LP tank valve (VALVES) question.

[ClydesdaleKevin]

Hey guys.  On our new (to us) Itasca Suncruiser, the propane tank is HUGE.  100 lbs I believe.  I think that it is that large because it is a diesel pusher, and the generator runs on propane. 

The propane tank has TWO valves, both of which were closed when we bought the rig.  I went through the stack of manuals that came with the coach, and I couldn't find any info on the two valves, not even the Winnebago manual specific to this model...it just gave me generic info that I already knew.

One valve says "Vapor," and the other valve says "Liquid."  I opened both of them, and all of the appliances work, and the Onan propane genny, which only has 86 hours on it, purrs like a very quiet kitten.

But I don't know if I am doing it right and safely!!!  Anyone know anything about these dual valve tanks, and what each valve does?  What exactly does "Vapor" vs "Liquid" mean?  I have no idea at this point...lol!

Kev

[HandyDan]

My old Holiday Rambler had the dual fuel option from the factory.  It has a huge LP tank, also.  The motorhome engine could run off liquid propane much like it would gasoline, while the range and oven ran off vapor.  I would surmise that your generator takes liquid LP. 

[ClydesdaleKevin]

Thanks Dan!  That was what I was thinking from the research I gleaned so far.  So should I close the "liquid" valve when not running the genny?  That is another good question...lol! 

Kev

[M500-Rich]

Kev my Dad has an 84 Cosmopolitan Pusher I have been maintaining for years. We never turn the liquid valve off unless we have to pull the Jenny for some major maintenance. He quite frequently just hits the switch and runs the ac units running down the highway when Mom starts getting hot

[Rickf1985]

One way to find out is to shut the liquid valve while the genny is running, It will probably run for another couple minutes as any liquid in the lines vaporizes and then shut off. Then you know that the liquid is the generator. While it is off make sure everything else still works. You will want to experiment with the gas usage of the generator before going to a place where you are unable to get it filled either while there or be able to go out for propane. Propane generators do use a fair bit of propane. There are charts that will tell you pretty close to the exact amount.

[Rickf1985]

Oh, on a lot of those newer units you also have an excess gas valve that will shut down the entire system if it senses too much use, pretty much like the OPD valves on the small bottles. You will also find that the propane detector inside is electronically connected to another valve on the propane system and if that detector ever goes off it shuts off your propane! What a pain that is! Check your manuals for that one because hair spray and many other things can set that thing off and resetting it is a procedure you will want to know before it happens.

[Froggy1936]

Also Right Guard or any aerosol that uses propane for gas , My propane detector goes off with right guard unless i turn on the exhaust fan. I would definitely explore the liquid line use, You do not want liquid at the stove or refrigerator ! Frank

[ClydesdaleKevin]

Thanks guys!  I'm going to guess that the liquid goes to the genny, and the vapor to the rest of the systems.  For now I'll leave both valves open, since we might want to fire up the genny on our trip out west if it gets too hot out...although this time of year we rarely have to run the AC while driving out west.

Kev

[Rickf1985]

Having a liquid line open all the way to the rear while driving would worry me. As a heavy wrecker driver years ago I saw a lot of RV accidents and when they got any major damage to the sides the propane lines were the first to go since they are usually metal lines. A liquid line is going to dump a LOT of liquid/vapor in a hurry which will be ignited very quickly by the fridge pilot or something similar. Look up the term BLEVE. This is all just cautious conjecture based on experience from many years ago, i run with my gas turned on for the fridge but it is not a liquid line. I am thinking there is probably an excess flow device in the line but it would be good to know that for sure. Unless you plan on running the generator I would leave it off, it only take a minute to pull over to turn it on if need be.


Just my personal opinion.

[HandyDan]

From what I can see, the liquid line only goes a very short distance.  The generator is back behind the driver's seat, so the line just goes from one side of the motorhome to the other.
Dan

[ClydesdaleKevin]

Right you are Dan!  The liquid line is very short.  But I think on our maiden voyage to Arizona we will err on the side of caution and leave it shut off until we pull in for the night and run the generator.

Kev

[Rickf1985]

I thought the generator was in the back, forgot the engine was back there. DOH!

[ClydesdaleKevin]

LOL Rick!  I'm still getting used to this new layout as well!

Kev