's and 70's with cold and snow!!