Propane smell?

[twindman]

I have gotten a rotten-egg/sewer smell twice inthe last month. Each time a tank was empty. When I shut it off and switched the changeover valve to the other tank the smell went away.
A couple of questions - I thought about 10 years ago they changed the smell to something else?? Right?
Also, I thought propane was heavier that air, so would settle down lower. So how does it end up in the living quarters?
Thanks all.

[rohrmann]

They have always used Mercaptan and still do, and that is the odorant you smell. Sometimes there is an excess amount of that odorant,which is an oily substance, that accumulates in the cylinders over time, and the smell will linger even if there isn't any actual propane present.
Yes, propane is heavier than air and does settle to the floor, and inside the rig, you have a gas appliance that can leak, and that's why you have a propane detector inside and mounted low near the kitchen.
If you are smelling sewer gas, that is not the Mercaptan, and you might have another problem related to the septic system in the rig.

[twindman]

I thought it was sewer gas, but each time I turned off the propane it went away. Still can't figure how the smell gets into the coach since the crossover pipe is below the bed.

[rohrmann]

Now, this I'm not sure of, but propane IS heavier than air, but Mercaptan might not be heavier, so I would be diligent about making sure you don't have even a slight leak. If you haven't replaced the pigtails going to your cylinders in a while, that would be a place to check. Also, there is an O-ring in the opening of the valve where you connect the pigtail to the cylinder valve that could have a crack that could cause a leak. The soap test should show a leak.

[Lee-CI]

Hauled transport loads of propane in a prior lifetime. Propane is a naturally odorless gas. The odorant additive is so powerful it takes but 10 ounces to treat 10,000 of liquid propane. Mere residue in crossover piping can make for an overpowering smell.

Really good advise from Bob in the above post.

[BB_TX]

Propane is heavier than air and will settle to lower surfaces in still air. But it would not take much of a breeze to stir that gas up enough to move upward.

Shutting off a tank would lead you to think it had to be in the outside plumbing as the inside pipes should retain normal pressure. And a leak should be more apparent at higher pressure than low.

Only leak I ever had was the little red regulator valve. And spraying it with soapy water did not show any bubbles. But finding no other leak source, and reading about others with that valve leaking, I took mine off and found residue around the very small vent hole underneath that valve where I could not get enough soapy liquid on to bubble. Replaced it and no more odor. Don't remember any odor inside though.

[twindman]

But the strange point not answered above - this has only happened when the tank is (going) empty. I remember reading something about this (the cause) but no details.

[GregN]

A chemical is added to propane to give it that distinctive “gas” odor. Some of the chemical condenses out of the propane and collects as a liquid at the bottom of the propane cylinder. When the gas is low in the tank the reduced pressure causes the odorant to evaporate making the gas smell stronger than usual. The extra chemical doesn’t burn completely with the propane so you will smell it when a stove burner is lit.

[Bourbon County]

Can't make a correlation with swapping tanks, but about the only thing inside the coach with a gas connection is the cooktop/oven.

I have a version of this in a different brand I bought for checking some gas piping in my house some time ago. I've since started carrying it in the RV. There are several different brands in a wide price range. They do work on LP and are very sensitive; you can see for yourself with a Bic lighter. Much quicker than soap bubbles.

https://www.amazon.com/Detector-Port...32216528&psc=1

[Foldbak]

Originally Posted by Bourbon County

Can't make a correlation with swapping tanks, but about the only thing inside the coach with a gas connection is the cooktop/oven.

I have a version of this in a different brand I bought for checking some gas piping in my house some time ago. I've since started carrying it in the RV. There are several different brands in a wide price range. They do work on LP and are very sensitive; you can see for yourself with a Bic lighter. Much quicker than soap bubbles.

https://www.amazon.com/Detector-Port...32216528&psc=1

A lighter???

[Bourbon County]

Originally Posted by Foldbak

A lighter???

Didn't explain that so good did I? What I meant was if you push the trigger on the lighter gentle enough to allow some gas to escape without actually lighting for just a fraction of a second, the sensor will pick that up. Not in the owners manual, just something I did to test it.

[TenOC]

Check your battery. A battery leak fluid smell the same.