Gas shut off valve

Ok now that I installed a gas sensor the person wants a gas cut off valve (of course) like the elk water valve I need something 3/4" has anyone used one or know where to get one?

Check with Grainger. I doubt that a standard solenoid is gonna cut it like it would for compressed air.

Yea I need something probably explosion proof.

I'd start with the gas company, ask them for some input. There may be some code issues. Similar to electrical devices, I bet the valve needs to be 'listed' for gas use, adding to the cost. HVAC and plumbing distributors may have what you need in stock.

Several years ago when I worked at UL I remember a coworker evaluating an electrically operated gas shutoff valve. It sticks out because it was rare. I dont know the company name but at least one did or does exist.

Digger said:

It sticks out because it was rare.

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yeah....that means expensive!

--Dan

I would stay away from doing that to a customers house. If it shuts off when it shouldn't and the house freezes there could be massive damage and you could be liable.

But, just to muse since I recommend not doing this, the Elk water valve should be able to be used for gas. I am sure it is not code but there is no reason it wouldn't work. Gas pressure once passed the companies regulator is only 10 in WC (about .36psi). It comes with iron pipe thread and is stainless steel.

Dont use the Elk valve - I seriolusly doubt that it is rated for a hazardous area and wont rpevent an explosiong should there be a gas leak at the valve.

This is not for the feint hearted, Gas will go bang if a spark is created by the valve - There is a whole industry built around explosion protection and electrical equipment.

You need ot define the hazardous area, temperature calssification, Class etc.

Two methods of protection (easiest is the first)
Explosion proof (big and strong - contains any explosion within the housing)
Intrinsically safe solenoid with associated IS barrier (not enough energy in the spark to ignite the gas)

Documentation should be done to prove that the installation complies.

Check with the Gas company for valve recomendations and even if they will allow it.

Mick

You do realize of course that pretty much every gas appliance in a home or anywhere for that matter has either a pilot light or spark igniter within inches of unions and valves. So the issue isn't with the little motor on there causing an ignition if there is a gas leak since there are plenty of much more obvious sources of ignition.

The issue is liability, end of story. No doubt that the valve is capable of performing the job as its components qualifications vastly exceed the demands it would be subjected to in this environment, and I mean vastly. Less than 1 psi, I fart with more force than that!

It would not pass code and it would put you at liability that you could not defend yourself from. So, don't do it. As I mentioned, I was musing.

As noted by other posters...while for water it's feasible to turn the main off when you're away for a long time. Shutting the gas can potentially damages the house by freezing, etc.

As i read the post i started considering this myself but then concluded that i would much prefer a gas detector and then a warning. I will then go shut it off myself. There is too much potential for error in programming rules and such..power failures..etc. that could work out badly.

For my entertainment sake... how many of you actually have gas sensors? I don't have any in my house..i do have smokes and carbon monoxide ofcourse. Arent the furnaces and such all more or less built to be safe in this regard?

What are we protecting against...a leak in the gas lines...how often does that occur and would the sensor really help or would it happen in a wall and you wouldn't even notice?

In case of water there is many many more connection points and thus potential for leaks.. then there is the ever notorious hot water heater leaks...(co-worker just flood his basement with one)...etc..etc..so sensors and a auto shutoff make more sense there..

I think everyone has either experienced a water leak or at least knows someone who has. They are common. I know two people who suffered 6 figure damage from water leaks. Of course all of us have seen the news when a house explodes from a gas leak. I don't know if anyone keeps a log on this, but I bet you don't have meaningful gas leaks that result in injury, loss of life, or property damage more than a handful of times in the entire country each year.

With gas lines under such miniscule pressure (at least in the house) it is not surprising that disasters are so unusual. It takes a fairly large hole in a gas line to leak enough gas to get the concentrations sufficient for combustion. When I moved into a house I lived in in college, the flexiline going to the oven had a sizable crack in it. I could just barely smell the gas which led to the discovery. It took 2 of us to figure out if it wasn't even just our imagination. If a water line had had a crack that big the kitchen would have been 3 inches deep in an hour.

