Monitoring Combustible Fluids with the SonAire ® M3is 95 kHz

The MassaSonic® SonAire® Series M3 and M3is Sensors include battery-operated wireless level sensors that can intercommunicate using ZigBee RF Modules. The M3is versions are intrinsically safe rated for zone Ø, CIDI, and CID2 environments These sensors have detection ranges from 4“ (100 mm) to 35“ (10.7 m).

The sensors are integrated with advanced ultrasonic technology to provide precision non-contact distance measurement for industrial or liquid level process control and tank monitoring. Compared to other long range intrinsically safe sensors, the M3is Sensor is unique due to its affordability, ease of operation, and ability to be installed and calibrated without using a target.

The sensor conveys narrow beam sound pulses, processes return echoes, and reports out the distance to the target. The sensor housing material is made of Kynar (PVDF) to provide excellent chemical resistance in the most challenging industrial environments.

The SonAire® Sensors are capable of measuring and storing data such as range, temperature, battery voltage, and other sensor parameters at user-prescribed time intervals. An LED detects the operating mode and an internal pushbutton switch is used to commission the sensor onto the ZigBee network.

The SonAire® Sensors are RoHS compliant, and the package is rated for immersion and high-pressure washing in compliance with IP67. Lithium AA type batteries are used that are universally available and can be easily replaced. The typical battery life is 4 years.

All SonAire® Series Sensors are available in two versions - Standard SonAire M3 Sensors are designed for use in all standard applications, and The SonAire M3is Sensors can be used in hazardous environments and are certified by Factory Mutual as complying to the requirements of Class 1 Div 1 (C1D1), All Groups, which is the maximum rating.

SonAire® M3is

The SonAire® M3is Sensor is suitable to monitor portable/fixed chemical tanks and combustible solid or fluid materials in remote locations or factories, where environmental hazards are an operational consideration. The sensor has been designed keeping in mind site privacy, like cloud-based inventory breaches.

The IS model is especially suitable for chemical operations, oil patch, waste storage, mining, or wastewater operation with methane gas. This intrinsically safe version can be readily used in lower rated areas, as it holds the highest FM certification for all groups (C1D1).

Key Features

The main features of the SonAire® M3is 95 kHz Sensor are as follows:

  • Chemically resistant PVDF construction
  • Intrinsically safe operation in hazardous zones
  • Built in temperature/sound speed compensation
  • Narrow beam
  • Enable set-up where powerlines are not available
  • Wireless, 10 sensors/gateway


The SonAire® M3is 95 kHz Sensor is used in the following applications:

  • Chemical tank monitoring of flammable materials
  • Wet well/lift station applications with Methane gas present
  • Silos with explosive dust condition risk
  • Solid and level measurements in hazardous zones
  • Mine, oil path and chemical operations
  • Quick, remote set-up sites


The following table lists the key specifications of the SonAire® M3is 95 kHz Sensor:

Model M3is
95 kHz
Minimum Detection Distance 12 inches
(300 mm)
Maximum Detection Distance 13 feet
(4 m)
Class Intrinsically Safe
Wireless Yes
Output Zigbee
Housing Material PVDF
Mount 2 inch NPT
Radio 100 mW
Operating Temperature -30°C to 70°C

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