Fuel Tanks and Static Electricity

[SCO]

Seems everyone is fuzzy about the whys of gasoline explosions from static electricity, especially with plastic tanks. I searched and found a good primer. <br /> http://nciaai.com/Static gen during fueling.pdf <br />If you have any stories regarding static caused fires , or expert /anecdotal knowledge, please share it. For example, I have read that sliding plastic containers in the back of a pickup is a bad idea. Why? If the plastic is non conductive, what difference does it make if the container slides? Is it the sloshing of gasoline that builds static electricity in an electrically isolated system? BTW, in the pdf, you can get to a summary of sorts on page 22.

 

[rons boat]

Re: Fuel Tanks and Static Electricity

Rub a plastic comb thru your hair or slide across a plastic carpet with dry shoes. The result is electrons all polarized and ready to equalize or jump. This is static electricity and the source of possible ignition. This is why a fuel truck has a static line to ground out the truck as it refuels. Rarely happens but..........

 

[SCO]

Re: Fuel Tanks and Static Electricity

That is a good point that seems contrary to what a lot of the lore is. Many say the plastic is non conductive and spark cannot go through it and it acts as an insulator allowing other materials to build up charge because the charge cant get out through the plastic. We all know though that the plastic comb will attract paper bits after it is run through hair. The comb seems to be holding the charge. Therefore why cant you ground a plastic tank?

 

[Arnold96]

Re: Fuel Tanks and Static Electricity

First, the reason sliding the tank in the back causes the buildup, is the contact and removal is what generates the static. A non conductor will hold this charge at the surface. However, most if not all gasoline cans are not just ordinary plastic. They are made to be slightly conductive so they can be grounded. That is why a regular gas can should NEVER be filled in the back of a truck but while sitting on the ground, and the nozzle in contact with the can. Same with a permanent boat tank, the nozzle should always touch the tank or goose neck while filling.

 

[SCO]

Re: Fuel Tanks and Static Electricity

I heard that too Arnold. I wonder now if the 6 gallon tanks in the back of the boat dissipate the static through the fuel hose or fiberglass that connects to the rest of the hull? It cant be a problem, but the below deck tanks must be strapped down. Could be to prevent wear or leakage.

 

[crab bait]

Re: Fuel Tanks and Static Electricity

i can't go with that.. plastic is plastic is plastic.. <br /><br />i should know i guess but don't.. all i know is 3 years ago ,, i sent an apprentice out on the job ,,to get some gas for our genarator,, in the company truck.. he never came back..i had a heck a time gettin' home that evening..<br /><br />the fillin'station was only a couple miles away.. on returnin' the plastic can on plastic bedliner blew up.. he stopped,, got out safe,,but the truck was totaled... <br /><br />he wouldn't even go out for 'break order' after that..<br /><br />i'm partnered up with the 5th year apprentice teacher.. i'll ask him about it tommorrow..

 

[SCO]

Re: Fuel Tanks and Static Electricity

Good story bait. Looking forward to the follow up

 

[crab bait]

Re: Fuel Tanks and Static Electricity

well,, as things would have it.. he was a 'no show' today.. an mite not see him anymore..either he or i ,,is goin' on a nite shift startin' tuesday..<br /><br />any way,, i asked another guy.. he tried to give me a song & dance.. but it didn't fly.. i stumped him at the rubber tires..<br /><br />you see,, it still has to see/go to ground.. that's electrical physics ..( i reckon ).. <br /><br />anyway,, it still blew up.. with 'the squid',, just drivin' down the road.. <br /><br />an he ain't they only one/time it happend to..<br /><br />but i'm obsessed now.. i'll 'sherlock' it out.. i'll give ya's my john henry on that...

 

[DJ]

Re: Fuel Tanks and Static Electricity

Crab bait,<br /><br />Arnold made a very good point about the conductivity of plastic. The point is that the static charge is not conducted by the plastic, it is attached to it on the surface. Both inside and outside.<br /><br />This point is proved by running the plastic comb through the hair trick. One builds up static electricity even while wearing rubber tennis shoes (tires). The point is that the static electricity has nowhere to go until you provide a ground.<br /><br />The pick up truck phenom. is even more prevelant with pick ups that have plastic bed liners.<br /><br />For boats: Plastic (permanent) tanks are attached to the boat for several reasons. 1. Safety from moving around. 2. Wear. 3. Static grounding.<br /><br />Your plastic six gallon cans are frequently attached to the motor by a fuel hose. This gives the static an outlet.<br /><br />All we have to remember is that static does not travel through a conductor like electricity that we normally think of, it travels around it.

