The air flow rate is measured using pressure sensors at discharge orifices at the top of the columns. The two air columns are fed by variable pressure regulators, which can be used to adjust the air flow rate through the column. The integral micro controller calculates the flow rates from the pressure readings and displays these on the front panel.
The apparatus comprises three clear acrylic columns mounted above a moulded ABS base. This column features an overflow pipe, which returns the water back into the sump. The base contains a water reservoir with a variable speed submersible pump, which pumps water through an electronic flow meter into the base of the left hand column.
Pressure drops on all three columns are measured by differential pressure sensors connected to tapping points at the top and bottom of the columns. The software also provides powerful graph plotting facilities. All process measurements are displayed simultaneously on the front panel display and are available on the USB output for data logging.
