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Explosion hazard filling a plastic tank?
|Author||Topic: Explosion hazard filling a plastic tank?|
posted 03-30-2002 11:44 PM ET (US)
I was filling up a bunch of plastic 5-6 gal tanks today in my car and always take them out and set them on the ground first. Someone told me that there can be a static electric charge then a possible spark as a result of the gas flowing out of the nozzle.
Can there be a similar danger with filling up the Montauk 28 gal Tempo also? It's not grounded either (is it)?
posted 03-31-2002 07:03 AM ET (US)
I know that there is a danger when filling plastic tanks when located on a plastic truck bed liner. It may have to do with plastic on plastic(?)
posted 03-31-2002 04:12 PM ET (US)
I'm not sure about plastic on plastic - but remember your high school physics static electricity experiments where hard rubber was rubbed against silk, wool, and all of the other combinations. Similarly, I am not sure about generating static electricity via flowing fuel through a nozzle - but I would doubt it. If that were the case, you would be required to ground your vehicle before refueling.
But one thing is certain - only metal will block static electricity. Years ago when using explosives, as taught by my mentors, we would always carry the blasting caps in a metal 'Prince Albert' can in a shirt pocket - to eliminate any possibility of static electricity problems.
Also realize that to have an explosion requires a proper air/fuel ratio.
Having been associated with safety analyses and accident analyses for many years, the last thing I want is a fire. Therefore, I do not want the fuel boundary to be compromised. Consequently, in my mind, the best boundary for fuel is metal.
However, the Coast Guard blesses the non-metal tanks and containers - so they are satisfied that there is not a significant problem with the non-metal tanks and containers. ---- Jerry/Idaho
posted 03-31-2002 04:41 PM ET (US)
Here is the explanation from experts. A little caution goes a long way. Be safe!
posted 03-31-2002 05:29 PM ET (US)
Jerru is correct about a static charge build up.
When we bunkered on the ships we always used a grounding strap between the the fill hose and fuel manifold to avoid an eletrostatic discharge. This is one reason why it is recommeded when you put the nozzel into the fuel fill on a boat that is is in good contact. This elimates the possible gap where a static electricty charge may ark over in the presence of fuel vapors and air within upper and lower explosion limits.
I too will look at that web site and see what they say.
posted 03-31-2002 05:48 PM ET (US)
opps, sorry Jerry.
I tried that link and could not bring it up.
posted 03-31-2002 06:05 PM ET (US)
Found it, Thanks Chip.
"Equipment on Trucks or Trailers
Motorcycles, lawn movers and other garden equipment, snowmobiles, jet skis and boats are examples of gasoline-powered equipment that are transported on trucks and trailers. Because Chevron is aware of three fires involving jet skis and snow-mobiles, we suggest, when practical, either:
Placing the equipment on the ground before fueling it from a dispenser, or
Gasoline, Static Electricity And Fires
Gasoline has a low electrical conductivity-- it does not conduct electricity very well. As a result, a charge of static electricity builds up on gasoline as it flows through a pipe or hose and this charge takes several seconds to several minutes to dissipate after the gasoline has reached a tank or container. If this charge discharges as a spark from a tank or container to the grounded metal nozzle of the gasoline dispenser hose, it may ignite the gasoline. Ignition requires that the spark occur near the tank opening where the gasoline vapor is in the flammable range.1 A spark discharge directly from the surface of the gasoline to the grounded nozzle also is possible. Normally, this will not result in ignition because the concentration of gasoline vapor near the liquid is above the flammable limit.
Theory and experience suggest that the condition most likely to lead to a spark discharge is filling a metal container or tank that is insulated from ground, i.e., one which is ungrounded. This is the situation that exists when a metal container is placed on a plastic bedliner."
The above is from the Chevron Web site, for complete information use the url.
posted 03-31-2002 06:46 PM ET (US)
Cheeze! I've been doing the opposite of what I thought was good safety. I left the metal tanks in the trunk and took out the plastic while filling.
I have NEVER actually read or directly heard of a gas-filling accident and always thought if it was something was so prone to disaster there would be many more notices on or around the gas stations.
(Now that I've read the Chevron article) I feel a little better and don't think I'll worry about so much about this. Thanks, Chip.
Still, I don't think I'll have the kids in the car when I'm filling the 10 six-gallon cans in the trunk anymore.
posted 04-01-2002 01:22 AM ET (US)
Just a couple of thoughts from one who lives in the static electricity capital of the world: when you fill fuel containers in a trunk or pickup bed you would seem to improve your chances of getting the "correct" mixture of air and fuel for an explosion as the heavy fumes settle into a space with raised sides. You don't need a lot of conductivity to get rid of static electricity. Tires always used to be made with carbon black to increase durability. This also made the tires a sort of semiconductor because of the carbon in the compound. I have read that owners of some brands of tires now routinely get shocks at toll booths because the carbon black has been replaced by silicon or silica(not sure) to reduce rolling resistance. The cars build up static electricity because of friction with the air, and don't bleed it off to the ground.
It only takes minute to place a tank on the ground. I don't like reading about the treatment of third degree burns. Dave
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