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I'm referring to the propane gas service and it's physical properties that it is much heavier than air, and an alarm is a simple and cost effective way to gain extra safety in the event of a leak.
LP is 1.5 the weight of air - not "much" heavier. Gasoline vapors are much heavier than air, like 4-5 times. I certainly agree about the alarm comment, but to recommend it only for LP is not basing the recommendation on facts.

I'm sure all of the regular contributors here exceed their SOPs. I just don't feel that HIs should be implying that LP appliances in a basement are more of a risk than NG appliances. NG is lighter than air. Are NG appliances more dangerous to install in a room with a ceiling?

The linked stories of catastrophic explosions offer no indication that they occurred because of "heavier than air" LP pooling in a basement.

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About 7-8 years ago I found an LP gas leak at a home I was inspecting. When I opened the crawlspace I was greeted with what looked like "ripples or waves" in the air about a foot off the ground. Above that was a layer of fog, it was LP gas in the crawlspace. Now, I always look before I enter if the home has LP gas. This home had a leak in the line that supplied the LP to the kitchen stove. Let's just say that inspection ended with everyone standing about a mile away down the road while the emergency folks took care of the little leak!

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Not to muddy the debate, but it may actually be SAFER if LP pools rather than rises. For NG to ignite, you need about a 14/1 air-to-gas ratio depending upon moisture contents. LP is a little lower, at about 12.5/1. If LP is leaking, and stays where it is, it would be difficult to inject enough air into the mix to make the LP volatile.

I used to work around oil-and-gas wellheads. It was much safer--not that I did it--to light a match directly beside the wellhead than it was forty feet away where the air-to-gas ratio was more conducive to ignition. And yes, this had to be explained to investors and even some of the roughnecks over and over again.

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I used to work around oil-and-gas wellheads. It was much safer--not that I did it--to light a match directly beside the wellhead than it was forty feet away where the air-to-gas ratio was more conducive to ignition. And yes, this had to be explained to investors and even some of the roughnecks over and over again.

What do you mean? The gas is in the pipe.

Marc

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For NG to ignite, you need about a 14/1 air-to-gas ratio depending upon moisture contents.

On an inspection of an industrial complex, I entered a building that had a severe NG leak and couldn't breathe. The gas company investigator said his measurements showed there wasn't nearly enough oxygen left in the building for the gas to ignite. I have since regularly worn a multi-gas/CO alarm on commercial inspections.
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I used to work around oil-and-gas wellheads. It was much safer--not that I did it--to light a match directly beside the wellhead than it was forty feet away where the air-to-gas ratio was more conducive to ignition. And yes, this had to be explained to investors and even some of the roughnecks over and over again.

What do you mean? The gas is in the pipe.

Marc

But at first it isn't. I was referring to the initial drilling of the well. Once the gas pay is discovered, you have to allow the pressure to decrease enough for the geologist to determine how next to proceed. Depressurization can take several hours. What comes next lots of times is Haliburton or Slumberjay fracturing the pay zone to increase porosity and pressure. Then, the 7" production casing has to be installed--+/-2,500 feet of it where I was in Kentucky--which can require several days, depending upon how smoothly the process goes. Gas is exiting the well during the entire process just described.

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For NG to ignite, you need about a 14/1 air-to-gas ratio depending upon moisture contents.

On an inspection of an industrial complex, I entered a building that had a severe NG leak and couldn't breathe. The gas company investigator said his measurements showed there wasn't nearly enough oxygen left in the building for the gas to ignite. I have since regularly worn a multi-gas/CO alarm on commercial inspections.

I think inadequate gas-to-air ratios are what happen lots of times when there are leaks. And it's also why we don't read about too many explosions.

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Great discussion. In any leak (natural gas or propane) there will always be areas that are too rich to burn, too lean to burn, and just right. Problem is, O2 levels change depending on how much air is introduced into the areas. Take Scott P's crawlspace. It was too rich to burn in the fog and likely displaced the oxygen as it filled the space, but opening the access now introduces a new air source, and can bring areas into the ignitable range.

