Do propane lines stay pressurized when tanks are off?

[kirkelli]

When i had my hose leak problem, the Camping world tech told me that most rv makers are using cheap hoses and they all leak. He said he seen this problem mostly when RV makers use a very short hose that does not leave any slack or if a tank is rotated enough it cause tension on the hose which allows gas to sneak throw the rubber seals in the the gas line swivels. I replaced my with 1 foot longer hoses, made in USA, and never had the issue re-appear. I am betting you are having this same issue.. try buying a quality made hose'(s) a little longer...

[jimmoore13]

SHOULD it leak down? Of course not.
DOES IT? Absolutely. Think of all the joints (untold numbers) and valves in the line (one at every appliance and 4 or more on your range). Also consider that rubber lines, no matter how good, will also ooze fuel right thru the line...witness air loss on your RV tires over time. Your RV tires have all the leak integrity of your rubber propane lines.

My old gas grill was a good product, but if I left the propane tank valve open, one of the valves on the grill would leak enough to slowly empty the tank over the course of several weeks. I could occasionally get a whiff of it.
Replace the valve? Perhaps. Shut off the tank? Damned skippy.

A suggestion for a "reasonable" test to determine how seriously to take this. The test: can you light your two-way fridge (assuming you have one) without having to purge the lines by first manually lighting your stove? If so, the leak-down is slight. Same with the hot water heater. If you hear it light right up, great. But if the spark igniter ticks away for 30 seconds...or worse, it has to try again, you have a problem. If you are ever in a position where you need to purge the lines to get the fridge or hot water heater to start, then you have a problem that needs your immediate attention.

Backup test: you should be able to light your stove QUICKLY with the spark igniter, and you should get a full ring of solid flame immediately. If you have to wait for fuel and then the burner lights only partially...or if you must use a long lighter to get it going, that's a FAIL, and it's time to track down what will be a "real" leak in the system.

That's my 2 cents.

[thenne1713]

Originally Posted by JimD

I always thought the propane lines would be held under their low pressure setting but now I am not sure. You would think they would.

Recently I was prepping for a trip and went to fire up the fridge to test the propane. It would error out due to no flame ignition. I then turned on the stove to bleed the line and it took a few seconds for it to light. Apparently there was no propane in the line.

The tank had not been shut off and nothing was changed since the previous use about a month prior. I would have thought the line would be at the same pressure it was before but apparently not.

I wonder what happened to the pressure that was in the hose previously. If there was a leak it wouldn't let air in it would bleed propane out.

I have a single tank system with no switchover. My old camper had the switchover and I am familiar with that operation. Seems to me I had to "bleed" the lines after it sat for a period of time. I always had both tanks turned on only when I was using it. Between trips I would turn the valves off and that would always require running the stove to get the propane into everything.

Is there a propane/gas expert out there who knows how the pressure regulator works and where the gas that is suppose to be in the line goes when not in use? Maybe it goes where all the socks go that disappear from a dryer.

Have you soaped the hoses themselves and watched for SLOW bubbles? Hoses do develop pin holes, BUT the factor you have NOT mentioned is pressure changes due to TEMPERATURE CHANGES. Some loss is considered acceptable with gases/ freons, sounds like you have done a most diligent search, but also ONE tiny, tiny, small leak on ANY fitting at any appliance/ connection/ crimp/ fitting may take years or only months to develop to a detectable... I have had freon leaks that were required recharge every year for three years, then NO recharge for 6-years... go figure

[JimD]

These are all great theories on leaks but my question is why doesn't the pressure regulator maintain the pressure even if there were a leak. Apparently the regulator doesn't do anything until there is a certain amount of flow.

Then the other question is, so your line has leaked down and there is very little if any pressure, how does the thing know you have opened a valve to get an appliance going?

I lost too many brain cells contemplating this.

[JFlightRisk]

I'm more worried where all those socks go to...