TIF 8800 combustible gas analyzer checking a furnace draft hood for spillage (C) Daniel FriedmanTIF 8800 Field Test
Case report using the TIF 8800 combustible gas analyzer to track down LP gas leaks
     


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Using the TIF 8800 combustible gas detector for LP gas leaks: this article describes field use experience with the TIF 8800 combustible gas analyzer.

Using an actual case history in which a building tenant reported a small LP gas explosion following tests by an idiot using a match, we describe what happened and how the TIF was used.

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Case History: LP Gas Leak Detected Using the TIF 8800

DJ Friedman

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 water.

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.

[Police 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.

Traditional "Tests" 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.

National 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.

Soap Solution 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.

Final Note

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.

 

Continue reading at TIF 8800 GAS DETECTOR or select a topic from the More Reading links shown below.

Or see HEAT EXCHANGER LEAK TEST

Or see GAS DETECTOR WARNINGS

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