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Extech RH490 Precision Thermo Hygrometer with Relative Humidity and GPP

List price: $525.00
You save: $95.10 (18%)

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.


  • Less Than 30 Second RH Response Time
  • Water Vapor in GPP (g/kg)
  • Dual Backlit Display
  • Simultaneous Display of:
    • Humidity or GPP (g/kg) plus Temperature
    • Humidity or GPP (g/kg) plus Dew Point
    • Humidity or GPP (g/kg) plus Wet Bulb
  • Slim Design with rubberized sides for better grip and for one hand operation
  • Data Hold and Min/Max Functions
  • Auto Power off with disable and low battery indicator


  • Humidity: 0 to 100%RH
  • Temperature (Internal): -22 to 199°F (-30 to 100°C)
  • Basic Accuracy: ±2%RH, ±1.8°F/1°CMax.
  • Resolution: 0.1%RH, 0.1°F/°C
  • Dewpoint: -22 to 199°F (-30 to 100°C)
  • Wet Bulb: 32 to 176 °F (0 to 80°C)
  • Absolute Humidity: 0 to 1120GPP (0 to 160g/kg)
  • Dimensions: 7.8x1.7x1.3" (200x45x33mm)
  • Weight: 7oz (200g)

Extech RH490 Datasheet (RH490.pdf, 136 Kb) [Download]

Extech RH490 Manual (RH490_UM.pdf, 106 Kb) [Download]

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