Measurement
Response Time |
Units |
Operational Range |
Resolution |
Accuracy
(+/-) |
Specification Range |
Wind Speed
1 second |
| m/s |
0.4 to 60.0 m/s |
0.1 |
Larger of 3% of reading or least significant digit |
0.4 to 40.0 m/s |
| ft/min |
79 to 11,948 ft/min |
1 |
79 to 7877 ft/min |
| km/h |
1.0 to 218.0 km/h |
0.1 |
1.0 to 144.0 km/h |
| mph |
0.8 to 135.0 mph |
0.1 |
0.8 to 89.0 mph |
| knots |
0.6 to 118.3 kt |
0.1 |
0.6 to 78.0 kt |
| Beaufort |
0 to 12 B |
1 |
0 to 12 B |
| 1 inch diameter impeller with precision axle and sapphire bearings. Off-axis accuracy -1% @ 5º off-axis; -2% @ 10º; -3% @ 15º. Calibration drift < 1% after 100 hours use at 16 MPH / 7 m/s. Sustained operation above 60 MPH / 27 m/s will wear impeller rapidly and may cause destruction of impeller. Replacement impeller (NK PN-0801) may be field-installed without tools (US Patent 5,783,753). |
Temperature
1 second |
| °F |
-49.0 to 257.0 °F |
0.1 |
1.8 °F |
-20.0 to 158.0 °F |
| °C |
-45.0 to 125.0 °C |
0.1 |
1.0 °C |
-29.0 to 70.0 °C |
| Air, water or snow temperature. Hermetically-sealed, precision thermistor mounted externally and thermally isolated (US Patent 5,939,645) for rapid response (fastest with airflow of 2.2 mph/1 m/s or greater). Calibration drift negligible. |
Relative Humidity
1 minute |
| %RH |
0.0 to 100.0 % |
0.1 |
3.0 %RH |
5.0 to 95.0 % non-condensing |
| Polymer capacitive humidity sensor mounted in thin-walled chamber external to case for rapid, accurate response (US Patent 6,257,074). (To achieve stated relative humidity accuracy, unit must be permitted to equilibrate to external temperature when exposed to large, rapid temperature changes and must be kept out of direct sunlight.) Calibration drift ± 2% over 24 months. Relative humidity may be recalibrated at factory or in field using Kestrel Humidity Calibration Kit (NK PN-0802). |
Pressure
1 second |
| inHg |
0.3 to 32.5 inHg |
0.01 |
0.05 inHg |
At 77.0 °F, 22.1 to 32.5 inHg |
| hPa / mb |
10.0 to 1100.0 hPa / mb |
0.1 |
1.5 hPa / mb |
At 25.0 °C, 750 to 1100 hPa / mb |
| PSI |
0.15 to 16.0 PSI |
0.02 |
0.02 PSI |
At 77.0 °F, 10.9 to 16.0 PSI |
| Air pressure at the location. Adjustable reference altitude allows display of station pressure or barometric pressure corrected to MSL. Monolithic silicon piezoresistive pressure sensor with second-order temperature correction. Maximum error over temperature range 32 to158 °F (0 to70°C) and pressure range 600 to 1100hPa is ± 0.074 inHg ±2.5hPa. Pressure sensor may be recalibrated at factory or in field. |
Altitude
1 second |
| ft |
-6000 to 30000 ft |
1 |
50 ft |
At 77.0 °F, <19,700 ft. Max error ± 98 ft |
| m |
-2000 to 9000 m |
1 |
15 m |
At 25.0 °C, <6,000 m. Max error ± 30 m |
| Temperature compensated pressure (barometric) altimeter. |
Wind Chill
1 second |
| °F |
0.7 to 135.0 MPH, -49.0 to 257.0 °F |
0.1 |
1.8 °F |
1.8 to 89.0 mph, -50.0 to 50.0 °F |
| °C |
0.4 to 60.0 m/s, -45.0 to 125.0 °C |
0.1 |
1.0 °C |
0.4 to 40 m/s, -45.6 to 10.0 °C |
| Perceived temperature resulting from combined effect of wind speed and temperature. Caclulated based on the NWS Wind Chill Temperature (WCT) Index, revised 2001, with wind speed adjusted by a factor of 1.5 to yield equivalent results to wind speed measured at 10 m above ground. (Specification temperature limits established by WCT Tables.) |
Heat Index
1 second |
| °F |
0.0 to 100.0 %RH, -49.0 to 257.0 °F |
0.1 |
3.6 °F |
70.0 to 130.0 °F, 0 to 100% RH |
| °C |
0.0 to 100.0 %RH, -45.0 to 125.0 °C |
0.1 |
2.0 °C |
21.1 to 54.4 °C, 0 to 100 %RH |
| Perceived temperature resulting from the combined effect of temperature and relative humidity. Calculated based on NWS Heat Index (HI) tables. (Specification temperature limits established by HI tables.) |
Dewpoint
1 minute |
| °F |
0.0 to 100.0 %RH, -49.0 to 257.0 °F |
0.1 |
3.6 °F |
-20.0 to 158.0 °F, 20.0 to 95.0% RH |
| °C |
0.0 to 100.0 %RH, -45.0 to 125.0 °C |
0.1 |
2.0 °C |
-29.0 to 70.0 °C, 20.0 to 95.0 %RH |
| Temperature to which the air must be cooled at a constant pressure for water vapor to condense into water. Calculated from temperature and relative humidity. |
Wet Bulb Temperature
1 minute |
| °F |
-49.0 to 257.0 °F, 0.0 to 100.0 %RH, 8.86 to 32.48 inHg |
0.1 |
3.6 °F |
32.0 to 100.0 °F, 5.0 to 95.0% RH, 8.86 to 32.48 inHg, <19700 ft |
| °C |
-45.0 to 125.0 °C, 0.0 to 100.0 %RH, 300.0 to 1100.0 hPa |
0.1 |
2.0 °C |
0.0 to 37.8 °C, 5.0 to 95.0 %RH, -2000.0 to 9000.0 hPa, <6000 m |
| Temperature indicated by a wet bulb psychrometer. Calculated from temperature, relative humidity and pressure. |
| Max/Avg Wind Speed |
One-button clear and restart of Max Wind Gust and Average Wind measurement. |
| Display |
Reflective 5 digit LCD. Digit height 0.36 in / 9 mm. |
| Display Update |
1 second. |
| Display Backlight |
Aviation green electroluminescent backlight. |
| Operational Temperature Range (LCD and Batteries) |
The operational temperature range of the liquid crystal display and batteries is 14° F to 131° F / -10 °C to 55 °C. Beyond the limits of the operational temperature range, the unit must be maintained within range and exposed for minimum time necessary to take reading. |
| Storage Temperature |
-22 °F to 140 °F / -30 °C to 60 °C. |
| Auto Shutdown |
After 45 minutes of no key presses. |
| Certifications |
CE certified. Individually tested to NIST-traceable standards (written certificate of tests available at additional charge). |
| Batteries |
CR2032, one, included. Average life, 300 hours of use, +/-depending on backlight use. |
| Environmental |
Waterproof (IP67 standard). Drop-tested (MIL.STD.810F; unit only. Substantial impact may damage replaceable impeller.). |
| Dimensions |
Unit 4.8 x 1.7 x 0.7 in / 122 x 42 x 18 mm. Case 4.8 x 1.9 x 1.1 in / 122 x 48 x 28 mm. |
| Weight |
Unit 2.3 oz / 65 g. Case 1.3 oz / 37 g. |