Interesting problem with propane system

[NMWildcat]

Thought I would share this problem and solution as my research didn't find anyone with a similar experience and this was a first for me.

Four days into a boondocking trip our Suburban stove stopped functioning due to no propane coming through any of the burners or the oven. All other propane appliances worked just fine (refrigerator, heater, water heater). I assumed the small regulator in the stove top before the manifold had stopped working and I would replace it when we got home. The flame on all the stove burners had been pulsing at an increasing rate for the last few months so I attributed this to the same regulator.

When we got home, I removed the supply line (after turning off propane) from the stove regulator to test if propane was making it that far. I heard a liquid gurgling sound from the copper line. Not good. I went below the RV and found the flex line that connected the copper stove line to the black pipe main propane line. When I disconnected the flex line about 2/3 of a cup of yellow, oily liquid came out (not water). This concerned me, so I disconnected the main supply line at the main regulator, and all the individual flex lines for the other appliances from the black pipe supply line. Then I blew out the black pipe line with an air compressor and got a very small additional amount of the liquid out.

When I reconnected everything, low and behold, the stove worked just fine and the burner flame no longer pulses. Evidently the liquid had built up enough to fully block the supply line to the stove. No idea why it didn't affect the other appliance lines unless the RV was tilted slightly to that side. Stove line is on one side of the RV and the other appliances are on the other side off of a tee in the main supply line.

Now the question is, "Where did that liquid come from and how do I prevent it from accumulating again?" I have read many internet ideas on where the liquid comes from but am not convinced any of them are correct. Next time I go by our propane distributor I will ask them.

Our RV is 10 years old so did that liquid accumulate over all that time, or did a recent event (refilling propane tanks) cause it? I don't know.

Happy RVing!

[MR.M]

That liquid came from the propane . bottom of the barrel stuff they put in to create the rotten egg smell in propane as it is odorless to start . So where you get it filled they may have been sucking from a low tank and that oily yellow stuff will for sure clog things up

[boondocking]

There is a very tiny amount of oil left in the propane when it is processed. Over a period of time it will condense out and accumulate in the lines and regulator.

[NMWildcat]

Thank you both for the comments.
What you say makes the most sense of what I have read. I have seen very small amounts (a drop or two) of the oily liquid when replacing hoses, but never almost a cup. Live and learn.

[cmulvey]

All good info. Thanks for sharing!

[eric1514]

Do you have any plans for cleaning out the lines? Just curious as I wouldn't know what to do short of removing stuff and blowing compressed air through as much of the system as I could.

[NMWildcat]

Originally Posted by eric1514

Do you have any plans for cleaning out the lines? Just curious as I wouldn't know what to do short of removing stuff and blowing compressed air through as much of the system as I could.

Yes sir. I blew out the main supply line (low point black steel pipe) from the main regulator all the way back to where the flex lines go up into the RV after disconnecting the flex lines.

[NMWildcat]

I am going to ask my propane guy if I need to worry about the tanks themselves. They are about due for a recertification anyway.

[jimmoore13]

Hmmm...
Learn something every day.
Great info and great thread.
I'll have to blow out my propane plumbing once in a while.

[chriscowles]

Originally Posted by NMWildcat

Thank you both for the comments.
What you say makes the most sense of what I have read. I have seen very small amounts (a drop or two) of the oily liquid when replacing hoses, but never almost a cup. Live and learn.

Did the liquid smell? If it had anything to do with mercaptan I'd think it would be nausea-inducing.

[NMWildcat]

Originally Posted by chriscowles

Did the liquid smell? If it had anything to do with mercaptan I'd think it would be nausea-inducing.

Definitely had the propane smell, but not overpowering. The dirt where I dumped it will smell odd for awhile

[jwfrede]

The oily stuff was probably oil, compressor oil. It's not likely to be heavy hydrocarbons from processing of the gas.

[boondocking]

Originally Posted by jwfrede

The oily stuff was probably oil, compressor oil. It's not likely to be heavy hydrocarbons from processing of the gas.

It is oil that is within the propane itself, it is not compressor oil.

[cariboo camper]

I had a similar problem Was told by a friend in the propane business that the oily residue you are getting is in the propane and is usually pushed through the lines and burnt off. If you have a large diameter pipe in in your system the propane will not flow fast enough and will deposit the oily substance eventually clogging the pipe. Not sure but I think he may have said the residue was in fact capstan.

[cariboo camper]

Interesting! you are the one usually offering valuable help to others. Enjoy reading your comments helping others, keep up the good work.

[Attila the Pun]

That stuff is mercaptan - or methanethiol (CH4S) - close relative of skunk spray. It's added to natural gas and propane because they are naturally odorless.
40 years ago I was working in downtown Cincinnati when a several-block area was evacuated because of a STRONG odor of natural gas. They suspected a major gas-line leak somewhere. Turned out that the leak was from a 55-gallon drum of mercaptan in the basement of Cincinnati Gas & Electric.

[NMWildcat]

Originally Posted by cariboo camper

Interesting! you are the one usually offering valuable help to others. Enjoy reading your comments helping others, keep up the good work.

Thank you! This is a great forum with some very helpful folks.
And your comment about the large propane pipe being a collector makes perfect sense. In my case, the larger black steel pipe is the lowpoint of the system and where the stove supply attaches is at the end of the longest run. And this is where most of the oily liquid was. Also, the copper stove supply line had a section that had a parallel dip in it (not a straight run down to main supply) that held liquid also.
On a side note; Before testing the propane lines I called Suburban with the stove model number to get the correct stove regulator. They told me I had to buy the entire manifold which included the regulator. I did find the regulator separate on Amazon although it wasn't an exact match but said it would work with my stove. Glad I don't have to replace anything!

[Chuck_S]

Recertification may not be a real economic benefit since new tanks are maybe $50. Not sure about the "exchange" places I admit to never used them.

https://www.phmsa.dot.gov/sites/phms...pane_en_v3.pdf

-- Chuck

[NMWildcat]

Originally Posted by Chuck_S

Recertification may not be a real economic benefit since new tanks are maybe $50. Not sure about the "exchange" places I admit to never used them.



https://www.phmsa.dot.gov/sites/phms...pane_en_v3.pdf



-- Chuck

Where I fill my tanks locally they will recertify the smaller (20lb - 40lb) tanks for free if you also fill it there. They also make up pigtails and crossover hoses that actually last and are cheaper than those bought in RV stores

[glen1971]

I've seen that oily residue a fair amount at work. Usually in low flowing propane devices. I had it once in my Camp Chef stove regulator. After I replaced it, I left the old one in the back of the truck until I made sure the new one was good. Bad move, as the sunlight warmed up the regulator enough and as soon as I saw what was leaking into the truck box, I knew the problem. Got it and bagged it before too much liquid leaked out.

If I remember right, it is about 15mL pee 1,000 liters that is added. Google says it is about 1-2 pounds of mercaptan per 10,000 gallons of propane.