Grounding Plastic Gasoline Can to Avoid Spark

[rzrbk]

I know you are supposed to remove a gas can from a truck bed (plastic lined) before you fill it; but lets say you have a big container which would be difficult to lift once it is full and on the ground.

To keep this in the truck bed and fill it, there should be a way a grounding clip can be used. Presumably, the pump nozzle and hose is already grounded. Would you ground the can to the nozzle, to a nearby structure, or other? Is it even possible to ground a plastic container?

Any help will be appreciated.

 

[jraef]

Not really. One purpose of setting it on the ground is to avoid a discharge of static electricity from plastic rubbing on plastic. If you ground it once prior to turning on the pump, then turn off the pump and put the handle away once you are done before you slide the can around on the bed, that should be fine. I would not count on the pump nozzle or hose to be grounded however. Just make sure you touch a bare metal part on your vehicle or the gas pump itself, that should be enough.

If of course, I'm wrong and you immolate yourself, please disregard this statement!

 

[itsmoked]

If you are using a metal fuel can just touch the nozzle to some part of the can preferably not the fume filled opening with the nozzle. This would put the can and the nozzle at the same potential preventing a spark near fuel.

Then just leave the nozzle in contact with the metal during filling since moving liquids can and do carry electrical charge and can build up a static charge that could again jump from the can to the nozzle. When you are filling your vehicle the nozzle is of course wedged in the fill spout touching metal.

Now filling a plastic container should be no different. If there is a large surface charge on the container from say, the plastic container sliding around back on top of a different type of plastic the same technique described before should still work essentially the same way. The major difference is that the static charge on a plastic container is a *surface* charge which tends to hang out where it is applied because it is harder for the charge to "distribute". This means most the charge from sliding around the back will be on the bottom where it originates.

 

[OperaHouse]

It is possible for the vehicle to develop a static charge. The primary reason to remove the tanks is to insure the tank reaches a ground potential before filling. There are documented cases of the fuel nozel creating a spark annd a burst of flame when it gets near the filler on the vehicle. I can think of ways to reduce this potential, but can not suggest ways to violate the law.

I went to woek on an EDM machine and the customer had modified the pumping system that basically used keroscene. I kept hearing the cracking of an arc. I liiked in the back and they had installed a metal T in the rubber hose. When the pump was running, a 1 1/2 inch spark would jump to the frame.

 

[MacGyverS2000]

Opera,

I believe the spark you are referring to (once incorrectly attributed to cell phones) is from static build-up of the operator, not the equipment itself. I watched many a surveillance camera video where the person starts the pump, gets back into their vehicle and shifts around on the carpeted seats, then gets out again and touches the nozzle. It's at this point the charge on the operator jumps to the nozzle, igniting the nearby fumes. The really crazy people try to remove the nozzle, which only makes it worse (think flamethrower).


Dan
Owner

http://www.Hi-TecDesigns.com

 

[OperaHouse]

I can't honestly morn the demise of a few cell phone owners. What I was refering to is that a static charge can build up from the vehicle to ground. Opening the gas door and removing the cap generally drain this off. Also, most vehicles have a flap in the fill tube. This serves to reduce the vapor around the filler to a level below which will ignite and likely drains to the nozzel before insertion. A can in the back of a pickup doesn't have this protection.

 

[Comcokid]

Static build-up between the vehicle and the ground is one issue.

The other issue (which was slowly discovered by the introduction of plastic blow-molded tanks on vehicles) is static buildup inside the tank caused by the sloshing of fuel inside the tank. A static charge would build-up with the inside of the tank itself acting as a huge Leyden Jar static accumulator. When someone went to fill the tank, the static charge inside the tank would jump to the gas nozzle (a ground path) and ignite the vapor inside the tank.

More modern plastic vehicular fuel tanks have plastics selected to elimiate this effect, and have vent and fuel lines wired to prevent accumulation of a static charge.

Make sure your large plastic container is properly rated for fuel storage. Check for information on proper use of a large plastic fuel tank.

 

[BrianR]

Use the technique used on aircraft and tanker trucks, connect a ground wire from the metal fuel drum on the plastic tray liner to the vehicle body. Then use the normal precautions for filling your truck and touch the filling nozzle to the body before putting it in the tank filler. Otherwise your'e in line for honorary membership of the Crispy Critters Club.

 

[Compositepro]

The reason to put a plastic fuel tank on the ground is to minimize the the voltage that the charge accumulation causes. Charge separation is caused by fluid flow through the pipe or hose. Whenever dissimilar molecules separate from each other one has a greater affinity for electrons than the other and will pick-up some charge. With a slow- moving, non-conductive liquid little charge separation occurs and the charged molecules are attracted to the conductive pipe walls where the charge will be neutralized. With a high velocity flow there is lots of turbulence which leads to lots of charge separation and when the fluid leaves the pipe the charge leaves with it. This charge accumulates in a nonconductive container which acts as a Leyden Jar (capacitor). The closer this charge gets to earth the less voltage is caused by the charge. If you lift the charged container off the ground the voltage caused by this accumulated charge will increase dramaticly. There are numerous incidents of plastic buckets just filled with solvent catching fire when lifted.
The charge does bleed-off with time. The thing to keep in mind is that charged liquid is mobile and so the charge can move in an electric field. Charges on a plastic surface are not mobile. So the best proceedure for filling a plastic container (or any container) is to fill it using a grounded pipe that reaches to the bottom. Charges in the vapor space can be neutralized with inductive neutralizers like Ion Cord which is made from carbon fiber and is therefore very chemical resistant.