Garage pump accuracy?

Honest John Back Room » Motoring discussion
What is life like with your car? Let us know and win £500 in John Lewis vouchers | No thanks
View Threaded
Mon 29 Mar 2004 09:24
Garage pump accuracy? - Cliff Pope
The other day I bought an indicated 20 litres of diesel in a jerry can for the boat I am restoring. To calibrate the dipstick in the new fuel tank I very carefully measured it into the tank 5 litres at a time, using an old antifreeze container that had a clear view stripe and was calibrated in litres.
I discovered I had only been sold 17 litres. That seems a big inaccuracy to me. Has anyone else ever tried checking the amount of fuel they have been dispensed?
Reply | Report as offensive | Link
Mon 29 Mar 2004 09:29
Garage pump accuracy? - Phil I
Perhaps wiser to check the accuracy of your old anti freeze container in the first instance Cliff??

If Ok then to Local Weights & Measures who will take immediate action.

Happy Sailing Phil I
Reply | Report as offensive | Link
Mon 29 Mar 2004 09:59
Garage pump accuracy? - Altea Ego
Thats a 15% shortfall - a lot! I would be shocked if a pump was delivering 15% less.
Reply | Report as offensive | Link
Mon 29 Mar 2004 10:58
Garage pump accuracy? - Cliff Pope
Good point about the antifreeze container. I thought I had covered that by choosing a container that had marked levels on it, rather than just vaguely 5 litres to somewhere near the neck.
Reply | Report as offensive | Link
Mon 29 Mar 2004 11:58
Garage pump accuracy? - Andrew-T
Extremely unlikely that any garage could get away with a discrepancy this big. Trading Standards are pretty hot on this particular error - they go round regularly with the calibrated copper jugs.

One way to measure your fuel may be by weighing your container empty and full. If you can find out the density of petrol at the correct temperature - otherwise use water and assume that one litre weighs one kilo.
Reply | Report as offensive | Link
Mon 29 Mar 2004 12:08
Garage pump accuracy? - Vin {P}
"use water and assume that one litre weighs one kilo"

Make sure you do it under the right conditions, and that the water is pure, or you could be fractionally out!

Litre: a metric unit of capacity equal to the volume of 1 kilogram of pure water at 4 degrees centigrade and pressure of 760 mm of mercury

V
Reply | Report as offensive | Link
Mon 29 Mar 2004 12:11
Garage pump accuracy? - Mapmaker
I'm sure Cliff wnats to fill his fuel tank with water..... :)
Reply | Report as offensive | Link
Mon 29 Mar 2004 18:19
Garage pump accuracy? - Andrew-T
Vin - the error at any normal temperature will be about 1 part in 1000.

And water in the container - there are various ways of drying it out. As long as you empty it thoroughly I don't suppose your fuel will be much wetter than at the filling station anyway.
Reply | Report as offensive | Link
Tue 30 Mar 2004 11:38
Garage pump accuracy? - Mapmaker
I think Vin was joking - as was I. I presume the suggestion was to calibrate the antifreeze container on the basis of 1kg = 1 litre. Then use the antifreeze container to fill the fuel tank.
Reply | Report as offensive | Link
Tue 30 Mar 2004 12:07
Garage pump accuracy? - terryb
One way to measure your fuel may be by weighing your
container empty and full. If you can find out the density
of petrol at the correct temperature - otherwise use water and
assume that one litre weighs one kilo.


That's the way they measure my 10 litres of Crozes Hermitage when I buy it in the Rhone valley!

Terry

"Just because I don't care doesn't mean I don't understand"
Reply | Report as offensive | Link

Our honest used car pricing is a little bit different to all the others. You can get to our values through make or model - you don’t have to follow a prescribed route. Plus, it’s live, which means we can react to changes in the market quicker than any printed price guide.

Honest Used Car Prices

From which small car to buy at which price point to the best UK-built cars, our Top 10s have the lot. Click now for your shortlist.

Unsure of what to buy? Our Top 10s are here to help you....