On leaks (doesn't matter if it's NG or LP or any other flammable), if we hit 10% of the LEL, we back out until it's ventilated. That sounds very cautious, but if we hit 10% as we are entering, then somewhere farther in, it is in the range, and on major leaks, areas that were too rich to burn due to displacing O2, can now be in the range due to the air we introduce when opening the door.

We also plug sheered off natural gas lines. It's too rich at the source to burn, but somewhere downstream it is in the range, so we also factor in where it's going and where it is likely pooling. For us on NG in homes, we go to the attic as soon as we can, as it will collect in poorly ventilated attics. LP, we also thoroughly check crawls and basements, as that is where it will collect.

To reiterate, I don't think any appliances are more dangerous than the others. I simply recommend LP detectors in basements because like Scott P's scenario, it collects low and occupants never smell it if they don't go there. NG migrates up through the living areas and is usually smelled by the occupants.

I also agree, gasoline vapors worry me more. I like plugging natural gas leaks much more than patching leaking gasoline tanks.

Not trying to thread drift and I know this isn't really home inspection related, but to really jack things up, underground leaks are even worse. They travel anywhere and everywhere, and often scrub the odorant out (NG and LP are odorless, they add the odorant so people will smell leaks). We run tons of those from underground boring and find readings in homes it's entered with no odor at all. By policy we check every building within 200' of an undergroung break (comes in through meter cans, around water and sewer lines that are poorly sealed, etc.).

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The numbers I find most often attributed to NG are flammability/ explosive limits of 4.4-14 % with stoichiometric combustion requiring 10 parts of air for one part of fuel.

LPG is 2.15-9.6% and 24:1

As stated, if you are out of these ranges then ignition is theoretically impossible.

Scott has made a great case for ALL home inspectors carrying a personal 4 in 1 alarm: LEL, CO, O2, SO2. Also, never enter a confined space such as a crawl without someone in the house knowing you are there and set a time limit before when you should check back in and instruct them to look for you after that interval. Wearing a fire fighter's PASS would be a good idea, too.

Roughly 15% of the population is not sensitive to most odorants used in NG or LPG. Be advised there are over a dozen various odorants that can be used so its not just ethyl or methyl mercaptan. Yes, there is growning evidence of "odor fade" where the odorant loses its effect or is neutralized by rust, water, clay soils, etc. Hot topic in the courts. Also, if your nose is not on the floor like my beagle, you may not smell a LPG leak. Use electronic sniffers before entry. The jump from 10% to 100% of the LEL isn't that much. Basically you're talking inches into a vapor cloud so at the first hit, I'd back off, evacuate then decide on a plan. IF you have a basic "geiger counter-type sniffer, you cannot quantify a leak. One that does % volume and % LEL will be they are not much use in locating low level leaks.

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Also remember, propane is heavier than natural gas and should not be used in an appliance where the floor level is below grade. If there is a leak, the gas will fill the lower level like water until it reaches a flame then danger of explosion exists.
There is no national code requirement prohibiting LP appliance installations below grade. The drain thingy in the diagram is nonsense.

LP could only pool "like water" in a completely sealed chamber that lacked any air movement (it isn't gasoline vapor). A LP leak is the same as a NG leak, above grade or below grade. With the correct amount of oxygen present it can ignite.

LP might not pool like water but, then again, it might. It's 1-1/2 times more dense than air so it can stratify pretty easily.

While I think it's a poor idea to put LP appliances in basements, I must admit that my house, which I built, has a propane furnace in the basement. It also has a propane detector at floor level, which operates a solenoid at the gas entrance.

If I found a propane appliance in a basement, I'd recommend installing a similar system.

I disagree with recommending them. Clients depend on us to provide solid information, not personal recommendations. People that don't know sometimes get overly concerned over nothing......

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. . . I disagree with recommending them. Clients depend on us to provide solid information, not personal recommendations. People that don't know sometimes get overly concerned over nothing......

I think recommending a propane detector/shut-off system is a solid recommendation.

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I do not recommend propane detectors/shut-off systems.

