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Open Roads Forum  >  Tech Issues

 > Propane leakdown

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ajriding

st clair

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Posted: 09/04/20 02:21pm Link  |  Quote  |  Print  |  Notify Moderator

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.

Lynnmor

Red Lion

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Posted: 09/04/20 03:08pm Link  |  Quote  |  Print  |  Notify Moderator

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





Old-Biscuit

Verde Valley

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Posted: 09/04/20 03:45pm Link  |  Quote  |  Print  |  Notify Moderator

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"WC
Valve out Propane Supply...then slowly open burner knob and drop system pressure to 8"WC then close burner knob
Monitor pressure for 15 minutes....no change in system pressure then system is GOOD

System pressure drops....how fast will indicate size of leak
But only 15 minutes is required for leak down test on low pressure side
And only 3-4 minutes on high pressure side

Doubt you have a leak....indicator green/red is NOT a accurate means of testing


Is it time for your medication or mine?


2007 DODGE 3500 QC SRW 5.9L CTD In-Bed 'quiet gen'
2007 HitchHiker II 32.5 UKTG 2000W Xantex Inverter
On the Road Debt Free April '07
Off the road still Debt Free Jan. '14

dougrainer

Carrolton, Texas

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Posted: 09/04/20 03:56pm Link  |  Quote  |  Print  |  Notify Moderator

The LP standard for leak test is as follows.

Pressurize to 11 to 14 inches WC
Install the manometer
Lower the WC to about 8 inches wc
Measure the Manometer for 3 minutes
The 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

ajriding

st clair

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Posted: 09/04/20 05:09pm Link  |  Quote  |  Print  |  Notify Moderator

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.

* This post was edited 09/04/20 05:34pm by ajriding *

MEXICOWANDERER

las peƱas, michoacan, mexico

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Posted: 09/04/20 11:01pm Link  |  Quote  |  Print  |  Notify Moderator

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"WC
Valve out Propane Supply...then slowly open burner knob and drop system pressure to 8"WC then close burner knob
Monitor pressure for 15 minutes....no change in system pressure then system is GOOD

System pressure drops....how fast will indicate size of leak
But only 15 minutes is required for leak down test on low pressure side
And only 3-4 minutes on high pressure side

Doubt you have a leak....indicator green/red is NOT a accurate means of testing




This 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.

dougrainer

Carrolton, Texas

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Posted: 09/05/20 07:09am Link  |  Quote  |  Print  |  Notify Moderator

THIS is the sealant to use. This Rector Seal will seal up to 3500 psi.
Doug

https://www.lowes.com/pd/RectorSeal-No-5........Ch3AMwT-EAQYASABEgINZfD_BwE&gclsrc=aw.ds

dougrainer

Carrolton, Texas

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Posted: 09/05/20 07:11am Link  |  Quote  |  Print  |  Notify Moderator

AND I STAND BY MY STATEMENT, YOU DO NOT USE ANY SEALANT ON A BRASS FLARE. FIX THE FLARE, DO NOT USE SEALANT. Doug

dougrainer

Carrolton, Texas

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Posted: 09/05/20 07:14am Link  |  Quote  |  Print  |  Notify Moderator

ajriding wrote:

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.


I guess you are testing the fittings/pigtail between the Tank connection and the INPUT of the LP regulator? If so, either the Pigtail is leaking at the crimp or your gauge has an inherent leak. Pigtails can leak when they get older at the crimp ring that secures the rubber to the fittings. Doug

JimK-NY

NY

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Joined: 05/12/2010

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Posted: 09/05/20 07:19am Link  |  Quote  |  Print  |  Notify Moderator

ajriding wrote:

So, it is not normal for the pressure to leak down overnight?
...


I think this is normal. I have not done a lot of experimenting but I know my regulator gauge goes from green to red within a day or two, perhaps even quicker. I have no idea where the propane goes but otherwise I have never had any indication of a leak.

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