Manufacturer: Vaisala
Model: PWD22
Vaisala PWD series of present weather detectors and visibility sensors provide you off-the-shelf accuracy and reliability. They are a sensor family that grows with your needs.
Tens of thousands of Vaisala present weather and visibility sensors are installed around the world, working reliably and accurately in diverse applications and climates. In Vaisala PWD series, you find the mix you require of visibility measurement range (MOR), characterization of reduced visibility, precipitation type identification, precipitation accumulation/intensity measurement, and report formats (WMO, NWS code tables).
Proven measurement principles for present weather
PWD22 identify the precipitation type by accurately estimating the water content of precipitation with a capacitive device (Vaisala RAINCAP® sensor element) and combining this information with optical forward scatter and temperature measurements. These 3 independent measurements are processed through sophisticated algorithms to produce an accurate evaluation of the weather type according to the WMO and NWS code tables.
Accurate visibility measurement
Calibrated with reference to a highly accurate transmissometer, Vaisala PWD series sensors use the proven forwardscatter measurement principle to report meteorological optical range (MOR). The visibility sensor is well-protected against contamination: the optical components point downward and hoods protect the lenses against precipitation, spray, and dust. This weatherproof design of PWD sensors provides accurate measurement results and reduces the need for maintenance. The optional hood heaters are recommended for wintry conditions to prevent ice and snow accumulation.
Easy installation
PWD sensors are less than 1 meter long. All are compact, light-weight, come with a cable and connector for easy installation, and can be mounted in many ways on any existing mast.
For meteorological and aviation applications
With a visibility measurement range of 10–20 000 meters, PWD22 is a two-inone forward scatter visibility and present weather sensor. PWD22 is recommended for automatic weather stations, especially low-power ones that are used for general meteorological and aviation applications.
PWD22’s ability to detect freezing precipitation makes it possible to issue warnings when the weather presents safety hazards for road and air traffic.
PWD22 is equipped with 2 Vaisala RAINCAP® sensor elements to improve detection sensitivity during light precipitation events – even light drizzle is detected. PWD22 also reports present weather in WMO METAR code format so it is easily integrated with AWOS systems.
| Item | Specification |
|---|---|
| Operating principle | Forward scatter measurement with 45° scattering angle |
| Measurement interval | 15 s |
| Reporting range of MOR (visibility) | 10–2000 m (32–6500 ft) |
| Reporting resolution | 1 m (3 ft) |
| Reporting uncertainty in operational conditions | ±10 % at 10–10 000 m (32–32 800 ft) ±15 % at 10–20 km (2.6–12 mi) |
| Measurement error (instrument consistency) | ±2.5 % |
| Weather type identification |
7 different types of precipitation (rain, drizzle, mixed rain/snow, snow) Precipitation (unknown type) Fog (mist), haze (smoke, sand) or clear |
| Weather type reporting | WMO 4680 (SYNOP), 4678 (METAR) and NWS code tables: 49 different codes supported from WMO 4680 code table |
| Precipitation detection sensitivity (threshold) | 0.05 mm/h (0.0020 in/h) or less, within 10 minutes |
| Precipitation reporting resolution | Intensity 0.01 mm/h Accumulation 0.01 mm |
| Precipitation intensity measurement | 0.00–999.99 mm/h (0.00–39.37 in/h) |
| Precipitation amount measurement | 0.00–99.99 mm (0.00–3.94 in) |
| Amount of new snow |
0.00–999 mm (0.00–39.33 in) |
| Item | Specification |
|---|---|
| Power supply | 12–50 V DC (electronics) |
| 24 V AC or 24 V DC for heater option | |
| Average power consumption | 3 W (peak 10 W) |
| With optional luminance sensor: 5 W | |
| With optional hood heaters: 65 W | |
| Outputs | Serial line RS-232 or RS-485 (2-wire) |
| 3 relay controls (open collector) | |
| Analog output current: 0–1 mA or 4–20 mA | |
| 8-m power/data cable (standard) with connector at PWD end |
| Item | Specification |
|---|---|
| Operating temperature | −40 … +60 °C (−40 … +140 °F) |
| Storage temperature | −40 … +60 °C (−40 … +140 °F) |
| Operating humidity | 0–100 %RH |
| Maximum operating wind speed | 60 m/s (134 mph) |
| Sensor orientation | Align receiver to look away from bright lights (sun or flashing beacons) |
| IP rating | IP66 |
| Item | Specification |
|---|---|
| Weight | 3 kg (6.61 lb) |
| Material | Aluminum |
| Dimensions (H × W × L) | 152 × 404 × 695 mm (5.98 × 15.91 × 27.36 in) |
