Frozen LP tank leaking??

richard5933 · January 02, 2018, 03:33:11 PM

Noticed a strange smell around our bus today while checking on it. Finally realized it was the smell of LP.

I checked on the tanks, which I'm positive I had firmly shut off before the recent cold spell. We have two horizontal tanks. One was about 2/3 full last time I looked. When I opened the cover on the tanks, the tank which was full has a coating of frost on the end of it, with a small pile of what looks like fine snow built up under the fill valve. Pressure gauge on both tanks now reads zero.

I'm assuming that the tank which was partially full leaked out.

Is this something that can be connected in some way to the sub-zero weather or just coincidental? Can tanks leak like this because of extreme cold? If so, any precautions to be taken?

First time having LP so I'm not sure which way to go on this. I'm guessing that one of my stops once the weather warms and I'm back on the road will be to the local propane dealer to have the tanks serviced, but I sure would like to know what's going on and what to expect.

eagle19952 · January 02, 2018, 03:37:32 PM

define cold.

propane won't gas/vaporize, below a certain temp.
at 30 below you can tell the content level 50 feet away by the frost line...

richard5933 · January 02, 2018, 03:50:25 PM

Quote from: eagle19952 on January 02, 2018, 03:37:32 PM
define cold.

propane won't gas/vaporize, below a certain temp.
at 30 below you can tell the content level 50 feet away by the frost line...

Been as low as -10 F this week. Today ranged from -4 F to a high of 5 F.

bobofthenorth · January 02, 2018, 03:53:08 PM

It definitely sounds like you have a leak - that's why they put the odor in there - so you will know when it is leaking. One possibility is a valve with a very slow leak which refrigerates the valve, shrinks it and effectively "opens" the valve further. Or a similar process on a fitting somewhere.

The "right" way to test it is to pressurize the system with compressed air and start looking for leaks. Personally I'd probably wait for warm weather, buy some propane and use the system pressure to test it. Either way you need to find the leak.

richard5933 · January 02, 2018, 04:10:12 PM

The system was filled in the warmer weather. Did a leak test and could find nothing leaking. I've been around the bus regularly and haven't noticed anything until this week when the smell became apparent.

The tanks are 30-pound horizontal tanks.

Can the extreme cold weather cause a leak to start that wasn't there during warmer weather?

richard5933 · January 02, 2018, 04:34:02 PM

This is what they look like right now. The top tank is the one that was partially filled until this week. There were absolutely no leaks that I could find prior to this.

I'm a little (okay, a lot) concerned about this. Not so much for the safety issues, as I know enough not to use the things until this is resolved. More so I'm concerned that if they need replacing I won't be able to replace with similar tanks. I don't see anything out there that's for sale now that has 30-pound capacity, is horizontal, and has the fill valve and access ports on the end. Maybe I'm panicking early - don't really know. But, I do know that I'll need to get these taken care of before hitting the road for our early season trips since the only heat is LP.

Richard
1974 GMC P8M4108A-125 (Current bus)
1964 GM PD4106-2412 (totalled Sept 2017)
Located in beautiful Wisconsin
KD9GRB

buswarrior · January 02, 2018, 04:37:43 PM

The cold works on propane pressure backwards:

"Propane pressure is directly related to the ambient temperature. For example, any volume of propane contained in a propane tank at 80 degrees Fahrenheit, the pressure is about 128 psi, at 50 degrees Fahrenheit, the pressure is about 78 psi and at zero degrees Fahrenheit, the propane pressure can reduce to 24 psi."

Looks pretty easy, haul those tanks out and trade 'em in for younger ones with fresh seals and fittings.

They look like regular forklift tanks?

happy coaching!
buswarrior

bobofthenorth · January 02, 2018, 04:59:56 PM

Its unlikely there's anything wrong with the tanks. They don't spontaneously develop leaks. The most likely culprit is the onboard plumbing followed by the tank valves and fittings. And yes, the cold could bring on a leak. Metal shrinks when it gets cold and once a leak starts the gas evaporating refrigerates the leak location which tends to make it worse.

richard5933 · January 02, 2018, 06:10:50 PM

This is the fill valve, and this is where the gas is leaking. Not sure how it's supposed to work, but right now the pressure is so low that I can easily push the center of the valve to release the seal by hand. Is there anything that keeps the seal pushed out other than the pressure of the gas? Is there supposed to be a spring in there? Either way, I'm wondering if the super low temps didn't reduce the pressure enough to cause this valve to let loose enough that the remaining LP seeped out. Maybe it wasn't as full as I thought it was. Either way, if it is the valve then I'm seeing them online for only about $15 each. Shouldn't be that tough to change out from the looks of things. Maybe someone else has had to do this?

