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November 7th, 2018, 03:21 PM  #1 
Member
Join Date: Oct 2012
Location: Georgia
Posts: 131

cpt function and doing the math for silo capacity
I am working with plc5.
I am using the CPT function but getting errors. The level of the silo is inputed at F51:031. The silo cuft is 3393 with 30' overall height. I need this computed and then I will multiply the Bulk Density to get total tons in the tank. This is what I have: (F51:0310)*(33930)/(300)+0 ( this is in error) (Input 17’ in tank InputMin 0) * (ScaleMax 3393 cuft capacity – ScaleMin 0)/(InputMax 30’ tall tankInputMin 0) + ScaleMin 0 (17’0)*(33930)/(300)+0 = 1922.7 cuft of material in silo at 17’ in a 30’ tank where the cuft of the tank volume is 3393. Any help would be appreciated. Thanks rm 
November 7th, 2018, 03:54 PM  #2 
Member
Join Date: Jul 2010
Location: TX
Posts: 37

Try using  (Right above the enter key on your keyboard) instead of / for divide.

November 7th, 2018, 03:55 PM  #3 
Member

First question is the bottom of the silo flat or is there a cone ?
The formula for volume of a cylinder is V=Pi R2 x Height use that to calculate the volume from the flat bottom up then if you have a cone calculate the volume in the cone by the level V=Pi R2 x (Height / 3) add the 2 together 
November 8th, 2018, 03:05 PM  #4 
Member
Join Date: Oct 2012
Location: Georgia
Posts: 131

The  for divide solved my error for the equation. I am able to scale the silo's that are linear (flat bottom). I have figured the silo capacity for a non linear with a cone but of course with the current method above that I am using, when I get to the lower range of the silo I am off some tons.
I have lot's of tanks with varying sizes. Is there a way to scale nonlinear possibly just for the cone volume. I can do the logic to control how I read once it gets down to the cone hopefully. I am trying to avoid programming multiple level points in the PLC5. 
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