Houses with natural gas have a main shutoff valve (Fig. A) located just before the gas meter. This valve, often called the street-side valve, is normally a rectangular nub (Photo 1). When the long side of the nub or handle is parallel to the incoming gas line, it's open and the gas is flowing. When it's turned a quarter turn, perpendicular to the incoming pipe, it's closed. The street-side main shutoff valve must be opened and closed with a wrench, and, truth be told, gas companies don't want you operating this valve; they only want their own employees, plumbing and heating contractors and fire department personnel to use it. They'd rather you use the house-side main shutoff valve located after the meter (Photo 2). This house-side valve—usually a ball valve—may be located where the pipe first enters the house or farther down the line, but it will always be located before the first appliance. If iron pipe is transporting the gas, it's often black; this differentiates it from similar-shaped, gray galvanized water pipe.

If your home is newer and you find a flexible copper pipe running from the meter into your utility room, you probably have a higher pressure gas system. Toilet Seat Drop On BallsIn this case, your inside main shutoff valve (Photo 3) is probably near your furnace or water heater, just before it enters a flying saucer–shaped doodad called a pressure regulator. Air Screen Seed CleanerThere's also a chance your home—especially if it's older—doesn't have a house-side main shutoff valve.Vacuum Cleaner Head For Timber Floors Well, don't just sit there; get up and locate those valves! Then tag 'em as we explain in Fig. B. In addition to the house-side main shutoff valve, individual gas appliances should have a service or appliance shutoff valve (Fig. A) that's immediately accessible, in the same room and within 6 ft. of the appliance.

These valves allow you to stop the flow of gas to your dryer, oven, furnace, water heater or gas fireplaces to make repairs or new installations without cutting off gas to your entire home. Most service valves are single-lever ball valves; again, handle parallel to the line means gas is flowing, perpendicular means it's cut off. On dryers and ranges, this valve is usually hidden behind them and can only be reached by sliding the appliance out from the wall. This service valve will usually be at the end of a fixed pipe and connected to a flexible supply pipe called an appliance connector. Take care not to kink or pinch this flexible pipe. When you repair or replace a gas appliance, use these shutoff valves to stop the flow of gas. (Most pros replace the flexible connector when they replace the appliance.) If you discover you have a faulty supply valve, or your system doesn't have one, turn off the gas using the house side main shutoff valve. For those with propane or liquefied petroleum gas, there's a main shutoff valve on the tank itself, and usually a main shutoff valve somewhere before the first appliance.

Some valves (both gas and water) manufactured before 1980 contain a lubricant to help the valve seal better and operate more smoothly. In many cases, this lubricant will have hardened or reacted with the gas to make the valve difficult to turn. Applying gentle heat with a hair dryer and working the valve open and shut in stages will usually free it up again. Sometimes you need to use a pliers to free the stuck handle.Now that you know where your gas valves are, also know this: it's not always safe for you to turn these valves off in an emergency. When gas reaches a certain concentration in a room or house, the slightest spark can set off a tremendous explosion. A light switch or telephone—even static electricity from your clothes—can produce such a spark. If you're working near the main or individual gas valve and clearly know the source of the gas leak and that gas hasn't been leaking for long, shut off the valve and get out. But if you're uncertain of the source or how long the gas has been leaking, clear yourself and your family out and call the gas company or fire department from a neighbor's house (not your own—remember, phones can generate sparks!).

Always err on the side of caution. It’s a good idea to get ready for gas emergencies before they happen, because sometimes projects involving gas lines don’t go as planned. When a gas project goes bad, that’s not the time to be searching for the right tool to shut the gas off at the meter. A good strategy is to buy an emergency gas meter wrench shutoff tool and secure it to the meter as shown in Photo 4. Pick one up at a home center for about $12. Also note: When you shut off main or individual gas valves, you'll be extinguishing the pilot lights to certain appliances. Many newer appliances have “pilot light–less” electronic ignition systems, but if you have older appliances, you'll need to relight the pilot lights. Most appliances have clear relighting directions on a label near the pilot light or in the instruction manual. But some pilots are pretty darn hard to reach. If you're uncomfortable with relighting the pilot light, hire a plumber or call your local gas service company.

What is a fuel shutoff solenoid? A fuel shutoff solenoid is an electronic switch that automatically stops the fuel flow from the tank to the engine. The valve is normally in the open position; however, a loss of electrical power to the valve or activating a switch in the vehicle closes the valve to stop fuel flow. Manufacturers install such switches on both gasoline and diesel vehicles. What are the symptoms of a clogged fuel injector? What are some symptoms of a bad mass air flow sensor? What Happens When a Fuel Filter Gets Clogged? The fuel shutoff solenoid is located in the fuel pump, but the electronic switch is inside of the driver's compartment. Once the switch is activated, the flow of fuel stops, and the engine no longer operates. Many of these switches also have a manual override feature to shut off the fuel in the event of a power failure. The solenoids are useful in stopping fuel flow in the event of an accident. With diesel technology, which has a longer history of fuel injection, the shutoff valve also serves as a kill switch to stop the engine from running.

In older Mercedes vehicles, the switch operated from the vacuum system, and activating the vacuum switch stopped the fuel flow and the engine. Manufacturers replaced the vacuum switch with a more-reliable electronic solenoid version on newer vehicles, eliminating the frequent need to open the hood and manually activate the switch from the vacuum system. What happens when water gets in a gas tank? The presence of water in a vehicle's fuel system can present several problems including the alteration of fuel to air ratio that will reduce engine power t... What are symptoms of water in a car's gas tank? When condensation from water contaminates a gas tank, the most common symptoms are poor fuel economy, engine running rough, stalling or failing to start, a... How do you know if your starter solenoid is bad? It is easy to tell a starter solenoid is going bad because the engine makes no noise when turning the key in the ignition. The solenoid is a device that ch...