View Full Version : Just how dangerous is gas

09-29-2004, 06:46 AM
So yesterday the bellsouth guy came out and hooked up my DSL line. When I got home there was a message on my machine from Bellsouth saying they had it hooked up. Funny thing the guy leaving the message is one of my "Brothers in Arms" from the Guard. He leaves his pager number, never realizing it is me, so I page him.

He calls me back and says "Mr Smith I have your DSL hooked up and your getting 3 meg, but you have a gas leak" We talk for a little while, the whole time I'm calling him Bo and it never registers with him who I am. Finally he says "Is this Smitty?" Than he says "Brother, you got a bad gas leak"

Me and my lackluster sniffer go out there and I can just barely smell gas. I get the wife out there and she smells it right away. So I call the gas company and within the hour they have a service tech there. These guys take gas leaks serious. The guy on the phone said no turning lights off or on and to stay away from the area, all good advice.

When the gas guy gets there he can't even smell the gas, and he is suppossed to be a gas hound dog. His electronic sniffer is not detecting gas, so he pulls out the handy dandy sprayer with soapy water in it and sprays all over the meter. After about 5 minutes or so he finds a small leak and tightens the fitting so the gas leak goes away.

We talk for a while about the lack of danger with gas. He tells us gas is really quite safe and you have to have an extreme concentration to have problems. He said you wouldn't have been able to even light the leak that we had, but that we did right by calling the gas company.

So just how dangerous is gas? The guy on the phone treated it like it was extremly dangerous, but the service tech on site downplayed the dangers of gas. Is he doing this to help build consumer confidance in gas or is it really not as dangerous as they let on on TV?


09-29-2004, 06:54 AM
Every so often around here a house is blown to splinters. Pretty darn dangerous.

Bruce Hooke
09-29-2004, 07:02 AM
Remember, the person on the phone cannot necessarily know that you are not, say, smelling the gas in your kitchen when the real leak is in your basement where lots of gas could have accumulated, but could not smell that strong from the kitchen. Or you could simply have a horrible sense of smell! So, I'm sure the people on the phone are trained to treat every leak as a near worst case scenerio. Furthermore, the people who answer the phone have probably never actually made a service call so they are just going on their official training. I would say that the service tech's take on the situation was closer to right. However, before you get too complacent it's worth remembering a few things:

1. Under the right circumstances a small leak can lead to a lot of gas accumulating in an enclosed area. This is definitely a very dangerous situation.

2. If you do get enough gas in a space for the mixture to be explosive and if a spark then sets it off, your house would be matchsticks. So, a wide margin of safety is prudent.

Like so many things I think a lot of it comes down to this concept: gas is not overly dangerous if it is handled intelligently, but unfortunately there are a lot of idiots out there...

Peter Kalshoven
09-29-2004, 07:07 AM
Chad, part of the problem is, "Which gas?"
Natural gas in an enclosed space can be very dangerous, but an outdoor leak will rise up and disappear. NG is lighter than air.
Liquified Petroleum Gas (aka Propane or LP) is heavier than air, and will pool. There are a lot more dangers with LP just because a leak can accumulate rather easily.
In other words, although gas is a very safe energy source, it's still nothing to screw with. If you smell a leak, better safe than sorry.

Ian McColgin
09-29-2004, 07:26 AM
Speaking as a retired utility regulator . . .

Anyone with gas appliances should add CO alarms to their smoke and fire alarms. Anyone with poor smell should also add a gas leak alarm. These things work well.

Gas leaks that are the company's responsibility are both more common and more safe than most folk realize. The customer usually pays for service on the pipe from the street on in but the equipment from the meter upstream is really the company's to maintain. While most gas companies have service plans for homeowners' equipment from the meter downstream, all that equipment in the house is the customer's property and thus the customer's responsibility.

Since "deregulation" - really restructuring - in the industry, many gas companies have had to spin-off their service units. And for inside work customers could always elect to call Joe the Plumber anyway. Nonetheless, many customers find it as well to stick with service from the evil monopoly as they can go fix whatever the problem. Joe the Plumber can't work on a leak at the meter. Also, Joe's wife is unenthused about service calls at ohdarkthirty on a frosty morn.

If you have propane service, you have a large outside tank. Those joints may leak and the tank might vent on a really hot day but there's little danger unless you have the tank located near a celler window allowing fumes to pool in your basement.

In cold areas, meters are often indoors to protect against the moisture in the gas from freezing. With improvements in gas supply and in the meters themselves, there's been a move to getting meters outdoors. Most gas leaks that effect houses are meter-related

Outside gas leaks can - rarely - seep through a foundation and pool dangerously in the basement but most outside leaks are an annoyance rather than an explosion hazard. I've even lit some to proove there was a leak. Kinda cool to have flames coming up in a lush lawn. (Trained professional. Don't try this yourself. HehHehHeh.)

Inside leaks in houses that have a basement or any other stagnant air place are a huge hazard. Natural gas is pretty odorless, which is why they add the mercaptan to make it stink like rotten eggs.

