Never going to happen, that was the point to my original reference to flight 800. That’s what the engineers at Boeing calculated also for the 747. Millions of miles without incident, and it was the only that one time when the conditions were just right when it happened. The potential was always there but since no one ever recorded a problem they figured there wasn’t one.
15:1 is the ideal mixture for combustion under pressure in a combustion chamber, but if your saying that an open bucket of gasoline will not ignite unless there is a 15:1 ratio or that fuel spilled on the ground isn’t capable of ignition until it reaches a 15:1 ratio I would have to see more proof before I would believe that. Fuel vapors and air in my book will ignite if given enough heat for combustion over abroad range of ratios. Now I’m open to new facts if they are presented to me.
I certainly do understand that the conditions have to be right for combustion; and I don’t claim to be able to explain why there have (never?) not been any accidents associated with this. But when the filler cap is off or the sending unit out there is certainly an opportunity for air to mix with the fumes in the tank, in what ratio this would be is anybody’s guess.
And please let me make it clear as I stated in the initial post that the only time that your going to create a spark is when the circuit is broken and that would only happen in a case like I found in the sender that I just serviced. Or, if for some reason the spring tension allowed the wiper to lift from the element.
Nifty, yes my friend, there is current running through a completed circuit, break the circuit at any point and one side will be positive and the other negative.
And Bill I’m trying to dissect what you said about the gauge passing current to ground at the gauge cluster?? This is a simple series circuit with two resistance components in it, one of them (the sender) being variable. Any current that passes thru the circuit passes thru both and arrives at ground potential through a ground lead from the sender bracket to the body or frame. With out measuring it I have no idea what the resistance of the meter is nor how much current is allowed to pass thru the circuit, I suspect that your correct in your guess that it is miniscule, or probably in the milliamp range. At 6v this will spark, maybe not a long spark but it will spark.
Denny Graham
Sandwich, IL