I understand what Randall is saying. I could recommend a whole bunch of stuff; child locks, fire alarms, smoke alarms, gas detectors, randon monitors, safety light bulbs, gfci, afci, handrails, t&p valves, etc. We are placed in an interesting position as inspectors of having to anticipate what our particular client wants us to do. Most inspectors follow an established protocol or SOP or try to be a fortune teller and guess the client's expectations.

Who can argue that we should inform our clients of everything possible? (given time and place restrictions)

Me thinks many inspectors try to do more and be more than most are capable of. Inspectors generally are not heros.

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I do not recommend propane detectors/shut-off systems.

I understand what Randall is saying. I could recommend a whole bunch of stuff; child locks, fire alarms, smoke alarms, gas detectors, randon monitors, safety light bulbs, gfci, afci, handrails, t&p valves, etc. We are placed in an interesting position as inspectors of having to anticipate what our particular client wants us to do. Most inspectors follow an established protocol or SOP or try to be a fortune teller and guess the client's expectations.

Who can argue that we should inform our clients of everything possible? (given time and place restrictions)

Me thinks many inspectors try to do more and be more than most are capable of. Inspectors generally are not heros.

We don't have to be fortune tellers or guess our client's expectations because we should be the ones creating those expectations.

Recommending safety items is one of the most fundamental aspects of our job. In my reports I address almost every one of the items that you listed. And, if you're not addressing, at the very least, smoke alarms, GFCIs, and handrails, then I'm, frankly, aghast.

It's got nothing to do with being a hero. It has to do with defining the condition of the home and identifying defects. Missing or ineffective safety items are some of the most basic defects in a home.

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I think recommending a propane detector/shut-off system is a solid recommendation.

I only see a dozen or so propane houses a year, but I've never seen (or heard of) such a thing. What does it look like?

I have this one, which seems to have been discontinued:

http://www.amazon.com/Propane-Detector- ... B001MLZCOA

A quick search revealed this one:

http://www.es-web.com/GS6-propane-detector.html

I think you could find one at most RV shops.

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Jim,

I am not saying I do NOT address those things, just that I do not think I address every thing.

Can you really believe you cover everything in your reports? Every circumstance, condition etc. Do you recommend radon monitors? There is a possibility your client has a high level of radon and you may be negligent when you fail to recommend.

No argument about our job being about safety. I do have an argument with inspectors that take a common issue and make it into a life threatening/saving issue.

In another thread today, you state your experience with a particular type of siding. Do you inform your client about your experience or do you report and recommend further evaluation? For the record: I have never seen HardiPlank installed correctly. No one that works for me has seen it installed correctly. What does that mean? We report it and then spend hours defending the obvious. Part of our job.

My personal observations about the inspection process is that often there are unskilled persons inspecting to a lowest common standard. Many inspectors are more entertainer than observer.

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I have since regularly worn a multi-gas/CO alarm on commercial inspections.

Where did you get it? Do you have a link for the detector?

The first one was some German brand that detected 3 gases, CO & O2. I probably got it over 20 years ago for under $200.00. A guy from a company that installs and services sewage pumping stations got it for me.

The one I have now, from MSA, was purchased in 2002 for $350.00. It only detects explosive/combustible gas and 02. I have a separate CO monitor from AIM Safety Co. that I got for about $120.00 - it was being discontinued.

There are many brands of multi-gas detector/personal alarms available, but they're more sophisticated now. They're also about twice the cost, since my last purchase.

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The first one was some German brand that detected 3 gases, CO & O2. I probably got it over 20 years ago for under $200.00. A guy from a company that installs and services sewage pumping stations got it for me.

The one I have now, from MSA, was purchased in 2002 for $350.00. It only detects explosive/combustible gas and 02. I have a separate CO monitor from AIM Safety Co. that I got for about $120.00 - it was being discontinued.

There are many brands of multi-gas detector/personal alarms available, but they're more sophisticated now. They're also about twice the cost, since my last purchase.

Yea, I thought the price was exceedingly high. I was looking around on some firefighter equipment sites and they were between $900 and $1200. Thats a lot of money, anytime and especially now in a down economy.

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