asked on
Home Heating Oil temperature contraction possibility
I was told that I have a 250 gallon cylindrical oil tank that lies horizontally underground. For 30 years the deliveries have been under 250 gallons even when nearly empty. Last February we were charged for 256 gallons.
Is there some temperature effect that may have caused an increase in number of gallons over the expected maximum?
Could the cold weather have caused a density increase?
Or is most likely answer a scam?
https://www.tevisenergy.com/heating-oil-scam/
We don't remember how low the tank was. It must have low.
ASKER
Thank you. The link provided will enable me to identify which tank I have and provide a measurable vigilant way to predict how much oil I need.
ASKER
I have never seen an oil meter before. probably because the tank is underground. I guess I could ask whether a meter could be installed.
on the fly meters exist. the delivery truck probably has one. but it seems easier to get the oil level of the tank which should be provided by some existing device...
Positive displacement flowmeters are great for delivery trucks because they accurately measure "buckets" of fuel that the display counts as the oil is delivered. "Custody transfer," "legal for trade" or "revenue grade" would be keywords to look for. Here is a supplier to the trade who offers such flowmeters.
The problem with measuring tank level is the fact that tank shapes vary from the ideal shown on the manufacturer's shop drawings. The dimensional variances are large enough to make a flow meter a more accurate way of measuring delivered oil.
I used to work for Paul Mueller Company, the last surviving manufacturer of milk tanks (for dairy farms). To illustrate the dimensional variances, each tank had its own factory calibration curve with the measured volume at each level increment (mm or tenth of an inch). That way, both the farmer and the dairy processor knew how much milk the cows had produced when the raw milk truck came to pick it up. The tank had to be leveled for the calibration chart to be correct, and if the ground settled over the years, you might need to recalibrate it.
ASKER
They find 1.4% for a 20 deg C change in temperature. But are the selling by weight or volume?
If the oil is delivered cold and warms up (and expands) in your tank, then you will wind up with more gallons than were delivered, not less.