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  • FIRST POST
    • agm2992mga
    • By agm2992mga 11th Jan 19, 3:07 PM
    • 1Posts
    • 0Thanks
    agm2992mga
    Not fully depressing nozzle trigger when fuelling at petrol station
    • #1
    • 11th Jan 19, 3:07 PM
    Not fully depressing nozzle trigger when fuelling at petrol station 11th Jan 19 at 3:07 PM
    Hi all,

    Is it true or just a myth that I've come across that not depressing the trigger fully when you are refuelling your vehicle at the petrol station is somehow more economical?
    Something to do with the pressure application/filtration, meaning more actual fuel and less air are pumped in, I gather.
    Or are the computers behind the petrol station clever enough to only charge you for the liquid fuel itself dispensed regardless of at what rate / speed?

    Negligible difference perhaps and therefore better to get in and out as quickly as possible for - after all - time is money!

    Thanks in advance for your informed responses.

    Cheers!
Page 2
    • A Nice Englishman
    • By A Nice Englishman 12th Jan 19, 12:39 AM
    • 2,154 Posts
    • 1,228 Thanks
    A Nice Englishman
    Surely if the fuel is pumped more quickly there will be more heat from friction and turbulence, increasing the volume? Good luck measuring the change without the sort of equipment found in a University Physics lab though!
    • LeeUK
    • By LeeUK 12th Jan 19, 12:46 AM
    • 6,194 Posts
    • 2,819 Thanks
    LeeUK
    Yup, and they will fine just as much for the pump giving too much fuel for the reading (so under charging the consumer) as for it giving too little.
    Originally posted by onomatopoeia99
    Really? I'm sure products in shops with stated weight on label can be over but not under.

    While I was still at school I had a part time job on the pumps.
    It was 1970-71. Can't remember which were and which weren't now, but some cars were very tricky to fill at more than a dribble, requiring the nozzle to be at the "right" angle. Others you could just dump the fuel in.
    Originally posted by Jackmydad
    Reminds me of a moped I had when I was 16/17, always had to spend what felt like 5 minutes trying to get the pump to dispense without clicking off. Some stations it was worse then others.
    • Tarambor
    • By Tarambor 12th Jan 19, 6:48 PM
    • 4,236 Posts
    • 3,248 Thanks
    Tarambor
    But if you do that you need to make sure you have those clip-on magnetic fuel conditioners on your fuel lines. Otherwise it'll keep trying to flow north - south regardless of which way the car's pointing and takes more effort to pump from the tank when you're heading sideways.
    Originally posted by Joe Horner
    You may be onto something there. If you clamp one around the petrol pump hose so all the molecules are in alignment does that mean you'll get more fuel in per measured litre? After all the molecules will be nice and neat instead of just a random jumble all colliding with each other.
    • david39
    • By david39 12th Jan 19, 7:41 PM
    • 1,940 Posts
    • 1,565 Thanks
    david39
    Adding to an earlier post regarding Trading Standard tests, when they check the quantities at the pump they don't just dispense 5 litres into a jug and say Pass or Fail.
    They check several ranges of quantities into accurately calibrated measures and they also repeat this several times at different rates of flow through the nozzle.
    The pump has to deliver the correct amount every time, otherwise they fail the pump. So there can be no difference to the amounts of fuel you receive irrespective of how quickly you put it in your tank
    • WobblyDog
    • By WobblyDog 13th Jan 19, 11:42 AM
    • 478 Posts
    • 303 Thanks
    WobblyDog
    Also always fill up at sea level as any bubbles will be smaller due to the greater air pressure. . .
    Originally posted by Jackmydad

    No, you should try to fill up at the highest filling station that you normally pass, to maximise the amount of free gravitational potential energy in the fuel. I did the calculation for this once, and the saving is well under 1% of the purchase price, so it's not worth bothering actually.
    • Mr.Generous
    • By Mr.Generous 13th Jan 19, 12:07 PM
    • 1,978 Posts
    • 2,915 Thanks
    Mr.Generous
    I'm just waiting for someone to suggest diluting the fuel with 10% paraffin like they did during WW2
    • Laffinarab
    • By Laffinarab 13th Jan 19, 2:15 PM
    • 20 Posts
    • 4 Thanks
    Laffinarab
    If you clamp one around the petrol pump hose so all the molecules are in alignment does that mean you'll get more fuel in per measured litre? After all the molecules will be nice and neat instead of just a random jumble all colliding with each other.
    Oh my god, please stop talking. The world that listens gets a bit less intelligent every time you open your mouth.... actually
    • Joe Horner
    • By Joe Horner 13th Jan 19, 3:09 PM
    • 4,556 Posts
    • 4,045 Thanks
    Joe Horner
    You may be onto something there. If you clamp one around the petrol pump hose so all the molecules are in alignment does that mean you'll get more fuel in per measured litre? After all the molecules will be nice and neat instead of just a random jumble all colliding with each other.
    Originally posted by Tarambor
    In theory yes, but the fuel companies caught on to that quite a while back. That's why they have the bend in the nozzle to jumble them all up again.

    Also, you have to do it before the measuring is done, which worked fine with the old style pumps where the delivery pipe ran up the outside to a sight glass but no good on modern enclosed pumps
    • Joe Horner
    • By Joe Horner 13th Jan 19, 3:18 PM
    • 4,556 Posts
    • 4,045 Thanks
    Joe Horner
    Really? I'm sure products in shops with stated weight on label can be over but not under.
    Originally posted by LeeUK
    Kind of sort of.

    Trading standards are more interested in the accuracy of the measuring equipment than the stated weight (provided it's not over-stated).

    So, if a nominal "1kg" pack of apples actually weights 1.05kg because apples don't come in exact weights that's not a problems as long as the scales used to weigh them correctly said they weighed 1.05kg.

    If you bought a pre-sealed 5l can of paraffin that had been filled to an accurately measured 5l, then they'd added a little more for some reason, that would be fine. But, with pump fuel, it's being measured as it's dispensed. So the amount delivered is a direct measure of the accuracy of the meter.
    • facade
    • By facade 13th Jan 19, 4:03 PM
    • 3,652 Posts
    • 1,902 Thanks
    facade
    I'm just waiting for someone to suggest diluting the fuel with 10% paraffin like they did during WW2
    Originally posted by Mr.Generous



    No need, the Government are going to dilute it with 10% ethanol to save you the bother.



    Charge the same for it mind......
    I want to go back to The Olden Days, when every single thing that I can think of was better.....

    (except air quality and Medical Science )
    • Car 54
    • By Car 54 13th Jan 19, 4:45 PM
    • 3,709 Posts
    • 2,302 Thanks
    Car 54
    No need, the Government are going to dilute it with 10% ethanol to save you the bother.



    Charge the same for it mind......
    Originally posted by facade

    That would be a bargain: the excise duty on ethanol is 28.74 a litre.
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