Freezing Propane Tanks. A Different Solution

[BIGGUNDOCTOR]

Interesting about heat since I also live in the desert. We have 3 months a year where it is at least 100 everyday with a week or more where it will be 110-115. I have recorded temps on my car's body that were 175, with interior temps of 160 (forgot to roll the windows down).

To keep my old Towmotor running during the winter I installed a cold weather kit AKA a piece of Tygon tubing stuffed into the exhaust pipe, and directed at the carb. Kept it warm enough to keep it from freezing up.

Is it possible to just insulate the tank to keep it from freezing?

[maddog]

Is it possible to just insulate the tank to keep it from freezing?

The basic problem is inside the tank where the propane is vaporizing and drawing heat from the liquid propane. On a warm day, wrapping the tank in insulation would prevent the air from warming the tank and replacing some of the lost heat. On a very cold day (very cold!) insulation might prevent the air from chilling the tank.

Tank storage: Propane is heavier than air and if it leaks it pools. If the tank is indoors the leaking propane can accumulate and flash suddenly. I have heard of cases where the propane has pooled in basement and blown up the whole house.

[Glenn]

I was in a hardware store today and there sat a brand new 100 pound propane tank for $130.00

100# Cylinder - 25 Gallon Bottle
OPD is not required
Filled by weight - weighs about 170 pounds when full
Holds 100 pounds of propane (23.6 gallons of propane)
Contains 2,159,400 BTU when full
Widely used for heating, cooking, and roofing applications
46.3"H X 15.1"W

Total heating values after vaporization:
Btu per cubic foot 2,488
Btu per pound 21,548
Btu per gallon 91,502

Maximum flame temperature in air, degrees F 3,595

One of things we have not discussed is transportation of the tanks. I am sure there are rules and regs on what you can and can not do in transit. But this would apply to any tank of any size. How are they PROPERLY transported?

[ciladog]

One of things we have not discussed is transportation of the tanks. I am sure there are rules and regs on what you can and can not do in transit. But this would apply to any tank of any size. How are they PROPERLY transported?

Before I had bulk delivery, I would bring a 100 lb cylinder to the welding supply for exchange. I only did it a couple of times while I was waiting for the propane company to install my storage tank.

I would lay the tank down and slide it into my pickup truck (truck has a cap on it). On the third trip, I get to the supplier and unload the tank and roll it over to the loading dock. I went inside to pay while they exchanged the tank. I go back to the loading dock and there is a guy standing there by the tank and he said, “How are you taking this?” “I’m going to lay it down and slide it into the truck”, I said. “I can’t let you do that”, he said.

Well we stood there for a while talking and I could not convince him to let me lay the tank down to get it back home. He told me that there are laws and regulations regarding propane tanks that prohibit them from being transported on their side (I guess this is not the case for liquid forklift tanks). He explained that it had something to do with liquid propane coming in contact with the relief valve.

I ended up paying the supplier $35 to deliver the tank 8 miles.

[Glenn]

That was the point of my question,
Propane tanks that deliver propane vapor, and fork lift motor fuel tanks that deliver propane as a liquid, are designed VERY differently.

DOT and ASME containers are different
Propane tanks for permanent installation are built to ASME Boiler and Pressure Vessel Code and their capacity is expressed in U. S. Gallons.
Propane cylinders for transportable use are built to DOT Hazardous Materials Regulations and their capacity is expressed in pounds of water.


20# cylinder
4.7 gal Capacity (gallons)
18 lbs Weight (empty)
38 lbs Weight (full)
18 inches Overall Height
12.5 inches Diameter
430,270 BTU Capacity

30# cylinder
7.1 gal Capacity (gallons)
24 lbs Weight (empty)
54 lbs Weight (full)
24 inches Overall Height
12.5 inches Diameter
649,980 BTU Capacity

40# cylinder
9.4 gal Capacity (gallons)
29 lbs Weight (empty)
70 lbs Weight (full)
29 inches Overall Height
12.5 inches Diameter
860,542 BTU Capacity

100# cylinder
23.6 gal Capacity (gallons)
68 lbs Weight (empty)
170 lbs Weight (full)
48 inches Overall Height
14.5 inches Diameter
2,160,509 BTU Capacity

I did locate this in my research
In cold climates, in order to keep vaporization of LP-gas at the highest level, keep the fuel levels above 50%.

[Dodge]

I ended up paying the supplier $35 to deliver the tank 8 miles.

