I put a pressure gauge inline between the tank and regulator for the first time ever.After I shut the gas off the pressure on the gauge will drop overnight from green (pressurized) to the red (meaning low low pressure).Should the pressure on the high side remain high for days/weeks or is it normal for that to drop? Im not sure if the regulator is venting it or if I have a leak after the regulator.Nothing bubbles, but there is one fitting I cannot get to.I used Nylog on every fitting.3/8 copper and flare fittings.There is only a space heater (has solenoid valve) and a stove.I cannot detect any odor.

Might be a very slow leak, but did you take temperatures into consideration?

RV Propane Leak Test.......High Pressure Side (before Regulator) Turn the main LP Gas Valve to the on position and listen for the initial PSST sound. After a second or two, the sound of flowing LP should stop. Next step is to notice the green band in the clear regulator cap. Now turn the main LP gas valve off at the LP tank for 3 to 4 minutes. Watch the green band in the clear regulator window, and it should stay green. If it turns red, (low gas indicator), this indicates a possible leak.Low Pressure Side (after the Regulator) Requires using a manometer connected to system.....stove top burner at manifold can be used Valve in Propane Supply....verify system is 11"WCValve out Propane Supply...then slowly open burner knob and drop system pressure to 8"WC then close burner knobMonitor pressure for 15 minutes....no change in system pressure then system is GOODSystem pressure drops....how fast will indicate size of leak But only 15 minutes is required for leak down test on low pressure sideAnd only 3-4 minutes on high pressure sideDoubt you have a leak....indicator green/red is NOT a accurate means of testing

The LP standard for leak test is as follows.Pressurize to 11 to 14 inches WCInstall the manometerLower the WC to about 8 inches wcMeasure the Manometer for 3 minutesThe system passes if no drop in pressure during the test.There is no such thing as a completely sealed LP system. The system will leak down the LP in the system when the Tank is turned off over days/weeks. YOU NEVER USE OR NEED TO USE ANY SEALANT ON A FLARE FITTING. NEVER!If a flare leaks FIX the copper flare, do not attempt to use sealant. PIPE fittings, you use sealant/teflon tape. Doug

So, it is not normal for the pressure to leak down overnight?This is not a red/green indicator as on a two-tank system, it is a dial, green range is full tank, as tank pressure lowers the dial moves into a red colored background (not unlike the red in your rpm tachometer).The dial measures psi and shows this with a needle.I should have explained this more clearly at first.Nylog is the stuff. It is cheap insurance for sealing things. It is used in the refrigeration industry as gospel. Use it on all your propane fittings from now on. Teflon tapes are of the past now unless you need to lubricate the threads..I did not use Nylog on the tank fitting, possible that is a leak? I will go bubble check that and nylong it and retest.**also, this tank I have had sitting in garage for 6+ months so I do not suspect it is leaking when closed.Temps change very little overnight here during summer, not enough to swing psi this much.If this is not normal then I will assume it is the pigtail, which is the only used part in the system other than the heater.

Old-Biscuit wrote:RV Propane Leak Test.......High Pressure Side (before Regulator) Turn the main LP Gas Valve to the on position and listen for the initial PSST sound. After a second or two, the sound of flowing LP should stop. Next step is to notice the green band in the clear regulator cap. Now turn the main LP gas valve off at the LP tank for 3 to 4 minutes. Watch the green band in the clear regulator window, and it should stay green. If it turns red, (low gas indicator), this indicates a possible leak.Low Pressure Side (after the Regulator) Requires using a manometer connected to system.....stove top burner at manifold can be used Valve in Propane Supply....verify system is 11"WCValve out Propane Supply...then slowly open burner knob and drop system pressure to 8"WC then close burner knobMonitor pressure for 15 minutes....no change in system pressure then system is GOODSystem pressure drops....how fast will indicate size of leak But only 15 minutes is required for leak down test on low pressure sideAnd only 3-4 minutes on high pressure sideDoubt you have a leak....indicator green/red is NOT a accurate means of testingThis is why I have a shutoff c0ck valve behind every propane appliance. My Manchester motor fuel 83 gallon tank has a high flow block off that stops the flow 100% and stays 100% shut off.

Propane leakdown | Good Sam Community

C_Schomer
Explorer
Sep 06, 2020
I have a an OLD Marshall reg that comes apart and I've made new viton internal parts to keep it working but a couple of weeks ago, I thought it was finished. I smelled mercaptan and I soaped it repeatedly and I couldn't see bubbles but when I rinsed it off and watched a little longer, I finally saw a TINY bubble in the water, on the bonnet of the low tank gauge. The bubble was too tiny to show through the soap. Water actually worked better than soap, that time. I checked the gauge diaphragm and all I had to do was tighten the bonnet nut a little tighter. Maybe I'll get another 20 years out of it. Craig
time2roll
Nomad
Sep 06, 2020
dougrainer wrote:
There is no such thing as a completely sealed LP system. The system will leak down the LP in the system when the Tank is turned off over days/weeks.
YOU NEVER USE OR NEED TO USE ANY SEALANT ON A FLARE FITTING. NEVER!
If a flare leaks FIX the copper flare, do not attempt to use sealant. PIPE fittings, you use sealant/teflon tape. Doug
Thank you for this information. I have always wondered about the leakdown after storage.
I agree no sealant to be used on a flare.
ajriding
Explorer II
Sep 16, 2020
I put a new hose from the tank to the regulator. Soaped it up and no bubbles on the hose crimp, or the connection at the reg. No bubbles anywhere.
Everything is new except the furnace.
The Nylog means the flare fittings are not leaking too.
The only thing unknown is the furnace solenoid gas valve. No propane smell though.

So, the pressure dial still goes down in pressure within hours. Is this normal, again??

Forum Discussion

Propane leakdown

About Technical Issues

Related Content

Propane!

RIP Propane

Propane tanks

Propane Refill

Propane problem