When the long side of the protrusion or handle is parallel to the incoming gas line, it is open and the gas flows. When it is turned a quarter turn, perpendicular to the incoming pipe, it closes. The first way to verify that the gas is turned off is to check the gas valve and confirm that it is in a position perpendicular to the gas line. If you suspect a faulty valve, listen for gas flow through the pipes and check the pilot lights currently on on any older appliance to determine if they are still on.
Newer appliances don't have pilot lights, so if you can't confirm that the gas is turned off this way, you'd better be cautious and call your gas company to come out and inspect your gas line. They will be able to confirm if the gas is out and if there are any problems with their system. Now that you know where your valves are located and have labeled them, let's talk about closing them. The long side of the handle is parallel to the incoming gas line, which means that the gas enters and flows.
Turning the handle perpendicular to the inlet pipe closes the valve and closes the gas. The same applies to single-lever ball valves with the handle parallel to the line, which means that the gas is flowing. Every time you close the main valve on your gas system, expect to run out of gas for at least an hour or two. If you have questions about turning off your home's gas supply on the meter, contact your gas utility provider.
Turning the gas back on is likely to require a visit from the gas company, so it should only be done in an emergency. This should cut off the flow of gas to your home, but the remaining gas in the line will take a short period of time to dissipate. Each gas appliance must have a gas line that goes to it and has a valve located just before the appliance. A good rule of thumb is to never shut off gas from any valve unless you hear or smell it, detect a broken line, or have other reasons to suspect a gas leak, and don't try to turn it back on yourself.
Like a propane tank shut-off valve, a gas shut-off valve for stoves controls the flow of natural gas to the appliance and must be disconnected before changing the tank (propane) or changing the appliance (when installing a new stove). In these circumstances, the valves can be closed to prevent a gas leak from occurring or to prevent gas from entering the home. Knowing the location of the main gas shut-off valve will help you quickly shut off the gas supply to your entire facility in an emergency. Keep in mind that it could mean running out of gas for at least a couple of hours and you'll need a visit from the gas company to turn it back on.
In some cases, simply shut off the gas from the appliance's shut-off valve if there is a gas leak or if it is necessary to replace or repair the appliance. If you can't find the gas shutoff valve for a specific appliance, you may need to close the main gas valve to fix the problem. The main shut-off valve that controls your home's natural gas supply may come into play during major construction or renovation involving gas lines or when closing or closing a home. Whenever you are worried enough to shut off the gas, leave your home and call the gas company to diagnose the scene and restore the gas before returning home.
However, it is worth repeating that if there is any chance of a major gas leak, leave the house and call the local gas company or fire department.