Highest 2% RH accuracy with Grains Per Pound (GPP) Display

Extech RH490 Precision Hygro-Thermometer

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Anyone whose job relies on calculating humidity levels will appreciate the Extech Hygro-Psychrometer. In addition to measuring relative humidity in 30 seconds, this handheld instrument captures dew point, wet bulb, temperature and water vapor levels (Grams per Kilogram and Grains per Pound). This utility tool will store maximum and minimum readings until the memory is cleared and includes a data-hold button for rapidly fluctuating measurements. Complete with carrying case and 9V battery.

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  • Quick Response

    Less then 30 seconds of RH response time.

  • Easy to Use

    Simultaneous display of: Humidity/Temperature, Humidity/Dew Point or Humidity/Wet Bulb

  • Data Hold and Min/Max functions

    Includes a data-hold button for rapidly fluctuating measurements

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General Specifications
Dew Point
-22 to 199 °F (-30 to 100 °C)
Relative Humidity
0 to 100%
Relative Humidity Basic Accuracy
Relative Humidity Max Resolution
Temperature (Air)
-22 to 199 °F (-30 to 100 °C)
Temperature (Air) Basic Accuracy
±1.8 °F/1 °C
Temperature (Air) Max Resolution
0.1 °F/ °C
Water Vapor
0 to 1120GPP (0 to 160g/kg)
Wet Bulb
32 to 176 °F (0 to 80 °C)
Additional Details
7.8 × 1.7 × 1.3" (200 × 45 × 33mm)
1 × 9V battery
2 years
7oz (200g)

Extech RH490 Precision Hygro-Thermometer