shender1 Posted October 4, 2003 Share Posted October 4, 2003 A quick question...may sound dumb...but...why dont we ground our cars before we refuel them? Quote I'm not aware of too many things. I know what I know if you know what I mean. Link to comment Share on other sites More sharing options...
filipo Posted October 4, 2003 Share Posted October 4, 2003 ..why dont we ground our cars before we refuel them? We do. The aluminum nozzle makes contact with the car's filler tube, thus equalizing the electric potential. No difference in electric potential = no spark. Quote Omar FilipovicKitplanes Magazine web editor Link to comment Share on other sites More sharing options...
shender1 Posted October 4, 2003 Author Share Posted October 4, 2003 Originally posted by filipo We do. The aluminum nozzle makes contact with the car's filler tube, thus equalizing the electric potential. No difference in electric potential = no spark. Isn't the idea to equalize the potential before you refuel? If you use the gas nozzle it is closest to the fumes. Quote I'm not aware of too many things. I know what I know if you know what I mean. Link to comment Share on other sites More sharing options...
TES111 Posted October 4, 2003 Share Posted October 4, 2003 Only if your pumping gas before you put it into the filler tube. There was a neat special about this on myth busters last night. Quote Link to comment Share on other sites More sharing options...
Jim Sower Posted October 5, 2003 Share Posted October 5, 2003 I have my gas cap retainer plate chained to the cap, and a foot more chain dangling from the retainer plate into the bottom of the tank. I connect the 100LL ground to the retainer chain. If I'm loading mogas out of plastic jugs, I have to ground the gas IN THE JUG to the airframe. I do that by wrapping Al foil or 14 ga copper wire around the outside of one filler spout with a wire going around the end of the spout and up the inside of it. It seems it's the fuel flowing through the plastic filler line and through the air that generates the static charge - particularly on very dry(?) (winter?) days. I connect all the components (fuel, filler tube, filler neck, fuel in tank, fuel pouring, etc.) to neutralize the charge. I ground the retainer chain to the hangar frame. I came up with this after a thread a couple of years ago that seemed to last for weeks. Lots of folks who knew, lots of folks willing to tell you more than they knew, lots of superstition and black magic, but I finally came up with something that I think will work and that I'm comfortable with. The subject probably isn't worth this much verbage ... Jim S. Quote ...Destiny's Plaything... Link to comment Share on other sites More sharing options...
shender1 Posted October 5, 2003 Author Share Posted October 5, 2003 Originally posted by TES111 Only if your pumping gas before you put it into the filler tube. There was a neat special about this on myth busters last night. How could you pump gas without putting the nozzle in to the filler neck and keep it from spilling on the ground? I'm trying to understand the differnce between fueling an aircraft and an automobile. It seems to me that grounding the aircraft before fueling is needless (although I do it as I have been taught). I refuel my car everyday without grounding and I have never heard of a car blowing up because of a stray spark. Quote I'm not aware of too many things. I know what I know if you know what I mean. Link to comment Share on other sites More sharing options...
No4 Posted October 5, 2003 Share Posted October 5, 2003 http://www.atlasaviation.com/feature%20articals/donttakeanystatic.htm Quote The Coconut King Link to comment Share on other sites More sharing options...
shender1 Posted October 5, 2003 Author Share Posted October 5, 2003 Thanks for the info. I can agree with grounding the aircraft,just to be safe, but it would seem to me that if grounding was this critical we would see more car fuel tank explosions. Any other thoughts on this? Quote I'm not aware of too many things. I know what I know if you know what I mean. Link to comment Share on other sites More sharing options...
John Slade Posted October 5, 2003 Share Posted October 5, 2003 Car fuel tanks and the filler nozzels are made of metal and the pump and nozzel are grounded, so you automatically get a connection when you insert one into the other. The static issue becomes much more important when you have a plastic airplane, or when you're metal fuel truck is sitting on rubber tires, or both. Quote I can be reached on the "other" forum http://canardaviationforum.dmt.net Link to comment Share on other sites More sharing options...
