Which type of direct electronic sensor for level measurement is placed above the water level?

The ultrasonic level-sensing system is placed above the water level and operates by emitting ultrasonic sound waves from a transducer. When these sound waves hit the surface of the water, they are reflected back to the sensor. The device measures the time it takes for the sound waves to return, allowing it to calculate the distance to the water's surface and thereby determine the level of water in the tank or container.

This method is effective because it does not require the sensor to come into contact with the liquid, making it suitable for various applications, including those involving liquids that might be corrosive or hazardous. Ultrasonic sensors can provide continuous level measurement and are versatile since they can work in different environments without intricate installation requirements.

In contrast, other types of sensors have varying operational principles and mounting positions. Capacitive level sensors can be positioned at different levels depending on their design and often require contact with the liquid to provide accurate readings. Pressure sensors measure the hydrostatic pressure exerted by the liquid column, which typically requires them to be positioned at the bottom of the container. Float switches rely on a buoyant object that moves with the liquid level, necessitating that they be submerged to function appropriately.