NA// Camper Propane Sytem \\NA

[wilkersk]

My camper has a built in propane tank that has a "slam-shut" valve. I googled this and what I found is that they are common safety devices on LNG pipelines. But I didn't really find anything about them on RVs except for the basics of how to reset it in the owner's manual.

When I go through the procedure to reset the slam-shut valve, I can purge the air out of the line to the stove and within about 30 seconds, I can light the stove. But, then I turn the stove off and try to turn the heater on, the fan turns on and I can hear the ignitor firing. But then it quits and about 2 minutes later the fan turns off. If I go back to turn the stove on, it lights but with only a weak flame that eventually burns out. I can repeat the procedure to reset the slam-shut valve and the stove will light. Logically, it would seem the gas flow to the heater is causing the slam shut valve to close.

Does this make sense? Did the slam-shut valve just suddenly become faulty? Anyone have any expertise here?

Oh yeah, I did crawl down and check the direct reading gauge/sender on the tank, it is full and the remote indicator shows full as well.

 

[Gary Ward]

I think what your describing is a check valve? It's there to stop the flow of gas if a major rupture happens down stream.
You normally turn on the gas and wait a few minutes for the gas pressure to equalize on both sides of the check valve and it will be open and stay open under normal flow rates.

But I am not sure that is what you have.
Got any pictures of the slam shut valve?
How do you reset the valve?
When was the last time you filled the tank?
Used it much since then?
Been in the LP gas business for 40 years.

 

[wilkersk]

I think what your describing is a check valve? It's there to stop the flow of gas if a major rupture happens down stream.
You normally turn on the gas and wait a few minutes for the gas pressure to equalize on both sides of the check valve and it will be open and stay open under normal flow rates.

But I am not sure that is what you have.
Got any pictures of the slam shut valve?
How do you reset the valve?
When was the last time you filled the tank?
Used it much since then?
Been in the LP gas business for 40 years.

According the the owner's manual, the slam-shut valve will close if it detects and abnormally high flow rate (as in a cut or broken line), or if it senses a high energy shock, like in a collision. I've heard of it also closing if you turn the normal (vapor) valve handle on too fast. Also, Google says Slam-Shut valves are common features that isolate sections of LNG pipelines in the event there is a leak (like when a pipeline is damaged from an earthquake or some sort of accident.

My problem is I don't know if the Slam-Shut valve on my camper is integral to the normal (vapor) valve, or is it separate. Also, I'm wonder if anyone knows if it's going to be a major expense if I take the camper in to a shop for repair.

 

[Gary Ward]

Turn off the main valve and turn it on very slowly, I bet you tried that but try it again.
Pictures would help. Where's the slam shut valve located?
I have never seen a check valve in a RV gas piping system. It probably has a back check POL fitting. It does what your were describing. That's the fitting that connects the outlet of the service valve to the inlet of the pressure regulator. That's why you sometimes need to turn it slowly so not to trip the back check POL. That's what connects the regulator to the tank service valve/on and off valve.

You need to check for the proper gas pressure at the heater while it's trying to light. Easy to make a water manometer out of piece of plastic tubing.
Or just install a new pressure regulator, a defective reg could stop the flow of gas under a . How old is it.
It should be a rectangular 2 stage regulator screwed right into the service valve on the tank using a POL fitting.
It sounds like you are about to run out of gas or you have a defective regulator.

Down on the tank is a 80% full bled valve that is designed to be opened with your fingers and then you could check for pressure in the tank.

 

[455 Bravo Uniform]

And you’re sure you don’t have a big leak to the heater?

Or, the same way you manually purged the stove of air, you need to figure out a way to purge the heater before the ignition times out.