AQ Elteknik AB Ultrasound Controller Manual 9
4. Air Sensor Mode
In Air Sensor mode the Air Sensor is used to measure the presence of bubbles in flowing liquid.
One or two Air Sensors model SAC, PAC, FCS or FCP can be connected to one Ultrasound
Controller.
Quick start guide
Install Air Sensors according to instructions in the Air Sensor Manual.
Connect cables, see page 6 or 7 and 10.
Switch on external power supply.
Read about navigating the menu system, page 8.
Display show: SET sensor MODE. Press MENU button to scroll to Press SELECT for Air Sensor
mode. Confirm by pressing SELECT button.
Go to SETTINGS to set parameters, page 11.
Fill Air Sensor 1 (AS1) with liquid. Select Calibrate LIQUID AS1 and Press SELECT button one
second.
Empty Air Sensor 1 (AS1) of liquid. Select Calibrate AIR AS1 and press SELECT button one
second.
Do the calibration in the same way for Air sensor 2 (AS2). The calibration order can be
mixed for sensor and liquid/air.
Do a simple validation: AIR should be indicated when the Air Sensor is empty and LIQUID
when it is filled with liquid.
Go to SHOW DATA for a more thorough validation of the calibrated values, page 13.
Ready.
Functional Description
Bubbles in the liquid flowing through the Air Sensor are monitored by the use of ultrasound. Inside
the Air Sensor two low intensity beams of ultrasound are transmitted across the liquid-path in
directions perpendicular to the liquid flow.
If a bubble moves into one of the ultrasound-beams the ultrasound will be partially deflected and
the intensity of the ultrasound decreases. The controller constantly measures the intensity of the
ultrasound and if the intensity becomes lower than the threshold it detects a bubble. Dense
particles in the liquid can also deflect the ultrasound in a similar way and can therefore be
detected.
The measurements of very low sensitivity and very very low sensitivity uses a different
measurement technique. It measures how ultrasound vibrations in the Air Sensor walls are
dampened by the presence of liquid inside.
The measurement accuracy depend on how well the Air Sensor is calibrated, the flow-rate, the
type of liquid, how the Air Sensor is mounted and weather there is a single bubble or many
bubbles and the Air Sensor size.
Orientation of the Air Sensor
If the Air Sensor is mounted horizontally orientation is important. Liquid flowing through the Air
Sensor tends to pull bubbles towards the center of the tube but when flow rate decrease bubbles
rises to the top. The Air Sensor is more sensitive to bubbles at the top if it is rotated so that the
cable connector (and label) is facing up. If instead low bubble sensitivity is desirable rotate the Air
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