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larbaum · Apr 30, 2011, 10:50 AM

I have installed an 1 1/4 underground gas line per code. I am ready for inspection and have installed a pressure gage and pressurized to 20 lbs of air. The pressure holds for 24 hours and then will drop to 8 0r 10 lbs. I have filled it up twice to make sure it will pass inspection but get the same results. Is this typical with temp changes or do I have a leak "every once on awhile"? It doesn't seem to be going down slowly as I check every hour and it hasn't moved. Bad gage? Leak? Help!

massplumber2008 · Apr 30, 2011, 04:03 PM

Hi Larbaum

What is the required time frame for the test in your area?

If you are holding 20 PSI for 24 hours then would probably pass inspection, but I think you are smart to check like you are here as it sounds like you have a small leaker to me. A temperature change WILL NOT usually lead to this great a drop in pressure.

Here, be sure you are not testing through the gas meter (should be capped at the meter bar) and that you are not connected to any of the appliances (means disconnect all appliances and cap at the unions ) and then pump the system up to 50 PSI. Once the new system is pumped to 50 PSI walk around with a soapy bubble solution and spray all the joints... should find the leaker this way. Heck, at 50 PSI, you may even hear it... :)

After you find the leak, fix it, then test the system to the required 20 PSI... see if it holds for the required test period. After the test holds as needed call for inspection and pass inspection. After all that you can reconnect all aplliances, purge air from the system by filling the system with gas and then as a basic safety precaution, test all union fittings and final connections with a soapy bubble solution and you should be all set here!

More questions? Let us know, OK?

Mark

PS: Make sure you test THROUGH all shutoffs... required, OK? Of course, uninons should be after the appliance shutoffs, so this almost didn't need to be said!

rojo1 · May 1, 2011, 02:53 AM

I believe the inspector wants to see the pressure hold for 10 min. on residential sys.

massplumber2008 · May 1, 2011, 06:08 AM

Hi Rojo...

Time frame and pressure requirements for gas tests will differ from state to state.

Some states want 20 PSI for 10 minutes.. some want 25 PSI for 15 minutes. My own state wants 3 PSI for 15 minutes and I am required to have a special gas tester gauge that reads in 1/10th PSI increments... ;)

With all that being said, I still think we have a small leaker here, but definitely sounds like he can pass the test no problem!

Thanks... Mark

hkstroud · May 1, 2011, 05:36 PM

Here is my guess.

You are using a pressure gauge the has a maximum reading of 20 lbs. You are pressurizing the gas line to far beyond 20 lbs. You have a leak. It takes 24 hours for the pressure to drop to 20 lbs. but because the maximum reading of the gauge is 20 lbs. no change shows on the gauge. After that the drop in pressure is registered on the gauge. You have a leak.

Just a guess.