11-12-2005, 12:59 PM #1
- Join Date
- Dec 2002
- Central NJ
Ventilation at (Inside) Natural Gas Leaks
I've had this question burning within for a while, and finally decided to throw it out there. How do you clear a building full of natural gas? Natural ventilation seems the most logical answer, however, that leaves me wondering. If the gas is left to sit inside longer, doesnt it allow for more opportunity to find some source of ignition?
Do you folks have other ideas including use of fans and hose streams dependent on circumstances?
Another question centers on shutting off leaking gas meters. Do you feel the use of a protective hoseline is appropriate to disperse vapors while shutting down the leak? Do you feel it isnt our job to shut off leaks? Do you mask up when shutting off a leak? Do you have engine companies lay lines and prepare for an explosion/fire?
What level of response is assigned to an interior gas leak in your district (first alarm, local alarm etc)?
I'm looking for various expierences and ideas to see if I'm on the same page. It is my opinion that when faced with a leak we must secure the leak when possible by shutting the meter, evaculate people and ventilate as quickly as possible to avoid an explosion. Let me hear what some other opinions are.
11-13-2005, 01:16 AM #2
I have heard of one trick used for temporarily sealing gas cylinders that have a leak, but are not ignited. You get a wet cloth and place it over the leak, and apparentely the escaping gas is so cold it freezes the water and makes a nice seal when the water expands to ice.
Never tried it myself though, so im not too sure how well it will work."There are only two things that i know are infinite, the universe and human stupidity. And im not so sure about the former."
For all the life of me, i cant see a firefighter going to hell. At least not for very long. We would end up putting out all the fires and annoying the devil too much.
11-13-2005, 03:59 AM #3
The response over here in LOndon is two Pumps...they wanted to stop us attending althogether (less calls attended the more they can cut back ) but they realised that was a dangerous move. Due to the risk of terrorism, a Hazmat Officer will also attend any calls to 'smells' such as gas.
the procedure is; arrive, make an entrance into the property, ventilate naturally and call and await the Utility Co. Hoselines and BA will only be deployed if the leak is severe and explosion looks imminent.
For large scale leaks the Police will also attand along with the Local Authority Emergency Planning Officer is residents need evacuating, he/she will arrange shelter and food.
Obviously for a burning gas main the gas is left burning and covering jets are deployed to protect exposures until the Gas Co shut down the supply.
I Have used a large clump of very wet Newspaper to cover a damaged gas pipe in a job where the flame was inadvertantly extinguished during the course of Firefighting. Nowadays we carry large tubs of Putty as part of our Environmental pack carried on front line Pumps that can be used to stop a host of leaks be they liquid or low pressure gas.Steve Dude
London Fire Brigade...."Can Do"
'Irony'... It's a British thing.
11-13-2005, 07:00 AM #4
- Join Date
- Jul 2001
- Not the end of the earth but I can see it from here...
We don't have multiple occupancy dwellings in my area, so having a big apartment building or other large capacity occupancy full of gas is not a problem we have to deal with. We have only single family dwellings, and normally when we get called to a gas leak it's not in the house but out in the yard (usually a car knocked over the gas meter).
A few years ago we didn't deal with these ourselves....deny entry to the area and wait for the gas company to show up. But eventually we figured that the easiest way to protect the public and prevent an ignition was just to stop the darned leak. We got some 1" "plumbers' plugs" from the gas company and now 90% of the time we are able to plug the leaking pipe and stop the leak. Then we wait for the gas company, we stand by while he makes the repair, and he gives us our plug back. It's a single engine response for us.
After watching the gas company guy do repairs on these things, in street clothes, I'm pretty comfortable going in with bunker gear & SCBA to install a plug. Takes only seconds and the hazard is mitigated. I've done it numerous times myself.