 

[crab bait]

Re: Fuel Tanks and Static Electricity

good explanation, DJ..!!<br /><br />but/so how does a plastic gas ,,with gas,, can 'BLOW' up in the plastic bed liner of the bed of a pickup truck,, slidin' around..??

 

[rons boat]

Re: Fuel Tanks and Static Electricity

The way to drain the excess electrons has been demonstrated by NASA and aircraft designers. They put a metal mesh throug out the composite (plastic) and that supposedly would solve the problem. Good luck on mixing in metal mesh screen in a 19.95 plastic fuel tank.. Maybe some fiberglass ones with a little more pricecy cost could be made safe. By the way the mesh is like chicken wire and is like a skeleton embeded in the tank.

 

[crab bait]

Re: Fuel Tanks and Static Electricity

ok,, here it is.. i found out today.. <br /><br />as per what DJ said,, static builds on the outside of the can while slidin' around on the trucks plastic liner.. <br /><br />it really picks up a static charge because of the gasoline ,,for some reason..<br /><br />what makes it go K A B L U U U W E E ..!!<br />is POTENTIAL.. static doesn't have to seek 'ground'.. it just has to seek a differance in potenial.. like the staticified gas can slidin'over or touchin' the 'bed bolts' or anythin' different .. and the static charge jumps/arcs/zaps to it,, causin' a spark..<br /><br />also was told,, you can blow yourself up in the wintertime.. by fillin' up your automobile while the nozzle is on 'auto'<br />fill..<br /><br />you get back in your car,,cause it's cold, jump out to stop the nozzle ( say at a certain price ) touch the nozzel .. an the static you created off the cold seat ,, BOOM..!!!

 

[SCO]

Re: Fuel Tanks and Static Electricity

That makes sense Crabbait, that the arc is from the container to the fuel, or from the fuel to outside the tank? Still fuzzy, but a lot less so. I use an omc 6 gallon portable plastic and a tempo tank. I'm going to secure them better than I have. The column of fuel makes a connection in the engine as does the fuel hose. Its the unused tank that I have to worry about.

 

[Yepblaze]

Re: Fuel Tanks and Static Electricity

First hand (not mine)from a few feet away.............<br /><br />The guy was filling his plastic jug in the plastic lined bed of his truck. Sure enough, WHOOOOOOSH!!!!!! as it ignited as a 2 foot blowtorch out of the 1- 1/2" opening.<br /><br />As some ran for the station shutdown switch, another was calling the fire dept, another was looking for a extinguisher. I told him to cap the jug which put the fire out.<br /><br />Had this occured while the jug was more empty and with some fresh air in it the entire experience would have been more spectacular.<br /><br />Me, when fueling into the back of my unlined pickup I maintain a portion of the nozzle handle to contact an area of chipped paint so as to ground it as I go.<br /><br />You betcha, I would not fill a plastic in a plastic!

 

[DJ]

Re: Fuel Tanks and Static Electricity

Crabby,<br /><br />Bingo!!!

 

[crab bait]

Re: Fuel Tanks and Static Electricity

thanks for the 'back-up',, DJ.. the 'answer' was killin' me..<br /><br />yeah,, SCO,, the way i see it,, it's the outside of the tank an the other object<br />( different potential ) that the spark jumps to.. like your finger is the tank & the doorknob is the other object..<br /><br />it's just that the 'fumey'stinky gas vapor gets in the way.. <br /><br />BOOM...<br /> that's why,, sometimes you'll get lucky,, sometimes you wont..

 

[crab bait]

Re: Fuel Tanks and Static Electricity

i don't think you have to worry.. your tank is connected to the motor .. as per DJ say

 

[SCO]

Re: Fuel Tanks and Static Electricity

Sometimes I take 3 spare tanks. Ive never heard of a spare spontaneously combusting on the water, but that doesn't mean it doesn't happen. When I replaced my floor, I didn't glass the floor in, it's removable, plywood painted with latex house paint. It might be like plastic on a plastic bedliner. BTW, in case you're wondering, I see commercial crab fisherman around here with no floor at all in their old fiberglass hulls. They just walk around the stringers and bulkheads.

 

[crab bait]

Re: Fuel Tanks and Static Electricity

i sure wouldn't reccommend that.. a floor gives ALOT more strength.. by tyin' in everthin' to everthin'.. <br /><br />to have no/an or just a lay-in floor ,, is like takin' a hardtop car an makin' it into a convertable .. by just cuttin' off the top an go..

 

[SCO]

Re: Fuel Tanks and Static Electricity

You're right crab. This is an experiment of sorts based on the overbuilt nature of this trihull and I struggled with this very issue. I shouldn't be suggesting that it is ok to do this in general.