Sounds like a racket
Seriously, though, I live in Nebraska, so that may be a factor, but I always stood my 100# tank up and strapped it securely to the corner of my pick-up box to and from supplier. Last time I got gas, I asked the the guy that filled it to help me re-load it (bad back). He said "no problem" and hoisted it into my truck. I hesitated and then ask if I needed to stand it up . He said I didn't because the top collar protects the valve, and there isn't a problem with it laying on it side like you have with acetylene bottles. Sure was easier than worrying about securing it upright in my pick-up box. As its is more than twice as high as the sides of the box, I was always concerned with it being top heavy and flipping out of the ratchet strap I used. I usually had more than a couple angry impatient motorists behind me because I would drive so slowly home. Now, laying on its side, I usually have enough junk in the box to keep it from rolling, but even empty all it takes is a couple of strategically placed 2 x 4s.
Scott

[Mainely,Bob]

I know in the oilfield there were some dual fuel(gasoline and LPG)welding and roustabout trucks we had that required having the torch tanks standing upright and strapped in with some type of collar holding them from being thrown out if the truck rolled.
I once asked the welding supply place why the fuel tanks for torches could not be transported in a horizontal position and yet the fuel tanks for the truck were permanently mounted that way.
His answer was "Completely different animal ,son".The fuel tanks used in any type of vehicle must be DOT approved,and that includes fork lifts.

[Dodge]

Yep, we had some forklifts that had horizontal tanks and some forklifts that had tanks that stood vertical. They were aluminum and were NOT interchangeable. "Completely different animals.." :)

[Jack Evers]

I disagree that the capacity in pounds is pounds of water. Water weighs 8.33 pounds per gallon hence 20 pounds of water is is only 2.4 gallons. Propane is 4.2 ppg and 4.7 gallons would be close to 20#.

[Jack Evers]

To reply to the statements about insulation, propane can supply about 20 psi of delivery pressure at zero degrees F (liquid temperature, not air temp) and probably 12 psi or so at minus 10*F. In other words unless the ambient temp around the tank is below zero, it would be counterproductive to insulate.

The complication is that almost 185 BTUs is required to vaporize a pound a propane. This either comes from outside the tank and is conducted through the walls or it comes from cooling the liquid. 0.6 BTUs will change the temperature of one pound of liquid 1 degree F. This means the energy required to vaporize one pound would cool a pound of liquid by about 300 degrees (185/0.6). If you are running at a level of about 2 pounds/hr (a 20 pound bottle lasting 10 hours),you must supply 185 times 2 = 370 btu/hour to vaporize the liquid. Assuming there is 10 pounds of liquid in the tank and all of the heat came from the liquid, the liquid temp would drop by 62 degrees (370/.6/10). That's OK if the liquid temp was 60 or 70 when you started and you only wanted to run an hour. It's not OK if the liquid was at something like 20 degrees when you started. It's also not OK if there's only 2 or 3 pounds of liquid.

In a practical case, then the heat of vaporization comes from both sources, but if the air temps are low and a limited amount of propane starts out already chilled, there won't be much heat conducted through the walls and the propane temp will drop quickly into an unuseable range. Water, a heat lamp, hairdryer, etc can help, but a larger tank kept relatively full is probably the best answer. As a farrier, I do travel with 20 pound tanks and on cold days my forge welds often get brazed instead of welded.

[tdaleh]

Just bought a 100# tank last week and on the label it says to transport in up right position.

[Jack Evers]

The reason is that if the safety pops in an upright position, you will vent vapor. If it's on it's side with the safety covered by liquid and you vent liquid, it's a good deal more hazardous.

[maddog]

It is also a hazard to transport propane cylinders in an enclosed compartment. The place where I fill my tanks will not allow you to buy 100#s of propane or more, if you show up in a PU truck with a camper shell. I don't know if this is a NM State law or Federal.

[Jack Evers]

Last I heard, there were no federal transportation laws on smaller quantities, but state laws could be put in place. Again, the last I read 90# was the break point for small quantities so 100# could be a federal law.

I did take the shutoff handle off my truck forge, forcing me to turn it off at the bottle. I was pretty bad about turning it off at the forge while working, then forgetting to turn the bottle off for transport under a cover.

[Ulric]

Good question. I might assume that companies with LPG forklifts have permits or should have permits. I do know that propane forklifts run on liquid not vapor and the tanks are different than those that deliver vapor.

It’s all spelled out in the National Fire Protection Association (NFPA) 58, LP-Ga publication. But since I don’t have a copy and am not about to purchase one I can’t quote from it.

Maybe someone on this forum has the knowledge and could comment.

