Nat Gas Shut Off

[Joel 67]

Ok, my previous question has inspired me to attempt to do my own gas line for a garage heater.

The house has a 1.25" black iron pipe from the meter that runs 30" or so to the furnace area (the dryer and water heater are in this area as well). This The stove is nearer to meter and is teed off this line.

There is a shut off at the furnace and the water heater but nothing at the dryer nor the stove. There is a master shut off at the meter. My plan is to shut off the lines at the furnace and water heater, then shut off the main valve, and then turn on the stove until it dies of it's own. I could also try running the dryer as well. Will this expunge all the remaining gas from the lines, or will there still be a dangerous amount of gas left?

All this is in my basement and there are not many windows down there. I could run a fan to blow the air towards the window but the fan motor could potentially be an ignition source as well couldn't it?

 

[HoosierBuddy]

You won't have to run the dryer.

Once there is no pressure in the line, you can break it open. It will stink up your house at that point, as the old pipes will be saturated with mercaptan (gas odorant)...so some ventilation would be recommended. This is assuming the valve gives you a good shut off and isn't leaking through.

HOWEVER...the "master shut off at the meter" may be a problem. If you're talking about the valve in front of the meter, that valve belongs to the gas company and not you. They may not be thrilled about you turning it off. If you are talking about a valve AFTER the meter, then sure...turn away. Most gas valves are 1/4 turn valves. If the handle or actuator is crossways to the pipe...then it is off.

ALSO...if you are saying the pipe has 1 1/4" outside diameter, that is 1" pipe. Pipe size is roughly based on the size of the hole in the pipe, unlike tubing which is based on the od.

 

[Joel 67]

Thanks. I will need to check if that shut off is before or after the meter. We have 1" of snow so I only gave it a quick look.

It is 1.25" ID pipe per the stamp on it

Just for clarification, running a fan in the basement does not pose a risk?

 

[t. jones]

There is always a valve in front of the meter that is the service shut off valve that they lock if they see hose clamps.

 

[tomroblee]

I wouldn't be to worried about purging the gas from your lines. If you have the supply turned off there won't be enough gas left in the lines to do much more harm than stinking a little bit.

Gas is generally supplied to homes at a pressure of about 1/4 psi gauge pressure or less. (Higher pressures may be supplied, but generally only when the gas pipes in the house are undersized---and your don't seem to be.)

Leaving your gas appliances on after you turn off the gas will not do much to purge the gas from the lines. As soon as you turn off the gas, the pressure in the line will drop rapidly (to atmospheric pressure) and the flame will go out almost immediately. Once the pressure in the pipes as dropped to atmospheric pressure ( a little over 15 psia), the pipes will still be full of natural gas.

 

[Torque1st]

Put shutoff valve on your new line where you Tee off the main line. Put shutoffs on your other appliances while you are at it. You may want to get a plumber to inspect and pressure test the lines after you are finished with each project.

 

[Identaltech]

Dont worry I would just shut it off.
Old dental units use to have natural gas ran to them. When we upgrade them to new ones that no longer use natural gas I see the plumbers just disconect at the union then cap the line without even shutting it down.
I would never do this but it is done all the time.
When I was done adding my gas line I pressure tested it and to calm the wifes fears called my gas company to check for leaks.
They did that for free and made the wife happy. (for a short period of time the is)

 

[Torque1st]

I see the plumbers just disconect at the union then cap the line without even shutting it down.
I would never do this but it is done all the time.

I have done that many times. Just have the cap/fitting ready, plug the pipe with your thumb to dope it up then put the cap/fitting on. I did it just a few weeks ago when I replaced the gas shutoff valve to my furnace. The old valve had a very tiny leak that was just enough to barely smell if conditions were right. I could never find it with bubble solution. I called the gas company to confirm the location of the leak with their sniffer then replaced the valve. It is easier and faster to do this than going around a re-lighting old appliances etc. The amount of gas that escapes is very small. I would not do it if I had a cigarette in my hand or mouth tho...

 

[6768rogues]

While you have it turned off you should add shut off valves to the appliances that don't have them. Use pipe dope or teflon tape that is made for gas lines. Personally, I like pipe dope better. Use a spray bottle with some soap in it to check for leaks.

 

[logguy]

A shut off needs to be within 3' of every appliance. If you never need to service or replace that appliance, you can just shut off that valve to isolate it from the rest of the system and won't have to shut off gas to your entire house. Shut it off at the service valve at the meter and don't worry about the residual gas in the line. Natural gas will only ignite at a very specific air/fuel ratio. You can use the fan to evacuate the odors, but there won't be enough to worry about an explosion.

The pressure needs to be checked, some homes have a 2 psi system which requires a regulator at each appliance, but most homes systems operate at 1/2psi.