So, one of the things mentioned in various lists of suggestions for hurricane preparedness is not lighting matches, candles, etc. in the presence of leaking gas. If the gas service to my house gets disconnected at some point during a storm (not sure how likely this is to happen in College Station, Texas) do I need to shut off the valves leading to the water heater and the oven because the pilot lights will be out?
No. Any gas valve is carefully designed to only allow the flow of gas when the pilot light is on. Generally there’s a temperature sensor that needs to be heated by the pilot light in order for the gas to flow. To get the pilot lit initially, you need to manually hold a button until the sensor gets hot enough.
This assumes, of course, that your system has been maintained, your gas valve is working properly, etc. But the designers of your system have definitely thought of this problem and designed safeguards into the system.
Does the age of the house make a difference here? How far back to these safety valves go?
If I understand the question here is what’s supposed to happen.
After the standing pilot lights in the house go out their thermocouples will loose heat and once that happens the gas control valves will shut down. This will keep gas from escaping. It is likely (these days) that only the water heater is still using a standing pilot.
On the other appliances the gas is always off until the electronic ignition or glow plug is activated.
Realize that we are only talking about what is happening at the individual appliance control valve.
I was a little surprised at this too. I’m sure it has to do with the age of the house. I can personally attest that this is not always true, and since every gas house I’ve ever lived in is also an old house (50 years or older) I’m thinking it’s a relatively new thing?
The true answer is that it depends. It’s not very likely that one will find a water heater without thermocouple protection because water heaters tend to die before getting very old, so you’re not likely to have one which predates that safety feature. Your house heater may be a different beast as they can be quite old. I’ve serviced many heating plants which have standing, non-thermocouple pilots. Cooking appliances may have a thermocouple supervised pilot for the broiler, but the cooktop burner pilots typically aren’t. To be completely safe, go to your gas meter and turn the valve there one-quarter turn so the flat part which you’ve put a wrench on is perpendicular to the piping. Now all gas into your dwelling is shut off. After the emergency is passed, you’ll need to relight all standing pilots.
I read somewhere that, after the fires caused by leaking gas in the Kobe earthquake, slam-shut valves are now to be fitted in all houses in that city. This type of valve already exits (on a larger scale) in the high-pressure gas distribution pipelines in many countries, but not on lower pressure local supply networks. They are actuated when there is a sudden drop in gas pressure . This is usually caused by a large escape of gas due to a pipe fracture or failure of down-stream equipment.
I’d say it is a good idea to shut off your house gas when you evacuate pre-disaster. In most homes the valve is right next to the meter. Instead of a turn-wheel, it’s usually a flat bar you have to grab with a wrench or pliers. When it is closed you’ll see two holes line up to put in a padlock for safety, if you want to.
If your house gets damaged, the automatic shutdown valve may not be there anymore.
I don’t know how the earthquake valves in Japan work, but here in California they are tripped by shaking, not a leak. If the valve is moved back and forth with a force greater than about a 4.5 quake, it trips and the gas is shut off. There is a push button on the bottom of the valve to reset it.
Thinking about it, I imagine that’s how the Japanese ones would work as well.
There are two different types of emergency valves-one is shake activated, and is not unlike the one in your fuel injected car/truck which must be reset after a collision, or the fuel pump won’t run, and the other type is called a EFV, or Excess Flow Valve. When a rate of gas flow which exceeds normal appliance consumption begins, the flow is blocked. Consumer kits to install gas appliances often include these valves.