No4 Posted October 5, 2003 Share Posted October 5, 2003 http://www.fiberglasstankandpipe.com/static.htm Quote The Coconut King Link to comment Share on other sites More sharing options...
TES111 Posted October 5, 2003 Share Posted October 5, 2003 Thats kinda my point shender. You wouldn't do that. On a car its grounded when the nozzel touches the filler tube. Because its metal. Since you are not pumping gas before you make the initial contact there are not enough fumes to expldoe if there was a spark. A cars gas tank is preasurized. I dont think that a planes tank ever gives you that woosh sound when you unscrew the cap. There-for you still have alot of gas fumes lingering in the air space of the gas tank. One spark and Kaboom. On a cars filler tube it is filled with fresh air when you unscrew the cap and get the woosh of fresh air rushing in. Quote Link to comment Share on other sites More sharing options...
shender1 Posted October 6, 2003 Author Share Posted October 6, 2003 I agreee with most of the points that have been given but I really dont see much differnce between refueling aircraft and automobiles. Pesronally I think the grounding of aircraft is maybe a good procedure if we are overly cautious but in reality the odds that a tank will explode are in our favor. Everything that has been said or discussed about this issue points out the danger of refueling without grounding but in every example given, the moment the difference of potential comes in contact with each other, there should be a spark and yet everyday cars don't explode. I dont think that there is any evidnece that longer filler tubes prevent this from happening. And...I think the wooshing sound has something to to with emmisions and not avoiding fuel tank explosions Quote I'm not aware of too many things. I know what I know if you know what I mean. Link to comment Share on other sites More sharing options...
LargePrime Posted October 6, 2003 Share Posted October 6, 2003 the woosh is out not in. But same difference. Vapor disapates so fast as to be a non issue. Entropy, Open area, Wind and all that On cars we have a metal tank touching a metal nozzel. Fuel behind the nozzel valve staticaly ballances when the nozzel touches. note that air flow over the metal tank keeps it pretty neutral. And the nozzel is in the open air too. Glass tank has no path to ballance with plastic filler tank. This could be an issue. Grounding both prior to filling seems to be a valid procedure. Side note. Plastic fuel tanks are not electricaly conductive BUT ARE STATIC ELECTRICALLY GENERATIVE. Perhaps most of us know this. Just filling an ungrounded plastic fuel tank can cause a spark, due to static build up from fuel flowing over the plastic. Quote We know who you are... Link to comment Share on other sites More sharing options...
Jim Sower Posted October 6, 2003 Share Posted October 6, 2003 <... but in every example given, the moment the difference of potential comes in contact with each other, there should be a spark ...> Difference of potential is key here. In the vast majority of situations there is none. Static buildup is caused by the act of fueling - the fuel leaving the nozzle. Prior to actually pumping fuel, there is no potential difference betweed the car and the nozzle. During fueling, they are connected and the nozzle is grounded so none can develop. Between fueling operations, the pump doesn't develop a charge, and neither does the car. Airplanes are the same. Problem is that plastic airplanes are not so simple to ground, and if you attempt to ground them in the common sites (engine or landing gear) there is no electrical path from the fuel leaving the nozzle and the ground cable. Also, the stories flying around invariably involve fueling with plastic jugs because a) static electricity forms more readily pouring fuel from a plastic container than a metal one (hose), and b) if the container, filler neck and fuel in the tank are not electrically connected, a charge can develop ie. how do you ground a plastic container. Remember grammer school? Creating a spark by running a comb through your hair does not work with a metal comb (nor on damp days). The glass and silk expirements we did in grammar school all involved rubbing two insulators together. That's why we have to be more careful with plastic fuel cans and plastic airplanes. Quote ...Destiny's Plaything... Link to comment Share on other sites More sharing options...
