The LG01 flow switch and bubble detector can detect low liquid flow, and air or bubbles present in the flow channel. This detector allows users to detect liquid flow and bubbles with great ease. This article discusses the modes and operations of the LG01 flow switch and bubble detector.
Detection of Liquid Flow
The sensor’s flow channel needs to be completely filled with liquid for the reliable detection of liquid flow. Bubbles with a diameter larger than 0.1mm are not able to be reliably detected in this way.
The output is 0V if the sensor displays a flow rate lesser than the specified Flow Switch Level (Figure 1).
The output is 5V if the sensor displays a flow rate higher than the specified Flow Switch Level, but below the Maximum Flow Rate stated in the datasheet (Figure 1).
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Figure 1. Detection of liquid flow.
In this example, the Flow Switch Levels specified are for water. The absolute Flow Switch Level may change when other liquids are used.
Detection of Bubbles or Air
The instantaneous flow rate must be above the specified Flow Switch Level in order for the presence of air or bubbles to be detected. However, the flow rate must be lesser than the Maximum Flow Rate specified in the datasheet. In addition, the diameter of the bubbles must be more than 2mm in order to achieve reliable detection (Figure 2).
The output is 5V when the sensor signals a flow channel completely filled with the liquid. The output is 0V when the sensor detects the presence of bubbles or the incomplete filling of the flow channel with the liquid (Figure 2).
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Figure 2. Detection of bubbles or air.

This information has been sourced, reviewed and adapted from materials provided by Sensirion Inc.
For more information on this source, please visit Sensirion Inc.