Richard
1974 GMC P8M4108A-125 (Current bus)
1964 GM PD4106-2412 (totalled Sept 2017)
Located in beautiful Wisconsin
KD9GRB

lostagain · January 02, 2018, 06:43:16 PM

It would be easy to replace them with 2 upright 30 pounders that can be taken to the propane retailer with the towed for refills. It is on my list to yank out my built in tank and use the space for portable cylinders. Driving the bus to get propane can be a hassle. Taking the cylinders with the towed while camped without moving the bus would be much easier.

If you want to retain your current set up, just take it to someone that can replace the valves and re certify them.

JC

oltrunt · January 02, 2018, 06:44:21 PM

I'd go with changing out the tanks followed by a visit to the local fire house. The FD will have sniffers to spot propane leaks and probably will welcome the chance to train with them----of course if they find a leak they will insist you fix it and they'll want to check it again. Can't get any better (or safer) than that. Jack

buswarrior · January 02, 2018, 06:44:38 PM

Due diligence?

Local propane regulations?

Many jurisdictions have regulations regarding age since last pressure test and re-valved.

edit: Those are not built in tanks, they are portable tanks, same as go on forklifts, etc. important to not get vapour and liquid feeds mixed up, and must be mounted in proper configuration, up and down are critical for not feeding a slug of liquid into a vapour system. end edit.

Here in Ontario, beyond 10 years, vendor is not allowed to re-fill, and being portable tanks, they would have to be removed from the coach to be filled.

Of all the DIY available to do on a bus conversion, repairing a leaking propane tank may be better left to the pros?

happy coaching!
buswarrior

richard5933 · January 02, 2018, 06:54:57 PM

We've got a good propane vendor in town, and a visit to them is on my list. I'm seeing filler valves all over the internet, so I'm going to assume that in theory they can be changed. I'll let them advise the best way to go about this, if it's actually necessary. The fact that it was all sealed up tight as a drum till the recent cold snap has me wondering exactly what the cause is.

From what I've been able to read online about certification, etc., it seems that permanently mounted horizontal tanks don't have the same re-cert requirements as portable tanks. I'll confirm that at the propane store as well. They (I assume) will be able to at least start the conversation with the photos I've got and at least be able to give me an idea of what the options are.

I'll have them do the work if necessary. Otherwise I'm not afraid of doing basic work on LP plumbing if they say it's a DIY project. I'm hoping that they just let me know about some common weather-related problem or the like.

I thought about changing out the horizontal tanks for a pair of vertical, but that would require a lot more re-plumbing to move the regulator and get the hoses to the tanks. I'd also have to remove the tanks each time they needed filling. Since we do not have a towed vehicle with us, it won't add any convenience since our only way to get the tanks filled is to drive the bus to the filling station. With two 30-pound tanks we should be able to go at least through a weekend on a fill, so I'm hoping to fill the LP when we fill the diesel and/or when we empty the black tank.

PP · January 02, 2018, 07:34:46 PM

Richard, I had the same thing happen on the main tank in our coach last winter (horizontal). We only use the main tank as a backup and use the 10 gal portable as the main. There are 2 'O' rings in that filler valve and the inside one dries out and shrinks when it's old and cold. You can buy a kit for it--but don't waste your time. The valves just screw in and out and they're readily available at your LP dealer or Ebay. I bought one on Ebay for @14.00 free shipping. The socket to replace it cost me $28.00 bucks. Took all of 2 minutes to replace using teflon tape. You definitely need the right socket though because you can't get on it properly with anything else. And you're absolutely correct, horizontal tanks aren't included in the Overfill Protection Device law that requires 12 year inspections. We discovered ours was leaking when I was out shoveling snow. I thought the sewer had frozen and backed up. Unfortunately, we had an almost full tank (naturally) so what we did, and I DO NOT RECOMMEND THIS

is we switched to the leaky tank and used it for almost 3 months until it was empty. Not sure what else we could have done short of opening it and just blowing it off. Anyway, we're still here so obviously it worked for us. Of course, we didn't have any neighbors at the time so we didn't have to worry about smokers, etc.
HTH Will

Lifes2short4nofun · January 02, 2018, 07:41:56 PM

They do look like regular forklift tanks and can be easily replaced if needed.

When you tested the propane system did you do a pressure drop test?

It is where they pressure the LP system and have a pressure gauge attached and let it sit for certain time frame to see if there is even a small leak somewhere and the pressure drops on the system.