Forecourt Fuel Pumps.

EcosseExile

EcosseExile

Member
T6 Pro
Although not just T6 related.

In my day job I'm a Service Engineer on fuel tanker trucks and our delivery system has a temperature compensation facility. Which means if you order 1000 litres of fuel (Derv, Gas Oil, Kero) it is corrected to the Industry standard 15 Deg C.

In real life fuel (very roughly) expands and contracts 1 litre per 1000 per degree.

What does that mean for you, I hear you ask? In this warm weather fuels may be 20 Deg which means that you will actually receive 1005 ltr.

I have noticed on my travels that more and more retail pumps are corrected to 15.

And as almost all stations have underground storage the chance of the product being over 15 or even at 15 is slim. Therefore you will always be getting slightly less than the reading on the pump.

You pays your money, you takes your choice.

Just watch out for the symbol, Vol@15.

Hope this helps.

Martin.
 
@fezza68 Indeed. Unfortunately very few people are actually aware of this. The only legal stipulation is you must run it Temp Comped for 12 months. This is to stop people TC in winter when it's cold and turn it off when it's warm.
 
I don't suppose we can do anything about that?
 
But.......surely as the fuel expands, its density becomes less. As the molecular density expands, there's less energy available through chemical reaction per litre of fuel.

Maybe.:sleep:
 
EcosseExile said:
In real life fuel (very roughly) expands and contracts 1 litre per 1000 per degree.

What does that mean for you, I hear you ask? In this warm weather fuels may be 20 Deg which means that you will actually receive 1005 ltr.
Click to expand...

Isn't this the wrong way round? At 20C you would actually receive less fuel than at 15C? (Especially if measured by mass.

In fact at both temperatures wouldn't you receive exactly the same measured volume at any temperature, but at 20C the mass of our 80Litres would be less than the mass of 80litres at 25C?

Edit that last 25C is a mistype, should be 15C
 
Last edited:
Skyliner33 said:
Isn't this the wrong way round? At 20C you would actually receive less fuel than at 15C? (Especially if measured by mass.

In fact at both temperatures wouldn't you receive exactly the same measured volume at any temperature, but at 20C the mass of our 80Litres would be less than the mass of 80litres at 25C?
Click to expand...

I agree Skyliner, correct according to me ( I wasted my youth studying Fluid Mechanics).
 
It is not about mass, it's about energy. As the temperature increases the product gets thinner reducing the energy, therefore more product is required to provide the same amount of energy. The opposite is true if it's colder than 15. You need less product to provide the same energy as it's more dense.
 
EcosseExile said:
It is not about mass, it's about energy. As the temperature increases the product gets thinner reducing the energy, therefore more product is required to provide the same amount of energy. The opposite is true if it's colder than 15. You need less product to provide the same energy as it's more dense.
Click to expand...

Energy and mass are the same thing.
Its actually about density. Basically the lower the temperature, the greater the density of the fuel the greater the number of molecules in each measured volume of fuel, therefore the greater the energy released from combustion (assuming there is enough oxygen to achieve complete combustion).
 
Skyliner33 said:
Energy and mass are the same thing.
Its actually about density. Basically the lower the temperature, the greater the density of the fuel the greater the number of molecules in each measured volume of fuel, therefore the greater the energy released from combustion (assuming there is enough oxygen to achieve complete combustion).
Click to expand...


Remind me not to pitch next to you this weekend :whistle:
 
EcosseExile said:
It is not about mass, it's about energy. As the temperature increases the product gets thinner reducing the energy, therefore more product is required to provide the same amount of energy. The opposite is true if it's colder than 15. You need less product to provide the same energy as it's more dense.
Click to expand...

Calorific value is measured in J/Kg, not volume........time to move on, it’s July!
 
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Surely everyone knows to fill up early in the morning to get your money’s worth?
 
I noticed this on the pumps at our local Esso this week, with a handy bit of green electrical tape placed over the lettering... the tape drew my attention to it.
 
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