propane plumbing

[Paul and Libby Smith]

Hi. would like to know if propane plumbing exposed underneath trailer would freeze,I have called a a propane dealer in minnesota, and he had no clue, I have lived and camped in florida most of my life, so I have no idea.. Iam planning a trip up north soon, and hopefully I could gain some knowledge from you folks. thank you Paul

[Chester Taje]

Mine has never freezed. I also barbacue in middle of winter in below temps.

[Gina D.]

Dr. Poodle, er, Propane, Peter H....

where are you?

[Paul from NWOnt]

Propane doesn't really freeze under normal circumstances. You should be aware, though, that when you approach 20 degrees or more below the freezing mark (0C/32F), propane doesn't like to flow. The real trick is to keep the bottles as full as possible as it's the liquid portion of the tank that drives the gas out. At minus 30, you'll be lucky to get flow if your tanks are less than half full. I don't have any scientific data to give you, all the information I've given is based on my experiences--- actual mileage may vary.

Apart from that, it's really about how well insulated your rig is, or how good of a sleeping bag you own.

[Byron Kinnaman]

Table #1 lists the vapor pressure inside a propane container, at a particular temperature, containing some liquid but not more than 80% total capacity. This allows for a 20% vapor space


[ATTACH][/ATTACH]


I found this, it might help.

[Benny K]

How does someone that heats a mobile home with propane get heat if the outside temps fall to -40 or colder?...I`ve seen a large number of mobile trailer parks where there are large propane tanks at the trailers that are used for heat and appliances....I`ve never tried my barbecue at home in temps like that, but will remember to try it this winter....Benny

[peterh]

According to Chemfinder, propane melts at 187.8C below zero at sea level. That's -306.0F. And while the temperature does come up a bit when pressure is applied, I'd suggest that, should you find yourself camping somewhere where your propane lines freeze, you probably should have turned back before passing under the nice arch with the inscription Abandon Hope All Ye Who Enter.

--Peter

[peterh]

Table #1 lists the vapor pressure inside a propane container, at a particular temperature, containing some liquid but not more than 80% total capacity. This allows for a 20% vapor space


[ATTACH][/ATTACH]


I found this, it might help.

Those are the stats for propane changing from a liquid to a gas.

[Byron Kinnaman]

Those are the stats for propane changing from a liquid to a gas.

YA!. Isn't that important when running propane devices. Or maybe I misunderstood the original question.

[Alf S.]

Hi: During the '80's I championed the "Alternative Fuels" program @ our local Chrysler Dealership. We sold full size pickups and passenger vans that were propane powered from the factory. When fueling these vehicles the pump jockeys used to have to wear heavy gloves to prevent freezer burns to their fingers when opening the spitter valve to allow the propane into the tanks. Most vehicles had multiple tanks along the side and across the rear and a special valve to allow them all to fill at once but to drain seperately...and a switch was on the dash to change over while on the road!!! This valve would sometimes freeze up due to the speed 60-70 mph + wind chill and you would run out of fuel @ highway speed A lot of switch flicking and coasting along would usually do the trick to thaw out the valve...so I know propane is cold on its own...and more difficult under extreem conditions...but essentially it is the by-product from gas wells and cheaper to buy and in abundant supply in Canada EH!!!
Alf S. North shore of Lake Erie

[Brian B-P]

The chart from Bryon is quite relevant: RV propane systems depend on the vapour pressure of the propane to push it through the regulator to the appliances, and so if the temperature is too low, you don't have usable propane, even though it hasn't actually frozen.

Reducing the pressure of a gas by passing it through a restriction causes it to cool, which is the effect which Alf described. In some situations this can be a real problem, with water from the outside air forming frost on the outside of the equipment, and perhaps even preventing mechanical linkages from working. If there is any water in the propane, this can freeze inside devices, blocking flow or interfering with their operation. The first year I had my Boler I ran the furnace to work inside early in the winter, and the regulator "froze up"... that would have been water, not propane, causing internal problems. It would take a huge amount of water in the propane to block the lines under the floor, but not so much to plug up the regulator.

