Pressure testing a houses gas lines

[andyh1995]

What would happen if when pressure testing a residential house you did not close off the shut off valves and instead pumped air directly at the gas valves for water heater/furnaces? Is it possible to damage the unit

 

[Twowaxhack]

What would happen if when pressure testing a residential house you did not close off the shut off valves and instead pumped air directly at the gas valves for water heater/furnaces? Is it possible to damage the unit

Yes, you can blow the gas control diaphragms out.

How much pressure did you use ?

When appliances are left connected and I want to test an existing system, I pump the lines up with a bicycle pump to 8”-15” water column and watch my gauge for 15 minutes. If no pressure drop I call it good.

I also test sometimes with nitrogen and a digital manometer. It’s much more sensitive and you can check the system for tightness in just a couple minutes.

 

[andyh1995]

Yes, you can blow the gas control diaphragms out.

How much pressure did you use ?

When appliances are left connected and I want to test an existing system, I pump the lines up with a bicycle pump to 8”-15” water column and watch my gauge for 15 minutes. If no pressure drop I call it good.

I also test sometimes with nitrogen and a digital manometer. It’s much more sensitive and you can check the system for tightness in just a couple minutes.

Hello, our test is 50 ounces for thirty minutes . The gas was shut off from national fuel for a leak. Would this potentially do damage at this pressure ?

 

[Twowaxhack]

When I test with higher than working pressure I disconnect the appliance and cap the supply outlet. This way if the valve leaks it doesn’t ruin your gas control of the appliance.

 

[andyh1995]

When I test with higher than working pressure I disconnect the appliance and cap the supply outlet. This way if the valve leaks it doesn’t ruin your gas control of the appliance.

So would it potentially ruin the appliance if I did not shut the valve off at that pressure? National fuel didnt seem to think so at all and it's throwing me a big curve ball. A co worker of mine said the same thing where you can test up to the fixture with this pressure but I was told diffrent

 

[Twowaxhack]

So would it potentially ruin the appliance if I did not shut the valve off at that pressure? National fuel didnt seem to think so at all and it's throwing me a big curve ball. A co worker of mine said the same thing where you can test up to the fixture with this pressure but I was told diffrent

It could potentially damage a gas control. That’s roughly 3psi.

I personally wouldn’t test to 3psi without disconnecting the appliances.

I actually did a low pressure test today, 8” wc for 15 minutes.

 

[andyh1995]

It could potentially damage a gas control. That’s roughly 3psi.

Appreciate it , thank you sir. Was a big thing with national fuel in our area because they seem to not do it at all and it caused alot of drama between me and the customer in regards to me capping off the fire place and leaving sections unfully tested because the valves were further back leaving a bit more pipe untested.

 

[Twowaxhack]

Appreciate it , thank you sir. Was a big thing with national fuel in our area because they seem to not do it at all and it caused alot of drama between me and the customer in regards to me capping off the fire place and leaving sections unfully tested because the valves were further back leaving a bit more pipe untested.

In that case I
disconnect the appliances and test with up to 15 psi.

Then if that held tight I would reconnect appliances and do a working pressure test of usually around 8-10” water column.

Here’s what I use to do a working pressure test.

One end has a Schrader valve you pump it up with air then close your valve.

 

[Twowaxhack]

Here read this. It pretty much settles it.

https://www.bradfordwhite.com/forthepro-bulletins/maximum-inlet-gas-pressure/

 

[andyh1995]

Thank you so much, I love to see the facts. This is what I was told and what I was working by for national fuel to tell me that I was wrong and start a big fuss with the customer

 

[andyh1995]

Any idea what would happen that would be noticeable to a homeowner in the event of the pressure affecting it ?

 

[Twowaxhack]

Any idea what would happen that would be noticeable to a homeowner in the event of the pressure affecting it ?

Everything from it simply not working properly to starting a fire when the valve malfunctions. Gas leaks…..etc.

