An important part of being prepared for natural disaster is knowing where to find and how to operate your home's utilities. Natural gas leaks can cause explosions or feed fires, and knowing how to turn off your gas can greatly reduce the risk of injury and property damage or loss in case of an emergency like an earthquake.
There are four levels of gas shutoff that you should become familiar with:
-Individual appliance -Individual unit in a multi-unit building -Main shutoff -Utility company shutoff
Each of these control the flow of natural gas from that point onward: an individual appliance shutoff will turn off gas to its appliance (for example a gas stove), while the main shutoff will stop the flow of gas to an entire building.
Individual appliance shutoffs are found on the gas pipe connecting the appliance to the gas supply (usually behind the appliance).
Unit shutoffs can usually be found next to each gas meter, and near the main meter.
The main shutoff is often located in the garage, basement, or next to / attached to the exterior of the building. It should be near the main gas meter.
Once you've located your unit and main shutoff points, make sure every adult in your household knows where they are. Next, make sure you know how to test the gas main's operation, and when to shut it off.
To test your gas main, you'll need a shutoff wrench. You can buy a special multi-purpose tool like this, which doesn't spark (important if there's a gas leak!) and has slots to fit standard gas valve sizes. Store your wrench near the gas valve. To check shutoff operation, you'll use the wrench to turn the valve no more than 45 degrees, and then turn it back. The valve and flow of gas are on when the valve is parallel to the pipe; perpendicular means the gas is turned off. If you turn the valve off and stop the flow of gas, it's not safe to turn it back on yourself. Call the gas company to inspect and turn it back on.
Check gas main operation every six months. If there's heavy resistance when you turn the valve or it feels frozen, do not force it. This indicates a problem that the gas company needs to assess and resolve.
When should you shut off the gas?
The gas should only be shut off in an emergency situation, and only when it is safe to do so. If the building has sustained heavy damage, there are signs of a heavy gas leak, there is a fire, or there are any other signals that you may not be able to safely enter the area, your wellbeing is the top priority. Gather your family and go to a safer location like your meeting point in your emergency plan, and call 911 to report.
BE EXTREMELY CAREFUL: even a small spark can cause a large explosion if there is a gas leak, so DO NOT operate anything that may spark including: lights, electrical appliances, lighters and matches, and even your vehicle. Vacate the area for safety as quickly as possible.
If the gas main location is safe, there are several signs and situations that indicate the gas may need to be turned off:
You smell gas: while natural gas is odorless, a rotten egg-like odor is added so that it is easy to recognize when there is a leak. You hear a hissing sound coming from the gas pipe You can't easily see a gas leak, but a disaster like an earthquake may cause a visible break in the gas line. You see that two unmarked wheels on the gas meter are spinning. The unmarked wheels are usually above or below the numbered wheels (the numbered wheels spin to indicate when a major gas appliance is operating, and their movement does not signal a leak). You are evacuating, and believe that your home may experience heavier damage or be at risk while you are away (e.g. an aftershock) You experience symptoms of natural gas or carbon monoxide poisoning including: headache, dizziness, nausea, eye/throat irritation, fatigue, chest or stomach pains, vision problems, loss of muscle control, or difficulty breathing
In the aftermath of an emergency, it could take days or even weeks for the utility company to turn gas back on. It's important to have a fully-stocked emergency kit, including food, water, and warmth.
To reduce the chances of a gas leak, have a plumber evaluate any rusted or old gas pipes. Your plumber can replace rigid gas connectors with flexible connectors, and can even install excess-flow gas-shutoff valves which automatically stop flow to individual gas appliances in case of a catastrophic leak.