How big is my oil tank and am I being diddled?

kathykate_2

Two things:

Is my oil delivery man diddling me? I ordered 1,000 litres of oil. He put it in, the delivery form says he put 1000 litres in, but I can't seem to make sense of how much he has put in when I look at the tank.

We have an old metal oil tank, came with the house. It has a sight tube on the side, with 8 notches hand-marked onto it at regular intervals (every 4 and a half inches) up the side. I've always imagined these mark significant litre marks ie 200 litres, but thinking about it, it's so old they probably mark gallons. After the 8th notch there is another 8 inches to top of tank. The last delivery took the oil up to the 4th notch.

The tank measures 6 foot x 4 foot by 4 foot. How can I work out how much a tank that big would hold? Then I might be able to make sense of how much these notches indicate, and then I might be able to work out if he's delivered the right amount. The tank was just about empty when he delivered, so now is a good time to work it out.

How easy would it be to keep 200 litres back for themselves? Surely a lucrative business if anyone were to do it!

I have worked out that 1000 litres is 220 gallons.

Any help appreicated, I hate being a suspicious so-and-so but would like to put my mind at rest I'm not being diddled. The reason I'm suspicious is because a couple of years ago I had 1500 litres delivered, which I marked on the tank, and this 1000 litres is not coming up to where it should in relation to that mark. :doh:

MJD

Despite what we may think about the metric system it is easier to work out if you work in metric.

I am assuming that your measurements of 6 foot x 4 foot x 4 foot is a rough measurement - therefore this will only give a rough answer.

here goes:

6 feet = 182.88cm
4 feet = 121.92 cm

Volume of the tank on the measurements given = 182.88 x 121.92 x 121.92 = 2718417.2 cubic cm

1 cubic cm is equal to 1 millilitre
1 litre = 1000 millilitres
Therefore your tank will hold 2718.41 litres

which converts into 597.96 gallons - It is probably a 600 gallon tank.

A couple of things to think about here - volume should be measured on internal measurements (not practical I know but I assume that the walls of your tank are not overly thick). I am assuming as well that the inside of the tank is a straight cubular rectangle and that it does not have a void built into it. If there was any sediment at the bottom this would affect the overall volume taken up by the fuel.

I am no expert on such things but I am aware that some liquids contract and expand at different temperatures - this is why fuel tanks should never be filled to the top and is why if a car sits in the sun just after having had the tank topped up it may suddenly start to leak fuel from the filler cap.

As for keeping 200 litres back for themselves - I guess nothing is beyond the realms of possibility. I assume that such delivery tankers are filled to a certain level and then checked again either when they get back to the depot or at least when they are next filled and one assumes that there would be documentation for this. It is not beyond the realms of possibility I suppose for a tanker driver to work his way around his deliveries delivering say 100 litres short to each customer then after 10 deliveries he could offload 1000litres into his own tank. this of course assumes that he is close by to his own tank - he will have a tachograph in the cab which will record where he goes and it also assumes that there is not a similar device on the fuel dispenser of the tank. I believe that some companies will give you a print out - bit like a till receipt - where the machine prints out exactly what the tanker has dispensed.

Another thing to think about is the sight tube. is it working correctly? it may have become clogged at one end - these things are temperamental. Are you able to dip the tank at all? I assume that there is a filler hole in the top - is there the headroom to drop a home made dipstick in it? failing that a weight on a piece of string to check the sight glass.

If you made a dipstick you could mark it off (and assuming that my calculations are correct - we are all human -) and assuming that yours is a 600 gallon tank and assuming that it is four feet high (you did not mention which measurement was the height) each inch would be 12.5 gallons (or 56.82 litres)

Better still if your tank is four feet high (approx 122cm) and the tank does hold approx 2720 litres then a mark every 4.48cm would be equal to 100litres - very approximately.

I hope that all makes sense!

aycor

were you in when it was delivered ?
our oil man delivers and gives us a printout from the tanker and you can check the delvery with the meter on the tanker. Then when the bill comes you can check again. these old tanks get full of debris at the bottom so a sight reading on the glass is only rough estimate
good luck

kathykate_2

Dear MJD and aycor

Thanks for your replies! MJD, your assumptions about tank were right. And your maths do indicate that he's delivered the right amount. ie I have 18 inches of oil in the tank, and 18 x 12.5 gallons comes out at 225 gallons. As 1000 litres is 220 gallons I think that's close enough. I'd like to think he gave me an extra 5 gallons but doubt it!

I think my much earlier marking of 1500 litres must have been when there was still some in the tank, hence confusion.

So, the current markings seem to be in litres, and, as 1000 litres has taken the oil up to the fourth notch, seem to indicate every notch is 250 litres. Still with me??!!

Aycor, I was in when it delivered, although he never came to see me. But I did get a printout from the tanker which stated 993 litres had been delivered.

Glad I got all that sorted!

Regards

oap

Hi, thank you for the interesting post, we had our oil delivered yesterday by a new oil company, ie not had them before, 33.9 plus vat, however, we were out and the dam man overfilled the tank, we could smell the oil at the bottom of our drive, in twenty years never had that happen before, he squeezed 990 litres in it, we ordered 1000 but warned them as there were two inches still in the tank it might not take 1000, now the gauge is leaking because it is spilling out of the top and running down and we have a bucket collecting it, what a carry on. It was all over our path too. Usually they check the tank and stop filling while they see how much more to put in, we always have had and did get yesterday an invoice with printout of where it started ie 0000 and ending in 990!!

moonrakerz

My tank is 6' X 4' X 4' which is a 600 gal. I have marked my sight gauge in 200 litre steps, they are three and a half inches apart.

MJD - it was a lot easier to go outside and measure it !!!

MJD

moonrakerz wrote:

My tank is 6' X 4' X 4' which is a 600 gal. I have marked my sight gauge in 200 litre steps, they are three and a half inches apart.

MJD - it was a lot easier to go outside and measure it !!!

Yeah I guess - but I didn't have to wait for it to stop raining!