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testo 420 – volume flow hood

testo 420 – volume flow hood

9,407.02SR Ex. VAT

SKU: T0563-4200
  • Volume flow hood for larger swirl outlets for measuring volume flow, temperature and relative humidity
  • Impressively light with a weight of 2.9 kg
  • Precise measurement even at swirl outlets thanks to integrated volume flow straightener
  • Fast set-up, convenient usability and practical functions such as measurement data management and on-site report creation via testo Smart App

Available in-store. 1 week via Aramex Delivery


Product Description

The testo 420 volume flow hood for larger air inlets and outlets enables fast and precise compliance with hygiene guidelines and requirements concerning indoor 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.

With the volume flow hood testo 420, these measurement errors can be significantly reduced. 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 3.3 metres.

Tension rods enable quick, easy set-up of the volume flow hood. 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 additional practical functions and download our free testo Smart App. The App connection enables mobile devices such as smartphones and tablets to be used via Bluetooth as a secondary display, for customer and measurement data management and as a remote control. This is particularly practical for using a tripod arm for high ceilings.

The App enables live measurement on HVAC systems using the start and stop function and the saving of measurement data on a smartphone or tablet. You can use the App on site to create the measurement report, and add customer and measuring site data as well as images. You can then send your readings and reports as PDF, Excel or JSON files 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. It’s easy to manage the measurement data 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.

Particularly practical: You can connect the testo 420 volume flow hood to the testo 400 VAC multifunction instrument via Bluetooth. This gives you access to other smart functions such as the entire customer and measuring site management system via the testo 400 IAQ measuring instrument.

Delivery Scope

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

Technical Data

Temperature – NTC
Measuring range-20 to +60 °C
Accuracy±0.5 °C (0 to +60 °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 range50 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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