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User inquiries about TankCalc
Common questions about tank volume computation

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Poor accuracy in table listing | Tank wider than tall

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Poor accuracy in table listing
I have used TankCalc for horizontal tank satisfactorily. But in vertical tank, calculated result shows same volume for different height/length. For me when I have entered Radius 94.7, Length 150 and r 11.5 all in cm. Then on computation [table generation], result for height 14 & 15 give same volume 63.34 [liters].

(The original post included a sample table with some random successive identical volume results for different height indices)
Okay, I see the problem. Please increase the number of cylinder integration steps to 400 (or more). The higher the number of integration steps, the more accurate the result. Go to the "Tune" tab and change the entry for "Cylinder integration steps" to a value substantially greater than 100.

In general, if you see table results of questionable accuracy or (as in this case) paired volume results in a table, changing the number of integration steps should be the first applied remedy.

The only reason for the default value of 100 is that this produces satisfactory accuracy in the majority of cases with reasonable program speed. Higher integration step entries improve accuracy but take more time to generate a table. If you have a fast computer, this issue may never come up for you, and you may want to use a larger default value.

The worst case involves the use of the slower inverse computation mode (height from volume) and a large integration steps entry. In such a case I might be offering the opposite advice — a smaller entry to save computation time.
Tank wider than tall
We are trying to calculate the volume in an Elliptical fuel vessel. The horizontal cylinder vessel Length is 2560mm. The vertical diameter is 1470mm, the Horizontal diameter is 2255mm, the Hemisphere caps left and right are, radius "r" is 175mm. Can this type of vessel be calculated on your tank calculator? Yes, sort of. Take the vertical dimension of the tank and perform all the usual computations. Then create a correction factor (cf) created by dividing the horizontal by the vertical dimension:

cf = h/v (greater than one).

Then create a table of TankCalc results and multiply all the volume results by this ratio.

Worked example:
"The horizontal cylinder vessel Length is 2560mm. The vertical diameter is 1470mm, the Horizontal diameter is 2255mm, the Hemisphere caps left and right are, radius "r" is 175mm."

TankCalc entries for this tank (all millimeters):
  • L = 2560
  • R = 735 (diameter divided by 2)
  • r = 175 (both left and right)
Full volume result: 4740.75 liters

Correction Factor cf = 2255 / 1470 = 1.534

Adjusted full volume result: 7272.31 liters (4740.75 * 1.534)

Table procedure: Create a table of results in TankCalc, transfer the table to a spreadsheet, and multiply the volume results by the computed correction factor.
In answer to the inevitable inquiry, "Why isn't this capability integrated into TankCalc?", my answer is that there are too many such variations to include in a finite-sized computer program. TankCalc's table results can be exported in many different forms, and special cases like this are more easily dealt with in a spreadsheet.
 

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