We were picking up some shoes at the Big Huge Mall and there was a huge sign for the big parking structure" “No Propane Powered Vehicles Allowed.” It was part of the main structure’s signage. Permanently stenciled next to “Exit” and “Entrance”. So it seems as if this building was designed to be non-propane friendly.
Okay, so that’s fine.
But why? Is the exhaust more dangerous? Are propane-powered vehicles more explodey?
That’s definitely weird; propane vehicles were specifically designed to work indoors because the emissions were pretty much harmless. Just about all (non-electric) forklifts, skid steers, and lifters operate on propane engines. (My company sells propane engines by Kohler specifically designed for them) Propane is a gaseous fuel though and the tanks must be filled under pressure, so perhaps there is a perception that a propane-powered vehicle is more at risk of explosion in the event of a collision.
If there is a leak propane hovers near the ground as it is heavier then air. If the parking structure has a basement level, or other type of bathtub structure the propane can gather in it. If there is a source of ignition in that section, such as a furnace or elevator motor it could really ruin your day if a lot of propane gathers there.
So does gasoline though, and in the summer the vapor pressure is plenty to insure a problem. I suspect that either it is a stipulation of their insurance carrier, or somebody in the ownership chain has had a bad experience with propane.
One issue is that most (all?) road vehicles that run on propane are conversions. Some by competent firms and/or individuals, but some are no doubt poorly done from a safety standpoint. This is in contrast to the typical lift-truck in a warehouse, which was designed for propane from the tires up.
Don’t I see tunnels all the time with signs prohibiting vehicles with propane tanks? Here’s one example where large amounts of propane are prohibited, although so is bulk gasoline. I think it’s because a fire in a tunnel fueled by propane is a real badassed situation. Although you would think that the gasoline in all those cars would be a problem, too.
The majority of propane vehicles are the afore mentioned forklifts.
I have a working theory: since forklifts are extremely heavy and have no suspension, driving through the garage shakes the garage like an earthquake.
(forklift operators often use our garage to deliver exposition materials to the loading dock on the 6th floor of our valet garage. One of these days I’m certain a forklift will simply crash through the floor due to raw tonnage of the vehicle)
It has to do with the propane tank being a pressure vessel. Although a gasoline leak will still create a nice fire/explosion, it’s not on the same scale as when a pressure vessel ruptures from fire exposure-that’s known as a BLEVE.
This strikes me as kind of dopey–I drive a propane powered vehicle and it amazes me the ignorance people have about the tanks and such. Yes, the fuel is under pressure, but the tanks themselves are incredibly tough and the valves are designed to shut down if an unacceptably high rate of pressure is escaping, such as if a valve were sheered off. People natter on about how “dangerous” my pressure tanks are, while blithely tootling around in gigantic SUVs which are carrying liquid fuel with a much higher BTU rating than propane and carrying it in large volumes in a plastic container that can be pierced by a determined person with a screwdriver. The only time I’d worry about my vehicle is if your vehicle crashed into me, your full tanks ruptured and it caught fire under my tanks. THAT would indeed cause everyone in the vicinity to become air pollution!
I had no problems taking my propane van onto a ferry up in Seattle, just had to put a red tag on it so they’d know what was what in the event of an accident. Sounds to me like insurance related ignorance…
But they don’t explode, do they? I thought all tanks like that had a pressure release type valve. Fire heats tank, pressure increases, valve releases, nice flame thrower type effect, no bang Right??
We had a lot of cars on lpg here in the 80’s, and there’s a few about now, with a large push in Australia for lpg conversions currently on. I’m not aware of numerous mushroom clouds over our cities from lpg fueled fire balls after car crashes. Or have I become oblivious to them and it’s just part of the background noise? :eek:
The pressure relief valve will pop and release pressure as the contents in the tank is heated. Creates an impressive blowtorch effect with a whistling sound. However, if the heat source is creating more btu’s than the relief valve can handle, the tank itself will eventually fail as the internal pressure continues to rise. Standard firefighting training emphasizes that if the whistle noise begins to rise noticeably in pitch, run like hell.
Ahh, you’re all wrong. Its Blast Levels Everything Very Effectively
Don’t forget, a sounding relief valve does not indicate an imminent BLEVE. As long as the liquid level inside the tank is below the level of flame impingement, there is a BLEVE potential. You can have the BLEVE with a low pressure condition inside the tank. Once the steel tank wall is heated (locally) to above 1000 F, the steel will yield to the pressure inside, then you get the big boom.
Solution? Cool each area of flame impingement with at least 500gpm. How you can do that to a 20lb LP cylinder and keep it on scene, I still haven’t figured out. For larger tanks, though, its cool, cool, cool.