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420 Volume Flow Hood

Testo 420 Volume Flow Hood measuring instrument enables you to measure flow velocity, volume flow, absolute pressure, temperature & relative humidity (with automatic zeroing ensures higher accuracy for low pressures).

Part Number:
0563 4200

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2398.80 incl. VAT)
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  • Competitive quote
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Testo 420 Volume Flow Hood

The testo 420 calculates overall volume flow on HVAC systems for instance in hospitals, office buildings or commercial buildings.

The testo 420 volume flow hood is the light, precise and the convenient solution for regulating volume flow at larger air inlets and outlets.  At swirl outlets in particular, the flow straightener significantly reduces the usual measurement errors.  This allows users to quickly and precisely fulfil hygienic guidelines for Indoor Air Quality, e.g. in industry, office rooms or in cleanrooms.

Handling the Volume Flow Hood is especially easy with a uniquely lightweight, ergonomic design and it is equipped with a measuring device for displaying measurement data.  The detachable measuring device can be tilted and removed for more comfortable readout of the measurement values.

A cleverly designed app enables mobile devices to be used via Bluetooth as a secondary display, for customer and measurement data management, plus as a handy remote control.  This makes using a tripod for high ceilings, for example, especially safe and comfortable.  Moreover, the user can use the app to finalise and send the measurement report directly on site.


Testo 420 Key Features:

  • Designed for larger swirl outlets; measures volume flow, temperature and relative humidity
  • Fast and precise
  • Complies with room air quality hygiene guidelines / requirements
  • Exceptionally light (2.9 Kg) with fast set-up
  • Flow straightener for more precise measurement at swirl outlets
  • Accurate calculation of volume flow in the 80 to 3,500 m3/h range
  • Tripod for measurements up to a ceiling height of 4 m
  • Hood dimensions: 610 x 610 mm
  • Hood tension rods allow speedy set-up
  • Removable and tilt-able measuring instrument with a large display
    • Displays all measuring values and comes complete with illumination function for easy-read measurements
  • App integration via Bluetooth for fast and easy monitoring and reporting on-site
  • Smartphone/tablet as a second display per App
  • App enable further analyses and documentation
    • Measurement data can be saved and measurement protocols created directly on-site
  • Administration of the measurement data is very easy on the PC without any additional software via the plug & play function



▶ Testo 420 Volume Flow Hood Explained:



Smart App Technology:

  • Enables live measurement on HVAC systems using a start / stop function (save measurement data in txt format)
  • Create the measurement protocol directly on-site using the App
  • Measurement results, such as the overall volume flow and the air exchange rate, can be directly assigned to customer-specific protocol templates
  • You can then send your readings and protocols via the e-mail function - Saving time and increase efficiency!


The testo 420 volume flow hood with its integrated measuring instrument was not just developed for volume flow measurement at larger ceiling outlets.  The measuring instrument can also be taken off the hood and used for pressure, flow and volume flow measurements in the duct.  This means you can save on the purchase of an additional measuring instrument.

Simply attach a Pitot tube and connection hoses (both optional) for measurements in 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 support for measurements in ducts.


What comes with the testo 420?

  • Testo 420 Volume Flow Hood Base
  • 24 x 24" Flow Hood
  • USB Cable
  • Batteries
  • Soft Case with Telescopic Handle / Wheels



Technical Specification for: Testo 420 Volume Flow Hood

Temperature - NTC
Measuring range-20 to +70 °C
Accuracy±0.5 °C (0 to +70 °C)
±0.8 °C (-20 to +0 °C)
Resolution0.1 °C
Reaction time45 s (t₉₀)
Humidity - Capacitive
Measuring range0 to 100 %RH
Accuracy±1.8 %RH + 3 % of mv at +25 °C
(5 to 80 %RH)
Resolution0.1 %RH
Differential Pressure - Piezoresistive
Measuring range-120 to +120 Pa
Accuracy±2 % of mv + 0.5 Pa at +22 °C, 1013 hPa
Resolution0.001 Pa
Reaction time1 s (t₉₀)
Absolute Pressure
Measuring range700 to 1100 hPa
Accuracy±3 hPa
Resolution0.1 hPa
Reaction time1 s
Volume flow
Measuring range40 to 4000 m³/h
Accuracy±3 % of mv + 12 m³/h at +22 °C
1013 hPa (85 to 3500 m³/h)
Reaction time1 s (t₉₀)
Resolution1 m³/h
General technical data
Weight2900 g
Dimensions610 x 610 mm (Standard hood)
Operating temperature-5 to +50 °C
System requirementsrequires iOS 12.0 or newer; requires Android 6.0 or newer; requires mobile end device with Bluetooth 4.0
EU-/EG-guidelinesEU-guideline 2014/30/EU
Battery typeAlkali manganese, mignon, type AA
Battery life40 h
Display size3.5"
Display functionDot matrix
Display ligthingwith illumination
InterfaceMicro-USB; Bluetooth® 4.0 wireless technology
Data transferBluetooth
Radio range10 m
Memory2 GB (internal)
Storage temperature-20 to +60 °C
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