Volume of a horizontal tank

go_bears

Member
Join Date
Feb 2009
Location
South Dakota
Posts
28
I have a horizontal tank curved on both ends. I need a formula to figure the volume. Actually I have a number of formulas but can't seem to get them to work when I program them. I can use either rs500 or rs5000. I like rs5000 better. I found some info on a old post but just can't get it to work. Any help would be great. The senser is 4-20mA to the plc, a 5\05 plc, and is at the bottom of the tank. My fellow employees have been working on this for a couple of weeks. Tech Connect didn't help. Thanks
 
Going from memory here
Cot(theta) = 1/Tan(theta) so in the formula listed in the link given cot^-1 = Tan(theta)
 
The problem with the formula in the above link, like so many things with round parts, is it requires either trig functions or square roots to do the calculations. Many PLCs don't have tehm available. On the other hand, squares and cubes are easy with even four function math, although you really need floating point math to make it work easily.

I took the tables below from data by Panner Bailin. You can either create a look-up table and interpolate, or use the formulas I obtained by using a spreadsheet to do a linear regression on the tables. (This is a very good technique for all kinds of obtuse and complex functions.)


d/D = Depth/Diameter
Volume fraction Vf (that is, %/100)

d/D Vf
0 0
0.05 0.01869
0.1 0.05204
0.15 0.09406
0.2 0.14238
0.25 0.1955
0.3 0.25231
0.35 0.31192
0.4 0.37353
0.45 0.43644
0.5 0.5
0.55 0.56356
0.6 0.62647
0.65 0.68808
0.7 0.74769
0.75 0.8045
0.8 0.85762
0.85 0.90594
0.9 0.94796
0.95 0.98131
1 1


Vf = (0.4055 x d/D) + (1.7764 x (d/D)^2) + (-1.17839 x (d/D)^3)

Dished Head Volume
d/D Vf
0 0
0.06 0.0104
0.12 0.0397
0.18 0.0855
0.24 0.1451
0.3 0.216
0.36 0.295
0.42 0.381
0.48 0.47
0.54 0.56
0.6 0.648
0.66 0.732
0.72 0.8087
0.78 0.8761
0.84 0.9314
0.9 0.972
0.96 0.9953
1 1

Vf = (-0.0009478 x d/D) + (3.00269 x (d/D)^2) + (-2.00179 x (d/D)^3)



No trig functions requied.
 
Last edited:
What I decided to do wass use indirect addressing and just plug the numbers in according to percent(which is proportional to the hieght). I used the website from above to get the numbers.
Thanks for all the help.
 
In old PLCs I used a lookup table and a linear approximation function (APR) that worked really well.
 

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