Help with an Algorithm for using a level sensor to estimate consumption.

Question

I'm developing a small HMI-Scada application for monitoring the level of Diesel in four vertical tanks similar to the screen shot below.
Tank Information:
20 Feet High
8 Feet Inside Wall Diameter
5,000 Gallons Capacity
(These Tanks supplies four Caterpillar Generators)
Since each tank already has an Ultrasonic Level transmitter installed (accuracy is plus or minus one Inch) I was thinking of using this Tank level information coming from that sensor to estimate consumption.
The problem I'm having right now is figuring out the correct math to use inside VB.Net to make this calculation work, considering that Diesel not used by the Generators will be returned back to the tank.
The consumption data we need is not needed in real time necessarily it is more like at the end of the day we need to know how much diesel was used by each generator, this will help management figure out and print a report with the total carbon emissions
for that day.
The HMI-Scada application is going to have a Microsoft SQL Sever collecting the Tank Level Information every one minute.
To avoid further complications when Mr. Diesel comes with his truck to refill the tanks we are planning to have him manually enter into the HMI-Scada application the total amount of gallons pumped into each tank.
Do anyone in this forum have an idea of how this can be done?

Answer 1

Hi,
 Is the 20 feet actually measured from the inside Bottom to the inside Top of the tank? Is the Inside Diameter actually 8 feet all the way from the bottom to the top of the tank?
 If those two answers are true then it seems like it would be easy enough to calculate.
 20 feet * 12 inces = 240 inches
5000 gallons / 240 inches = 20.833333333333333333333333333333 gallons per inch
So, if i am right then for example, if you had 200 inches of fuel at the beginning of the day and 80 inches at the end of the day it would be:
20.833333333333333333333333333333 * 200 = 4166.6666666666666666666666666667 gallons to start with
20.833333333333333333333333333333 * 80 = 1666.6666666666666666666666666664 gallons at end of day
So the gallons used would be
4166.6666666666666666666666666667 - 1666.6666666666666666666666666664 = 2500.00 gallons used for the day
Example code:
Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
Dim GallonsPerInch As Double = 5000 / (20 * 12) 'Gallons Per Inch
Dim StartingInches As Double = 200.0 'get inches at Start
Dim EndingInches As Double = 80.0 'get inches at End
Dim GallonsUsedToday As Double = (StartingInches - EndingInches) * GallonsPerInch 'Gallons used from Start to End
MessageBox.Show("Gallons Used = " & GallonsUsedToday.ToString)
End Sub
If you say it can`t be done then i`ll try it
Thats right Razerz.
So where height is the change in the tank levels the volume is
V = (pi)(radius ^ 2)(Height)
V = (3.14)(4)(4)(Height) = 50.24 (height) cubic feet
V = (50.24 cuft) (7.48 gal/cuft) (height) = 376 (height) gallons
So for an inch of height:
V = 376/12 = 31.3 gallons per inch
Just for fun
5000 gals / (12)(31.3) = 13.29 feet high
Normally the tank does not fill to the top.
Check my math.
So all you need to do is Constant(change in height) = gals. Once we get the constant right.
PS In fact it would be best to just measure the depth when the gas man fills the tank and calc the constant. I doubt the tank is exactly 8 feet. I mean you calc the constant once. And at that time check it is linear ie the tank is a cylinder.