When propane vapourizes, it takes heat, causing another problem with unwanted cooling. That means the remaining liquid is cooled, and thus propane tanks which are used in cold enough conditions form frost on the outside. Since the liquid propane is cooled, and cooler propane has less vapour pressure, eventually a situation is reached in which there is not enough vapour pressure in the tank to keep it flowing... even if it is warm enough outside for a reasonable pressure.

The reason for keeping the tanks full in a steady flowing situation is just to have more opportunity for heat flow through the tank walls into the liquid to keep up with the cooling caused by vapourization. Logically, a heater on the propane tank would fix this, but I don't know if there is a safe and approved device for that purpose. As far as I know RVs, even those which have heated fresh and waste water tanks, do not have heated propane tanks.

[Paul from NWOnt]

The reason for keeping the tanks full in a steady flowing situation is just to have more opportunity for heat flow through the tank walls into the liquid to keep up with the cooling caused by vapourization. Logically, a heater on the propane tank would fix this, but I don't know if there is a safe and approved device for that purpose. As far as I know RVs, even those which have heated fresh and waste water tanks, do not have heated propane tanks.

Thank you for giving me the explanation for my findings. This also explains why the 400 pound tank feeding my cabin doesn't stop working at low temperatures.

[Pete Dumbleton]

Umm, you guys are barking up slightly the wrong tree by looking at 'pure' propane. Typically, LP isn't just propane, it's often a mix of propane and butane (and other stuf like odorant and moisture and perhaps anti-corrosion oil in the big storage tanks). There are summer and winter blends and I'd presume there are even proportion differences for really cold temperatures.

People who fly hot air balloons have to plan their flights and fuel their tanks based on the expected temperatures aloft. Changes in plans or conditions call for changes in the fuel mix.

It's a common problem for SnowBird RVers from the Far North to leave Florida in early Spring with tanks full of 'Florida Sunshine LP Blend' and find out when they get near home too early that tanks with seemly lots of LP left inside act as if they are empty because the blend won't produce gas at low temperatures. I've never heard of the propane itself freezing, just the system not working because it won't produce usable gas. Or the system freezing because the regulator vent has collected water (improper mounting; vent should face down so it drains).

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

Here's an interesting article pointing out that freeze-up of gas lines in use is less likely with two-stage regulators than with the cheaper one-stage kind. Conversion from a liquid to a gas and then dropping the gas pressure takes heat and if too much is needed at one spot, the inevitable moisture in the system may freeze.

http://www.propane.ca/Resources/page10.asp

[Neil W']

When we owned our service station in the Okanagan in BC Canada we sold propane. I have on a couple of occasions seen the valves freeze when you're filling a tank on a winter day. I was always able to break them free and get them to close. The systems for appliances and vehicles are different. Appliances use gas and vehicles actually use the liquid propane. That is one of the dangers of overfilling tanks for our appliances, BBQ's etc. If you get liquid into an appliance meant for gas you have a serious problem. When the liquid changes to gas it expands approx. 20 times. In other words you have instantly 20 times the gas you require. Not pretty.

[Brian B-P]

To build on Neil's point...
A propane-fueled vehicle normally withdraws the propane from the tank as a liquid (which means the tank doesn't need to be supplied with the heat to vapourize the liquid propane), and converts it to gas in a vapourizer, which in turn gets its heat from engine coolant (which means the part which reduces the pressure doesn't risk freeze-up).

Even with liquid withdrawal the vehicle tank should still cool somewhat, because as the liquid is taken out some of the remainder must vapourize to fill the space, but this is only a small fraction of the propane (in the end, just one times the tank volume), so it doesn't need to absorb heat from the surrounding air at nearly the rate (per pound of propane used) as the tanks for our vapour-fueled RV appliances.