Gas line leak check

37chief

Well-known Member
Location
California
I installed a new propane 3/4 inch line from the tank to the house. The reason for a new line, the inspector installed a test gauge. He said the line needed to hold one pound for three minutes. The test failed. I found the line to be bad. I installed a new line. I pressurized the new line it held 15 lbs for around two hours. Then dropped 1/2 lb. I am sure it will pass the inspector test of one lb for three minutes. Is there an acceptable drop allowed, on a gas line pressure test. The gas is regulated to one lb entering the house. Any thoughts? Stan
 
(quoted from post at 20:34:31 02/15/17) I installed a new propane 3/4 inch line from the tank to the house. The reason for a new line, the inspector installed a test gauge. He said the line needed to hold one pound for three minutes. The test failed. I found the line to be bad. I installed a new line. I pressurized the new line it held 15 lbs for around two hours. Then dropped 1/2 lb. I am sure it will pass the inspector test of one lb for three minutes. Is there an acceptable drop allowed, on a gas line pressure test. The gas is regulated to one lb entering the house. Any thoughts? Stan

The line should not leak at all.

1#(28"wc) seems way to high, standard is about 11"wc
 
You think it may have dropped due to temperature drop? A new line is supposed to hold 1 1/2 times the working pressure with a minimum of 3 psi. for at least 10 min. (more for long runs or large pipe) with no readable drop. 1 pound into house? That is a little unusual.
 
(quoted from post at 19:55:42 02/15/17) You think it may have dropped due to temperature drop? A new line is supposed to hold 1 1/2 times the working pressure with a minimum of 3 psi. for at least 10 min. (more for long runs or large pipe) with no readable drop. 1 pound into house? That is a little unusual.

Some of the new systems have two regulators, one at the tank and one at the house.
 
But not 1 pound. Some systems may have a 2 psi system but then you need special regulators at each appliance. That is used sometimes in places that have really long runs of lines inside like in apartment.
 
If it's one lb. entering the house then you need another regulator at the appliance. I am unfamiliar with that type of propane system but we have a high pressure nat. gas system, with 2 regulators. a slight drop might be temperature related, but I would watch it for a longer period of time.
 
Stan the standing pressure test usually is at a lower pressure on a new line and it is isolated from the tank and the pressure regulators. If you hit the pressure regulators with 15 they are probably junk now. Max for the appliance regulator is usually a half pound. Reducing regulators can take more than that but do not have the book. Most new construction on Nat Gas and Prop here supply is 2 PSIG to a step down regulator near the appliance feeding it 11 inches.Usually they keep the standing pressure test low to keep from bursting the diaphragm. This sounds like just replacing the line, 3/4 inch carries a lot of BTU's most around here for a tank to house are 5/8 or less on the higher pressure side of the house regulator.Most pressure gauges are not sensitive enough, did you soap test also,they seem like they drop every time we checked but never understood why.Even when I pressure check refrigeration systems there is a fluctuation of the gauge on digital gauge sets over night.The line should be OK.
 
I don't remember the amount of pressure drop but any gas line test I've ever seen was done for 24 hours. If it's leaking any at all in a few minutes that would be unacceptable to me. I can run 200' of air hose from my computer and not loose any pressure that quick.
 
Pressure test on new LP lines are at higher pressure than normal working pressure. The rego 2nd stage regulators I use say inlet pressure of 5-20 pounds so 15 pounds shouldn't hurt but the line should have been isolated for a proper pressure test.
 

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