nicknorman Posted April 11, 2017 Report Share Posted April 11, 2017 Missed this thread earlier, but just picking up on a couple of the old points: Yes aircraft tend to use a static earthing line when refuelling, but as far as I know this is primarily when refuelling with Jet fuel (which is pretty close to diesel) rather than petrol. This is because jet fuel in flow is far more prone to static generation than petrol. Offshore refuelling, we (they - we had a man for it) connected an earthing line to the airframe. Then actually at the refuelling nozzle there was another short earthing line which was plugged into a small socket near the filler cap. The delivery pump wouldn't run unless it detected a circuit between the two earthing points. The hose was of course conductive, but with gravity refuelling (like a car) there was a risk of a spark between the nozzle and the airframe. With pressure refuelling (fuel line plugged into a socket on the airframe) it was assumed that there was a permanent connection between the fuel line and the airframe, and anyway jet fuel on its own isn't combustible - you need air too. As to mobile phones, the risk of sparks is virtually zero and an urban myth. The risk of distraction is significant and primarily in America, where you have a little catch on the nozzle trigger so you don't have to keep squeezing (removed by law in the U.K.), people allowed their fuel to overflow whilst nattering on the phone and then were surprised when the vapour exploded in Arizona heat. Finally - we refuelled at that now deceased pontoon a couple of years ago - missed death by inches! Link to comment Share on other sites More sharing options...
mross Posted April 12, 2017 Report Share Posted April 12, 2017 Arizona doesn't get that hot! The self-ignition temperature of gasoline (petroleum spirit) is about 247–280°C Link to comment Share on other sites More sharing options...
nicknorman Posted April 12, 2017 Report Share Posted April 12, 2017 1 hour ago, mross said: Arizona doesn't get that hot! The self-ignition temperature of gasoline (petroleum spirit) is about 247–280°C No but it does ensure that any spilt petrol vaporises almost immediately. Vapour flows out and then just has to find a source of ignition. As we know, liquid petrol doesn't burn, only vapour. Link to comment Share on other sites More sharing options...
IanM Posted April 12, 2017 Report Share Posted April 12, 2017 What they did find in America was people putting the nozzle in the filler, locking the 'trigger' on then going to sit back in their car until the pump stopped. They then got out by sliding on the seat a bit, touched the metal nozzle and the static created by sliding on the seat then caused a spark as the person earthed themselves. Link to comment Share on other sites More sharing options...
MtB Posted April 12, 2017 Report Share Posted April 12, 2017 15 hours ago, nicknorman said: Missed this thread earlier, but just picking up on a couple of the old points: Yes aircraft tend to use a static earthing line when refuelling, but as far as I know this is primarily when refuelling with Jet fuel (which is pretty close to diesel) rather than petrol. This is because jet fuel in flow is far more prone to static generation than petrol. Offshore refuelling, we (they - we had a man for it) connected an earthing line to the airframe. Then actually at the refuelling nozzle there was another short earthing line which was plugged into a small socket near the filler cap. The delivery pump wouldn't run unless it detected a circuit between the two earthing points. The hose was of course conductive, but with gravity refuelling (like a car) there was a risk of a spark between the nozzle and the airframe. With pressure refuelling (fuel line plugged into a socket on the airframe) it was assumed that there was a permanent connection between the fuel line and the airframe, and anyway jet fuel on its own isn't combustible - you need air too. As to mobile phones, the risk of sparks is virtually zero and an urban myth. The risk of distraction is significant and primarily in America, where you have a little catch on the nozzle trigger so you don't have to keep squeezing (removed by law in the U.K.), people allowed their fuel to overflow whilst nattering on the phone and then were surprised when the vapour exploded in Arizona heat. Finally - we refuelled at that now deceased pontoon a couple of years ago - missed death by inches! Easily defeated by the coach driver I saw the other day. He pulled to the pump, put the nozzle in his fuel tank then produced a tennis ball from his pocket. He grinned at me, pushed the tennis ball into the nozzle handle to keep it engaged, then went for a stroll around his vehicle checking bits and things, a bit like a pre-flight walk around! 300 litres later, the auto-shut-off device in the nozzle assembly turned the fuel flow off anyway. Do they not have those in America? Or do they just fail sometimes? Link to comment Share on other sites More sharing options...
WotEver Posted April 12, 2017 Report Share Posted April 12, 2017 We used to have the latches in the UK. The remnants are still on the nozzles (flappy bit of steel). HSE gone mad again. Link to comment Share on other sites More sharing options...
BruceinSanity Posted April 12, 2017 Report Share Posted April 12, 2017 23 minutes ago, Mike the Boilerman said: Easily defeated by the coach driver I saw the other day. He pulled to the pump, put the nozzle in his fuel tank then produced a tennis ball from his pocket. He grinned at me, pushed the tennis ball into the nozzle handle to keep it engaged, then went for a stroll around his vehicle checking bits and things, a bit like a pre-flight walk around! 300 litres later, the auto-shut-off device in the nozzle assembly turned the fuel flow off anyway. Do they not have those in America? Or do they just fail sometimes? Can't answer your last question, but the cork float on the ring of my filler cap key is ideal for this purpose. If anything, the auto shut off function is too quick, operating before the tank has filled to the bottom of the filler tube. Link to comment Share on other sites More sharing options...
nicknorman Posted April 12, 2017 Report Share Posted April 12, 2017 2 hours ago, Mike the Boilerman said: Do they not have those in America? Or do they just fail sometimes? I think they just fail sometimes, or at least allow a gob of fuel out before they trip. Yes there are defeat devices, a bit like the folk who stick things into the Nene lock operating buttons to prevent sore fingers! I sympathise with that one! Link to comment Share on other sites More sharing options...
Machpoint005 Posted April 12, 2017 Report Share Posted April 12, 2017 2 hours ago, Mike the Boilerman said: Easily defeated by the coach driver I saw the other day. He pulled to the pump, put the nozzle in his fuel tank then produced a tennis ball from his pocket. He grinned at me, pushed the tennis ball into the nozzle handle to keep it engaged, then went for a stroll around his vehicle checking bits and things, a bit like a pre-flight walk around! 300 litres later, the auto-shut-off device in the nozzle assembly turned the fuel flow off anyway. Do they not have those in America? Or do they just fail sometimes? Demonstrates the well-known fact that however safe a system is, human ingenuity will find a way to make it dangerous. 5 hours ago, IanM said: What they did find in America was people putting the nozzle in the filler, locking the 'trigger' on then going to sit back in their car until the pump stopped. They then got out by sliding on the seat a bit, touched the metal nozzle and the static created by sliding on the seat then caused a spark as the person earthed themselves. Unless they'd had a heart attack in the meantime (stereotypical lazy Yanks and all that...) Link to comment Share on other sites More sharing options...
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