Case History: LP Gas Leak Detected Using the TIF 8800
During the ASHI 1990 Annual Conference in Phoenix we received
a frantic telephone call: There's been a gas explosion at your
rental house in Poughkeepsie... The author headed straight for
the airport, immediately lining up at the Quantas ticket counter for
the next flight to Australia.
Fortunately, it wasn't that bad. A gas leak in the base
of an LP gas cook stove had caused a flame rollout which badly frightened
the tenants. There had been no explosion. And no damage. They had
reason to be scared, having been burned out of their previous home,
an apartment, when children on an upper floor played with matches
by dropping lit ones into a hole in the wall.
Flames rolled out of the oven
What actually happened? An LP gas oven was in use. The occupants heard
a noise, saw a ball of fire and flame roll out of the bottom of the
stove at the broiler door. They called the fire department who shut
off the LP gas tanks outside. No damage anywhere. Of course, now there
was no domestic hot water and no cook stove.
From Phoenix, an experienced, well qualified plumber was called in
New York <197> with express instructions: go to the property, find
the gas leak, fix it. If you cannot find it, make sure there is a
sound shutoff valve in the gas line at the stove, shut it off, and
re-light the water heater pilot so that the occupants can have hot
On the author's return from Australia the tenants described the procedure
of the experienced, qualified plumber. While our event did
not make the news, a similar one did
NY Poughkeepsie Journal, 26
February, 1991, p. 2B and the news article came in handy. More
on that later.
The experienced, well qualified plumber did not come to the house.
He sent an employee who was not experienced, and not qualified. Putting
it politely. We'll call him Bud. Bud stood in the center of the kitchen,
flicked his BIC, and when there was no explosion, informed our
tenant No gas leak here, lady. Really.
There was additional discussion between tenant and Bud about the stove.
Bud asserted that it was all fine, that maybe the pilots on the stove
were set too low. (This stove has no pilots, it's got electronic ignition,
but Bud refused to believe that detail.) Bud left
all gas lines on. The stove continued it's small leak. The tenant,
wisely, did not use it, and thought it had been turned off
as we'd instructed.
Home from traveling and following a visual inspection for obvious
damage to piping and valves from gas source to the appliance, we made
use of the TIF at every joint, elbow, connector, and control
from gas source to, through, and inside the stove, with the sensitivity
dial set high.
Using the TIF8800 Combustible Gas Analyzer we found that the stove
had a double fault: the oven control never completely shut off gas
to the broiler, and the thermostatic safety valve at the broiler never
completely shut off gas flow into the burner. As the cost of repair
parts plus service charges was close to the cost of a new stove, the
Checking further outside we also found and had corrected a long-standing
leak at the stem of the shutoff valve on the LP tank. The local gas
supplier was reluctant to repair this item as they considered it both
safe (it was outdoors after all) and good business.
Two weeks later, after calming down, we saw a news article
reporting Millerton Blaze leaves 4 homeless.
Beat clipping at left.] The report described a fire that started
from a faulty gas line and which caused extensive damage to a home.
The fire apparently started in the kitchen on a gas line behind the
cooking range, according to the fire department. Forty fire fighters,
two ambulances, no deaths. Lucky.
We called our plumber friend and directed his attention to the news
article. We let him sweat a moment before explaining that no, this
was not the house to which we'd sent him a couple of weeks before.
But it could have been! Following a refund of the $135. charged by
the plumber for his service call, we presented a mini-class to his
service people on gas leak detection.
This class outline has not
been reviewed nor approved by anyone. Criticism is welcome and should
be addressed to the
Journal editor. Feedback will be reported
in future issues.> At that class we learned that the plumber has a
TIF8800, though it was not used at our tenant's house. Perhaps
the mechanic was unfamiliar with its operation.
Looking for Gas Leaks
The National Fuel Gas Code and other publications from the American
Gas Association and the Gas Appliance Manufacturers Association contain
more complete details of proper detection and repair procedures for
gas piping and equipment.
for Gas Leaks
Matches and Lighters
We spend time talking about it because, no joking, people still do
this. Don't do it! It's prohibited by the AGA & NFPA.
Fuel Gas Code, ANSI Z223.1-1988 and NFPA 54-1988, Para. 4.1.5 p.
64> It's dangerous. It looks stupid to customers. It's bad for business.
