Float Less Water Level Sensor

Float less water level sensors are an efficient method to measure tank level for several reasons.

• Float less design is typically a non contact technology which eliminates the requirement of material compatibility between the liquid and the float since there is no float.
• Float less design also ensures there are no issues with viscous medias coating floats and causing them to fail.
• Float less level sensors are by default a no moving parts technology, therefore there is no risk for mechanical failures that occur in float based sensors.
• Float less and non contact level sensors are smaller by design which reduces shipping cost and transit time compared to large stem and float-based sensors.
• Float less level sensors small design also reduces installation time and the amount of personnel needed to install.

Float Less Level Sensors for Liquids can be broken down into a few main sensing technologies, Radar, Capacitance, and Ultrasonic to name a few.

Radar non contact level sensors work by sending out short microwave signals toward the liquid via the sensor.  The microwave signal then hits the liquid surface and bounces back toward the sensor.  The sensor utilizes the time-of-flight principle which uses the known speed of the microwave, and the time it took for the signal to return, divided by two (since it had to travel down to the liquid and then back up to the sensor) to determine the distance between the liquid level and the sensor.  Since most level is based on the height of the liquid, not the height of the non-liquid (air), the air height is subtracted from the total tank depth to determine the liquid level!

Capacitance level sensors work by using two electrodes within the sensor that form a capacitor.  The capacitor will then process capacitance based on the dielectric constant of the liquid as it encounters the sensor.  The liquid media will have a higher dielectric constant than the air in the tank and will thus increase the capacitance.  This increase in capacitance triggers the sensor to change outputs and thus detect liquid level. 

Ultrasonic level sensors work by emitting sound waves at a high frequency towards the liquid.  The sound waves then reflect off the liquid and the sensor uses the known speed of sound to calculate the distance.  Similarly, to Radar, since most level is based on the height of the liquid, not the height of the non-liquid (air), the air height is subtracted from the total tank depth to determine the liquid level.  Sound waves are slower than microwaves so ultrasonic signals can be affected by high moisture, vapors, and debris in the air.