Bleeding a gas line indoors can be a very hazardous procedure, and it is not recommended that anyone without qualifications in gas plumbing attempt to do this. Bleeding a home gas line is not the same as bleeding the line on a car.
There is a great deal of power behind the gas lines in your home, and you could easily be seriously hurt if you attempt to do this. However, for those who are determined to do this, bleeding a gas line can be used to relieve pressure while you work on another part of the gas line.
Step 1 - Prepare
Before you attempt to open the gas line in your home, make sure that the area is well ventilated. Doors and windows should be fully opened, and you should also have a fan blowing the gas away from you, and towards an open entrance. Next, make sure that all of the electrical devices in your home are turned off. Sparks can be dangerous, so this includes phones, musical devices, and PDAs.
Step 2 - Tie the Line
Place ties or clamps on the gas line so that the item you wish to work with is sandwiched tightly between two of the ties. Add ties a little further on from the item, so that you have double-tied the line. Make sure that the line is completely sealed, and then turn off the gas at the mains.
Step 3 - Bleed the Line
Put your mask over your face, and put on protective goggles if you desire. Take the gas line, and open the valve of the item you are working on. Push the gas up through the line until all of the gas for that portion of the line is completely empty. Leave the valve open for a few more minutes, and ensure that all of the gas is now gone from the room and from the item you were working on. Proceed to fix whatever part of the line you need to, and then close the valve on the item.
Step 4 - Reopen the Gas Line
When you are ready, reopen the gas line by removing the furthest ties first, and then moving along to the ties closest to your item. Turn the gas mains back on. Check the line for signs of a leakage, and then close the floorboards where you have been working. Check that the item is working to your satisfaction, and allow the room to be fully vented before turning on the electricity. Once you are fully satisfied that there is no more gas in the room, turn off the fan and close the windows. Allow the doors to remain open for another few hours, but the gas should disperse eventually, leaving the room safe to use again.
If you plan to bleed a large item, such as a boiler, then you should seek the advice of a professional before proceeding.