Testo 420 - Flow Hood


Testo 420 - Flow Hood

The uniquely light testo 420 volume flow hood

Light, precise and convenient: the testo 420 flow capture hood makes volume flow measurement at larger air inlets and outlets considerably easier. At only 2.9 kg, it is the lightest volume flow hood on the market. And with its integrated flow straightener, the measuring device for volume flow measurement sets new measuring precision standards at swirl outlets. This allows users to fulfil hygiene guidelines and requirements for indoor air quality and volume flow in ventilation and air conditioning systems quickly and precisely, e.g. in industry, office areas or cleanrooms.



The testo 420 volume flow measuring hood offers you the following

  • Ergonomic: uniquely light at less than 2.9 kg in weight (standard flow hood 610 x 610 mm).
  • High-precision: flow straightener significantly reduces the usual measurement errors at swirl outlets.
  • Efficient: fast set-up, easy handling and convenient operation via testo 420 App.

Volume flow hood testo 420 for determining volume flow

Advantages of the testo 420 volume flow hood

  • Light: unique weight of less than 2.9 kg. You will feel the difference, particularly for frequent measurements.
  • Precise: air turbulence at swirl outlets is pacified. This allows reliable measurement of the air flow.
  • Flexible: optional exchangeable hoods for a variety of measuring tasks • Efficient: monitor measuring values and send them by e-mail directly on site via App
  • Convenient: the tilting display makes it easier to read out the measuring values. By removing the instrument, and with the corresponding accessories, you can comfortably carry out pressure and Pitot tube measurements too.
  • Smart: the App allows you to use mobile devices as a second display or remote control.


The testo 420 volume flow hood for larger air inlets and outlets enables fast and precise compliance with hygiene guidelines and requirements concerning room air quality. It provides reliable support with the calculation of the overall volume flow on HVAC systems, for instance in hospitals, office buildings or commercial buildings.


High measuring accuracy at swirl outlets thanks to volume flow straightener

Volume flow is frequently measured at swirl outlets. Air flows are often incorrectly measured due to the turbulent air at these outlets.

The testo 420 volume flow hood means you can significantly reduce these measurement errors. The integrated volume flow straightener calms the turbulence and converts it into a virtually uniform air flow. This enables accurate calculation of volume flow in the 80 to 3,500 m3/h range.


Exceptionally light volume flow hood with fast set-up

The volume flow hood with ergonomic handles and tiltable display has an exceptional weight of less than 2.9 kg. This means that frequent volume flow calculations in large rooms and measurements above head height can also be carried out reliably and comfortably. In the process, a large measuring button on the volume flow hood ensures easy recording of the readings.

The dimensions of the hood are 610 x 610 mm. We offer additional hoods as accessories for further ceiling outlets. The use of our optional tripod arm is a great help for air inlets and outlets which are located very high up. It can be extended up to 4 metres.

The volume flow hood is quick and easy to set up thanks to tension rods. The trolley which is included in the scope of delivery ensures safe transport.


Create protocols directly on site and mail them using the App connection

Take advantage of further practical functions and download our free App. Because the App connection enables mobile devices such as smartphones and tablets to be used as a secondary display and remote control via Bluetooth. This is particularly practical for using a tripod arm for high ceilings.

The App enables live measurement on HVAC systems using a start and stop function and the saving of measurement data in txt format. You can 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. This means you save a considerable amount of time and increase efficiency.


Volume flow hood with removable measuring instrument - performance overview

The volume flow hood for HVAC systems is equipped with a measuring instrument for displaying measurement data. The device can be tilted and removed for user-friendly reading of measuring values.

The testo 420 measuring instrument enables you to measure flow velocity, volume flow, absolute pressure, temperature and relative humidity. The automatic zeroing ensures higher accuracy for low pressures.

All measuring values are easy to read on the large display which has an illumination function. For analyses and documentation, measurement data can be saved and measurement protocols created directly on site using the App connection. Administration of the measurement data is very easy on the PC without any additional software via the plug & play function.

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.

You merely have to 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.


Delivery Scope

testo 420 volume flow hood including measuring instrument, 610 x 610 mm hood, 5 x tension rods, USB cable, batteries and trolley.

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Product Images (click to enlarge)
  • Testo 420 - Flow Hood
  • Testo 420 - Flow Hood
  • Testo 420 - Flow Hood
  • Testo 420 - Flow Hood
  • Testo 420 - Flow Hood
  • Testo 420 - Flow Hood
  • Testo 420 - Flow Hood