TES111 Posted October 6, 2003 Share Posted October 6, 2003 Will a plastic container omit a spark? Prime please correct me if I am wrong. Out with the bad and in with the good? Quote Link to comment Share on other sites More sharing options...
marbleturtle Posted October 6, 2003 Share Posted October 6, 2003 So why doesn't my lawn mower blow up when I fill it's plastic tank from my 5 gallon plastic gas can? Not trying to start something here... just curious! Quote This ain't rocket surgery! Link to comment Share on other sites More sharing options...
Jim Sower Posted October 6, 2003 Share Posted October 6, 2003 <... why doesn't my lawn mower blow up when I fill it's plastic tank ...> Fair question. How much do you use your lawn mower in winter? Actually, It might have a lot more to do with how long it takes to put how much fuel in the lawn mower. I have 20 hp garden tractor that only takes a couple of gals. The humidity seems to have a lot to do with it too. Going back to grammar school, the glass rod-silk scarf trick didn't work some days, and the spark as you walk across a room and grab a door knob only works under ideal circumstances. Besides all that, you need a combustible mixture - better than 16:1 or 18:1. The fumes that knock you out if you put your nose in a gas tank are about 30:1 or better. Bottom line: there's lots of conditions that have to be met and that makes the odds small. The stories about Piper Cubs blowing up only mention the one that DID. The studies and anecdotes obviously ignore the thousands that did NOT blow. Quote ...Destiny's Plaything... Link to comment Share on other sites More sharing options...
filipo Posted October 6, 2003 Share Posted October 6, 2003 <... why doesn't my lawn mower blow up when I fill it's plastic tank ...> The flow rate plays a role. Fuel flowing out of the plastic can moves slowly generating little static electricity over a period of time. On the other hand, fuel flowing from the gas pump nozzle moves quickly, and you should keep the plastic can on the ground while filling it. Quote Omar FilipovicKitplanes Magazine web editor Link to comment Share on other sites More sharing options...
LargePrime Posted October 7, 2003 Share Posted October 7, 2003 A plastic container cannot emit a spark. It can charge a fluid that can emit a spark. So does that mean a plastic fuel can emit a spark? I have seen carbon impregnated plastic gas cans that cannot build a static charge. But, as mentioned, one does not often gas cans blowing up, so it's not a problem I ever wanted to solve. But if I had it I guess I would know how to solve it??? The quick witted marbleturtle said... "So why doesn't my lawn mower blow up when I fill it's plastic tank from my 5 gallon plastic gas can?" I dont know. Perhaps you arent trying hard enough? And I abase myself before to the Gods who enforce on topic postings. Although they seem scarce. Quote We know who you are... Link to comment Share on other sites More sharing options...
filipo Posted October 7, 2003 Share Posted October 7, 2003 A plastic container cannot emit a spark. Have you ever taken off a sweater or pullover in complete darkness? Quote Omar FilipovicKitplanes Magazine web editor Link to comment Share on other sites More sharing options...
LargePrime Posted October 7, 2003 Share Posted October 7, 2003 Ya. but I realy dont think this is the place to talk about it... Geesh... Try and stay on topic. Quote We know who you are... Link to comment Share on other sites More sharing options...
filipo Posted October 7, 2003 Share Posted October 7, 2003 Funny... or you missed my point. Quote Omar FilipovicKitplanes Magazine web editor Link to comment Share on other sites More sharing options...
shender1 Posted October 7, 2003 Author Share Posted October 7, 2003 I want to apologize to rmaddy for getting us off the subject. I was reading this thread and thought I might get a quick answer to the question. Sorry! Quote I'm not aware of too many things. I know what I know if you know what I mean. Link to comment Share on other sites More sharing options...
marbleturtle Posted October 7, 2003 Share Posted October 7, 2003 Oh... the humanity! Quote This ain't rocket surgery! Link to comment Share on other sites More sharing options...
John Slade Posted October 8, 2003 Share Posted October 8, 2003 No big deal. I've split the threads up. In general, start a new thread if you want to start an unrelated discussion. Thanks, John Quote I can be reached on the "other" forum http://canardaviationforum.dmt.net Link to comment Share on other sites More sharing options...
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