# Oil tank question

I used to have a rectangular oil tank which I dipped to check usage. Because
of its shape and size, I knew that an inch on the dipstick equalled 6.25
gallons of fuel.
Recently though, we got a new tank, a plastic Titan model and I got a chart
from the makers, but because it is an irregular shape, ther doesn't seem to
be any direct correlation between depth and quantity. the chart says:
Litres Millimetres
100 103
200 190
300 280
400 365
500 465
600 570
700 680
800 775
900 865
1000 960
1100 1055
1200 1160
1289 1315
Does anybody know of a way say what 5 mm on a dipstick would indicate?
Regards
PJ Macguire
No, cos it's an irregular shape
In message , P & H Macguire writes
You have just said above that it's an irregular shape ...
On Dec 18, 9:20 pm, "P & H Macguire" wrote:
Depends which 5mm :)))
Why not draw a chart of the above and convert the dipstick level with that?
cheers, Pete.
But I'm sure you could come up with a reasonable approximation by making an assumption about the shape ...
a previous thread on this subject, albeit with cylindrical tanks.
Because the shape is irregular 5mm will indicate different volumes up and down the range. If you drop the figures into a spreadsheet and calculate the litres per mm at each of the depths then you'll see that the figure ranges between 0.97 l/mm and 1.08 l/mm and on average about 1.05 l/mm. Only the first and last depths are less than 1l/mm.
So 5mm indicates a little over 5l except when it indicates a little under 5l!
Guy
It's not far off linear, sorry I couldn't be arsed to scale data to fit google chart's weird encoding.
,01.09,02.80,03.65,04.65,05.70,06.80,07.85,08.65,09.60,10.55,11.60,13.15|01.00,02.00,03.00,04.00,05.00,06.00,07.00,08.00,09.00,10.00,11.00,12.00,12.89&chtt=Litres%20per%20mm
That's a help; It's probably accurate enough for my purposes; I check the usage every Saturday morning so I can keep tabs on what we're using. Thanks everybody.
Regards
Pat Macguire
In article , P & H Macguire writes
Certainly, 5mm means it's f'ckn empty . . .
As others have said, it means different things at different fill level but if you difference the heights per 100l it appears to vary between 85 and 110mm per 100 litres which is 4.5 - 5.9 litres/5mm.
If you bung the figures into Excel & make a graph there is a definite linear relationship. Buggered if I can answer your question though.
You could add a fixed amount every time the level drops to a fixed point & see what difference it makes.
Is it weekly useage you're checking or merely how much has gone/is left on a week by week basis?
Umm, didn't you/don't you have a sight tube? You don't even need to get your hands messy wiping off the dipstick.
When the tank was installed it came with an electronic device called a Watchman which sends a signal to a plug-in indicator, but it only shows tenths of a tank (1/10th = 122 litres) which isn't really useful for a weekly check.
Regards
Pat Macguire
On Dec 19, 12:20 am, "P & H Macguire" wrote:
No. But except at lowest amount of your table the realktionship between mm and the number of litres is in the range of 93 to 96 percentpercent. That's close enough for practical purposes. For example at 1000 mm the litres are /
In my previous house, I wired in an "Hour Meter" in parallel with the pressure jet burner, that gave me a very good indication of fuel used even on a daily basis. The data correlated very well with external temperature (after adjusting for wind speed). (Riello Burner, 20Kw, Nozzle 0.65/60W, rated 2.43 l/Hr) Regards Don
Hmm, you didn't really answer my earlier question, see above. Why is it you feel the need to take 'accurate' measurements on a weekly basis?
My tank also came with a watchman, but I also asked for a sight tube to be fitted. The tank is quite out of the way, and I check the watchman on a daily basis, but only bother looking at the sight glass when the watchman gets down to about 3, as I know I'm getting low on fuel by that stage. In the end, that's all that matters, knowing when I need to top up.
That is what I do with a "calibrated" sight tube rather than a dipstick. Bung the oil depth into a spreadsheet that tells me the useage that week and uses the previous 4 weeks useage to make a projected re-order date. That is normally correct within a week.
Which reminds me I've been away and missed this Saturday, the last projected re-order date was 31 Dec and it's been consistantly colder the last week as well. Oil delivery in Christmas week? Hum...
Good lord. What a lot of work. I glance at the tank every few weeks as I'm passing and if it's below 1/4 full, I make a mental note to respond to the next Boilerjuice email.
What opening the tap taking a reading closing the tap then plugging the figure into the spreadsheet, no work at all.
You don't use much oil then, if it gets cold and windy we can go from 1/4 full to "running on air" in two weeks. That's about 400 to 500l of oil, thankfully it only very rarely stays both windy and cold for that length of time.
Boilerjuice NFG around here. "Sorry, we were unable to obtain a quote in your area. We are currently in discussions with further oil suppliers to cover your area and we'll contact you by email when these become available."

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