Ultrasonic Level Sensing

What is it?

Ultrasonic level sensors are used for non-contact level sensing of water by us. The sensors emit high frequency sound waves from the top of the tank that are reflected back to and detected by the sensor.

What this means is that our core sensors never come in contact with water as they sit on the inner top wall of a tank as depicted in the image above. This brings a host of benefits for the system:

  • Sensor face no corrosion as they are IP5 water/humidity resistant.
  • Accuracy of the reading is very high (<1mm)(<100ml)
  • No salt deposits on sensors
  • Maintenance free design
  • Can indicate the exact amount of water in a tank
  • Programmability

Why do we use ultrasound?

Metal/Resistive/Capacitive Sensor

Float Based Sensor

Metal/Resistive sensors :

  • require periodic cleaning to remove salt deposits
  • can malfunction with leakage currents and damage the main unit
  • are prone to wire joints breaking/shorting
  • dissolve due to corrosion over time (6 months to 15 months)
  • require periodic replacement

Capacitive sensors:

  • are affected by faint salt deposits
  • are prone to wire joints breaking/shorting
  • highly sensitive to noise
  • can malfunction with leakage currents

Float :

This type of sensor works either on a reed switch or a mechanical switch which gets activated upon a float-able cavity rise/fall due to the level of water in a tank. This being a mechanical solution doesn't suffer with corrosion but has its own set of problems:

  • Being a mechanical device it gets affected by salt deposits
  • Any small debris in the tank can render the sensor ineffective
  • Wires prone to breakage/shorting
  • Low accuracy

All of these solutions generally require extensive cabling and maintenance. The general nature of these sensor coming in contact with water causes most of the associated problems.