What To Look For When Choosing A Fuel Pump From The Variety Now Available.
There are basically three main questions to ask when choosing a fuel pump that is suitable for your needs:
- How fast do you want to refuel your vehicles?
- How accurately do you want to measure the fuel you use?
- Where is your fuel storage tank?
Let’s cover each question in turn.
You will want to refuel your vehicles as quickly as possible to prevent a bottleneck at the fuelling point. If the fuel pump dispenses at too fast a speed it can create excessive frothing in the vehicle tank which will prematurely shut the nozzle off. This means drivers have to repeatedly wait for the froth to settle & then top up the tank, thereby slowing down the refuelling cycle. The following guide should help you decide:
Low speed, 50 litres per minute
Cars, light vans, forklifts, jerry cans, small plant
Medium speed, 70 litres per minute
Large vans, small rigid trucks, agricultural vehicles, large industrial plant, small PSVs
High speed, 90 litres per minute
Ideal for filling vehicles with large capacity fuel tanks such as buses & coaches, articulated vehicles, heavy plant, quarry & mining
This is the most crucial question. Higher accuracy pumps will cost more but if you are using any significant quantity of fuel you may quickly recover the extra cost. Lower accuracy, lower cost pumps should ideally suit the smaller fleet. There are two basic types of meter in most fuel pumps:
Flowmeters - sometimes known as nutating disc meters.
- Approximate accuracy of +/- 2%
- Accuracy varies with delivery speed and fuel type
- Should be calibrated after installation and regularly checked
- If topping up tanks to the brim, the accuracy will wander out even further
Piston meters - sometimes known as positive displacement meters.
- Accuracy of +/- 0.5%
- The actual accuracy will be constant at different delivery speeds, so topping tanks up to the brim will not cause a problem
- Check calibration after installation but only re-check annually unless you have a particularly high fuel usage
OK, so one is more accurate than the other, so what?
The accuracy percentage is how closely the fuel figure shown on the pump matches the quantity of fuel actually drawn.
Example of a +/-2% pump
If a driver fills a vehicle with fuel until 100 litres is shown on the pump display then it means he actually delivered anything between 98 & 102 litres (100 litres +/- 2%) This gives an uncertainty of 4 litres.
Example of a +/- 0.5% pump
If a driver fills a vehicle with fuel until 100 litres is shown on the pump display then it means that he actually took between 99.5 & 100.5 litres (100 litres +/- 0.5%) This gives an uncertainty of 1 litre, 4 times better than the +/- 2% pump.
The same theory applies to your overall fuel usage. If the total of all your individual refuelling adds up to 10,000 litres in a month then you actually used between 9,800 & 10,200 litres if you have a +/- 2% accuracy pump. This is an uncertainty of 400 litres a month, at 112 pence per litre this equates to an uncertainty of £448 per month. So you don’t have to be using very much fuel to justify the cost of a higher accuracy pump.
All key and card operated fuel monitoring systems connect to the output of the meter in the fuel pump. This means that the figures produced by your fuel monitoring system can only ever be as accurate as the pump it is connected to. If you have a worn, old or inaccurate fuel pump don’t expect your fuel monitoring figures to be any better!
Where is your fuel storage tank?
If your tank is below ground you will need a pump with a much better suction capability to be able to lift fuel from the tank when it’s almost empty. If your tank is above ground, less suction lift is necessary but you need to be careful that the installation is protected against leakage in the event of damage to the dispensing equipment. The pump you decide to install will only work correctly if properly connected to the storage tank. A 90 litre per minute type pump won’t deliver at 90 litres per minute if it is connected to the tank via a 1” bore pipe. If in doubt ask a competent fuel engineer to check your tank & pipework.
If you have any doubt about your installation always ask a competent fuel engineer to carry out an inspection.