In the rural areas around here, every farmhouse has a big white propane tank out back. I bet I've heard dozens of stories about someone having a leak and not knowing about it until they'd lost a lot of propane. Every couple of years a propane explosion takes out a house or small business in the rural area. What keeps propane from escaping from a tank car? Why does the railroad appear to have a much better safety record than rural homeowners, when the homeowners never launch a full tank of propane into a ditch at track speed?
Thanks to Chris / CopCarSS for my avatar.
Murphy,
The short answer is closed valves with wrench tight plugs in all vapor and liquid lines.
Homeowners lose gas due to leaks under the valves or at pipe joints. I suspect some joints can not be checked, and those that can be seldom if ever are.
Tank car valves are checked when cars are hydro tested, which IIRC is a five year cycle for propane cars. I suspect that the gaskets under the valves on the manway cover are replaced when the car is hydro tested. Much better to do it in the shop than to have to transload 30,000 gallons who knows where and send the car to the shop for repairs.
Think of it as the difference between professional and amatures, or an ounce of prevention is worth a pound of cure.
Mac McCulloch
The reason residential propane tanks are outside is that propane is heavier than air. If you had a leaking tank in the house it would collect in the basement or crawl space and create an explosion hazard. Outside it disipates in the air. If the house exploded, then the leak was inside and anyone present should have smelled it.
Tanks that hold or transport it have pressure relief valves that prevent over pressure explosions though you can hav a roaring fire at that valve. Only a fire that heats it beyond the relief valve's capacity to vent will cause the tank to fail. Obviously, if the tank fails in the presence of an open flame, the escaping gas will be ignited and the results will be catastrophic.
Dave
Lackawanna Route of the Phoebe Snow
23 17 46 11
Phoebe Vet The reason residential propane tanks are outside is that propane is heavier than air. If you had a leaking tank in the house it would collect in the basement or crawl space and create an explosion hazard. Outside it disipates in the air.
The reason residential propane tanks are outside is that propane is heavier than air. If you had a leaking tank in the house it would collect in the basement or crawl space and create an explosion hazard. Outside it disipates in the air.
You bring up an interesting point. Maybe any propane tank should be downhill of a house basement so fumes do not drift into house / basement ? Going to ask my daughter about hers.
The one time I rented a house with an external propane tank I didn't like the looks of the tank (failed paint, rust) or the connected plumbing (ditto, plus rounded-off hex unions and plier marks.) Rather than chance it, I paid to have extra 220VAC circuits installed for the stove and a new flash water heater.
A couple of months later the city inspected it and condemned it. The owner wanted me to pay for the replacement - until I pointed out that I was all-electric and had shut off all gas, including pilot lights. He ended up having it removed and replaced with (cheap) baseboard heaters where the wall heaters had been.
Less than a year later my family was living with my parents and I was on my way to the Great Southeast Asia War Game. I've never been back, so I don't even know if the house is still there.
If that propane tank had looked half as good as the propane tank cars spotted in my neighborhood industrial park I would have filled and used it in a heartbeat.
Chuck
blue streak 1You bring up an interesting point. Maybe any propane tank should be downhill of a house basement so fumes do not drift into house / basement ? Going to ask my daughter about hers.
And if on flat ground, downwind would be the best option.
Norm
As has been noted, lack of regular inspections is probably the biggest issue.
Remember, too, that a tank located a distance from a structure has to get the gas to the appliances somehow, and that's underground. Copper is often used, and I'm sure the installers try to do it with one contiguous piece, but you never know.
And since the line is underground, it's subject to a number of possible "insults," be it someone planting a tree or a sharp rock pushing up to the surface.
Uphill and upwind is where we as firefighters go for leaks. Just having the tank away from the structure can make a difference. Downwind, by the prevailing winds for the area, also makes a lot of sense.
We went out to a house some years ago where the LP supplier hadn't tightened up the bleeder valve when he filled the tank. Easy fix, although brass tools are the items of choice for that...