Even if the gas in the area is not enough to support an explosion,
and even if you think it's quick and dirty but ok you cannot
flick your BIC in every location where a test is needed.
You face certain and total loss of any lawsuit involving damages.
Bubble tests are the traditional method for checking piping. There
are some limitations: results are inconsistent, testing is slow, and
you cannot cannot see every place where bubbles may occur. Soap cannot
be used in all locations - eg. at air shutter near gas valves.
Pressure tests of gas piping were not discussed though this may be
the procedure in new installations
Using the TIF 8800
This instrument detects combustible gases at 50-1000 ppm, including
Methane, Ammonia, Acetone, Acetylene, Alcohol, Benzene, CO, Ethane,
Hydrogen, Hexane, Isobutane, N-Butane, Pentane, Propane.
Common LP Gas Leak Points
In addition to a careful visual examination of all gas piping, fittings,
valves, from gas-source to points of final use, spend some extra time
with the TIF at:
Unions, at the pilot control and at right-hand side of many DHW gas
controls, at the flare fittings and valves in gas appliances.
Note that sometimes leaks are present at so many fittings in old gas
lines that you may not believe the instrument. Believe it unless you're
testing at fresh pipe dope.
Watch for perforated flexible gas lines at appliances, leaky appliance
controls and pilots, valves, and unions. Also check LP tank main valves,
and flare fittings on LP lines.
False alarms with the TIF 8800 testing for LP Gas Leaks
These are not LP/Natural gas leaks, but can cause the TIF to respond:
moisture, < >flue gases, < >pipe dope, < >especially if recent, dead
cats (methane), < >methane from sewer gas or flatulence, < >auto exhaust,
< >any organic/combustible solvent.
Turning on the TIF
Go outside for a reference signal, in non-contaminated air. Let the
instrument warm up. It can take a long time in cold weather, if there's
a bad battery, low charge, or bad sensing tip.
Turn the adjusting knob (there's only one so you can't go wrong) slowly
to full sensitivity to verify that it will signal, and listen for
gradual increase in tic rate. If you cannot get a range of tic rates,
the instrument is not working properly. If it won't tic in the intermediate
ranges there's a bad battery or bad tip.
Adjust for slow steady tic. Rapid tics mean more sensitive. Use higher
sensitivity for small leaks. Test to see that the instrument responds
at a known source. Follow gas from source to final use, checking every
connection, every component.
How close to piping? From touching it to 1/2" away, around every fitting/component
being tested. Don't contaminate the tip with soil or pipe dope.
Take advantage of the flexible tip probe to reach to valves and controls
inside ovens and heaters.
If customer has reported odors, flame rollout, or some other event,
and you cannot find and repair a leak, leave the gas shut off at the
source and verify that it has been shut off. Document what you said
and what you did, in writing. It can be as simple as a note written
on a bill.
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 "Table Z-1 Limits for Air Contaminants, 1910.1000 Table Z-1" OSHA standard for air contaminant limits (http://www.osha.gov/pls/oshaweb/owadisp.show_document?p_table=STANDARDS&p_id=9992) - includes for CO2, Carbon dioxide.........| CAS No. 124-38-9 | 5000 ppm | 9000 mg/m3 limits for carbon dioxide as an air contaminant.
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We use gas sampling equipment provided by the two most reliable companies in the world, Draeger-Safety's detector-tubes and Drager accuro� bellows pump, the Gastec� cylinder pump and detector-tube system produced by Gastec or Sensidyne, and we also use Sensidyne's Gilian air pump. For broad screening for combustibles and a number of other
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Air Pollution Toxicology: APTI Course SI:300, Introduction to Air Pollution Toxicology, US EPA Air Pollution Training Institute, Environmental Research Center, Research Triangle Park, NC 27711, Sept. 1993, web search 08/28/2010, original source: http://yosemite.epa.gov/
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Fluorine, Its Compounds, and Air Pollution,: a Bibliography with Abstracts, US Environmental Protection Agency, Office of Air Quality Planning and Standards, Research Triangle Park, North Carolina 27711, December 1976. Web search 08/28/2010, original source: http://nepis.epa.gov.
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"Choosing and Using a Carbon Monoxide CO Monitor," Dan Friedman, The ASHI Technical Journal, Vol. 2 No. 1, July1991
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