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Gas detector-CO detector?


blazenut
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As for home inspections, which gas detectors do you guys carry?

When I first started back in 1994 I felt that I needed to have a gas detector. I think I used it a dozen or so times, they tend to have many false positive alarms.

I just don't see the need for one. My nose can smell pretty darn good and if I get a whiff of natural gas, I keep sniffing. I do use a liquid leak detector if the need arises.

As for a CO detector; I have one and again I think it has been used a dozen or so times. If I do use a CO detector it will be for my own information and it will never make it in my report that I used one. CO is a funny gas that can appear and then disappear depending on the prevailing conditions.

I don't think I would recommend getting either tester. I just don't see the need for them.

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I bought a Monoxor II twelve years ago when I started out, but seldom use it anymore.

I did pull it out last week while in the basement of an old house. The flue pipe of a 30-year-old furnace was shoved about three inches into an unlined chimney and the draft wasn't pulling much of my lighter flame into the flue. As we know, those old chimneys have a tendency to implode, so I turned on the Monoxor II to make certain I wouldn't assume room temperature while mucking around among the spider webs.

For me, having a CO detector is more about self preservation than anything else. But I'll probably never buy another one.

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I use gas monitors/analyzers and a CO analyzer, but not for each inspection. I use them mostly for when it's necessary to illustrate a point I'm trying to make or document something (notice I don't use "detectors").

When finding a gas leak, around here it's necessary to identify the location, as no one authorized to fix the leaks can find them.

I also use a multi-gas monitor for certain commercial building inspections.

I use equipment from AIM Products, Bacharach and BW Technologies. There's definitely training needed if using analyzers.

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  • 1 year later...

I have a Ridgid Gas Sniffer and I have to disagree with the "there's no need to use it" idea. Since purchased about 1 1/2 years ago I have located at least 30-40 gas leaks at different customers' homes and some houses have found multiple leaks. Even found very tiny leaks that were hard to find even with bubbles. Leaks on the gas meter that were on the gas company's side, leaks on propane tanks from improperly installed tank connections. A gas leak, aside from being a potential danger, also cost money. Don't always rely on your nose to smell it.

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I have a Ridgid Gas Sniffer and I have to disagree with the "there's no need to use it" idea. Since purchased about 1 1/2 years ago I have located at least 30-40 gas leaks at different customers' homes and some houses have found multiple leaks. Even found very tiny leaks that were hard to find even with bubbles. Leaks on the gas meter that were on the gas company's side, leaks on propane tanks from improperly installed tank connections. A gas leak, aside from being a potential danger, also cost money. Don't always rely on your nose to smell it.

Well, sure. If I dragged out the Tif, I guarantee that I can find at least one gas leak in every single house that I inspect. (Well, ok, only those houses that have gas service.) There are leaks in every house that has gas appliances. I learned early on that it's just silly to go chasing after them all. Nowadays, I only chase those that I can smell.

The tiny leaks that can't be found with bubbles might not even be leaks. You are aware of all of the things that your sniffer will react to, right? If there're aren't bubbles, I have a hard time believing that the gas leak (if it actually is one) is worth fixing. It certainly doesn't pose a hazard and the amount of money that's wasted is really, really, tiny.

- Jim Katen, Oregon

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I'm with Katen. I used my Tiff on thousands of houses before finally realizing it was not worth the effort.

There are some gas control valves that the mfg's. know leak minute amounts of gas.

Years ago, in a fire science class, we were placed in a closed room where the same amount of stink that would be found in a natural gas LEL was injected into the room. It was so strong it made my eyes water.

Point being, they load the stink into the gas so if there's even a teeny tiny leak, you'll smell it.

Noses work pretty good. I used to think that was heresy, now I don't.

I use the Tiff only for making a point nowadays.

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The tiny leaks that can't be found with bubbles might not even be leaks. You are aware of all of the things that your sniffer will react to, right? If there're aren't bubbles, I have a hard time believing that the gas leak (if it actually is one) is worth fixing. It certainly doesn't pose a hazard and the amount of money that's wasted is really, really, tiny.

- Jim Katen, Oregon

Yes, I am aware and have indeed gotten "false readings" here and there but I do not solely rely on the sniffer to detect a leak. I do verify leak with bubbles.

