Bounder: Propane leaking

[mojoracing]

My daughter called this evening and told me that when she went outside she smelled propane and heard something leaking. She opened the compartment where the propane tank is and could tell the hissing was coming from the general area of the regulator. We just had the tank filled a few days ago and had used very little propane since. The day we had it filled, the outside temp was in the 40s. Today the temp went up into the 70s and with the sun on that side of the motorhome, im sure the tank temp was higher than that. Could it be that the gas expanded and the regulator or something in the vicinity is allowing the access to bleed off or has my regulator went bad? She has shut the tank off for now and the leak has stopped.

[malexander]

The regulator actually does have a vent on it. Although, the temp change should "blow" the relief valve on the tank itself. It normally is just a quick spurt though. YMMV

[twinboat]

The regulator vent is to let atmospheric pressure work against one side of the diaphram, while gas works against the other.

If gas is coming out the vent, the diaphram in the regulator is bad.

[KIX]

If the leak was coming from the regulator vent then the diaphragm inside the regulator has a hole in it. In that hte leak stopped when the tank valve was turned off the leak may well be fromthe regulator. You could mix up some soapy water, turn the tank valve on and soap around the area of the hissing to pinpoint the leak. Just make sure there are no sources of ignition nearby.

[mojoracing]

Not sure exactly where. She didn't pop the plastic cover off that is over the regulator. I was just hoping expansion was causing it to release the extra. I wasn't there when they filled it so I'm not sure if they filled it to 80% or what. Not sure you can even fill it to 100%. Even if they filled it to 80%, I think that such a great temperature variance could cause it to expand the extra 20%. She's going to check it in the morning when its cool outside and see if it still leaking. If it is I will have her pop the cover off and try and pin point where the leak is coming from. I'm surprised that these things go bad like that.

[twinboat]

The safety valve that would let off "overpressure" will not be controlled by the valve. It has to be on the tank itself to work.

[KIX]

Originally Posted by mojoracing

Not sure exactly where. She didn't pop the plastic cover off that is over the regulator. I was just hoping expansion was causing it to release the extra. I wasn't there when they filled it so I'm not sure if they filled it to 80% or what. Not sure you can even fill it to 100%. Even if they filled it to 80%, I think that such a great temperature variance could cause it to expand the extra 20%. She's going to check it in the morning when its cool outside and see if it still leaking. If it is I will have her pop the cover off and try and pin point where the leak is coming from. I'm surprised that these things go bad like that.

Temp extremes (40° at fill and 70 later) is why the tank is only filled to 80%. Also, your tank on your 2014 MH has an automatic "stop fill" incorporated into the fill valve

[mojoracing]

No, I understand why they only fill to 80% but do you think that temperature difference would cause it to expand enough for it to release pressure?

[malexander]

Originally Posted by mojoracing

No, I understand why they only fill to 80% but do you think that temperature difference would cause it to expand enough for it to release pressure?

Highly possible.
I fill my own tanks at home off of my 500 gallon tank. I store them inside.
If it's cool outside when I fill them, then it warms up during the day, they will vent some. I know because I can smell the gas when I go into the hangar.

[KIX]

Originally Posted by mojoracing

No, I understand why they only fill to 80% but do you think that temperature difference would cause it to expand enough for it to release pressure?

I don't think so. If shutting valve off stops leak then filling tank is not the issue. You said shutting valve off stopped leak.

[malexander]

Originally Posted by KIX

I don't think so. If shutting valve off stops leak then filling tank is not the issue. You said shutting valve off stopped leak.

May just be coincidence that the diaphragm in the regulator ruptured when turning the valve back on after the filling.

[mojoracing]

Your right, I was dead set on thinking the pressure relief valve would be part of the regulator or at least down stream when in fact that would make no sense. If the tank pressure rose, it would have to vent whether or not the valve was open. That being said, it has to be the regulator (most likely) or something downstream from the valve. Thanks, had a brain fart there.

[KIX]

Originally Posted by malexander

May just be coincidence that the diaphragm in the regulator ruptured when turning the valve back on after the filling.

That would be a likely time for the diaphragm to rupture.
You probably also have a 2 stage regulator. The high pressure side would likely give an audible sound if ruptured vs. the low pressure side.
One other potential source is the valve stem although they're usually not loud enough to hear "hissing". If you find it is leaking (with soapy water spray) it will likely stop when valve is back seated or closed.

[malexander]

2 stage regulators really aren't that common on RVs, are they?