RF4 RainFlow for Rain and Hail Monitoring
Overview
Features
Details
Specifications
Case Studies and Downloads
Overview
The RF4 RainFlow for Rain and Hail Monitoring is a non-mechanical rain and hail sensor. An acoustic instrument, the RF4 measures:
- rain and hail precipitation
- High-resolution disdrometry (number and size of raindrops)
Features
Details
With the hemispherical surface, the measurements cannot be obstructed by dust, dirt, or leaf matter removing the need for ongoing maintenance.
Data output options include:
- SDI-12
- RS485 (accessory required)
- Analogue (0-2.5V or 0-5V)
The RF4 RainFall Sensors is:
- Non obstructable
- Instrument with no mobile parts – totally sealed acoustic instrument
- Universal mounting kit available
- Omni-directional – even under the highest winds
- Corrosion free and resistant to the highest winds and the most extreme conditions
- Plug-and-Play or totally configurable – microcontroller inside
- Can be connected to almost any external unit
- SDI-12 and IoT compatible – internal memory
Specifications
| Measurement characteristics | |
| Measuring surface | 160 mm outer diameter hemisphere (402 cm2) |
| Precipitation detected by the sensor | Liquid (undifferentiated): rain, drizzle/rain, mixed rain/snow, sleet. Solid: hail. |
| Rain Intensity accuracy | 15% at 100% duty-cycle (most global precision and accuracy criteria) |
| Rain DSD | 27 classes from ≤ 0.75 mm to 7.0mm with a detection threshold (minimum detectable diameter) of about 0.5 mm |
| Measurement accuracy (liquid only) | A spatially distributed flux of controlled drops of a nominal diameter equal to the centre diameter of the class ± 20% produces an output centred in the corresponding class with typically  50% of the flux concentrated into the two lateral size-classes. |
| Hail detection* | Counting of the number of hailstone impacts up to 5 impacts per second and for hailstone diameter detection threshold of 0.5 cm. |
| Particle velocity | Not measured. |
*Note: For more specific hail detection, use the HailFlow HF4 sensor, variant of the RF4 specialised in hail detection.
| Voltage ranges and measuring scales | |
| Voltage outputs | Continuous analogue voltage or pulse analogue voltage, user selectable +0 to +2.5V or +0 to +5V are available. Pulse threshold, integrator timeout and duration are also user selectable. The continuous analogue voltage persists on the outputs so that output voltages can be read at any time. |
| Rain intensity scaling | Sensitivity @voltage range +2.5V: [10 mV/(mm/h)] i.e. +2.5V corresponds to 250 mm/h |
| Sensitivity @voltage range +5V: [20 mV/(mm/h)] i.e. +5V corresponds to 250 mm/h | |
| Hail Sensitivity @voltage range +2.5V or +5V: 5 hit/s |
| Construction and Dimensions | |
| Material | Stainless steel, plastic and anodized aluminium (breakdown voltage > 40 V/μm) |
| Installation | Universal mounting kit provided (ordering reference: RFBRA) |
| Weight | 1.4 kg without mounting kit |
| Dimensions (HxWxD) | 260 mm x 430 mm x 160 mm with mounting kit |
| Supply | Ratings |
| 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%). |
| Outputs | |
| Analogue | Pulse and continuous (and persistent) voltages, 0-2.5V or 0-5V |
| SDI-12 | Yes, 1.3 certified (fully complies with the NR Systems SDI-12 Verifier) |
| Serial 3V3 TTL | Yes |
| Modbus RTU (RS485) | Yes, with the Modbus adapter accessory |
| Environmental conditions | |
| Temperature range | -40°C to +80°C. (an even operate over this range.) |
| Relative humidity | 0 to 100% |
| Protection | IP67, survive to 1 m temporary immersion in salt water |
| Standards | EN 61326-1: 2013, CE compliant. 2014/30/EU, CE compliant |
Case Studies and Downloads
