Thread: Gas valve or water valve?

I have never seen a gas shutoff valve that looks like this. Is this just a water valve the homeowner stuck in the gas line going to the dryer?

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To me, it looks like a water valve.

Originally Posted by Tom Cissell

I have never seen a gas shutoff valve that looks like this. Is this just a water valve the homeowner stuck in the gas line going to the dryer?

Don't know who installed the Water cutoff on the gas line.

Functionally it should be fine.... water 60psi - residential gas .5 psi.

This is actually something I've wondered about before. I've seen valves that look like they're intended for gas being used for water. So, is a valve a valve? Or, are there problems swapping back and forth?

I always thought that water molecules were bigger than gas molecules so that (corrosive effects aside) that gas values would hold water but not necessarily vice versa.

To the best of my knowledge you can't swap back and forth as valves in plumbing have to compy with NSF 61 (safe for drinking water) vs. a gas valve which would not have to comply with this rule.

Plus, if I remember right, gas valves need the AGA/CGA or the newer CSA marking indicating its approval for gas.

Basically, you can't just throw any valve on gas or plumbing.

That has to be a water line, or that house wouldn't still be there. Natural gas would leak out around the stem and blow the place to smithereens.

No. It is a gas line running to a gas dryer within three feet of the valve. The water is all rigid copper in this house.

I thought Roper was a Canadian Market brand, not one with approvals or listings for the US Market...

Originally Posted by H.G. Watson, Sr.

I thought Roper was a Canadian Market brand, not one with approvals or listings for the US Market...

Nope, all kind of Roper appliance down here in FLA.

Wrong, can't do that. I'm surprised it isn't leaking, but that may only be because that it's never used.

That's a globe valve for water. Replace with gas cock listed to ANSI Z21.15. Where there's one stupid thing, there's probably more. Did you trace all the other accessible gas piping for shutoffs?
done

Originally Posted by Tom Cissell

I have never seen a gas shutoff valve that looks like this. Is this just a water valve the homeowner stuck in the gas line going to the dryer?

At a People's Energy seminar in Chicago I asked about this. As particular as they are they do allow such a valve on gas lines.

Do this client a favor, call the gas utility for a courtesy inspection. They will turn off the gas until this valve has been replaced. This valve is a bomb looking for an opportunity to detonate.

If it is a "listed" valve and marked WOG it is approved to be used in a system for Water,OIL or GAS.

It's a water Globe valve, write it up! Needs to be replaced with a gas cock!

What is a water valve and galvanized pipe doing in a gas line?

I've been a licensed plumber for over 35 years and have used brass ball valves for both water and gas for the last 30 of those. Same valves out of the same box for both. As long as they are rated and approved for WOG, they work great. And there is nothing wrong with galvanized pipe in a gas line either. That's an urban myth that galvanized flakes off with gas. Just doesn't happen any more with galvanized than with black iron or copper and approved in our codes out here and, as far as I know, in the other codes as well. Some utilities and propane companies say the same thing about copper pipe — another urban myth. BTW, it looks like a gate valve to me, not a globe valve.
To all you who said to "write it up" to be replaced without looking at the valve, are off base. You are home inspectors, not plumbing professionals. If you don't know something, write it up and say you don't know if it is right or wrong and recommend a professional in the trade or profession that would know if it is right or wrong to evaluate it.

Ralph, I know it's just a picture, but that doesn't look like a ball valve to me, look at the valve stem.
Oh, wait, I read the rest of your post and agree it may be a gate valve. Those are OK for gas?

Must be marked on valve WOG (water oil gas) or its wrong. To me it looks wrong. I would go as far as recommending replacement with new style fast acting valve .

Originally Posted by Ralph Holden

BTW, it looks like a gate valve to me, not a globe valve.

I'm not a plumber, but that does not look like a gate valve to me.

I have been a licensed Mechanical HVAC Contractor for over 30 years, I have a 1st Class Enineers License for Boilers, and recently a Home Inspector the last 5 years. It is very easy to see the difference between a globe and gate valve. This looks like a globe valve and it needs to be replaced with a gas cock. So write it up! The globe valve is round with a wider base and is not a good idea for gas, it has a rubber seat and the packing stem can leak also. The gate valve at least drops straight down and the brass seals against brass. It still needs a gas cock installed. I have even seen water ball valve in the gas line and I write them up to be replaced also. Tom, it is not a good idea to leave in place a valve that can leak like this one. Did you leak test the valve and gas line? I would recommend that it be replaced with a gas cock. I guess it comes down to can you see WOG on the valve but I wouldn't let it go.

Ralph, as a professional plumber, I assume you own and have read the code? You know, the one that states an appliance gas shutoff must be listed to ANSI Z21.15? Modern gas cocks are tested and listed to this std. because of certain failings of other valve types. That listing, for instance, allows only valves with a non-displaceable valve member. It also requires positive stops full open and closed, which a globe or gate valve does not.

I hope I attached the photo correctly. It is of a Mueller 100-205NL 1" gate valve similar to the one in the original post. It is round with a wide base just like Mr. Hagman said only globe valves are shaped. It is rated for 300# WOG. It's description doesn't say it conforms to Ansi Z21.15 but it is made by a reputable company and labeled as suitabile for gas. I do own and use all current code books that apply to my area (California). I have not read the entire ANSI Z21.15 standard Mr. Harper referred to and do not understand what a "non-displaceable valve member" means. But I do know that gate valves stop positively when fully opened or fully closed.

