Slight smell of gas when Fridge running.

[ROBFP]

Hi, we have a 1984 Dodge Roadtrek 190 van and everything was going great, till we recently ran out of gas. Ever since then we have a very slight smell of gas. If we turn the fridge off but leave the gas still on then the smell goes, so we have narrowed it down to coming from the fridge when it is running. The fridge is a Dometic propane only fridge and we normally leave it running all the time but have now started switching it off a night to be safe.

When the gas tank was filled I asked the person filling it how will he know when it is dilled and he said the pump will stop. Th last and first time we had in filled in Canada the person open a little value first and filled till gas came out of this and then stopped. If i now open this value gas comes out. I think the tank has been over filled, but cant think why this would result in a smell of gas, unless i has broken the regulator. Any ideas?
Thanks from a Brit in the US.

 

[Chet18013]

Actually the little valve is at about the 65% level of your tank. They fill the tank with liquid propane and open this valve. It will hiss as the tank is filled and when the gas reaches that level, liquid propane starts to come out. You see this as a cloud that immediately turns to super cooled vapor. It is at this level they stop filling your tank. They must leave about a 30-35% void volume in the tank for the propane to vaporize, and your stove, fridge and heater use the vapor to burn. At no time is liquid propane ever allowed to be fed to your appliances. If the tank was over filled, opening the little vent valve would result in liquid coming  open and flashing into a white cloud as is condenses the moisture in the surrounding air.

Are you sure it is propane gas you are smelling? When the refrigerator cooling coils start to fail, you will get an pungent odor of traces of ammonia. Many people will mistake this for propane. If your fridge starts to get warmer and you have to keep turning the cooling level dial to a colder setting, this is a sign the coil is failing and not a propane leak. You will especially notice the odor when you open the fridge door after it has been closed for several hours.

 

[Larry N.]

Hi, we have a 1984 Dodge Roadtrek 190 van and everything was going great, till we recently ran out of gas.
...
Thanks from a Brit in the US.

You might note that "run out of gas" in the U.S. generally means running out of gasoline (petrol). We usually talk about propane or LP gas in your case. I mention this only to minimize the chance of mis-communication.

 

[Gary RV_Wizard]

I think Chet is on the right track - the smell is unlikely to be propane. Turning the fridge off only stops the burning of the propane. If there was a leak at the fridge propane line, it would continue whether the fridge is on or off. I'm afraid your fridge has an ammonia leak and will soon stop cooling.

As for the tank, Chet correctly described the operation and use of the little valve. The ASME-certified tank in your coach also contains an automatic shutoff mechanism that prevents it from being filled to more than 80% of capacity, which is the maximum allowed by law and the tank specs. The propane fill person is not supposed to rely on the overfill device when filling the tank, but many do.

 

[ROBFP]

Thanks a lot for the replies. It wasn't ammonia smell, as we have had this happen before, much to my expense of having to purchase a new fridge. The strange thing is we have now turned the fridge down and the smell has gone, the freezer side is still freezing though and i can still have a cold beer
On this Roadtrek model it doesn't vent the hot air to the outside of the van as all newer ones do but has a vent on the kitchen worktop, so we do get heat coming inside the van along with a hot smell when first starting the fridge.

Could it be the jet needs replacing and not burning all the gas that was going to the fridge? But i suppose it isn't really to much of an issue now as the smell has gone.

Once again thanks a lot for the replies, it is so good to be able to ask for advice and help on this forum. Just hope i can help someone on here who is travelling in Europe and repay the favor.

 

[ROBFP]

I tested the little valve and i do get propane coming out still, so would it be a good idea to find a very open space turn everything off and then open the valve till the propane stops coming out? Or now leave it till the fridge has burnt it off, i do run the fridge 24/7 on propane.

 

[Lou Schneider]

Propane gas itself is odorless, so during processing they add a small amount of mercaptin oil to it to give it the odor you can smell in case of a leak.

Over time, some of the odorant settles out of the liquid propane and collects at the bottom of your propane tank.

When you ran the tank dry, the last of the propane gas had an unusually heavy charge of the odorant and it settled along the plumbing in the system.

That's what you're smelling now - burning propane gas with too much mercaptin oil in the mixture - and you'll continue to smell it for a while until the oil deposited on the surface of the gas lines is reabsorbed by the fresh gas flowing through the plumbing.

BTW - it's highly unusual for a refrigerator to be vented to the inside of an RV.  Be sure to keep a window or vent cracked open to avoid carbon monoxide buildup inside the van.

The check valve on the side of the tank is not an overpressure valve.  Propane is dispensed and stored in liquid form and boils into gas inside the tank, forming a gas bubble above the liquid.

When you use propane, you draw from the gas bubble above the liquid propane in the tank.  This reduces the tank pressure and more liquid boils off to take it's place.

The problem is liquids are not compressable, but expand and contract as the temperature changes.  If your tank is filled more than 85% with liquid propane, there's not enough room for the liquid to expand into when the temperature rises.

That's the purpose of the overfill valve.  It's inlet is at the 85% level in the tank.  You'll always get clear propane GAS if you crack it open because the tank is pressurized.  But if the level of liquid propane is above 85% it's inlet gets submerged and you'll see LIQUID propane when you open it.

Liquid propane comes out as a dense white cloud and you may see some liquid droplets in it before they vaporize.

 

[livingthedream]

When my tank gets overfilled the pressure builds when driving. When I stop I can see propane be vented from the safety release valve on the tank. I smell this in my RV in weird places but usually only after I was driving.

 

[Gary RV_Wizard]

I tested the little valve and i do get propane coming out still,

If liquid propane, yes you can bleed some off in the manner you described. If gaseous, that is normal and do not bleed any further.

 

[ROBFP]

Thanks for all the replies and info. Sorry for the late reply but havent had intermet access for the last few days.  We have Been in the Volcanic National Park.
I am really confused by this fridge as it does smell sometimes and other times there isnt a smell, but as i only have two weeks left in it, we are now switching it off at night and just running it during the day.
We already have a carbon dixoide detector, so feel happy about the exhaust gases ( these do vent outside)

 

[ROBFP]

Did vent the tank and it was coming out as a liquid and dropping on the ground but didnt keep going till gas came out as too be honest it worried me a bit too much.

 

[Gary RV_Wizard]

It's not a problem to vent it as long as there is plenty of ventilation and no sparks or flames near by.

 

[Frank Hurst]

Be careful when handling propane gas because of the danger of being "burned" by the cooling effect of propane gas on bare skin.