NOT off topic: a propane gas question

RRP · January 2008

I live here in the Midwest where it gets COLD in the winter. In my pre-egg life I used to cook with propane gas. Sometimes when it got cold propane simply was too cold to be in it's gaseous state. I want to use this point soon, but I can't seem to find information concerning this problem on the net. Anybody know?

BENTE · January 2008

here is something i copied maybe it will help

When you purchase it, it's in a liquid state. Tank gets filled to 80%. Allows for 20% expansion. When vaproized, it expands 270 to 1. Liquid propane "boils" at -44F. If surrounding area is colder than that, it stays in liquid form, and won't come out of tank. Not usually a problem w/propane. However, as a rule fill your tank in the same general locality as you're going to use it. Example to avoid: filling a tank in freezing temperatures in the northern states, and driving to Arizona: When you filled the tank it was filled to 80% capacity; but going to the heat of Arizona could cause the propane tank to become "overfilled".

Propane expands 1.5% for every 10 degree increase in temperature. That's why tanks are never filled beyond 80%. It's crucial to keep filled tanks so that escape valve is on top so that any "overfilled" volume will be expelled as a vapor, and not in its liquid form. This is why it's dangerous to paint propane tanks a dark color to "match your rig" -- it will heat up to higher temperatures and become "overfilled".

also found this

Vapor pressure of liquid propane at various temperatures

Temperature of Liquid (F)
Approximate Pressure of Gas (psi)

-40
1.3

-30
5.5

-20
10.7

-10
16.7

0
23.5

10
31.3

20
40.8

30
51.6

40
63.3

50
77.1

60
92.5

70
109.3

80
128.1

90
149.3

100
172.3

110
197.3

also check out http://www.propanecarbs.com/propane.html

gdenby · January 2008

From the "Propane 101" page:

"Propane is a liquid at -50°F and boils at -44°F. In other words, at 10 degrees below zero, propane is well past its boiling point."

So its going to have to be pretty cold for a propane burner not to work. I understand the same is true for MAPP, and I have used it as low as 15 above.

gdenby

Fidel · January 2008

I can see wher at -20 or -30 there would not be enough PSI in the tank to allow for adequate flow through a hose to a burner. The low pressure may be the issue and not necessarily that the propane is too cold to vaporize.

fishlessman · January 2008

Cylinder Size 20 & 30

Outside Temperature 20 30
+60f 24,000 32,000 BTU/ hour
+50F 21,200 28,300
+40F 18,450 24,700
+30F 15,700 21,000
+20F 13,000 17,300
+10F 10,250 13,700
0 7,500 10,000
-10F 4,780 6,400
-20F 2,050 2,700

the chart is based on 25 percent full of a 20 and 30 gallon tank. the way i read this is that if you try and get more btus from this size tank than noted above, the tank will freeze up, its not just the temp outside. found this here, ive never had problems with a tank over 40 gallons, but the smaller ones freeze up if your trying to get the most out of them btu wise
http://www.yamaha-propane-natural-gas-generators.com/fuel_consumption.htm

fishlessman · January 2008

Ron, dont know what point your going to make about propane, but my 1038 square foot house needs roughly 125 gallons of propane a week to maintain 68 degrees on single digit cold days. roughly 3.50 a gallon here. i heat with coal and the propane forced hot water system is for a back up system only. i think it would be cheaper to heat with lump than propane in this house.

Spring Chicken · January 2008

It absolutely amazes me how much I learn from this Forum. I thought I had a fairly good understanding of propane having sold it, piped and plumbed for it, soldered with it, burned it in a fireplace, used it as fuel in two different automobiles, lit cigarettes with it, cooked with it and even used it as a propellant when spray-painting the town's firetruck, mostly in another life. (yes, I was in a breezy open area away from everything and everyone when painting the firetruck)

Now I've learned something I wouldn't have even known to ask about.

Thanks for enlightening me.

Spring "When I Think I know Everything, Someone Goes And Asks A New Question" Chicken
Spring Texas USA

WessB · January 2008

More facts than I ever knew, and can relate to most of them..

slyrye · January 2008

Ron,
After selling and repairing propane appliances for close to 30 yrs. my experience is telling me you have butane gas in your tank and not propane! Many retailers in warmer climates can sell it as propane, only difference being propane has egg smell put in were butane does not. It causes big problems up here in the northeast when people come back from Florida in their RV"s after filling up their propane tank down there, propane and butane are very similar gasses, with butane freezing in the liquid state. Most likely is your regulator is what is frozen, take a pan of boiling water and pour over it to thaw it and get the gas moving thru.
My 2cents worth

B & C · January 2008

I am not sure that I can give you a great explaination but I will try.

Propane acts and is capable of being used as a refrigerant gas in addition to being a fuel. Propane gas in a cylinder has a pressure in the cylinder that varies with a corresponding temperature of the liquid in the tank. At equilibrium (no gas being removed ) the pressure of the propane gas in the tank is directly related to the temperature of the tank and the tempersture of the air around the tank.

As you remove propane from the cylinder it leaves the tank as a gas with liquid left in the bottom of the tank and vaporized gas left in the top part of the cylinder. As the gas is removed from the tank, the temperature of the tank and the remaining propane liquid in the tank drops towards the vaporization temperature.

When the propane gas is removed and more liquid propane is vaporixed, the temperature of the remaining liquid and the tank begins to drop towards the temperature of vaporization of propane for the given pressure of the tank. In colder climates with a colder air temperature surrounding the tank, the tank and the liquid propane start out colder and the propane losses the abilty to vaporize as quickly because temperature difference between the surrounding air and the vaporization temperature is reduced. As propane is released from the tank, the liquid propane gets colder from the vaporization of the propane. as the liquid propane gets colder, it will become less able to vaporize quickly. The slower it vaporizes the less propane gas you will get to burn. The less propane gas you get to burn the lower the pressure of the gas you are burning. The effect is that the propane appliance will act as if it is starved for fuel.

The less liquid propane in the tank (the tank's wetted area is smaller and the more tank surface not in contact with the cold liquid) the easier the liquid propane will be to vaporize. The part of the tank that is not filled and not in dirrect contact with the liquid propane will take heat from the surrounding air and use that heat to increase the rate of vaporization. So as a tank has less and less liquid propane it's ability to vaporize the liquid propane improves.

Just another fact, you can never measure/ evaluate the volume of propane in a tank by measuring the pressure of the tank, you must weigh the cylinder in order to know how much propane is in the cylinder. If a tank is outdoors and in the shade, you can by measuring the pressure of the gas in the tank and consulting a refrigeration chart for propane gas, and get from the chart, the temperature of the propane, the propane tank, and the air temperature surrounding the propane tank (they are all at the same temperature - equilibrium) as long as no gas is being removed at the time. And the reverse is also true, if you know the temperature of the air surrounding the propane tank, and the propane is at that same temperature, by looking at a refrigeration chart for propane the pressure of the tank will be shown on the chart for that particular temperature.

I hope my explaination is ok and that it was also not too confusing.

NOT off topic: a propane gas question

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