A gate valve is designed for isolation or "stopping" but not metering, whereas a globe valve is designed for metering flow but not stopping. Both incorporate a displaceable valve element. Both usually, but not always have a rising stem (some gate stems do not rise). The globe valve offers a lot of friction due to its tortuous pathway inside whereas a gate valve is usually a straight shot. However, both designs usually reduce the effective flow area and thus are not "fully ported".

Now, the code does allow WOG valves in other applications and other places but we're talking about an appliance shutoff. Here the NFGC and IFGC concur in calling for gas cocks listed to Z21.15 specifically. They must have a reason. From talking with Ted Lemoff at NFPA (they guy who wrote NFGC and sits on its review board), yes, they have had issues with other types of shutoffs at appliances, hence the requirement for the special purpose gas cocks.

Ralph, I'm calling the valve in the OP a globe based upon the one photo provided. In it, you'll note the bulbous shape across its base like a globe valve. See the shadow for a better view. Gate valves don't' have a bulbous base because they are axial flow.

I keep it simple: when working around gas appliances, if I don't see a gas cock made of brass with a quarter turn ball valve,or if I see a nut & washer, ground key or displaceable element, and no markings, or if they are leaking or the mechanism is either too stiff to operate by hand or so sloppy, it will leak, I replace them. Shutoffs are cheap. Most of the time, I end up removing an illegal bushing and adding the sediment trap that was left out not to mention replacing the ground union where the installer put dope all over the seat causing it to leak and re-working a lot of PTFE tape joints with approved dope. Teflon legal but bad choice as threads of it can and do clog valves. Then I support the pipe because that last few feet is rarely properly supported or secured. Lastly, where required, I electrically bond it.

I agree with your comments about galvanized steel gas piping. I have checked with the local suppliers and all my gas around here, both NG and LPG is claimed to be under the 0.3 grains of hydrogen sulphide per SCF so it is allowed. In fact, that is what PECO uses when setting or servicing their gas meters.

Originally Posted by Bob Harper

I agree with your comments about galvanized steel gas piping. I have checked with the local suppliers and all my gas around here, both NG and LPG is claimed to be under the 0.3 grains of hydrogen sulphide per SCF so it is allowed. In fact, that is what PECO uses when setting or servicing their gas meters.

Not that I know what I'm talking about, but I'm going to bet that the regulations (and beliefs) about gas corroding pipes persist from the era of Town Gas.

Until the mid-20th century, "gas" was produced from the thermal decomposition of coal, and was a significantly different product than the Natural Gas of today. It contained many impurities not found in modern gas, the most significant of which being Carbon Monoxide... which is where we get the concept of suicide by sticking one's head in the (gas) oven.

You guys are awesome. Thanks for all the good discussion. I called it out.

Originally Posted by thaddeus cox

It contained many impurities not found in modern gas, the most significant of which being Carbon Monoxide... which is where we get the concept of suicide by sticking one's head in the (gas) oven.

Are you saying that one cannot kill themselves by sticking their head in a gas oven and turning the gas on?

Thaddeus is partially correct in that actually there were dozens of types of gas made from coal gasification with names such as "blue gas", "water gas", etc. I have pages on it in the Gas Engineer's Handbook. The main thing is he is correct about the high concentration of CO in these gases. Natural gas, which is primarily methane, is not directly poisonous but is, like propane and CO2 considered a simple asphyxiant. These gases can displace oxyen below the 16% concentration in air required by humans to live.

Now, most NG and LPG come with a witches brew of various nasty contaminants that in more recent times get "refined" out. However going back into the '70s and before, it was not uncommon to find gas with significant levels of hydrogen sulphide in both NG and LPG and that is the main pollutant that causes corrosion. In uncoated copper, it can form hydrogen sulphide "black flakes", which have been proven in court to clog gas controls and lead to fires and explosions. In galvanized steel, it can form zinc sulphide and do similar but note in both cases, it also results in the erosion of material in the pipe.

Now, you can stick your head inside and oven full of NG and even at its upper explosive limit of 14% to air, there would be enough air to breathe as the fuel needs 10 parts of air to one part NG. You should be just fine with your head in there for a few moments..............until something ignites the fuel :-)

Originally Posted by Bob Harper

Natural gas, which is primarily methane, is not directly poisonous but is, like propane and CO2 considered a simple asphyxiant. These gases can displace oxyen below the 16% concentration in air required by humans to live.
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Now, you can stick your head inside and oven full of NG and even at its upper explosive limit of 14% to air, there would be enough air to breathe as the fuel needs 10 parts of air to one part NG. You should be just fine with your head in there for a few moments..............until something ignites the fuel :-)

"These gases can displace oxyen below the 16% concentration in air required by humans to live."

"You should be just fine with your head in there for a few moments..."

That was precisely my point ... ... it is not the ignition of the gas which is required to kill you (i.e., the CO put out by the ignition and burning of the gas), it is the lack of oxygen which will still kill you.

As a Sparky I'll be slightly off-topic also... Is an appliance feed the only place where a 1/4 turn is required??