Post by thread:[OT] Volume of cylindrical tank, more info 2

My first thought was a look-up table, but the tank is not always the same size ! (both diameter and length can vary) It is not possible to fill it up and do the table sequentially. The level can be measured with a stick put in tank. The system must be calibrated according to the reading of the stick. spam_OUTjuha.tuomiTakeThisOuTliperi.inet.fi

Alas, you must normalize the readings. Assume up front that zero to full scale raw is empty to full (or you may need more linear math). Convert through the pi ecewize linearization that I mentioned before, but shoot for a 0-4095 or 0-65535 full scale. The last step is to apply a programmable scale factor to convert to true volume. The linearizing relationship will hold true f or any cylinder. Chris Eddy Juha Tuomi wrote: > My first thought was a look-up table, but the tank is not always the same size ! (both diameter and length can vary) It is not possible to fill it up and do the table sequentially. The level can be measured with a stick put in tank. The system must be calibrated according to the reading of the stick. > > .....juha.tuomiKILLspam@spam@liperi.inet.fi

On Thu, 25 Mar 1999 20:59:24 +0200 Juha Tuomi <juha.tuomiKILLspamliperi.inet.fi> writes: >My first thought was a look-up table, but the tank is not always the = >same size ! (both diameter and length can vary) The equation is complicated enough that it is simplest to just use a table. You should be able to find published tables and equations in a chemical engineering reference book. It is a common problem. The same table can be used for any size tank by scaling the values. For example, if you have a table for a tank of height 1m and length 1m, this formula will find the volume in any tank: Volume = Table[h/H] * L where h is the measured liquid height in the tank, H is the actual height of the tank, and L is the actual length of the tank, all in meters. If you don't have much space for the table, it's possible to reduce the table size by half by realizing the tank is symmetric around the half-full point. Finally, the ends of real tanks generally aren't flat, they are somewhat hemispherical. Either fudge for that in the table or just add a little to the length of the tank used for calculations. ___________________________________________________________________ You don't need to buy Internet access to use free Internet e-mail. Get completely free e-mail from Juno at http://www.juno.com/getjuno.html or call Juno at (800) 654-JUNO [654-5866]