Non-Invasive Ultrasonic Level Switch

Point level measurement in liquids with non-invasive ultrasonic level switch

Non-invasive ultrasonic level switches are ideal for point level measurement in liquid applications that benefit from non-invasive operation such as high pressure vessels (i.e. compressors), tanks with high viscous materials or corrosive liquids, tanks with high purity or sanitary liquids, and detection of liquid-solid interface. ABM’s non-invasive ultrasonic level switches are easy to install on plastic or metal tank exteriors – no drilling into walls and no downtime, offer simple calibration and are maintenance-free.

Level Measurement: Sensor Selection

We offers various level sensors to meet the demands of your application. Use our product configurator or submit the level application form – our trained engineers with over 40 years of experience are here to support you.

level switch

Ultrasonic Level Switch Working Principle

The non-invasive ultrasonic level switch emits a short burst of ultrasonic energy. The energy is coupled through a rubber membrane to the tank causing the tank to vibrate. The tank vibrations are detected and analysed by the switch. Based on the vibration patterns the switch is able to detect the presence or absence of liquid inside the tank, and directly opposite the switch. When the liquid inside the tank is below the switch point of the switch, the switch’s relay will be in the energized state referred to as the normally open (N.O) state (connecting the relay common to the relay normally open connector). When the liquid inside the tank is above the detection zone of the switch, the relay will be in the non-energized state referred to as the normally closed (N.C) state (connecting the relay common to the relay normally close connector).

The switch has two modes of operation “thin tank” and “thick tank”. Thin tank mode is ideal for plastic tanks of any thickness and metal tanks with a wall thickness of 0.5 mm or 0.016”. For thicker metal tanks the thick wall mode is recommended. Please note – the liquid detection method and calibration are different for thin tank mode and thick tank mode.


  • Low cost, point level measurement
  • Maintenance-free – no moving parts and no contact with liquid
  • Easy to install on plastic or metal tank exterior, no drilling into walls or down-time during installation
  • PVC electronics enclosures with standard PVC transducer or high temperature Teflon transducer
  • Single or multiple alarm points (single pole double throw relay output 8A/230 VAC)
  • 3-wire operation with RS485 communication for diagnostics and data logging
  • Remote monitoring option with ABM Remote Dry Contact Monitor
  • Very simple 2 step training using push-button

Specification Sheet

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