Elliptical tank level measurment

[zachary.wilson]

Howdy Everyone,
We are getting an elliptical water tank for our makeup system in our plant water system. We plan to use an ultrasonic reflective sensor for the level that uses a 4-20ma signal with a converter to go to the IO link balluff block we have available to go back to the plc. My question is short of making a data table with the levels and calculating the level to inches is there another way of doing this? with it being a round tank on its side obviously an inch of level at the bottom or top of the tank is not the same as an inch at the middle of the tank. We have used a scale with parameters before but that was a linear scale and this wouldn't be. Any help would be appreciated. Thank you.

 

[parky]

How good is your maths here is an example depending on the shape of the tank

https://myengineeringtools.com/Data_Diagrams/Volume_Horizontal_Cylinder_Tank.html

 

[drbitboy]

How good is your maths here is an example depending on the shape of the tank

https://myengineeringtools.com/Data_Diagrams/Volume_Horizontal_Cylinder_Tank.html

+1 for another opportunity to say the word "sagitta" (my brother is chuckling right about now).

OP title refers to an "Elliptical tank" - I wonder if they mean a cylindrical tank mounted with a horizontal axis of symmetry and elliptical heads?

The formulae are not overly complex, as noted by @parky; the question is what level of fidelity is required e.g. is the axis actually horizontal, or is it tilted slightly?

See also this link for a horizontal tank. There are two options: one if the PLC has arcsine/arccosine functions; one if it does not. I expect there are other posts if you go back farther.


But frankly, unless PLC memory is an issue, a dip-table is probably easier to understand.

 

[kolyur]

If the tank is truly elliptical and on its side:
https://www.had2know.org/academics/ellipse-segment-tank-volume-calculator.html

 

[glennz]

Howdy Everyone,
We are getting an elliptical water tank...

The few times I've had to do this (and my work is almost exclusively water systems) the tank supplier has provided the proper equation upon request. I'd try them.

 

[Holmux]

The size of the tank might be a factor in this solution
I would do the lazy approach, connect the ultrasound sensor and a flowmeter to the same PLC, and log the data.
I my book this would be the must accurate scale

 

[parky]

D = dia of tank (meters)
H = actual liquid height (Metres)
L = length of tank (Metres)
Actual amount in tank (Cubic Mtres) = L*D^2/4*(ASIN(2*H/D-1)+PI()/2+(2*H/D-1)*(2*H/D*(2-2*H/D))^0.5)
This is for a horizontal tank with flat ends.
Warning though at some point part of this calc i.e. divide may cause a divide by zero & shut the PLc unless trapped, this requires any divide portion of the calc to trap the divide by 0 & place zero in the result.

 

[Tom Jenkins]

The manufacturer should be able to provide a chart of volume vs. depth. Enter the values into Excell, chart them, and use the add trend function to get an empirical polynomial equation. Use as many terms as you need to get the accuracy needed. Note: I always format the parameters of the equation in scientific notation and go to at least 5 decimal places.

 

[JeffKiper]

Rockwell has an add on instructions made for tanks. Its called a strapping table. Basically its a dip table that you get from the manufacturer and linearized