analog tank level

Peter Nachtwey

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• Oct 9, 2008

• #16

No! PLC knowledge is good but forever knowledge is better.

Tharon said:

You still have to integrate everything before that using the equation you derive using the triangles for your area.

It still is all boiling down to integration.

Click to expand...

No, some trig and algebra is all that is required.
I am giving someone else a chance to show off. Someone, anyone? Put on your thinking cap and put a strain on the brain. Hopefully someone new other than the regular know-it-alls.
js.jim is waiting for an answer.

 

tgoulding

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• Oct 9, 2008

• #17

Isn't this a 'Non-Linear Equation' represented as follows;

V = πh2 (3r-h)

3

where V = Volume, r = Radius of Tank, h = Height of Liquid.

 

tgoulding

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• Oct 9, 2008

• #18

Isn't this a 'Non-Linear Equation' represented as follows;

V = πh2 (3r-h)

3

where V = Tank Volume, r = Radius of Tank, h = Height of Liquid.

 

Tharon

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• Oct 9, 2008

• #19

Ok.

You have to calculate the area of the circle at the end that is covered by liquid and multiply that by your hieght.

A little bit of trig and algebra leave you with an equation for the circle area based on the depth of the liquid.

Use this as a guide:

http://www.mathopenref.com/segmentarea.html

 

ctw3

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• Oct 9, 2008

• #20

I am not good enough at maths to attempt the problem, but here is a site which might help

http://www.arachnoid.com/tank_volume/

It makes a table and all! Sweeet

cheers

 

Peter Nachtwey

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• Oct 9, 2008

• #21

I hope Tharon didn't stay up all night just to find the answer

I will need to check this when I wake up. There seems to be a difference. Between ctw3 and Tharon's answer. In Tharon's case C=2*arccos(radius-level/radius).

 

js.jim

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• Oct 9, 2008

• #22

ratio of increase

if i am not mistaken
the tank is 12 ft high and around 30 ft long
it seems that the ratio of increase of change should be the same until half full
then the ratio of decrease should be the same on the top half
since i am going to know the volume by putting product in the tank by 100 barrels and getting the analog signal reading i should be able to get the ratio of change to do the math

RIGHT?????????????????
THANK YOU ALL FOR YOUR HELP
to make it hard the tank sits slightly out of level but i dont think enough to hurt to much so it drains out all the way

 

Last edited: Oct 9, 2008

milldrone

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• Oct 9, 2008

• #23

js.jim

Just curious. Does the tank have elipsoidal ends? Is the tank level or sloped? Does the tank have a circular cross section or oval?

 

gww212j

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• Oct 9, 2008

• #24

This site may be of interest as it shows calulations for trig method and for integration.

http://mathworld.wolfram.com/CircularSegment.html

 

Peter Nachtwey

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• Oct 9, 2008

• #25

So what would you guys do without the internet?

I thought the pie slice and subtracting the isosceles triangle was obvious.

 

tgoulding

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• Oct 9, 2008

• #26

Hi Peter,

Solving the Math Calc is an easier question to answer than what we would do without the Internet. Surfing is a lot quicker than digging out old college notes and books, brings back bad memories.

 

halosome

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• Oct 9, 2008

• #27

We are dealing with several tanks with various shapes. This is the way we do: fill the tank! Record the level and volume. Then make a table with certain number of rows depending on the precision requirement. All the rest of work are 5th grader math.

 

Tharon

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• Oct 9, 2008

• #28

Peter Nachtwey said:

I thought the pie slice and subtracting the isosceles triangle was obvious.

Click to expand...

I would have had to open my closet and dig out my college books. I never sold a single one back to the book store, so I have everything from Algebra to Advanced Calculus, and Basic Circuits to Operational Amplifiers and PLC class books.

The internet merely lets me do a ctrl-F and autofind what I'm looking for rather than dig through all the books in my closet.

I really should dig out some of them and bring them to my office at work, they would be very handy at times.


Edit:
And no, I didn't stay up all night. I went to bed and when I woke up it dawned on me. Sometimes a rested mind makes the answer come easier.

 

Tharon

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• Oct 9, 2008

• #29

Peter Nachtwey said:

I will need to check this when I wake up. There seems to be a difference. Between ctw3 and Tharon's answer. In Tharon's case C=2*arccos(radius-level/radius).

Click to expand...

The difference is that my solution assumes a cylinder shaped vessel, like a barrel on its side.

CTW3's solution has a more accurate tank shape, that similar to a propane tank. This is more likely to be used as a liquid storage vessel than a drum barrel is. His calculations take into account the rounded ends.

 

Andybr

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• Oct 10, 2008

• #30

Without wishing to spoil the maths party I would point out that most serious Level (rather than just distance) transmitters will do this calculation for you and give you a Volume output. Cylindrical tanks with and without domed ends are normally selectable without any custom parameterisation.

Andybr