 

[andyh1995]

Goodmorning Twowaxhack, another question for you on the same topic. Went to a call yesterday where national fuel was out again and had both the water heater and dryers gas line both disconnected and capped off and was told they were leaking gas internally. What was said is to much air was pumped into the system by somebody and I was wondering if this happened and the solenoid of the gas valves were blown would it cause gas to push through the fixture when they're on standby and have homeowners have the smell of gas at these appliances. If you have any articles like you did previously it would be an enormous help.

 

[Twowaxhack]

If someone over pressured the gas controls then it can most definitely cause the gas control to leak.

Who needs proof of that ? The link I posted to Bradford and White said it and it’s no different for other appliances.

 

[andyh1995]

I wanted the proof as I was just curious and love the idea of an official article, very intresting though. So the solenoid inside the gas valve breaks and it's constantly letting gas flow through into the fixture ?

 

[andyh1995]

Also with the water heater disconnected, it had a Honeywell gas valve and I've called the manufacturer and they said a small smell of gas closer to the valve is normal if there's to much gas pressure. Do you think this could be a mistake by the national fuel guy shutting it off if I was to put a manometer there and I'm getting 14-15 water column?

 

[Twowaxhack]

I’m not sure what you’re trying to accomplish.

Over pressuring gas valves can damage them.

Good luck to you sir.

 

[fairfieldfanatic]

Great idea to pressure test your gas lines! But the key word is “LINES”. Not the appliances. Most appliances will say something like “1/2 PSI MAX”. So disconnect the appliances, cap them off or use a shut off valve such that you’re only testing the delivery lines.
In my case, I piped the house with 1-1/4” main line and 1” lines branched out from there. I made an adapter that had a 1/4” npt and a dial pressure indicator to monitor. Using a small air compressor, I pumped the system up to 50 psig. Why ‘so high’? Because the street Natural Gas source is around 40-45 psig, so if my gas meter or regulator FAILS OPEN, the house will see all of that! So, . . . test for it.
Back to my method; with a static 50 and a dial gauge verifying it, I sprayed every joint with leak indicator and verified at least twice. An hour or more later, came back to the dial indicator to check if it moved.
By this time, the Gas Co inspector showed up (by appointment) and checked my setup. He said they don’t go to “This level of testing, and know of ant contractor either”.
For good measure, after the house was operational, I used a gas ‘sniffer’ to detect anything, both on the first day and a week later.

 

[Twowaxhack]

Great idea to pressure test your gas lines! But the key word is “LINES”. Not the appliances. Most appliances will say something like “1/2 PSI MAX”. So disconnect the appliances, cap them off or use a shut off valve such that you’re only testing the delivery lines.
In my case, I piped the house with 1-1/4” main line and 1” lines branched out from there. I made an adapter that had a 1/4” npt and a dial pressure indicator to monitor. Using a small air compressor, I pumped the system up to 50 psig. Why ‘so high’? Because the street Natural Gas source is around 40-45 psig, so if my gas meter or regulator FAILS OPEN, the house will see all of that! So, . . . test for it.
Back to my method; with a static 50 and a dial gauge verifying it, I sprayed every joint with leak indicator and verified at least twice. An hour or more later, came back to the dial indicator to check if it moved.
By this time, the Gas Co inspector showed up (by appointment) and checked my setup. He said they don’t go to “This level of testing, and know of ant contractor either”.
For good measure, after the house was operational, I used a gas ‘sniffer’ to detect anything, both on the first day and a week later.

If your meter regulator blows out and your system sees 50psi street pressure then you don’t have to worry about your pipe leaking…….your appliances will leak and your house will probably blow up.

It’s happened before in at least one city I know of. Multiple homes burned to the ground.

https://www.chicagotribune.com/news/ct-xpm-1992-01-18-9201050882-story.html

 

[fairfieldfanatic]

Twowaxhack; not if you setup with safety valves as I have. Before the appliances I’ve installed valves that if they see any sudden pressure spike, will close themselves off. Test the valve by simply blowing into them, and they will shut themselves.
Whoever had their houses burned down, . . . didn’t have these valves in place.