I have heard of one trick used for temporarily sealing gas cylinders that have a leak, but are not ignited. You get a wet cloth and place it over the leak, and apparentely the escaping gas is so cold it freezes the water and makes a nice seal when the water expands to ice.Chief Dwayne LeBlanc
Paincourtville Volunteer Fire Department
"I have a dream. It's not a big dream, it's just a little dream. My dream — and I hope you don't find this too crazy — is that I would like the people of this community to feel that if, God forbid, there were a fire, calling the fire department would actually be a wise thing to do. You can't have people, if their houses are burning down, saying, 'Whatever you do, don't call the fire department!' That would be bad."
— C.D. Bales, "Roxanne"
11-13-2005, 12:17 PM #5
Cant recall ever responding to a natural gas leak inside. Have had alot of gas lines hit by construction crews. Our response to these is the same as a structure, 3 engines, 1 truck, 1 squad and a DC.
First crew checks out the leak (full PPE/SCBA) with a CO2 extinguisher in hand, then reports back to the IC. We do this face to face, no radio TX near the leak. If the leak is large enough, handlines are put in place while we wait for the gas co. We don not shiut off leaks, but we will assist the gas co.Fire Marshal/Safety Officer
"No his mind is not for rent, to any god or government"
Success is when skill meets opportunity
Failure is when fantasy meets reality
11-13-2005, 09:21 PM #6
Our community is piped with Propane. Similar to NG/LNG, but heavier than air, so it is more difficult to dissipate in closed spaces. Fill a basement with it, and you must ventilate. To answer your question regarding ventilation, our SOP is:
1. Respond and secure perimeter outside gas envelope. Perimeter size is determined by situation, and evacuations performed as necessary to clear hot zone. Wait for Gas company if possible (45-60 minutes away after 5pm), if not reasonable to wait, begin evacuation, and leak control procedures.
2. Shut off all gas supplies and accessible ignition sources in building/area. Determine current spread using a CGI.
3. If gas is found in a confined space, attempt to ventilate naturally.
4. If gas cannot be vented naturally, IC can choose either to introduce an intrinsically safe fan, or use a water stream if damage is not a concern (i.e. flood the water out of a ground vault, blow it out of a building). You can also dissipate small pools of gas as they develop with a narrow fog.
You could use a non-intrinsically safe smoke-ejector in certain circumstances.
1. You have adequate ducting to keep the electric fan outside the gas envelope.
2. You tape up your connections and switches, and bring the electric fan into the envelope already running.
We do not use gas powered ejectors, regardless of ducting options.
Natural Gas should be easier to ventilate and disperse, but as always, it is better to let the gas company do it if possible. They generally have a better supply of intrinsically safe equipment (and training) than we do. We have found that is not always the case though, and just this past summer we had to pull an experienced utility worker out of an excavation after he was overcome by propane while trying to squeeze off a leak. He did not follow his own company's protocol for dealing with a dig up.Never argue with an Idiot. They drag you down to their level, and then beat you with experience!
11-14-2005, 11:31 PM #7Originally Posted by dmleblanc
The new PVC gas lines being used these days don't respond well to standard plugs (they use a device much like a small hose clamp around here), and you have to be careful of the static charges built up by the escaping gas. The Thankfully Nat. Gas goes straight up, so we just secure the area and wait for the gas co. to show up and take care of the problem if outside.
If it is inside a building we normally evacuate and shut of the gas at the meter.
11-16-2005, 05:20 PM #8
- Join Date
- Jul 2005
We also wait on the gas company for outside leaks. If it's at a meter and we can shut it off, then we will - but for incidents where workers cut or drill into an underground line we just evacuate as necessary and let the gas co. take care if it when they arrive. We too had clamps we used to use, but the gas co had 2 workers burned a few years back when a leak they were clamping ignited from static and we no longer use the clamps unless the IC determines the risks would be worth the benefits.....We lay lines to protect the gas workers many times, but it depends on the situation.
As far as inside leaks we shut them off from the outside meter (unless it's damaged) then ventilate using PPV. Even large apartment buldings can be fully cleared in a few minutes with PPV. Everyone's evacuated from inside during this. Crews use full PPE including being on air. Crews also have 4 gas monitors to help them assess and find gas in buildings.
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