Calculating liquid content in a cylinder ...

Tank contents measurement is one of the most common measurements in industrial processes.

Yet, it can prove difficult to measure volume accurately, especially if your storage tank has irregular or curved sides.

We'd like to offer you a few simple, reliable solutions.

Low cost methods...

1. Direct Calibration
This is the simplest and most reliable method, as it automatically takes into account any curvature of your tank, offset in the pressure sensor, SG of liquid etc.

Connect your pressure sensor to the INT2-P meter and start with an empty tank.

Set the meter for direct calibration and use the linerarisng function (see manual for details)

Set the 1st cal point so that the display reads 0.

We now want to pump into the tank known volumes of liquid, and we will set the meter to read the tank volume at each point.

Ideally, aim to fill the tank to the brim, and do so by filling to 10 evenly spaced volumes.


2. Theoretical Calibration
What if you can't start from an empty tank and it will be difficult to pump in known volumes up to the capacity of the tank?

You can calibrate using the theoretical method, but you will need to know the relationship between volume, (going in 10 steps from 0% to 100% of tank volume) and your sensor signal in mA for each volume.

You will need to know the volume in the tank at different depths.

This method is only suitable if you know the mathematical relationship between your pressure sensor signal and volume in the tank.

You should write a table of signal vs. volume. The more points you include, the greater will be your overall measurement accuracy.

Let's assume you use a pressure sensor with 4-20mA output. You may get a table something like this ...

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