Gas Safety

Wayne_16

Unknown

Testing before entering a building

How many of you use a Combustible Gas Detector before entering a building which has an odor of gas?

What is the upper and lower explsive limits of natural gas?

How about propane?

If the level of gas is over the lower explosive limit what would you do?

In an interview with a group of legal people who also work with an insurance company which insures many trades and contracting businesses this came up. They felt that everyone who works on gas in anyway will have all the safety equipment needed to insure their own personal safety.

In all my classes this comes up and very few plumbing and heating professionals have CO detectors or CGI meters.

Unknown

Come on folks

anyone interested in saving lives - the life you save may be your own.

Derheatmeister

Yes we do use a Tif and CO when we enter!

And if the propane was leaking that can be very dangerous even if some time has pasted and the basement was "aired out"!

Derheatmeister

Yes we do use a Tif and CO when we enter!

And if the propane was leaking that can be very dangerous even if some time has pasted and the basement was "aired out"!

scrook_3

go gas, go boom!

Odorized Natural Gas (90% methane, 10% ethane -- Amerada Hess Corp. MSDS)
LEL: 3.8 - 6.5%, UEL: 13 - 17%, density: 0.6 (air = 1)

Methane: LEL: 5 - 5.3%, UEL: 14 - 15%

Propane: LEL: 2.1 - 2.2%, UEL: 9.5 - 9.6%, density: 1.5 (air = 1)

For those using acetylene torch fuel: LEL: 2.5%, UEL: 80% (yea, it's wide!)

For those using MAPP torch fuel: LEL: 2 - 3%, UEL: 11 - 13%

If over LEL, RUN! (and DON'T turn out the lights on the way out!) Once out call Fire Dep't, then call the Gas Co.)

Unknown

Scrook, very good

however do you use a CGI or CO tester before enetering a building? If so what is your meter of choice?

Bob Harper

passing gas

I wear a Scott Bacharach Mini SA everyday everywhere I go, which is set to alert at 35 ppm though I check it often. If I enter an enclosed space with reported fugitive gas, I have my Gas Trac II going, which is a triple function: CO, % LEL/% vol, and survey tick rate. This monitor can be set for either CH4 or C3H8, which excluded false positives. For LP gas, I hold the probe right next to the floor while NG I sample waist high and at the ceiling. If I get a hit from a fitting, I have non-corrosive high viscosity and thin-film soap bubble solutions to localize and confirm any leaks. I use 20% LEL as the evacuation level but have used much, much lower if the % volume is rising quickly. I locate the meter outside and break the cock loose and leave a wrench on it prior to entry. If high levels are detected upon entry, it gets shutoff and everyone evacuated at once. For LP, I locate the tank, open the bonnet, and ensure the shutoff operates. If there is a separate second stage regulator, I locate it and confirm it has a ballvalve shutoff immediately upstream.
Luckily, most of my responses are chronic low levels but back when I was a factory regional product liability mgr./ technical rep. I responded quite often.

Timmie, I find most techs use the TIFF 8800A, which is sensitive to only 500ppm CH4 whereas my Gas Trac and Bacharach's Leakator 10 are sensitive down to 20 ppm. Also, most survey meters give false positives to ~30+ hydrocarbons. Very few techs use a quantitive meter as your suggest. Around here, its usually only the gas utilities that measure the quantity of gas.

