Strong Propane Smell from Furnaces when Tank is Low

[Jim Stoltz]

Is there a scientific explanation for this? When my RV's propane tank is nearing empty, I get a strong propane smell from the furnaces. It does this whether I'm using the frame-mounted tank or the 20 lb. cylinders. When I first noticed it last year, I nearly went nuts looking for a non-existent leak.

I was just out there goofing around with a couple of things and smelled propane. Checked the onboard tank monitor and saw it was nearing empty. Switched to a fresh 20 lb. cylinder and it's okay again - no smell. 

Is this "normal"?

[Jim Stoltz]

I should mention that when I get the smell, the furnaces are still generating heat. They're not "out" and blowing propane around with the blower fan.

[Lakota Wolf]

The phenonomen of the smell is the additive they put in L.P.G. the old rotten egg smell.... When the tank nears empty the settled additive along with the actual **liquid propane is fill the gas lines. L.PG. is in the tank as a liquid *Gas. (Chemistry class) liquid gas. The gas is is heavier toward the bottom and flows heavier thru the lines and that pungent smell (safety additive) is more noticable. ( The science channel had an article on the same issue your having.. But this was on a cabin cruiser boat.It was also mentioned on the show that your fixing to run out of propane.

[Jim Stoltz]

Thank you! Great explanation. No need to worry I guess.

[david craft]

Ethyl mercaptan. One pint per 10,000 gallons LP. Smelliest stuff on the planet they tell. Accumulates in older tanks in the oil left behind from evaporated LP. You can rinse the tank with alcohol and get some relief, though Im not sure how much.

[Jim Stoltz]

It's not worth all that so long as I know what it is. Thanks!

[Lakota Wolf]

Yea mercaptan, which I think they got from my son in laws socks. Usually when your tanks are refilled the *Purge helps remove some of it. But as long as it don't stink when there is gas in there I would use the stink as a warning your running low ( or my son in law is near by ).

[Jim Stoltz]

Yeah it only stinks when it's running low. I'm going to invest in a propane detector before next season anyway just to be safe. In the meantime, I like to run the heat when I'm tinkering out there. When I smelled that smell yesterday I checked the gauge and sure enough it was almost out. It usually starts to stink below 1/4 tank. I hooked up a 20 lb. tank and the smell went away almost immediately.

[Manny]

Hi Jim,

Did You ever figure it out. I could tell that no one here could understand what you are talking about or asking about. I have the same problem. It's only when there is like a gallon left and its inside the RV which makes one wonder why inside rather than outside. But it is perfect when a new tank is in...... I have a few Ideas but I want to see if you figured it out yet

Manny