In short, I think worrying about a gas leak beyond the regular precaustions is likely to cause more problems than it solves. I suppose there is no harm in a gas detector that just sounds an alarm. As I mentioned before, an error that shuts the gas off on a cold winter day could destroy a house and I bet a lot more probable than the setup ever having the opportunity to save your house/life. One of those "cure is worse than the disease" situations.

Interesting topic. After a small water filter hose let go in the middle of the night under my kitchen sink and ran all night ($75K damage) I decided to add sensors to my HAI panel. Installed water sensors at each suspect location and a shut-off valve on the main. Added CO (every floor) and Natural Gas sensors (basement and first floor) as well. After researching all of the issues as noted above and a lengthy conversation with the local fire department, I opted not to install a shut-off to my gas main.

According to the fire department, the majority of gas explosions are the result of exterior work or failure of exterior systems. Using a shut-off value wouldn't help in these cases. It appears that internal leaks may present the same potentially deadly threat as CO; asphyxiation. Therefore I have treated natural gas in the same way as I treat CO: monitor and alert.

As this is a Life/Safety issue, please don't use my comments as anything more than my personal opinion.

Rick

ricks said:

Interesting topic. After a small water filter hose let go in the middle of the night under my kitchen sink and ran all night ($75K damage) I decided to add sensors to my HAI panel. Installed water sensors at each suspect location and a shut-off valve on the main. Added CO (every floor) and Natural Gas sensors (basement and first floor) as well. After researching all of the issues as noted above and a lengthy conversation with the local fire department, I opted not to install a shut-off to my gas main.

According to the fire department, the majority of gas explosions are the result of exterior work or failure of exterior systems. Using a shut-off value wouldn't help in these cases. It appears that internal leaks may present the same potentially deadly threat as CO; asphyxiation. Therefore I have treated natural gas in the same way as I treat CO: monitor and alert.

As this is a Life/Safety issue, please don't use my comments as anything more than my personal opinion.

Rick

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The on-demand hot water tanks that mount on the exterior of the house are also helpful. This avoids the risk of CO in the house and reduces the risk of NG in the house also.

Natural gas is non-toxic and completely innert as far as human physiology is concerned. However, natural gas still can kill by asphixiation. As the concentration of NG rises in a room, the concentration of other gasses will necessarily drop. In other words if you replace half of the air in a room with NG, the concentration of oxygen will go from roughly 20% to 10%. Depending on your general health status, you will tolerate more or less of this problem. People like Lance Armstrong and those who spend a great deal of time at high altitudes will tolerate this much better than the average Joe. Someone who already has lung disease or anemia will succomb much easier. The odorant in NG would be very powerful at these concentrations which is why it is such a rare event that people are injured this way. I have heard of pets being killed this way.

This is much different than CO. CO aggressively binds to hemoglobin preventing oxygen from binding. So very small concentration of CO can effectively incapacitate your red blood cells and thus block delivery of oxygen to your tissues, even in the presence of 21% oxygen. And, of course, CO has no odor. Once CO has binded to hemoglogin, it requires a great length of time at 21% oxygen (and no CO) to knock the CO off and get oxygen back on board. If you breath 100% oxygen, or better yet, get into a hyperbaric chamber breathing 100% oxygen at 2 or 3 atmospheres of pressure, the CO will be displaced fairly quickly. The trouble, of course, is the time that was spent getting the person to that high oxygen environment.

Sorry, don't want to confuse anyone. Didn't mean to imply that NG and CO are the same, chemically or by physiological effect. Just saying that "I" treat them the same as far as an automated response. If it's there, let me know so I can act on it.

Rick

P.S. Maybe I'll automate the pet door.

There is a market in CA it is reg you have to have a earth quake gas shut off in some houses. Unfortinally these are all mechnical.