Whenever you smell gas, call the company. If you only smell it outside, no big worry and don't be surprised if it takes the company a while to find and fix the problem. It's a bit like deck leaks - the problem can be on place and the drip quite another.

If you smell gas inside, treat that very seriously.

Most gas leaks are at joints exposed to trouble - in the underground mains or in the joints in and around the meter. Usually in-house plumbing is trouble free. Most newer appliances, whether those with auto-ignition or those with pilot lights, shut off the gas supply if there's any trouble. That's why most gas leaks are fairly harmless outdoor leaks and the small number that do completly obliterate a home are usually outside leaks where the gas seeped into a basement and pooled there.

Like many folk, I have propane on Granuaile. Lovely convenience. Scares the bejezus out of me. Plan to switch to a diesel cook stove in a year or so. Gas afloat is a very different issue from gas ashore.

Gas is wonderfully safe almost all of the time. Problem is, when it's not safe, it's spectacularly not safe.

Stay warm.

Domesticated_Mr. Know It All
09-29-2004, 08:01 AM
Speaking of the dangers of gas, I made a big pot of bean soup last night. :eek: :eek: tongue.gif :D

09-29-2004, 08:12 AM
You'll smell the leak in concentrations far below the danger level AT THE PLACE YOU ARE SMELLING IT. Which is not to say the concentration might not be higher elsewhere as was said above. I understand the stink put in gas is a mercaptan in the same family of chemicals as skunk squirt and the stuff that makes yer pee stink after eating asparagus.

09-29-2004, 08:13 AM
here ya go KIa


Domesticated_Mr. Know It All
09-29-2004, 09:17 AM
It's too late for that stuff Popeye and talk about dangerous! :eek:

One of the kids refered to me as a "crop duster",whatever that is. :D

09-29-2004, 09:20 AM
"Clark Gable" beans is my favorite brands.

One can and you're gone with the wind.

Nicholas Carey
09-29-2004, 08:12 PM
How dangerous is gas? Well...

A few weeks back, here in Seattle, "Woman survives gas explosion that ripped apart Bellevue house (http://seattlepi.nwsource.com/local/189231_explosion03.html). Here's her house:


She just died yesterday from her burns.

They're still researching the cause of the leak. It looks to be an underground leak in the gas pipe coming into the home, with electrolysis as the suspected cause.

09-29-2004, 09:07 PM
Yikes. One guy on a three inch hose and no hose strap. No wonder he hasn't turned it on.

The only building I've seen that was blown up by a gas explosion, natural gas, had no fire.

John Bell
09-29-2004, 10:08 PM
The mother of a friend died in a horrific LPG gas explosion in Schleswig, Iowa a few years back. Evidently, someone nicked the LP line feeding the furnace while digging around the foundation. The gas leaked into the basement. Being heavier than air, it pooled on the floor. She went downstairs one morning, turned on a vacuum cleaner, and the resulting explosion blew the house apart. Debris was scattered for almost a mile. :(

After that, I'm not sure I'd ever want propane inside my house. Or boat. :(

Ron Williamson
09-30-2004, 05:18 AM
I had a customer with a new NG fireplace.
They'd used it about 6 months before they went for a two week holiday.When they came home,they turned on the fireplace and the leaking gas inside lit and blew out the front,lighting their floor and carpet on fire.
There had been a tiny leak in a factory installed joint.Unused,the gas built up in the enclosure.

Harry Miller
09-30-2004, 06:24 AM
Ron, did the NG fireplace have a pilot light or electronic ignition? If the latter, would a pilot light have stopped the buildup from happening?

Andrew Craig-Bennett
09-30-2004, 06:37 AM
Some very good information on this thread.

The one place that I absolutely will not have gas is on the boat. Kerosene, every time!

09-30-2004, 07:02 AM
The gas in question is natural gas and the leak was outside, no gas appliances inside.

So if I understand this right, NG under most situations is safe when installed correctly and there are no areas for it to accumulate (part of the reason being it is lighter than air), but it also has the potential to spectacularly dangerous.

I've thought about adding a gas water heater. The gas company will give me a 40 gallon water heater for free, all I have to do is pay to have it hooked up.


Garrett Lowell
09-30-2004, 07:07 AM
Chad, in order for NG to become dangerously explosive, the correct ratio of fuel/air must be met, and then, of course, an ignition source must be found. The ratio is 4-14%. Lower than 4%, not enough fuel. Higher than 14%, not enough oxygen. As with everything, as long as your gas appliances are properly maintained and functioning, your odds of a catastrophe are absurdly low.

Ron Williamson
09-30-2004, 11:51 AM
Piloted, with closed combustion(sealed firebox with air from outside the house).
The leak was in some of the pipework below the firebox.
When it was installed,I put a mantel around it,and was happy to find that I hadn't put a screw into a gas line.

Peter Kalshoven
10-14-2004, 08:07 PM
Originally posted by Ian McColgin:

Gas is wonderfully safe almost all of the time. Problem is, when it's not safe, it's spectacularly not safe.
Ian, that may be the best description of gas I've ever heard.