Testo Testo 425 NTC, Thermal 20m/s Max Air Velocity Air Velocity, Temperature, Volume Air Flow Anemometer

  • RS Stock No. 512-0317
  • Mfr. Part No. 0560 4251
  • Brand Testo
Technical Reference
Legislation and Compliance
RoHS Status: Not Applicable
COO (Country of Origin): DE
Product Details

testo 425

From Testo, the 425 hot-wire anemometer designed for measuring air velocity, air temperature and volume flow. The pocket-sized meter provides instant, accurate spot readings at ventilation ducts, air grills and air outlets. Constructed from tough, impact resistant materials the robust hand-held meter is an ideal instrument for HVAC engineers, technicians and installers.

Compact in design, the handheld anemometer uses a combination of hot-wire and NTC thermistor technology to deliver rapid, accurate readings. The 425 anemometer records the flow speed, calculates the volumetric flow and measures the temperature. With a measuring range of 0 to + 20 m/s, the meter can even be used for low flow speeds. A fixed telescopic probe with small 7.5mm dia sensor head can be extended to a maximum length of 820mm for applications where measuring space is hard to reach or limited.

An easy to navigate keypad and soft control buttons make the Testo 425 handheld anemometer incredibly easy to use. With minimal effort the user can select the function to be measured, the mode you wish to record and the unit the data will be shown. With a large backlit LCD display, all collected data is clearly shown on the front screen, even in low light conditions. A handy auto-off feature also helps to conserve battery life.

Features and Benefits

• Compact, robust ABS housing
• Accurate, rapid results
• Easy to control keys
• Precision air velocity and NTC thermistor sensors
• Measurement of flow velocity, volume flow and Temperature
• Compact 7.5mm diameter sensor sits on top of telescopic probe
• Multi-point and timed mean calculation of volume flow, flow speed and temperature reading
• Shows air flow results in 3/s
• Shows volume flow results in m³/h
• Shows temperature results in °C
• Hold button to freeze readings
• Auto-off function for battery conservation
• Easy to read Illuminated display


Hot-wire anemometers are the perfect instrument for engineers and technicians looking to carry out tests and surveys on ventilation, air conditioning equipment. They are used to measure airflow and temperature quickly and accurately. The information and data they provide are vital in a wide range of applications and environments. They are essential for reporting, forecasting, planning and most importantly health and safety. Some of the more common applications are

• Environmental testing
• Air conveyors
• Clean rooms
• Air balancing
• Fans /motors/ blowers
• Furnace velocity
• Paint spray booths
• HVAC system performance


Q - Is there a recommended replacement battery?
A - Yes, the Testo 425 digital anemometer uses a 9V battery for its power supply. See RS part number 826-4435

Supplied with

alkaline battery and instructions

Attribute Value
Measurement Parameters Air Velocity, Temperature, Volume Air Flow
Maximum Air Velocity 20m/s
Best Air Velocity Accuracy ±5% + 0.03 m/s
Air Velocity Resolution 0.01m/s
Probe Type NTC, Thermal
Temperature Measurement Resolution 0.1°C
Best Temperature Measurement Accuracy ±0.7 °C
Power Source Battery
Battery Type 9V
Battery Life 20 h
Dimensions 182 x 64 x 40mm
Weight 285g
Height 40mm
Length 182mm
Width 64mm
Minimum Operating Temperature -20°C
Maximum Operating Temperature +50°C
Model Number p Testo 425
4 in stock for FREE next working day delivery
24 available from Europe for delivery within 1 working day(s)
Price Each
£ 349.00
(exc. VAT)
£ 418.80
(inc. VAT)
Per unit
1 +
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