Ron Hazelton

The Northridge Valve Offers Automatic Defense Against Gas Leaks from Earthquakes

Safety

Savers

Heating

HOUSE DOCTOR Transcript

HD011 “Earthquake Gas Valve” from episode 614

RON:

In January of 1994, a 6.7 magnitude earthquake rocked the Northridge area of Los Angeles. The temblor caused nearly 17,000 gas leaks throughout the city. Regardless of where you live in the United States, earthquakes pose a very real threat.

Well, now there's a valve available that will automatically shut off your gas in the event of an earthquake. It's called the Northridge valve. It's made by the Seismic Safety Products Corporation. And here to explain a little bit about this is Niall Osterhout.

Hi, Niall. Thanks for joining us. What you're holding right here is this same valve, but cut away so that we can see the internal workings.

NIALL:

Yes, that's correct. The gas enters the valve here, comes up over the top of the ball, back down here and out into the house. When an earthquake occurs 5.2 or greater, the ball drops and closes off the gas. And to reset, you just rotate the knob.

RON:

How does that work?

NIALL:

There's a magnet built into the knob in the side of the valve that picks that ball up and sets it back up.

RON:

So the magnet sort of captures the ball and lifts it back up on the pedestal.

NIALL:

That's correct.

RON:

Now it's ready to go again.

You said 5.2 or greater it takes to trip this off. What's the likelihood of a false tripping from, say, something like a heavy truck driving by?

NIALL:

This valve is guaranteed not to false trip.

RON:

Now, what about installation? Is this something that a homeowner can do themselves? Do you recommend that they have a plumber do it?

NIALL:

A homeowner can do it themselves, yes. It's a pretty simple job. If the homeowner doesn't feel good about doing it, we do recommend hiring a plumber.

RON:

So someone that's used to working with the threaded pipe wouldn't have any problem with this. I'll tell you what. Let's go ahead and install this right now and just see what's involved.

NIALL:

All right.

RON:

Now the first thing you'll need to do when installing the automatic gas shutoff valve is to turn off the gas supply to your house. This is a pretty typical shutoff valve right here. But before we actually turn this to the off position, we've got to go back here and loosen this lock nut on the back side. Just use an adjustable wrench for that. Turn it just about a quarter of a turn. And let's readjust our wrench here and place it on the shutoff valve itself.

Now this is in the on position here. The valve is parallel with the pipe. We'll turn it 90 degrees like that so that it's perpendicular to the pipe. And that shuts the gas off for the house.

Now normally you don't have to do anything on the inside. But if you have an older furnace or an older gas range, say more than 25 or 30 years old, then you should go in and turn the pilots off to those before you turn the gas off out here.

Step two is to loosen these couplings or unions right here that attach the gas meter to the piping. Now this is, of course, the pipe that's over here on this side. That's the gas coming into the meter. This is the gas going out of the meter and into the house. Let's go ahead and loosen those up. And then we're going to drop the meter free.

Okay. Our meter's free now. I'm going to sit this over here. Leave it in the upright position. Now in this installation, what I want to do is remove this T right here next. So use two pipe wrenches, one on the T, one on this short nipple.

And then we'll pull this baby up and unscrew it. There we go.

Now next, let's take this elbow off here. Okay, that's fairly loose. Take it off by hand. We're just going to replace this with a new one. Now anytime you're screwing two pieces of pipe together, especially with gas, you've got to seal the threads.

This is a pipe sealant right here. You want to put this sealant on the inside of the elbow right here all the way around. You want to coat the threads thoroughly. And then, of course, on the end of this nipple right here again, making sure that we've got sealant all the way around and well inside the threads. Then we can go ahead and screw this on. And I'll tighten this back up with a pipe wrench.

Now in this installation, we want to set the automatic shutoff valve about six inches to the right. So to get over there, we're going to put a six-inch nipple into the end of that first elbow and then attach another elbow onto that and then a short nipple, which is going to go into the back of the automatic valve.

Now we want to tighten this valve with a pipe wrench placed right on the body itself. I'm going to bring this around so that it's approximately level. Now we're doing some final leveling right here right now.

Now because that ball has to balance on top of that pedestal, this valve has to be installed in a level position both this way and this way. But look at this. You don't have to use a level to do that because they've built right in a leveling device. This chain right here acts like a pendulum. And as long as the end of this is within this circle down here, this hole, the valve is level in both directions.

With our valve in place, let's go ahead and reinstall our gas meter here. And we'll just hand-tighten these down. This, of course, is attaching it to our supply line here coming up out of the ground. I'll hand-tighten this just for now. And then we'll put this T back on over on this side. It's the one that we took off earlier. And then I'll snug these up using a large pair of channel locks.

To connect the gas meter to the automatic shutoff valve, we're going to use a flexible gas line here. This is a special line that's designed for exterior use.

And the reason we're doing this is that in an earthquake, if the house starts to shake one way and the ground starts to shake another, this prevents the pipe from snapping and breaking in half. It gives, as you can see, some ability to move back and forth without breaking. And once again, we want to use two wrenches, one there, one on this nut, and we'll snug these up.

I'm putting the automatic valve in the off position right now. And now we're going to turn the gas supply back on by turning this valve up like this so that it's parallel with the pipe like so. Now remember, we loosened that nut on the backside here, so we're going to have to re-tighten that. Let me just open up the wrench a little bit here. Okay. Put this on here…

Okay, good. Now we want to check all the pipe fittings, starting right down here with a soapy water solution, looking for any possible leaks. If we had leaks here, we would see bubbles coming up. So far I don't see anything all the way around every valve.

