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). |
Air Flow
1 second |
| cfm |
0 to 99,999 cfm |
1 |
3% of reading |
0 to 99,999 cfm |
| m3/h |
0 to 99,999 m3/h |
1 |
0 to 99,999 m3/h |
| m3/m |
0 to 99,999 m3/m |
1 |
0 to 99,999 m3/m |
| m3/s |
0.0 to 9,999.9 m3/s |
0.1 |
0.0 to 9,999.9 m3/s |
| L/s |
0 to 99,999 L/s |
1 |
0 to 99,999 L/s |
| Automatically calculated from Air Velocity measurement and user-specified duct shape (circle or rectangle) and dimensions (units: in, ft, cm or m). Maximum duct dimension input: 258.0 in / 21.5 ft / 655.3 cm / 6.55 m. |
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. |
Humidity Ratio
1 second |
| gpp |
0.000 to 5000.0 gpp |
0.1 |
typical accuracy 10% |
-20 to 130°F, 5 to 95% RH, 8.86 to 32.48 inHg |
| g/kg |
0.00 to 720.0 g/kg |
0.01 |
typical accuracy 10% |
-29 to 54°C, 5 to 95% RH, 300.0 to 1100.0 hPa |
Density Altitude
1 second |
| ft |
-49.0 to 257.0 °F, 0.0 to 100.0 % RH, 8.86 to 32.48 inHg |
1 |
246 |
32.0 to 100.0 °F, 5.0 to 95.0 %RH, 8.86 to 32.48 inHg, <19700 ft |
| m |
-45.0 to 125.0 °C, 0.0 to 100.0 %RH, 300.0 to 1100.0 hPa |
1 |
75 |
0.0 - 37.8 °C, 5.0 to 95.0 %RH, -2000 to 9000 hPa, <6000 m |
| Air density converted to equivalent sea level elevation at the International Standard Atmosphere. Calculated from pressure, temperature and relative humidity. |
| Max/Avg Wind Speed (Air Velocity), Crosswind, Headwind/Tailwind |
One-button clear and restart of Max Wind Gust and Average Wind measurement. |
| Data Storage / Display |
Minimum, maximum, average and logged history stored and displayed for every measured value. 2000-point data logger with graphical display. Auto data storage; interval settable from 2 seconds to 12 hours. Manual data capture. |
| Data Upload |
Requires optional PC interface (NK PN-0830) and provided software. RS-232 connection with USB adapter available. |
| Display |
Multifunction, multi-digit programmable dot-matrix display. |
| Display Update |
1 second. |
| Display Backlight |
Choice of aviation green or visible red electroluminescent backlight. Automatic or manual activation. |
| Clock / Calendar |
Real-time hours:minutes:seconds clock, calendar, automatic leap-year adjustment. |
| 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 |
User-selectable: 15 or 60 minutes with no key presses or disabled. |
| Languages |
English, French, German, Italian, Spanish. |
| Certifications |
CE certified. Individually tested to NIST-traceable standards (written certificate of tests available at additional charge). |
| Batteries |
AAA Alkaline, two, included. Average life, 400 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 5.0 x 1.8 x 1.1 in / 12.7 x 4.5 x 2.8 cm. |
| Weight |
Unit 3.6 oz / 102 g. |