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HDI-Hail Sensor

Make:  Sommer    Model:  HDI
✅ Maintenance-free and lightweight, corrosion free, UV/Ozone stable, non-obstructable.
✅ Resistant to shock, vibration, lightning, corrosion, humidity, animals, insects and splashes.
✅ Very low power consumption.
✅ Plug-and-Play and configurable to fit any application.
✅ Adaptable to any structure.
✅ Compatible with almost any external analog or digital central unit.


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 percentage of all detected impacts according to classification table.


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.


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





General Specification



• 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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