Wind Speed
1 second 

Larger of 3% of reading or least significant digit

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

Measures air, water and snow temperature.  Thermally isolated, hermetically sealed, precision thermistor mounted externally (US Patent 5,939,645).  Calibration drift negligible.

Pressure  
1 second  
(mb & PSI 4000 model only)

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

0.01

0.02 PSI

At 77.0 °F, 10.9 to 16.0 PSI

Monolithic silicon piezoresistive pressure sensor with second-order temperature correction. Maximum error over temperature range 32 to 158 °F (0 to 70°C) , +/- 0.06 inHg / +/-2.0 hPa. Calibration drift typically -0.03 inHg / -1.0 hPa per year. 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

Calculated from the primary measurements of wind speed and temperature.  Utilizes 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.)

Max/Avg Wind Speed

One-button clear and restart of Max Wind Gust and Average Wind measurement.

Pressure Trend

Continuously updating three-hour barometric pressure trend indicator: rising rapidly, rising, steady, falling, falling rapidly.

Display

Reflective 4 digit LCD.  Digit height 0.36 in / 9 mm.

Display Update

1 second.

Display Backlight

Aviation green electroluminescent backlight.

Clock / Calendar

Real-time hours:minutes clock.

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.