Third Failed Propane Regulator

[Jeffrey Lee]

This LP regulator is installed on a chassis-mounted propane tank & system on a small campervan. The original regulator was replaced in 2004, which then failed and was replaced in 2017. I just noticed this 2-year-old reg. is now leaking.

The first replacement was a Marshall brand, the most recent a Cavagna brand, and the typical failure mode is that they spontaneously begin leaking the brown, oily fluid often known as 'onion oil,' added to LP as a safety odorant. They usually leak from the second-stage diaphragm housing, though my autopsy on a previous reg. revealed a brown, goopy mess inside both diaphragm housings. The rubber diaphragms themselves appeared to be intact, and continue to function, but I am concerned that this indicates a failure.

Before I take it to a local RV specialist, has anyone here seen similar failures? Appreciate any ideas on the cause!

 

[tx2sturgis]

Quite possible that the frame mount tank is contaminated with that residue, combined with rust.

It's coming from somewhere!

How old is the tank?

 

[Jeffrey Lee]

Tank is 30+ years old. When the reg was replaced in 2017, the tank was declared OK to continue using, but was not flushed, etc.. Might be the next step.

I've also read that when driving with the main LP valve on, the jostling of driving can allow liquid, rather than vapor, propane into the supply lines and regulator, and eventually lead to fouling. Ever heard of this?

 

[bullfrog]

I have always turned off the main tank valve on my motorhome when traveling just as a safety precaution and never had a failed regulator in over 15 years so maybe your thinking is correct.

 

[JD GUMBEE]

The trick for mine was filling the tank with less gas.
We were overfilling the thing and it raised holy hell with regulators.

Kudos to the "leave it off till we stop for the night" advice!
Settling before using makes total sense.

 

[highdesertranger]

the odor they add is colorless, propane is colorless. so that color is something that is not supposed to be there. highdesertranger

 

[XERTYX]

I have no experience with propane other than I turn it on and it works or I turn it on and it doesnt. I know HDR must be right that its colorless but I know it leaves a residue. I've watched videos on home LP tanks being converted to a smoker grill and it will draw flies for ages after it's been opened. It has to be washed out with soap and water to proceed from that stage.

I think the rust idea is in line with what's going on. A 30 year old tank possibly covered in rust on the inside, oil that I'm told they add to lubricate seals, and possibly the odorant combined to make sludge that fouled the diaphragm.

I assume a 30 year old tank has been filled multiple times at hardware stores etc as you cant exchange one that old. So a flush should help. Remember if there is a minuscule amount of oil added but it's been refilled regularly over 30 years there could be old and new blends of oils/chemicals residue in there that never were burned built up over 30 years.

My advice would be to try a new tank, if the diaphragm did fail consider replacing the lines eventually. If it made it past 2 diaphragms maybe your lines are contaminated.

Just the 2 pence of an uneducated speculator. Take it for what it is. Or dont.

 

[highdesertranger]

it's a permanently mounted tank not a portable. highdesertranger

 

[Zoomyn]

"Often seen in Vintage Airstreams"

- works perfect for bunches of seasons but each delivery or refill adds in more liquids, poor quality propane from low-volume distributors filling from the bottom of their holding tanks, and continuous cold-weather use all gangs up to leave that oily crap behind so after eleventeen years the crud starts appearing. Some of the 30/40 pound tanks can get a quart or more of that noxious crap holding in them.

Probably more cost effective to replace the lines involved and drop the tank to solvent wash the inside if it is a critical device, though $35 a pop for a new regulator every two or three years is pretty cheap, as long as it isn't shutting down heat and hot water in bitter cold weather.

Residential gas supplies have a stubbed in 'T' immediately before water heaters and furnaces or other high-draw devices that allow foreign material creeping along the pipes to settle out before it gets to the burners, there is a cap that is removable to drain/dump gunk out at the lowest point of the 'T'. Plumbing in one of those before that regulator could stall forced repairs for quite a while.

 

[XERTYX]

it's a permanently mounted tank not a portable.   highdesertranger

Ah. I didnt realize. As I've said I'm a novice at propane. As well as RV architecture X2.

...so after eleventeen years... 

Residential gas supplies have a stubbed in 'T' immediately before water heaters and furnaces or other high-draw devices that allow foreign material creeping along the pipes to settle out before it gets to the burners,

That made me smile. Haha. Eleventeen years. I've never heard anyone else use that phrase other than myself.


So just before the appliance a T with a capped downward facing pipe to act as a trap for oil, metal shavings, fruit bats, or anything else that's creeped in? That's brilliant. 


I've never designed anything using propane more elaborate than disconnecting and replacing a 250 gallon residential propane tank with a 20 lb grill tank. That was all plug and play. 


Sorry not trying to stray from topic but if I bought a vintage motorhome i might need to understand the mechanics here if i find myself in the same position.

 

[Jeffrey Lee]

Thanks, all.

I have a spare reg. here so will swap it in, and will no longer drive with the main valve on, to see if that makes a difference in its longevity. Otherwise, might be time for a full flush and purge of the tank.

BTW, it seems there are more theories regarding the source/cause of this brown oil than who shot JFK:

https://www.rv.net/forum/index.cfm/fuseaction/thread/tid/23677889/print/true.cfm
https://yarchive.net/car/rv/propane_tank_oil.html
http://www.irv2.com/forums/f59/learned-something-new-today-about-propane-2532.html

 

[XERTYX]

I only read part of the first thread. Haha.

The solution is very simple. Just unhook everything and test your system with litmus paper to determine if it's an acidic substance.

Haha. Oh lord. Reminds me of when the Villian told James Bond the simplest way to disable an alligator was to simply pull out all of its teeth. XD

 

[Doubleone]

You could plumb a liquid trap into the pipe before the regulator as described above. Pipe traps are often used in shop air lines to separate air/water. Basically it has a 90º turn with a vertical member that allows air to pass but gravity pulls out any liquid to the bottom leg. Shops have a valve at the bottom leg to flush out the collected water. Just consider the differences between air and propane... Air is at 125psi and propane is at about 300 psi and it's flammable. If air leaks out it's a nuisance, if propane leaks it's a situation. Adding some pipe length would also help in vaporizing any migrating propane liquid too.