SF4 SandFlow sensor for Sand and Dust Monitoring
The SF4 SandFlow sensor for sand and dust monitoring is a non-mechanical sensor that measures particles and wind when contact is made with the measuring surface of the sensor.
An acoustic instrument, the SF4 enables the:
- measurement of solid particle flux (such as sand) in grammes per square metre per second (g/m2/s)
- estimate of the wind speed
The analogue voltage sensor is selectable to either 2.5 volt or 5 volt, with the maximum voltage output reflecting either 250 g/m2/s for particle flux or 250 km/h for wind speed.
The SF4 is compatible with any SDI-12 logger or IoT Node (such as the MFR-Node or S-Node).
Low-power, maintenance-free, and with no moving parts, the SF4 is ideal for long-term remote monitoring of solid particle flux. With no moving parts, 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 SF4 SandFlow Sensors is:
- Maintenance-free
- Constructed to resist
- high winds,
- extreme temperatures (−40 °C to 80 °C),
- high humidity (up to 100% Rh)
- Instrument with no mobile parts – totally sealed acoustic instrument
- Mounting kits available for simple mounting
- Plug-and-Play or totally configurable – microcontroller inside
- Can be connected to almost any external unit
- SDI-12 and IoT compatible – internal memory
Measuring characteristics
| Measuring surface | 32 mm diameter, 920 mm long cylindrical tube |
| Physical phenomena detected by the sensor | Flux of solid particles transported by the wind (sand flow, aeolian sand transport, and more generally all kind of solid particle fluxes of the same range of kinetic energy generating impacts on the measuring surface).
Wind speed (more generally, an estimation of the average speed of the laminar aeolian flux generating friction on measuring surface). |
| Measurement accuracy | Flux: For a given controlled flux homogeneously distributed along the measuring surface of the sensor (such as particles of a given shape profile, density, Young modulus, falling speed and incidence angle), the response of the sensor varies of ± 5% and the variability between two sensors is below ± 10%.
Wind: In laminar established conditions and without external parasitic turbulences or low-frequency noise, the wind speed accuracy is ±15%. |
| Particle velocity | Not measured. Can only be an interpretation of the wind speed measurement. |
Interfaces
| 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 |
| Maximum ratings: 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. |
| Wind speed scaling | Sensitivity @voltage range +2.5V: [10 mV/(km/h)] i.e. +2.5V corresponds to 250 km/h
Sensitivity @voltage range +5V: [20 mV/(km/h)] i.e. +5V corresponds to 250 km/h |
| Particles flux scaling | Sensitivity @voltage range +2.5V: [10 mV/(g/m2/s)] i.e. +2.5V corresponds to 250 g/m2/s
Sensitivity @voltage range +5V: [20 mV/(g/m2/s)] i.e. +5V corresponds to 250 g/m2/s |
Mechanical data
| Material | Plastic and aluminium |
| Installation | Universal mounting kit provided (ordering reference: SFBRA) |
| Weight | 1 kg without mounting kit 5 kg with mounting kit |
| Dimensions (HWD) | Sensor alone: 1040 mm  32 mm With mounting kit: 1040 mm  874 mm  40 mm |
| 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%). |
Environmental conditions
| Temperature range | -40°C to +80°C. Can even operate over this range. |
| Relative humidity | 0 to 100% |
| Protection | IP67 |
| Standards | EN 61326-1: 2013, CE compliant 2014/30/EU, CE compliant |
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