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| SENSORS | ||||
|---|---|---|---|---|
| SENSORS | ACCURACY | RESOLUTION | SPECIFICATION RANGE | NOTES |
| Wind Speed | Air Speed | Larger of 3% of reading, least significant digit or 20 ft/min Speed | 0.1 m/s 1 ft/min 0.1 km/h 0.1 mph 0.1 knots 1 B* 0.1 F/S* | 0.6 to 40.0 m/s 118 to 7,874 ft/min 2.2 to 144.0 km/h 1.3 to 89.5 mph 1.2 to 77.8 knots 0 to 12 B* 2-131.2* | 1 inch|25 mm diameter impeller with precision axle and low-friction Zytel® bearings. Startup speed stated as lower limit, readings may be taken down to 0.4 m/s |79 ft min|1.5 km/h |.9 mph |.8 kt after impeller startup. Off-axis accuracy -1% @ 5º off axis; -2% @ 10º; -3% @ 15º. Calibration drift < 1% after 100 hours use at 16 MPH|7 m/s. Replacement impeller (NK PN-0801) field installs without tools (US Patent 5,783,753). Wind speed calibration and testing should be done with triangle on impeller located at the top front face of the Kestrel. Measuring wind speeds above 60 m/s / 134.2 mph can damage the impeller |
| Ambient Temperature | 0.9 °F 0.5 °C | 0.1 °F 0.1 °C | -20.0 to 158.0 °F -29.0 to 70.0 °C | Airflow of 2.2 mph|1 m/s or greater provides fastest response and reduction of insolation effect. For greatest accuracy, avoid direct sunlight on the temperature sensor and prolonged sunlight exposure to the unit in low airflow conditions. Calibration drift is negligible for the life of the product. For further details, see Display & Battery Operational Temperature Limits. |
| Relative Humidity | 2%RH | 0.1 %RH | 10 to 90% 25°C noncondensing | To achieve stated accuracy, unit must be permitted to equilibrate to external temperature when exposed to large, rapid temperature changes and be kept out of direct sunlight. Calibration drift is typically less than ±0.25% per year. |
| Pressure | 1.5 hPa|mbar 0.044 inHg 0.022 PSI | 0.1 hPa|mbar 0.01 inHg 0.01 PSI | 25°C/77°F 700-1100 hPa|mbar 20.67-32.48 inHg 10.15-15.95 PSI | Monolithic silicon piezo-resistive pressure sensor with second-order temperature correction. Between 1100–1600 mbar, unit will operate with reduced accuracy. Sensor may not operate above 1600 mbar and can be damaged above 6,000 mbar or below 10 mbar. Calibration drift is negligible for the life of the product. |
| Compass | 5° | 1° 1/16th Cardinal Scale | 0 to 360° | 2-axis solid-state magneto-resistive sensor mounted perpendicular to unit plane. Accuracy of sensor dependent upon unit’s vertical position. Self-calibration routine eliminates magnetic error from batteries or unit and must be run after every full power- down (battery removal or change). Readout indicates direction to which the back of the unit is pointed when held in a vertical orientation. Declination/variation adjustable for True North readout. |
| CALCULATED MEASUREMENTS | |||
|---|---|---|---|
| MEASUREMENT | ACCURACY (+/-) | RESOLUTION | SENSORS EMPLOYED |
| Air Density | 0.0002 lb/ft3 0.0033 kg/m | 0.001 lbs/ft3 0.001 kg/m3 | Temperature, Relative Humidity Pressure |
| Air Flow | 6.71% | 1 cfm 1 m3/hr 1 m3/m 0.1m3/s 1 L/s | Air Speed, User Input (Duct Shape & Size) |
| Altitude | typical: 23.6 ft/7.2 m from 750 to 1100 mBar max: 48.2 ft/14.7 m from 300 to 750 mBar | 1 ft 1 m | Pressure, User Input (Reference Pressure) |
| Barometric Pressure | 0.07 inHg 2.4 hPa|mbar 0.03 PSI | 0.01 inHg 0.1 hPa|mbar 0.01 PSI | Pressure, User Input (Reference Altitude) |
| Crosswind & Headwind/Tailwind | 7.1% | 1 mph 1 ft/min 0.1 km/h 0.1 m/s 0.1 knots | Wind Speed, Compass |
| Delta T | 3.2 °F 1.8 °C | 0.1 °F 0.1 °C | Temperature, Relative Humidity Pressure |
| Density Altitude | 226 ft 69 m | 1 ft 1 m | Temperature, Relative Humidity Pressure |
| Dew Point | 3.4 °F 1.9 °C 15- 95% RH. Refer to Range for Temperature Sensor | 0.1 °F 0.1 °C | Temperature, Relative Humidity |
| Evaporation Rate | 0.01 lb/ft2/hr 0.06 kg/m2/hr | 0.01 b/ft2/hr 0.01 kg/m2/hr | Wind Speed, Temperature Relative Humidity Pressure, User Input (Concrete Temperature) |
| Heat Index | 7.1°F 4.0°C | 0.1 °F 0.1 °C | Temperature, Relative Humidity |
| Moisture Content | Humidity Ratio (“Grains”) | 4.9gpp .7g/kg | 0.1 gpp 0.01 g/kg | Temperature, Relative Humidity Pressure |
| Probability of Ignition (PIG) | PIG Accuracy dependent on proximity of inputs to reference table steps. | 10% | Temperature, Relative Humidity |
| THI (NRC) | 1.5 °F 0.8 °C | 0.1 °F 0.1 °C | Temperature, Relative Humidity |
| THI (Yousef) | 2.3 °F 1.3 °C | 0.1 °F 0.1 °C | Temperature, Relative Humidity |
| Relative Air Density | .0.3% | 0.1% | Temperature, Relative Humidity Pressure |
| Wet Bulb Temperature - Psychrometric | 3.2 °F 1.8 °C | 0.1 °F 0.1 °C | Temperature, Relative Humidity Pressure |
| Wet Bulb Temperature - Naturally Aspirated (NWB TEMP) | 1.4 °F 0.8 °C | 0.1 °F 0.1 °C | Wind Speed, Temperature Globe Temperature, Relative Humidity, Pressure |
| Wind Chill | 1.6 °F 0.9 °C | 0.1 °F 0.1 °C | Wind Speed, Temperature |