[Deleted User]

inficon handheld

had a related svc call recently
'the store smells like gas or something, and the customers are getting dizzy'

and upon entry, it sure did smell, but like burnt propane. laddered the roof, and sure enough, #3 rtu was smoking like a chimney, and the 'smoke' was getting pulled into the make-up air duct. shut it off and did some pressure tests; propane - supposed to be @ 3"wc, but it was @ 8ish and had terrible flames at the 1st and 2nd burner tubes. took off the hexc panel to discover that the ceramic baffles were sooted so bad that they were rendered almost completely useless. of course, i didn't have any on the trk, so i cleaned them as best i could. fired it and reset the pressure. bad valve?
a few days later, another similar call, but i'm to meet the amerigas folks at the back of the store. they got a call for a propane smell and discovered an underground leak in the piping from the tanks to the store. they shut the supply down, and i turned all the rtus off. they installed 3, 300gal temp tanks, and i put two of the 4 units back in svc. and lo and behold, #1 smoking. terrible flames/1 and 2 baffles sooted over, cleaned, fired and checked pressure. a-ok. put in a quote to replace all the baffles when amer gets the piping finished and the store back on-line. two weeks later.....amer just finished the piping/inspection late friday, and the baffles are on my trk

Unknown

The lack of response tells

me that many of you gamble with your lives everyday.

Wayne_16

Well, I agree with you Tim.

The last full time job I had in service, I ended up buying my own, co alarm, which I wore on my belt all the time. I set the first alarm to sound at 9ppm and the second alarm at 15ppm. I wanted to know what I was getting into.

I purchased the unit thanks to the many folks on this site asking questions and informing all of us to use and alarm in our daily routine. It was quite suprising how much ridicule I took for having the unit clipped to my belt all the time from co-workers and management. It did make for informative conversation with customers thou. This was the largest company in town, yet management did not see the need or concern to protect their employees. ps; the unit would alarm in their own building, with a production shop out the back door, fork lifts, makeup air units etc.

Bob Forand

Tim

Well Tim, this is a great question. I do not use a detector, but am in the market for one. What do you suggest ? And how expensive are they ? Do the also measure levels of co2 ?

Unknown

Bob, I have a Sensit Gold

which measures O2, CO, and either natural gas or LP depending on what you set it for. I will e-mail you some information on it.

billtwocase

gas

or be safe with oil. It's about time gas gets some bad publicity. peace

Mark Eatherton

While on the subject of gas safety....

How many of you use conventional liquid soap detergent as a means of locating leaks on gas systems?

How many of you use something like the premixed leak detection fluids?

ME

Bob Harper

non-corrosive test soln

You should be using only pre-mixed non-corrosive test solutions for several reasons. If you use ordinary soaps, you can cause stress cracking from the Cl ions.
Using a commercially prepared soln. also gives you the credibility of a soln. with known properties. For instance, some post on their packaging they can detect leaks at a rate of X number of CCs per year. If I'm sitting in a deposition, I'd rather be able to say I used something tested and predictable rather than a home brew.
A third plus is viscosity. You can buy various viscosity solns for varying temperatures and pressures. For instance, higher pressure leaks will blow away thin-film solutions while high viscosity solns. may take forever to indicate very low level leaks.

What do you think Mark?

Larry (from OSHA)

and what about

the case of ABOVE the uel? The bottom line is if you don't test, you don't know... My limited experience with gas explosions gave me the perspective that coming down into the explosive range from above results in a greater chance for a bad experience. The combination of fuel, oxygen and ignition source (which was a call for heat) occurring at the same time gave this building the chance to expand rapidly. No one died but several were injured.


Larry

Unknown

Ideal burning speed

at a 10% gas 90% air mix will send the building into splinters. Lower Explosive explosions usually just break windows and crack walls with severe inside damage to household items. Upper explosive will do about what the photo Larry showed with many times a fire if the gas is being continously fed from a source.

Mark Eatherton

BINGO!!

I never realized that the solution we concocted (dawn dish washing detergent mixed with windshield washing fluid) could damage the body of aluminum gas valves. I know an expert witness who found that a plumbing contractor who was looking for a leak used a similar solution on a gas valve, and later when no one was home, the valve cracked in two and spewed natural gas into the home until KABOOM, she blew up.

Proceed with caution, and as master Harper said, use only those pre mixed, NON corrosive test solutions. Otherwise, you could be on the hook for some MAJOR liability.

Thanks for chiming in Bob. You're a pleasure to read.

ME