Diesel & Petrol suppliers

[m8internet]

How often are the storage tanks at garages cleaned? If it's a busy site, when would they have a chance to do it?

Virtually never, the costs are so prohibitive
I've been involved in the industry for near on 20 years now and I'm only aware of just a handful of tank cleaning inspections in Scotland on a BP or Shell forecourt
The rest have were declined and the tank was drained and then simply filled with foam

The tank will have a water monitor, above which an alarm will sound
Fuel sales are then normally suspended until the tank is inspected, which usually takes place within the next business day
If water is found then the fuel is removed and the cause traced

The tank will also have a probe to measure the ullage
Sadly they are not very accurate as they are only to give an indication of how full or empty
Equally, they tend to lag behind use and deliveries
The tank has to be mointored once a day, once a week, and once a month for tolerance
This usually highlights a loss through evaporation or leakage

Another consderation is linked tanks, usually at larger forecourts and usually only on diesel tanks
This allows quicker dropping of fuel as it effectively all goes into one big tank

Next is the tank construction
The feed pipe is usually set at about the 1000 litre limit
If you look at offset fils you will see the tank grade and capacity, such as Unleaded 14,500 litres
Once a tank is down to 1000 litres the pumps can no longer syphon and delivery stops at the pump
Another design is a dispenser, this is where the petrol pump itself is unpowered and silent (often leading to complaints that no fuel was delivered)
This is easier to maintain as there is only one pump
However, if the pump fails then no fuel is delivered at any nozzle!

If you ever see a forecourt with covers on grades, then you know a tank has gone down to the lower limit
That suggests poor ullage control and avoid for at least the next two weeks (three deliveries)

[Grahamy]

i did quote last week or so on here that ive never noticed a difference in performance or mpg....... well i had been using asda diesel so i emptied the tank and refilled at shell, now the car has so much more power its unreal

[Readster]

I rest my case
You pay for what you get it seems

[Grahamy]

I rest my case
You pay for what you get it seems

there both 102.9 at the moment

[m8internet]

there both 102.9 at the moment

Asda = BP
Shell

The Asda fuel is almost identical to BP
If they were both 102.9 I 'd go to Shell
Equally, if tesco was 102.9 I'd still go to Shell
Most likely that BP would be 103.9
However if BP Ultimate Diesel was 105.9 then I'd use that