Perfect example:

I went out to a customer's house for an "issue" with gas water heater. Arrived at the call to find the knob on the gas valve melted. During my questioning of the customer, realized that the husband (we'll call him Mr. Fix-it) had went to the local hardware store and bought a new thermocouple b/c of a constant pilot outage. this was one full month before this "issue". I was able to get the pilot relit only to find that the pilot tube connection to gas valve was barely tighter than hand tight. This was a small leak but a leak none the less. His response, "I thought I smelled a little gas but I thought it was just when it first fired up. Luckily they were home when this occured or they would have came back to a stack of charred wood. Just sayin'.

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  • 4 years later...

I can start to smell a natural gas leak when there's a leak of appx. 250ppm at the source (based on my small tipped wand I use), and I'm not a woman. Usually, I can smell the gas odor when there are free air readings of 0-20 ppm. The LEL of natural gas is around 50,000ppm.

Most people start to scramble and evacuate their home when free air readings are very minute (usually less than 100ppm free air). Your nose is the best instrument, followed by a good spray bottle with the proper mixture of soap and water (seam solution)

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Strange how at lot of the stuff we were told we needed when we started out has turned out to be a bunch of hooey. I'm on my third gas detector and it hasn't proven to be very reliable and it's likely I won't be replacing it. One of the more dependable methods of detecting odors is listening to the client's wife. When they say they smell something it's time to stop and investigate.

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  • 1 year later...

Originally posted by Plumber26

I have a Ridgid Gas Sniffer and I have to disagree with the "there's no need to use it" idea. Since purchased about 1 1/2 years ago I have located at least 30-40 gas leaks at different customers' homes and some houses have found multiple leaks. Even found very tiny leaks that were hard to find even with bubbles. Leaks on the gas meter that were on the gas company's side, leaks on propane tanks from improperly installed tank connections. A gas leak, aside from being a potential danger, also cost money. Don't always rely on your nose to smell it.

I would be careful about testing and reporting on leaks at gas meters and propane regulators. These have a vent that is designed to release gas at certain excess pressures. You will often detect gas "leaks" that are part of the normal function of the regulator; this seems especially true for propane tanks and regulators. (which is why there are clearance requirements between gas meters, regulators, tanks, and potential ignition sources like air conditioners and electrical panels).

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  • 4 weeks later...

At 4.4% by volume the LEL of methane would be 44,000 ppm. Most housewives I've encountered on complaints of a "gas leak" could smell the odorant at levels around 5+ ppm. Add to that around 15% of the population is not sensitive to the odorants used and you see that smell is not a reliable leak detector. Moreover, certain odorants are susceptible to "odor fade" such as from rusty pipes or damp clay soils. That''s why there are over a dozen odorants in common use and not just the mercaptans.

You need to know the detection level of your gas sniffer. Those old TIFF 8800a's are sensitive to methane only down to 500 ppm. Sniffers sensitive to 10-20ppm are now common and very affordable. Note these are not gas specific so you will get false positives from all sorts of hydrocarbons such as thread cutting oils, pipe dope, many leak detection fluids, and even formaldehyde from damp fiberglass insulation.

Use only non-corrosive soap bubble test solutions. Soaps that have chloride ions in them can cause stress cracking of the base metal. I recommend using only commercially prepared solutions that are known non-corrosive and documented detection properties. Note that highly viscous solutions work better on higher leak rates while the thin viscosity solutions can detect more minute leaks .

The official action level requiring evacuation and constitutes a recordable event is 20% of the LEL.

There is a phenomenon know as "trace gas leakage". The ANSI Z21.78 std. allow for a max. of 200 cc/hr. of gas leakage through the seals of a combination gas valve and 235 cc/hr. through the main operator at 3/4 psi.

All gas regulators require a vent to adjust the pressure against atmospheric pressure. Whenever the pressure fluctuates in a piping system, a momentary 'burp' of gas might be detected at the vent screen. A sustained significant leak is consistent with a ruptured diaphragm, which would require the gas be shut off immediately and the regulator replaced before placing it back into operation.

HTH.

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  • 1 year later...

I know. I know. Resurrecting an old thread, but....

Has anyone's opinion changed on this? Have detectors become more applicable to the job? I'm looking at a couple, but not completely sold on them. Problem being... my nose doesn't pick up on odors well.

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