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So why has my lawn mower never blown up in my face when I fill it from a plastic container? The same conditions exist. Don -----Original Message----- From: Greg Bullough [mailto:[EMAIL PROTECTED] Sent: Monday, February 11, 2002 9:42 AM To: [EMAIL PROTECTED]; [EMAIL PROTECTED] Subject: Re: [COUPERS] MoGas At 08:02 PM 2/10/02 -0700, larry wilkins wrote: >What you missed is to always use a plastic gas can, thus eliminating the >possibility of any sparks in the first place. One would think so but... Not so! Indeed, plastic fuel cans have been the cause of many fueling accidents in boats and planes. The movement of the fuel itself over plastic creates friction and that can create static electricity on the surfaces, which is not easily discharged due to the insulative qualities of the surface. To prove my point by way of common household demonstration, wait until a dry day and shuffle over your carpet (wool or plastic) wearing your Reebok or Nike tennies. Then go touch something grounded and enjoy the ZAP! This is also a good way to train the cat not to sleep on the couch. Now try the same stunt using your tap-shoes that you wore back when you went to Miss Lulu-Belle's Academy of Tap and Ballet. Lo and behold, no ZAP! Tap, but no zap. Remember, this is static electricity. It sits on objects as a charge. When two different charges meet, ZAP! And polyethylene does a middling good job of generating and holding a static charge. Especially when paired up by a carbon-compound like gasoline. The reason you ground before fueling is to equalize the charge between the rubber-tired airplane and the fueling implement. You aren't really 'grounding' anything per se (though the wires on the pumps are grounded to earth). What you are really doing is equalizing the static charge in the fueling implement and the airplane. So if you DO draw a spark, you want that spark to be away from the gas fumes which lurk at the top of the filler neck. (They're heavier than air, and make a 'pool' right on the surface of the gasoline). And if the charge wasn't equal, you wanted to draw that spark... ...before any fumes were around. That's also why you don't do your first grounding at the fuel filler neck. That invites trouble. You equalize the charges on the pump/can-airplane, AWAY from any fumes, then proceed to fuel. Maintaining a constant contact between the fueling implement and the filler neck also ensures that any charge that builds up due to the flow of gas (such as through the rubber hose) drains off without producing a spark. Why is this more of a problem with airplanes than cars? Because airplanes have fuel fillers that usually are right on the tank, right by the fuel (true of boats in many cases as well). So there is apt to be a big 'puddle' of explosive gas right where the nozzle is going to contact the first metal. Others have suggested ways of making plastic implements safe for fueling planes via laminating metal to them and providing ground wires. Some of their advice may be good. Greg ==^================================================================ This email was sent to: [EMAIL PROTECTED] EASY UNSUBSCRIBE click here: http://topica.com/u/?aVxiLm.aVzvvT Or send an email to: [EMAIL PROTECTED] T O P I C A -- Register now to manage your mail! http://www.topica.com/partner/tag02/register ==^================================================================
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