Discussion in 'Instruments / Avionics / Electrical System' started by Aerowerx, Jun 24, 2015.
You know all modern car electric fuel pumps are submersed in the fuel inside the tank don't you.
It's like the fable of cell phones causing gas stations to explode.
Do you realize how much power you would need in the cell phone for that to happen? Don't know about anyone else, but I certainly wouldn't want to be anywhere near that phone (RF exposure danger).
They say it is coated with Teflon and can be used in petroleum liquids. I would want to ask them that question, though, before using it.
No, I didn't know that.
You don't want electricity in your tank, but a leprechaun smoking a pipe is OK?:ermm:
That's right. Its a fable. Myth.
RF can't ignite fuel unless its RF strong enough to burn you to a crisp first. What sets gas off is sparks from electricity crossing gaps in a circuit. If you don't have those, you have no fire risk.
I'm guessing you could probably run a glow plug or spark plug submersed in gas safely, as long as it doesn't reach the vapors above the gas.
I'll let you try that little experiment first. Remember, stop, drop, and :roll:.
Submerged fuel pumps are also electrically sealed/isolated so if you run the tank dry, you're not likely to become a road-based version of TWA 800.
Yeah, I saw that they said that it can be used but I was just curious how long it could be used without being rotated out.
Correct me if I am wrong but I was always told that the concern was about electrical arcing between the connections and the battery and not RF ignition. Remember that energies as low as 1 millijoule can ignite fuel vapor. The range can go as high as 100 J but most studies (Nestor, 1967; Ott, 1970; Shepherd 1997 etc) show a range of <1J to 25 J depending on temperature, vapor concentration and atmospheric pressure; your average visible spark is often cited (see previous citations) as 3 to 25 J. By comparison, a NiCad AAA battery contains about 1200-1300 J although the discharge rate is fairly low from what I understand.
Even in the vapor it'd be OK. There is near zero risk of fire in a sealed gas tank. The vapor pressure of gasoline is such that above the liquid, there is too much gas vapor and too little oxygen for combustion.
And Steve, I've seen in-tank electric pumps with totally unsealed motors. And the fuel gauge sender in my old Jeep, a potentiometer of bare wires with a copper wiper immersed directly in the gasoline, running 5V.
Way to go . You just stole a whole episode from Myth Busters by presenting scientific facts. On second thought that never really stopped them from doing some of the episode they have aired :emb: :gig:.
Don't need myth busters for this one. Just take any push mower and flood the engine with fuel. Then try and start it. You just proved what happens. But I am sure someone will try and make a 20 min. segment on some show about what happens.
You open your car door. The dome light goes on and... :shock:
The guy at the next pump, with the '90 Chevy pickup truck complete with broken plug wire, turns his key and...:shock:
The point being that there are lots of chances for a spark to occur at a gas station. But the concentration of fuel vapors would have to be high enough that you would choke on them first.
My thought on the RF...IF you had sufficient power, and IF there was a resonant loop of metal, and IF there was a small gap in the loop, then you MIGHT get a spark. But again the vapor concentration would have to be high enough.
Yeah...you know, I'm just totally wasting my life and so are the eighty or so years of my predecessors in both aviation and automotive crashworthiness research. The comparison between the two is since most light aircraft crashes impact at about the same speed as highway traffic (figuring that a very high percentage happen close to stall speed) and the weights are comparable (for example, a 2015 Mustang weighs right about what a Cessna 206 does...3500-3600 lbs). Yeah, there's nothing to be gained by use of better restraints or reducing risk of being burned alive or crushed by the instrument panel. Someone call Ford and tell them to start making the Pinto again....
NOTE: Apologies for not commenting earlier, I didn't see this post until just now.
Yup, either way, cell phones are a ridiculously small risk of ignition. Honestly, the best chance of ignition is static electricity at the tank inlet. There was a study done by the NHTSA in the 1990s or very early 2000s that said that there was a really simple reason why most of the fires involved younger people. Older folks are more likely to ground themselves- eliminating any charge developed from the upholstery- upon getting out of the vehicle because they have to touch the frame more upon exiting. There also has been- reportedly- a significant drop off in fueling fires ever since people started being nearly universally required to pay first. Either activity would likely cause one to ground the static charge before exposure to the one potential area of an ignitable fuel vapor concentration.
I look at E-ABs as something other than reliable transportation, even though, as I write this, I am1800 nm into a planned 5,000 nm trip. As you said, the scenery is best seen from just a few thousand feet. Seeing the change in the landscape, while flying where one wants to fly without constraint, is a real joy. Before yesterday, I didn't know that South Dakota has an area covered with small lakes.
But if you really want to experience flying at its core, one must become competent in aerobatics. That will also make anyone a safer pilot, although, ultimately, safety in personal aviation comes from one's attitude. When I say competent in aerobatics, I mean in full 3-D flight, including all stick forward maneuvers, not just RV-style gentleman's aerobatics.
I've never flown an ultralight, but I expect to one day, and I look forward to many late afternoon flights just puttering around the patch.
You know that Boeing builds (built?) airplanes with fuel pumps in the tank, don't you?
If only you could make an altimeter that cheap & simple!
Use the fuel gauge from a sailplane...
Separate names with a comma.