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The Extech HD500 is a handheld 3-in-1 combination meter that integrates a relative humidity sensor, a Type K thermocouple input, and a built-in non-contact infrared thermometer into a single instrument. Extech describes it as a Psychrometer with Infrared Thermometer, combining the functions of a humidity meter, a Type K thermometer, and an infrared surface temperature sensor in one heavy-duty handheld housing.
A psychrometer measures the moisture content of air, typically reporting relative humidity along with derived values such as dew point and wet-bulb temperature. The HD500 covers the full 0 to 100%RH range and computes dew point from -90.4 to 140°F and wet bulb from -6.88 to 140°F, alongside ambient air temperature from 14 to 140°F. The integrated infrared thermometer adds non-contact surface temperature measurement, and Extech positions this combination as well suited to home inspection applications where humidity, air temperature, and surface temperature all need to be checked together.
Extech Instruments was founded in 1971 and became part of FLIR Systems in 2007, which is how the company is identified on this datasheet ('A FLIR Company'). FLIR Systems was itself acquired by Teledyne Technologies in 2021, placing the Extech product line within the broader Teledyne FLIR portfolio today.
| Specifications | Range | Basic Accuracy |
|---|---|---|
| InfraRed Thermometer | -58 to 932°F (-50 to 500°C) | ±2% or ±4°F/2°C |
| Distance to Target Ratio | 30:1 | — |
| Type K Temperature | -148 to 2501°F (-100 to 1372°C) | ±(1% + 1°C) |
| Air Temperature | 14 to 140°F (-10 to 60°C) | ±(2% ±4°F/2°C) |
| RH Range | 0 to 100%RH | ±2%RH |
| Dew Point | -90.4 to 140°F (-68 to 60°C) | — |
| Wet Bulb | -6.88 to 140°F (-21.6 to 60°C) | — |
| Dimensions | 10 x 2.9 x 2" (255 x 75 x 50mm) | — |
| Weight | 12.3oz (350g) | — |
Please review the Manufacturer's Data Sheet to verify published specifications. Feedback on this webpage is always welcome — please reach out to your Test Architect at any time for questions or concerns. Thank you, we truly appreciate you being our customer.
Model No
Extech
Condition
New
Manufacturer
Extech
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