Propane leak test

[JimK-NY]

Due to a slow leak at one tank, I cleaned the seals on my propane tanks and also replaced the old, stiff pigtails. I have used soapy water on connections in the propane compartment and cannot detect any leaks. If I open a propane tank valve I see green on the regulator. When I close the valve the green mark will stay for at least a couple of hours and then the regulator will turn to red. Once the green stayed overnight but changed to red again the next day. Is this some normal bleed out of the regulator or do I have a leak somewhere? At this point I have no idea what to check.

[ScottG]

Chris Bryant wrote:
You are always going to have a small leak- the solenoid valves on appliances do not seal perfectly- ANSI standards call for less than 240 cc/hr leakage as being acceptable.
The reason for using a manometer is so you can quantify the leak to make certain is is within allowable limits- something that you cannot do using the changeover indicator.

X2.
And you have to remember the pressure after the regulator is so low that even the tiniest release will cause the indicator to go red.

[JimK-NY]

Thanks for the followup on this. I am not sure about the life expectancy of a regulator. Mine is 5 years old with about 2 years of use. I need to replace the tank and then do another leak check. I guess propane pressure should work like the water pressure. I can turn on the pump to charge the pressure, then turn off the pump. Unless the temperature changes, the pressure will be maintained for days and when I turn the pump back on it will still not be needed.

[Old-Biscuit]

FYI.......LP Regulator

Should NOT leak from vents......should NOT leak around crimped body

Any leaks detected on regulator........new regulator

1st stage has a very small pin hole vent......it allows air movement in/out as diaphragm moves and 2nd stage has larger screened vent for air movement in/out.

Vents are on top side of diaphragms........propane on opposite side.
Propane out vent.......diaphragm cracked/torn

[JimK-NY]

Thanks for all the help. I think I have found the problem.

A few weeks ago I asked about a leak at the pigtail connection. I was told to check the tank seals and the pigtails. I cleaned the tank seals and replaced the pigtails, mostly because after 5 years the hoses were stiff. Anyway I tested for leaks after those steps and all seemed fine. Then I discovered I still had a slow leak. I checked the pigtail connections again with no signs of a leak. I just did an additional test and after 10 minutes I see very small bubbles under the pigtail nut. I conclude the leak is due to the tank seal. The tank is an Paraco exchange tank from Home Depot. All of the propane tanks at my local Home Depot are older than 12 years and very few have recertification markings, including the tank with the leaking connection. Fortunately I found that Lowes has new exchange tanks and will accept the old junkers from Home Depot.

Thanks for all the help and suggestions. At least I learned the rest of the system seems sound.

[JimK-NY]

derh20 wrote:
i don't know if the is helpful or not, but i had a leak once and it turned out the person that filled my tank did not tightened that screw fully that is used to get the air out of the tank before filling. i can't remember the name of that screw.

I do know. The pressure drops off within a few hours. I don't see how building or buying a manometer is going to help me find a leak. The high pressure in the pigtails is going to help charge the system with or without a manometer. If very slow leaks are acceptable and normal, then I am finished either way but I still cannot find them.

At this point I will check the bleed screws on the tanks. I did not think of them. Thanks.

[dougrainer]

JimK-NY wrote:
Thanks. If I understand the manometer will show the drop in pressure but not the volume rate of leakage. Anyway it sounds like there will always be some leaking due to the valves on the furnace and HW heater. I guess I should be able to see those leaks with soap testing. I will give it another try. I was thinking that the leak was at the regulator.

Chris should have clarified his remarks about inherent leakage. NO, the valves and solenoids will NOT really leak, but will over months. This type leakage is not seen or soapy water seen. I stand by the, "if your red indicator comes on within 24 hours, you have a serious leak that needs found and fixed". A common leak on older RV's IF you have an Atwood DSI water heater is the gas Valve solenoid. You put leak detector on the orifice and see if it bubbles after a few minutes. That type leakage is NOT normal and the Gas valve must be replaced. Doug

[ksg5000]

Next time you fill your propane tanks use a commercial outfit like suburban .. they will likely find/fix the leak for free.

[derh20]

i don't know if the is helpful or not, but i had a leak once and it turned out the person that filled my tank did not tightened that screw fully that is used to get the air out of the tank before filling. i can't remember the name of that screw.

[beemerphile1]

Chris Bryant wrote:

JimK-NY wrote:
Thanks. If I understand the manometer will show the drop in pressure but not the volume rate of leakage.

In a way it does show the rate- no drop from an 8" water column movement in 3 minutes means the leak is small enough to be inconsequential (some states call for up to 15 minutes- the time I use for testing). The trouble with watching the changeover indicator is that you have a volume of high pressure LP in the pigtails, which can keep the pressure up even with a leak.

Amazingly some people would rather guess than know.

[hawkeye-08]

Good info on the testing, I bookmarked it.

[Chris_Bryant]

JimK-NY wrote:
Thanks. If I understand the manometer will show the drop in pressure but not the volume rate of leakage.

In a way it does show the rate- no drop from an 8" water column movement in 3 minutes means the leak is small enough to be inconsequential (some states call for up to 15 minutes- the time I use for testing). The trouble with watching the changeover indicator is that you have a volume of high pressure LP in the pigtails, which can keep the pressure up even with a leak.

[JimK-NY]

Thanks. If I understand the manometer will show the drop in pressure but not the volume rate of leakage. Anyway it sounds like there will always be some leaking due to the valves on the furnace and HW heater. I guess I should be able to see those leaks with soap testing. I will give it another try. I was thinking that the leak was at the regulator.

[Chris_Bryant]

You are always going to have a small leak- the solenoid valves on appliances do not seal perfectly- ANSI standards call for less than 240 cc/hr leakage as being acceptable.
The reason for using a manometer is so you can quantify the leak to make certain is is within allowable limits- something that you cannot do using the changeover indicator.

[JimK-NY]

Thanks but I don't see a reason to build and install a manometer. I already know I have a slow leak. I just finished soap testing all of the connections I could see or reach. I think I checked every connection except within the furnace compartment since I did not remove the door. I think there is a vent on the back of the regulator that I still need to check. I tried before but probably need to try again with a mirror and flashlight.