Something died under my house. Worse in the bathroom. It’s not unusual about once a year for a mouse or rat to die in the walls of the bathroom. When I stepped outside onto the front porch, the smell was much stronger, but smelled more like propane. The grill is kept on the front porch. Convenient to the kitchen. Out of curiosity, I lifted the cover off the grill and heard a hiss. I discovered that the gas was turned on high somehow. It hasn’t been used in over a week and the smell just started today. I know I turned if off after using it last cause I run a brush over the grill right after turning it off. If I turn the grill off, the hissing goes away. The tank still feels about half full, so it somehow got turned on last night. Does someone have a warped sense of humor?

Why would the outside of the tank be wet on the upper part and covered in ice crystals on the bottom part?

No clue how it got turned on, but the icing is normal when those small tanks see a high draw. I tried to run a propane "torpedo" heater off a 20 pounder and got exactly the same effect on the outside of the tank.

As propane decompresses from a liquid to a gas, it gets REALLY cold.

Is the air temp close to freezing? My guess, the ice level is the level of liquid propane in the tank. The venting lowered pressure and reduced the temperature inside, like when you spray a can of compressed air, it gets cold!

quote:

Originally posted by wingspar:

Why would the outside of the tank be wet on the upper part and covered in ice crystals on the bottom part?

The propane in the tank is actually liquefied under pressure. It boils off to release gas. With your leak, the pressure was relieved, and the liquid propane boiled off quickly, sucking heat out of the tank, and the surrounding air, to do so - making the tank colder.

The ice line is probably the level of propane in the tank.

It turns back into a gas by 'boiling' into gas vapour. ... This, in turn, makes the gas bottle feel colder than the ambient temperature. The gas bottle gets even colder when you are actually using the gas. So, with sufficient humidity and when you are using gas very rapidly, condensation or ice can form on the gas bottle

From experiance the frost line is where the gas is. As the propane is used the stuff gets colder.
I have compressed cans of air to clean keyboards and such. As I use it the bottom gets cold. I had a frien that used canned air for a spray gun. He put the can into a cup of hot water to keep the pressure up.

Thanks for all the quick replies. Outside temp is currently 50 degrees and raining.

The part where the ice is would be the level of the liquid propane in the tank. I've seen this happen to a tank when it's used for a long period at a high rate. Mostly when a tank was connected to a portable propane heater that was cranking out heat.

I turned the grill off about 15 minutes ago, but left the tank on. All the frost is gone leaving a puddle of water on the front porch. I just turned the tank off and put the cover back on. It had to have taken quite an effort to turn the gas on at the grill. Probably going to leave the trail cam out there for a while.

Seems interesting for sure, I haven't used propane in a long time, but the tanks do make nice targets for 460 S&W, 50AE, etc...

Have you noticed that when the tank is filled it gets warm or hot? Compressing a gas increases the temperature; expanding a gas decreases the temperature (the principle of air conditioners, among other things). Rapidly expanding gasses cool rapidly. On a day with high humidity, water condenses on a surface that's cooler than the dewpoint of the atmosphere (the temperature to which the air must be cooled to be 100% saturated). You see condensation on the top half, and frozen condensation where a rapid temperature dropped as the tank emptied and the vapor pressure in the tank decreased.

https://www.grc.nasa.gov/WWW/K...irplane/glussac.html

When the Thresher submarine went down off the coast of Cape Cod in 1963, the Navy found in the accident reconstruction what you found on the propane tank.
When Thresher did an emergency blow, the valve oriface the compressed air flowed through was too small and the air had too much moisture in it causing the valves to freeze shut.

I can’t say how your gas got turned on. But you should be turning it off at the propane tank first then the grill. I wouldn’t leave the propane tank valve on unless you are cooking off and on in a few hours time.

My sister was nearly killed from the cat walking on the stove top in the middle of the night and turning the gas on.

Got any critters in the yard?

I’ve never noticed a propane tank getting warm when it has just been filled.

I’ve had this tank sitting on the front porch for I don’t know how many years. More than 15, that’s for sure, and I never turn it off at the tank and have never had a problem, except the time I did leave it on low and forgot to turn it off. Didn’t discover that till the next time I went to grill something.

There is a tin foil drip pan under the grill that mice or rats will get into once in a while and make a huge mess. They will rip the pan into pieces and throw them all over the place causing grease to drip all over the place. As for turning the grill knob to on would seem to be impossible by any animal. I suppose it’s possible for a mouse to step on it right and spin it, but it would have to spin a long ways. I’ll see if I can remember to take a photo of the knob tomorrow.

PV/T = (Pressure x Volume) / Temperature

As pressure and volume goes down, temperature has to go down. Lowering temperature causes the condensation to form first. As the temperature continues to go down, the water freezes starting from the bottom.

quote:

Originally posted by wingspar:
I’ve never noticed a propane tank getting warm when it has just been filled.

Correct. Propane tanks are filled by transferring liquid propane from one container to another. Gas pressure is vented as the liquid goes in. There is no compression and no heat generated.

You're smelling propane in the bathroom/house?

Be careful!

Do you have a crawl space or basement?

Propane is heavier than air.

If it's settled in a low spot in the house, it could explode from any sort of ignition source, any spark.


EDIT: GET OUT. CALL 911. Request emergency electrical cutoff by the power company at the pole before it gets to your house!

I'd get All the power cut, out away from the house. Open crawlspace, basement, doors, windows. Get the hell out! Call 911

I’ll admit, it got dangerous in the house for a little while and I may have been a little nonchalant about it at first. Once I realized what was going on and I got the propane shut off, the house has been aired out. I’ve since cooked dinner with a propane supplied gas stove. How it got to the bathroom, I’ll never figure it out. Must have got under the house and the wind carried it back there and it smelled like something died in there. Didn’t smell like propane at all, but once the kitchen and living room started smelling like propane it confused me at first. Where was it coming from and why did it have a propane smell to it. I have the tank shut off now.

I'm confused a bit. If you mean that the propane tank valve was open and the grill valve was also open. Then of course you have propane wherever you have air movement. And the smell added to propane is detectable at very very low levels (that's the reason they use it). But (and I'm saying this as a firefighter) anybody who doesn't shut off a gas grill tank (not the valve on the grill) is really not paying attention to the risks.