Testo 420 - Differential Pressure Measuring Instrument

Brand: Testo

Use the CEC compliant Testo 420 differential pressure measuring instrument to carry out simple, efficient tests on filters.

You can also use this instrument in conjunction with a pitot tube to easily measure flow velocity and volume flow in ventilation ducts.

The CEC compliant Testo 420 differential pressure measuring instrument is suitable for accurate differential pressure measurement up to 120 Pa, suitable for checking filters in HVAC systems.

The Testo 420 calculates flow velocity and volume flow. This instrument can also be used for absolute pressure measurement.

Differential Pressure Measuring Instrument with Practical Functions

You can use a pitot tube and compatible connection hoses (both optional) to measure the flow velocity and volume flow in ventilation ducts.

Timed and multi-point mean calculation, as well as the combination of the two, together with simple input of the duct geometry, provide you with accurate flow measurements in ducts.

Automatic zeroing ensures higher accuracy for low pressures. All measuring values are easy to read on the large backlit display.

Documenting the Measurement Data

Measurement data can be stored in the Testo 420 for analysis and documentation.

It's easy to manage the measurement data on a PC without any additional software, via the Testo 420's plug and play capability.
  • Differential pressure measurement, useful for checking filters in air conditioning and ventilation systems
  • Calculate flow velocity and volume flow using an optional pitot tube
  • Live data feed integration now available with the MeasureQuick App
  • Match with a Testo CEC compliant air flow capture hood to measure volume flows at supplies and returns (0563 4200)



Delivery Scope

  • Testo 420 Differential Pressure Measuring Instrument, Batteries, and Certificate of Calibration

Differential Pressure

  • Measuring Range: -0.480 to 0.480 inH₂O / -120 to +120 Pa | +19.7 to +2756 fpm / +0.1 to +14 m/s
  • Accuracy: ±2 % of mv + 0.002 inH₂O at +72°F, 405 inH₂O / ±2 % of mv + 0.5 Pa at +22°C, 1013 hPa
  • Resolution: 0.001 inH₂O / 0.001 Pa | 0.01 fpm / 0.01 m/s
  • Reaction Time: 1 sec (t90)

Absolute Pressure

  • Measuring Range: 280 to 440 inH₂O / 700 to 1100 hPa
  • Accuracy: ±1 inH₂O / ±3 hPa
  • Resolution: 0.1 inH₂O / 0.1 hPa
  • Reaction Time: 1 sec


  • 6 x 3 x 1 in. / 150 x 85 x 35 mm

Operating Temperature

  • 23°F to 122°F / -5°C to +50°C


  • EU-guideline 2014/30/EU

Battery Type

  • Alkaline, type AA

Battery Life

  • 40 h

Display Size

  • 3.5"

Display Function

  • Dot Matrix

Display Lighting

  • with illumination


  • Micro-USB


  • 2 GB (Internal)

Storage Temperature

  • -4°F to 140°F / -20°C to +60°C
Show More