Now it's time to check the valve itself and see if it's sealing properly. Let's take this plug out right here. We're going to set the valve open. Okay, you can hear the gas coming out. That's that whistling sound. It's in the open position now, all right? Tap it like this. The ball bearing has fallen into the hole below. The gas now should be completely off. So what we'll do is we'll spray some soap on here, and If we did have a leak here, let me show you what it probably would look like.

Just open this up a little bit. Okay, a little bit here. There, see that bubble coming out right there? If we had anything like that, we'd know that we weren't getting a tight seal inside the valve.

This valve sells for about $199. And installation, if you're going to have a professional come in and do it, could be anywhere from $150 to maybe $200. It really depends on the configuration of your plumbing and how much work is involved.

So if you live in an area that has even a mild prospect of earthquakes, this could be a life-saving device to install in your home.

From the archives of the House Doctor

Protect Your Home From Gas Leaks

In 1994, a 6.7 magnitude earthquake in Northridge, California, caused nearly 17,000 gas leaks across Los Angeles. Regardless of where you live, earthquakes pose a significant threat to home safety. On a recent episode of House Doctor, host Ron looked at a life-saving solution: the Northridge Valve. This single automatic shutoff valve could prevent catastrophic gas leaks if a major earthquake strikes your neighborhood.

Earthquake Preparedness

It's easy to think of earthquake preparedness as a California problem. But seismic activity affects nearly every region of the United States, and even a moderate quake can rupture gas lines inside and outside your home. Gas leaks from broken lines are a leading cause of structure fires and explosions in the aftermath of earthquakes.

The Northridge Valve, made by Seismic Safety Products Corporation, was engineered specifically for this problem. It installs in your gas line just after the meter and monitors for seismic activity around the clock — no batteries, no electricity required.

How the Valve Works

The mechanism is elegantly simple. Gas flows through the valve normally, passing up and over a small ball bearing that rests on a pedestal inside the housing. When a seismic event of magnitude 5.2 or greater occurs, the vibration dislodges the ball, which falls into a seat below and blocks the gas flow entirely and instantly.

The valve is guaranteed not to "false trip" from everyday vibrations like heavy trucks passing by. Only a genuine seismic event will trigger the shutoff mechanism.

Resetting the valve after a quake is just as simple: a magnet built into the reset knob lifts the ball bearing back onto its pedestal. Once reset, the valve is immediately ready to protect your home again.

Installation Advice

If you're comfortable working with threaded gas pipe, this is a manageable DIY project. That said, if you have any hesitation about working with gas lines, you can hire a licensed plumber.

One critical detail is the valve must be installed perfectly level in both directions, since the ball bearing relies on gravity to stay in position. Fortunately, the Northridge Valve includes a built-in leveling indicator — a pendulum chain that hangs freely inside a target ring. As long as the chain tip sits within the circle, the valve is properly leveled. No separate level required.

Installation Overview

Turn Off the Gas Supply
Locate your main shutoff valve at the meter. Before shutting off the valve, loosen the lock nut on the back side with an adjustable wrench. Then rotate the valve 90° so it sits perpendicular to the pipe. If you have an older furnace or gas range (25–30+ years old), turn off the pilots on those appliances first.
Disconnect the Gas Meter
Loosen the coupling unions on both sides of the meter — the supply line coming from the ground and the outlet line going into the house. Carefully free the meter and set it aside upright.
Remove the Existing Fittings
Using two pipe wrenches — one on the fitting, one on the adjacent pipe — remove the T-fitting and elbow in the area where the new valve will be placed. Always use two wrenches to avoid stressing the existing pipe.
Apply Pipe Sealant and Reassemble
Coat all threads thoroughly with pipe joint sealant before assembling any fitting. Use new nipples and elbows as needed to position the shutoff valve approximately where you want it — in this installation, about six inches offset from the original elbow position.
Mount and Level the Valve
Thread the valve onto the pipe assembly and snug it with a pipe wrench placed directly on the valve body. Adjust until the pendulum chain hangs within the target ring. The valve must be level side-to-side and front-to-back.
Connect with a Flexible Gas Line
Use an exterior-rated flexible gas connector to link the meter to the shutoff valve. This is crucial: in an earthquake, the house and the ground may move independently. A rigid pipe connection could snap; the flexible line allows movement without breaking.
Restore Gas and Check for Leaks
Turn the main supply valve back on and re-tighten the lock nut. Then check every fitting with a soapy water solution — look for bubbles, which indicate a leak. To verify the valve itself seals properly, open the valve, tap it to trigger the ball drop, and spray soapy water around the valve seat. No bubbles means a tight seal.

Important Safety Reminder

After any work on your gas line, always check every connection with soapy water before considering the job complete. If you smell gas at any point during or after installation, leave the area immediately and call your gas utility from a safe distance. Never use open flame to check for leaks.

Is It Right For Me?

If you live anywhere with even a mild seismic risk — and that covers a large portion of the United States — an automatic gas shutoff valve is one of the most cost-effective safety upgrades you can make to your home. For roughly the cost of a weekend home improvement project, you get around-the-clock protection against one of the most dangerous secondary effects of an earthquake.

The installation takes a few hours. The protection lasts the lifetime of your home.