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HDI-Hail Sensor

Make: Sommer                                      Model: HDI
✅ The HDI sensor measures the impact of individual hailstones on a stainless-steel disc using a special acoustic detector, signal processing and calculation
✅ Measurand : Hail stones.
✅ Sensor Type : HDI Sensor.
✅ Signal Output : Analog (0-2.5V or 0-5V), SDI-12, RS-232, Modbus RTU (RS485).
✅ Supplied With : Signal converter, RS-232-ModbusRTU adapter and Extension cable in custom length per meter, Factory test/ Calibration Certificates.

HDI-Hail Sensor:

The HDI is a very low-power, maintenance-free, totally sealed and mechanically ultra-robust acoustic instrument with no mobile parts. It is able to detect hailstones between 0.5 and 7.5 cm diameter and willsurvive the most extreme hail episodes. The sensing part of the instrument is a three layer polished stainless disc supported by an unbreakable stainless-steel arm. Impacts of hailstones (or any other lithometeors in the same range of kinetic energy) induce a measurable change in internal acoustic pressure.
It features continuous or pulse analog voltage outputs and supports SDI-12 communication, serial RS232, and Modbus RTU RS485 (using an optional adapter). The full configuration of the sensor can be customized at any time with a Plug-and-Play PC connection or remotely, using serial commands.

Extremely robust and reliable acoustic hail sensor

The HDI sensor measures the impact of individual hailstones on a stainless-steel disc using a special acoustic detector, signal processing, and calculation. The sensing surface is a 200-mm-diameter omnidirectional head containing the electronics of the system. The HDI can detect hailstones between 0.5 and 7.5 cm and up to 25 hits per second. Comparable to so-called disdrometry, it can distinguish between 15 size classes. The size distribution is reported as a percentage of all detected impacts according to the classification table.

Hail sensor HDI

The hail sensor HDI is shipped with a robust, stainless steel mounting arm. With the included USB converter, the sensor can be directly connected to a PC and configured for your needs.

Fields of application

The HDI is the sensor of choice wherever damage by hail is of concern: in farming on fields and in greenhouses, on infrastructures like facades, roofs, and solar panels, or on vehicles.

Application and features of HDI-Hail Sensor:



✅ Meteorology (hail, solid precipitation, lithometeors)
✅ High resolution hail monitoring and warning
✅ Roadside, railway, airport protection
✅ Building and infrastructure surveillance and insurance
✅ Agriculture
✅ Land management
✅ Solar power plants
✅ Applied scientific research
✅ Extremely robust and reliable
✅ Acoustic hail sensor with size classification




Weight (Mass)

• 3.2 kg without mounting kit
• 5.4 kg with mounting kit


260 mm x 450 mm x 200 mm (with mounting kit)

Precipitation Type

Solid only (hail).


• Analog Pulse and continuous (and persistent) voltages, 0-2.5V or 0-5V
• SDI-12 Yes, V1.3 (distrometer output via extended SDI-12 commands)
• RS-232 Yes
• Modbus RTU (RS485) Yes (Note: requires the Modbus adapter accessory)

Collector Area

Measuring surface: 200 mm outer diameter disc

Measurement Range

• Sensitivity @voltage range +2.5V: [100 mV/(hits/s)] i.e. +2.5V corresponds to 25 hits/s
• Sensitivity @voltage range +5V: [200 mV/(hits/s)] i.e. +5V corresponds to 25 hits/s

Power Supply

• Voltage : 6 V to 30 V DC (9.6 V and 16 V DC in case of powering through the SDI-12 terminals)
• Current : < 1 mA in stand-by mode and 20 mA max in acquisition mode.
• For a typical nominal duty-cycle of 10%: 2.1 mA (20 mA for duty-cycle of 100%).


For a given controlled elastic momentum impact (such as spheres of equal diameter, density, Young modulus, falling speed and incidence angle) , the response of the sensor varies typically by ± 10%, depending on the spatial position of the impact on the disc and on the sensor (± 10% variability between two sensors).

Operating Environment

Temperature range : -40°C to +80°C
Relative humidity : 0 to 100%

Protection Level

IP68, survive to 3 m immersion in salt water


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