Another propane question?

[DonandBonnie]

Last week we had to return to the frozen wasteland of Ohio to take care of some personal business. Didn't want to come, but had no choice. Anyhow, one morning just after daybreak, Bonnie took the four legged fur balls out to do their morning constitutional. She checked the propane and announced that the gauge was red. Outside temp at the time was 14 degrees.

About three hours later after I have my morning coffee quota and got the kinks out of my bones I went out to change over the tank and remove the empty one. Lo and behold the gauge was green. By this time the temp had risen to the high 20's, pushing toward the freezing mark. The compartment door with the reported empty tank had been basking in the sun since it came up. I did see that there was a frost line about six inches from the bottom of the tank. I did ask Bonnie if she moved the lever. She said she hadn't. The tank provided propane for approximately twelve more hours before finally showing empty.

My guess is that as the tank emptied the contents froze in the cold temperatures and with no gas flowing, it changed over to the opposite take. My question is one that I hope I don't have to experience too often. Does the regulator have the ability to revert back to the original tank if it again senses a flow of propane?

BTW, after three nights of temps in the low teens and daytime temps in the 20's, the Big Shy was comfortably warm inside with no outside precautions, other than removing the water hose when not in immediate use. One 30 lb. propane tank lasted two days.

[DQDick]

I can't answer the question about whether the regulator will revert back or not, although I suspect it might if left in the original position. I can give you a clue as to why temperature affects tanks so much. This article speaks to home propane tanks, but the principle is the same and to a certain extent exaggerated for us since our tanks are much smaller. Here's the link: http://www.ehow.com/about_6659739_co...ne-tanks_.html

[WaltBennett]

Can't find it, but there is something somewhere that gives the temp. that propane itself will freeze and it's way below what you had. I had a tour in Fairbanks and many used propane for heat there. Only time people there worried was when the temps got below -30. The mostly empty tank lower pressure from the cold is what caused the regulator to switch over and then back when the tank warmed.

[DonandBonnie]

There is definitely a relationship between temperature, tank pressure/size, and propane flow that causes freezing. A while back before I understood how the regulator worked, I was boondocking and attempted to run the furnace and the generator at the same time. The outside temp wasn't as cold as here but the propane froze at about half a tank. The propane flow was too great for the system to handle. In my pre-MOC education days, when the furnace quit working, I would go out change over the regulator and then open the valve on the opposite tank.