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Ultrasonic water level sensor is a non-contact liquid level gauge. It can be used to measure liquid level and flow in various containers or pipelines. It can also be used in the measurement of water level in drains, reservoirs, rivers and lakes. It is especially suitable for sewage and corrosive applications such as urban drainage pumps. Measurement of the water level before and after the trash rack.
link:http://www.gallopsensor.com/level-meter/ultrasonic-level-meter/split-type-high-quality-and-reliability.html
Split Type High Quality And Reliability Ultrasonic Water Level Sensor