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Spring Hill (Nashville area), Tennessee
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Propane heating
[#27] Posted: 06/22/2011 - 2:22:23 PM |  |  |
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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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Scott Patterson
http://www.traceinspections.com
"Minds are like parachutes they only function when open"
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Lexington, KY
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 Propane heating
[#28] Posted: 06/22/2011 - 3:25:46 PM | | |
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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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Lafayette, Louisiana
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State: PA & NJ
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Lexington, KY
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Propane heating
[#31] Posted: 06/22/2011 - 4:32:54 PM | | |
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Quote: Originally posted by MarcQuote: Originally posted by Bain
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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Lexington, KY
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Propane heating
[#32] Posted: 06/22/2011 - 4:44:48 PM | | |
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Quote: Originally posted by Bill KibbelQuote: Originally posted by Bain
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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Olathe, KS
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Propane heating
[#33] Posted: 06/23/2011 - 07:24:50 AM | | |
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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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Kevin Wattenbarger
Allied Home Inspections, Inc. Olathe, KS
"Helping You Understand Your Home's Health"
www.AlliedHomeInspections.com
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Collins, NY
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Propane heating
[#34] Posted: 06/23/2011 - 6:00:54 PM | | |
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Where I live there are so many underground NG leaks you can smell them driving down the road, sometimes for miles. One of my clients works for the local provider and carries a bound book more than 1/2" thick of the known leaks in his territory.
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Tom
http://clearcreekhomeinspection.com/
Life is tough enough as it is, it's tougher when your stupid. Don't do stupid things.
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Drexel Hill, Pa
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Propane heating
[#35] Posted: 06/24/2011 - 04:55:50 AM | | |
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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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Castle Rock, co
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Propane heating
[#36] Posted: 06/28/2011 - 12:26:04 PM | | |
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Quote: Originally posted by Jim KatenQuote: Originally posted by Bill KibbelQuote: 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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Gaston, Oregon
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DeWitt, Mi
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Propane heating
[#38] Posted: 06/29/2011 - 04:34:03 AM | | |
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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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Les
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Denver, CO
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Gaston, Oregon
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Propane heating
[#40] Posted: 06/29/2011 - 07:45:44 AM | | |
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| Quote: Originally posted by Les
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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Jim Katen, Oregon
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Gaston, Oregon
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Propane heating
[#41] Posted: 06/29/2011 - 07:54:09 AM | | |
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Quote: Originally posted by GaretQuote: Originally posted by Jim Katen
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-...01MLZCOA
A quick search revealed this one:
http://www.es-web.com/GS6-prop...tor.html
I think you could find one at most RV shops.
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Jim Katen, Oregon
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DeWitt, Mi
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Propane heating
[#42] Posted: 06/29/2011 - 08:02:02 AM | | |
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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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Les
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Rochester, New York
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Collins, NY
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Kenmore, WA
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Propane heating
[#45] Posted: 06/29/2011 - 08:57:50 AM | | |
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Quote: Originally posted by Tom RaymondQuote: Many inspectors are more entertainer than observer. Quote: Let me get this right; I shouldn't wear a clown suit?
Like Mike Homes? 
ONE TEAM - ONE FIGHT!!!
Mike
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McLouth, KS
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Propane heating
[#47] Posted: 06/29/2011 - 5:12:56 PM | | |
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Quote: Originally posted by davidmcgQuote: 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 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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| Bill Kibbel, Historic & Commercial Building Inspections - Old House Resources |
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McLouth, KS
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