The propane tanks/cylinders are commonly stored outside I believe, at least ours were.
The 'bottle' on the tank, remains connected...though I can't recall if we closed the valves or not before we shut down for the day.
...and unfortunately I have to admit to popping the valve off a full one due to an improperly placed pallet, horrible rack layout and lack of attention to detail.

[thingmaker3]

Something that has not been mentioned in this thread is the fact that storing propane tanks inside a building without a special permit is a violation of the Uniform Fire Code.

Any permitting requirements are strictly local. Always check with YOUR fire marshal.

The following is from the NFPA:

Buildings frequented by the public are limited to cylinders with a propane capacity of 1 pound. The total quantity stored is limited to 200 pounds of propane.

Buildings not frequented by the public are limited to a maximum quantity of 300 pounds of propane. The cylinder size is not restricted.

Storage in "Special Buildings", meeting the requirements of Chapter 7 of NFPA 58 is limited to 10,000 pounds of propane.

[Jack Evers]

This has gotten me thinking, if the air around the tanks is say 20 degrees or higher, just a plain old fan aimed at the tank would help. I may try to run the numbers this week.

[Dragons lair]

From what I understand the frosting is due to the liquid turning to a gas. So how is it the tank will freeze
up over night? I would be looking for a leak. Some folks don't smell propane. My coworkers(2) run to open the doors
in a 3,000 sqft shop every time i crank up the forklift The other 3 of us don't smell it at all. A Co/Gas alarm is a great friend.
Ken.

[maddog]

This has gotten me thinking, if the air around the tanks is say 20 degrees or higher, just a plain old fan aimed at the tank would help. I may try to run the numbers this week.

True. But how are you going to estimate the efficiency of the heat transfer from the moving air to the liquid content?

[pkrankow]

From what I understand the frosting is due to the liquid turning to a gas. So how is it the tank will freeze
up over night? I would be looking for a leak. Some folks don't smell propane. My coworkers(2) run to open the doors
in a 3,000 sqft shop every time i crank up the forklift The other 3 of us don't smell it at all. A Co/Gas alarm is a great friend.
Ken.

Have the seals inspected next time you refill your tank The repair was $1 for parts and labor per tank with a refill when the o-rings went bad on the tanks where I used to work. Turn the tank off when the fork is parked. If you still are not at the bottom of the problem, talk to a forklift mechanic about the rest of the fuel system.

Phil

[Dragons lair]

Naw they ain't complaning about a leak. Its the exhaust they don't like. It did arrive with a bad O ring and was fixed.One of them quit his construction job cause they used a propane reddy heater.
Ken.

[edge9001]

Last I heard, there were no federal transportation laws on smaller quantities, but state laws could be put in place. Again, the last I read 90# was the break point for small quantities so 100# could be a federal law.

I did take the shutoff handle off my truck forge, forcing me to turn it off at the bottle. I was pretty bad about turning it off at the forge while working, then forgetting to turn the bottle off for transport under a cover.

I can't speak to local and state laws but federal hazmat laws allow the transportation of anything less than 100 pounds of any hazardous material. anytime you transport more than that, placards are needed as well as appropriate vehicle and a driver licensed to transport hazmat. for propane it would be a hazmat license as well as a tank license.

less than 100 pounds of anything can be transported by anyone as long as the appropriate precautions are made, such as a DOT regulated tank or transportation method to include tank containment(strapped down and capped properly)

As i said i can't speak to local law or state laws, as well as the companies policies.

[Jack Evers]

True. But how are you going to estimate the efficiency of the heat transfer from the moving air to the liquid content?

It's been a long time since I took my graduate level heat transport course, but I think that I can still figure out an estimate if I can locate my book.

Now you're putting the pressure on.

[ThomasPowers]

"How can a tank freeze up over night?" Well around these parts it's typically 30 degF colder at night than in the day time and many shops don't heat over night either so a tank that might be OK at 50 to 60 degF shop during the day might be a trifle sluggish in a sub zero shop in the morning!

[kevin1050]

I also homebrew (makes me a very popular guy) and think this might help with freezing tanks. It is a brewbelt, it keeps your fermenting brew around 70 degrees. I ordered one and will try it out on my 20lb tank. Since it is below freezing now in MD and I work in an unheated garage it might work. I will let you know how it works out. Cost around 25 bucks. What says you?

Wraps around any size fermentor, plastic or glass.

These heat belts used to come with no packaging or instructions. Now, the manufacturer puts it in a nice new package with instructions. On this package, there's a warning against using the belt with glass fermentors. We don't believe that this is a real issue because the belt doesn't get very hot, and because many people have been using heat belts on glass fermentors for years. But you should be aware that the manufacturer doesn't recommend use with glass fermentors - so we can't either!