Sell Test Equipment

425 Testo Thermometer

The 425 is a thermometer from Testo. Thermometers are a type of electronic test equipment used to collect information in a variety of applications. Professionals use thermometers to measure and document information during electrical troubleshooting, vehicle repair/maintenance, HVAC applications and energy audits, science experiments, semiconductor technology manufacturing, and circuit terminal testing. Used and refurbished test equipment thermometers log data in Fahrenheit and Celsius and use an easy-to-read digital display screen. ValueTronics has thermocouple, infrared, dual K-type, non-contact, heavy duty, and other thermometers.

Additional Features:

  • Measurement of flow velocity, volume flow and temperature
  • Point and timed mean value calculation
  • Max./min. values
  • Hold button for freezing measurement value
  • Display illumination
  • Auto-off function
  • TopSafe, protection of the instrument from dirt and impact (optional)

General Technical Data

  • Operating temperature: -20 to +50 °C
  • Storage temperature: -40 to +70 °C
  • Battery type: 9V block battery, 6F22
  • Battery life: 20 h
  • Dimensions: 182 x 64 x 40 mm
  • Weight: 285 g
  • Housing material: ABS

Sensor types


  • Measuring range: 0 to +20 m/s
  • Accuracy ±1 digit: ± (0.03 m/s +5% of m.v.)
  • Resolution: 0.01 m/s


  • Measuring range: 20 to +70 °C
  • Accuracy ±1 digit: ±0.5 °C (0 to +60 °C); ±0.7 °C (remaining range)
  • Resolution: 0.1 °C

The Testo 425 is a compact anamometer with a fixed thermal flow velocity probe. The probe head has a diameter of 7.5 mm. With the extendable telescope (length max. 820 mm), the measuring instrument is suitable for flow velocity measurement in ducts. The Testo 425 also measures extremely accurately in the low flow velocity range. The volume flow is directly shown in the display. For the purposes of volume flow calculation, the duct area can be easily entered into the Testo 425. 

In addition to this, the instrument can be switched over to display the current temperature. Timed and point mean value calculation provide information on the average volume flow, flow velocity and temperature measurement value. The Hold function allows the current measurement value to be frozen in the display, min./max. values are also displayed at the press of a button.

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