The LP tank at our banquet hall is buried...
Larry Resident Microferroequinologist (at least at my house) Everyone goes home; Safety begins with you My Opinion. Standard Disclaimers Apply. No Expiration Date Come ride the rails with me! There's one thing about humility - the moment you think you've got it, you've lost it...
Interesting. When the railroad looks over a propane car, is it a detailed look at all the fittings and such, or just a spot check and sniff check? What happens when a railroad finds a leaker?
A quick quasi-off-topic propane story. When I was a kid, we had a nasty little shetland pony. 45 years later I still have scars from that beast. My folks sold it to our white trash neighbors. The man and his son came home one night falling down drunk and decided to show the pony who was boss. They both got on the pony. As we were told the story, they both got the full 8 second rodeo ride out of the adventure before Ruby (what a *sweet* sounding name for a pony) rubbed them off on the propane tank. That knocked the copper pipe loose and emptied their tank. Ruby-1 Two drunk idiots-0.
The inspection Ed described is a mechanical inspection, same as all cars get at his yard.
When a shipper offers a car for transportation he certifies to the railroad that the car is, among other things, "in proper condtion for transportation...". The carriers rely on that as a matter of course. They manway cover should be sealed with a shipper's seal, and even if it is not sealed, carrier employees do not crawl to the top of the car to inspect the fittings or test tightness of plugs.
When I worked for a major hazmat carrier we stressed a walk around inspection to check placards, wheels on the rail, no obvious mechanical problems and making sure the car was disconnected from the loading/unloading apparatus. That is about all a switchman can reasonably be expected to do before pulling a car. That is not to be taken as a knock on switchmen or brakemen. Remember these things are done day and night, fair weather and foul including in the middle of thunderstorms.
Railroad response to leaker is to fix it, get it fixed, not pull from shipper, or spot to consignee, or transfer. Actually response is highly variable. I once transfered a car of hydrochloric acid righ outside a consigenee's gate because they were too chicken $hit to take the car. Most customers were better than that I must admit and some were outstanding.
former Bureau of Explosives Inspector,
former Superintendent of Hazardous Materials Control.
Phoebe Vet The reason residential propane tanks are outside is that propane is heavier than air. If you had a leaking tank in the house it would collect in the basement or crawl space and create an explosion hazard. Outside it disipates in the air. If the house exploded, then the leak was inside and anyone present should have smelled it.
That is one of the standard clues when looking at a gas explosion in a house: If the explosion has pushed the lower part of the structure outwards, it is most likely a LPG-caused problem, whereas if the upper part of the building is pushed outwards, that indicates a natural gas explosion, as natural gas is lighter than air and, thus, a natural gas leak tends to collect at the top of the building.
Note that propane has to enter the house to be used for heating, cookstoves, etc., so that, even with the tank outside, the gas can easily collect indoors due to leaks of poorly-maintained equipment.
avonlea22I see a lot of non-odorized propane traveling through my area. That scares me a bit as you won't even know if it's leaking or not.
Murphy Siding avonlea22 I see a lot of non-odorized propane traveling through my area. That scares me a bit as you won't even know if it's leaking or not. Why would there even be non-odorized propane out there? Is it in tanks that note it as such?
avonlea22 I see a lot of non-odorized propane traveling through my area. That scares me a bit as you won't even know if it's leaking or not.
Why would there even be non-odorized propane out there? Is it in tanks that note it as such?
Johnny
Murphy SidingWhy would there even be non-odorized propane out there? Is it in tanks that note it as such?
I would suspect that mercaptan (the odorant) may not stay mixed all that well in the larger quantities carried in tank cars. I know there have been instances of mercaptan "falling out" of natural gas if there is a leak of NG.
Murphy Siding Why would there even be non-odorized propane out there? Is it in tanks that note it as such?
Oh yeah, it's clearly labeled.
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