Using a pressure transduce to measure volume....

Hello all,
I have seen in several post where pressure transducers are being used fo volume of liquid in a tank. How excatly is this done? What information is need to set up the scaling? We use a Ultrasonic level sensor on one of the machines we manufacture, the cost is higher than our pressure transducers and the tank is not the same diameter in the middle that it is at the top and the bottom. Therefore the volume read by the Ultrasonic sensor is not accurate.

Thanks,
Micheal

The volume read by the pressure sensor will not be inherently more or less accurate than the ultrasonic. Both are effectively giving you height of the liquid in the tank.

You need to come up with a model that relates volume in your tank to the height of the liquid. This is relatively easy for some shapes, a bit harder for others. Search for an equation for the volume of your tank relative to the measured height and then use the height returned from the sensor to calculate volume.

Keith

The pressure sensor is just giving the height of hte liquid, not the volume. That is also true of the ultrasonic sensor.

You need to have an equation or a look-up table that relates height to volume. For a simple straight sided tank, you just multiply the height by the tank area. For a hopper bottom tank, for example, you need two equations. One equation is for the bottom portion and is a function of volume and height (like a cone, for example). Then, above a specific level, you switch to the first equation.

Thanks for the info

Michael.
The answers above pretty well cover your question but if you are using an ultrasonic level sensor at the moment this might be able to give you the required output. Most of the "fully featured" ultrasonic level transmitters I have used provide a faciltiy for calculating the volume in a non regular tank. It would certainly be worth digging out the manual and having a look.
Andybr