Testo 420 NIST Calibrated Air Flow Capture Hood 24" x 24"

400563 4200
400563 4200
Minimum Purchase:
1 unit
  • Testo 420 Air Flow Capture Hood 24" x 24"
  • Testo 420 Air Flow Capture Hood 24" x 24"
  • Testo 420 Air Flow Capture Hood Differential Pressure Instrument
  • Testo 420 Air Flow Capture Hood Base
  • Testo 420 Air Flow Capture Hood Case
  • Testo 420 Air Flow Capture Hood 24" x 24" in use
  • Testo 420 Air Flow Capture Hood instrument detached in use
MSRP: $3,695.00
Price: $3,140.75
— You save $554.25


Testo 420 NIST Calibrated Air Flow Capture Hood 24" x 24"

Lightweight, tough and accurate

Also available without NIST Calibration

The new testo 420 flow hood system is a lightweight, accurate and convenient solution for balancing volume flow at registers and returns. At turbulent outlets, the patented flow straighteners significantly improve measurement accuracy & stability, save time and eliminate the uncertainty of measuring turbulent outlet ducts. Positioning is especially easy with its ergonomic handles, and low weight of less than 6.4 lbs. The optional tripod stand provides convenient handling when testing in large buildings, or at greater heights. The testo 420 flow hood has a wide variety of optional interchangeable flow skirts in different sizes and configurations. The lightweight testo 420 is easy to setup and disassemble and comes in a convenient rollaround case.

The detachable 420 Multi-function flow instrument provides accurate and convenient measurements using the 420 flow hood, Pitot tubes, or the testo flow matrix. Bluetooth connectivity allows for a wide variety of test functions and reporting options using your smart phone or device. The powerful testo 420 App makes testing and reporting versatile, customizable, and convenient. The detachable 420 Multi-function flow instrument is a powerful and precise differential pressure instrument with available calculating and reporting functions built-in. When installed on the testo 420 flow hood, this multi-function flow instrument can be tilted or positioned for convenient viewing and handling. View measured data from a remote location wirelessly on a smartphone or tablet (up to 65ft.).

Key Features & Benefits

  • Includes NIST certificate of calibration
  • The hood features a unique flow straightener, which significantly improves measurement accuracy, saving you valuable time on difficult tasks
  • Volume flow hood weighing less than 6.4 lbs
  • The testo 420 control unit can be tilted for a more convenient view of the display
  • The included Bluetooth / app feature allows for wireless connection to mobile devices, for remote monitoring, as well as remote operation
  • The testo 420 app can send measurement reports directly from the work site via email
  • The testo 420 is also a CEC approved air flow capture hood
  • Live data feed integration now available with the MeasureQuick App

Exceptionally Light

The testo 420 air flow capture hood with ergonomic handles and tiltable display has an exceptional light weight of less than 6.4 lbs. This means that frequent volume flow calculations in large rooms and measurements above head height can be carried out reliably and comfortably. While in use, a large measuring button on the capture hood ensures easy recording of the measurements.

Removable Control Unit

The control unit of the testo 420 enables you to measure flow velocity, volume flow, absolute pressure, temperature, and relative humidity. The automatic zeroing ensures higher accuracy for low pressures. This integrated measuring control unit was not just developed for volume flow measurement at ceiling outlets, as it can be removed from the capture hood and be used for pressure, flow, and volume flow measurements in the duct. You only need 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 accurate flow measurements in ducts. This means you can save on the purchase of an additional measuring instrument.

testo 420 App

The testo 420 app enables live measurement streaming of HVAC systems using a smartphone or tablet. The app features a start and stop function and enables you to save your measurement data in .txt format, and creates the measurement protocol directly on site. Measurement results, such as the overall volume flow and the air exchange rate, can be directly assigned to customer-specific folder templates. You can then send your readings and protocols via the in-app email function, saving you a considerable amount of time and increasing efficiency.


Measuring range -4° to 140 °F / -20 to +60 °C
Accuracy ±1 °F (32° to 140 °F) / ±0.5 °C (0 to +60 °C)
±1.4 °F (-4° to 32 °F) / ±0.8 °C (-20 to +0 °C)
Resolution 0.1 °F / 0.1 °C
Reaction time 45 sec (t90)
Measuring range 0 to 100 %rH
Accuracy ±1.0 %rF/year Drift
±0.03 %rF/K (at 32 to 60 °F ) / ±0.03 %RH/K (at 0 to 60 °C )
±1.0 %rF Hysterese
±1.8 %rH +3 % of mv (at 77 °F, 5 % to 80 %RH) / ±1.8 %RH +3 % of mv (at 25 °C, 5 % to 80 %RH)
Resolution 0.1 %rH
Differential Pressure
Measuring range -0.480 to 0.480 InH₂O / -120 to +120 Pa
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
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
Volume flow
Measuring range 29 to 2354 CFM / 50 to 4000 m³/h
Accuracy ±3 % of mv + 7 CFM at +72 °F / ±3 % of mv + 12 m³/h at +22 °C
405 InH₂O (50 to 2060 CFM) / 1013 hPa (85 to 3500 m³/h)
Resolution 1 CFM / 1 m³/h
Reaction time 1 sec (t90)
General technical data
Weight 102 oz. / 2900 g
Dimensions 24 x 24 in. (Standard hood) / 610 x 610 mm (Standard hood)
Operating temperature 23° to 122 °F / -5 to +50 °C
System requirements requires iOS 12.0 or newer; requires Android 6.0 or newer; requires mobile end device with Bluetooth 4.0
EU-/EG-guidelines EU-guideline 2014/30/EU
Battery life 40 h
Battery type Alkaline, type AA
Display function Dot matrix
Display lighting with illumination
Display size 3.5"
Data transfer Bluetooth®
Interface Micro-USB; Bluetooth® 4.0 wireless technology
Radio range 32.808 ft. / 10 m
Memory 2 GB (internal)
Storage temperature -4° to 140 °F / -20 to +60 °C


  • (1) Testo 420 NIST Callibrated Air Flow Capture Hood Base with Bluetooth
  • (1) 24" x 24" Capture Hood with Flow Straightener
  • (1) USB Cable
  • (1) Batteries
  • (1) Soft Case with Telescoping Handle and Wheels

Software / App

MeasureQuick Logo

The measureQuick App supercharges a variety of BlueTooth smart tools with rich diagnostics, data logging and reporting capabilities. Now you can see intuitive visuals informing about each job, piece of equipment, or system all in one place!

Download the measureQuick App for your Android or iOS devices

Google Play Store Apple App Store

Carry out measurements and documentation for your mobile applications easily via app: Use the testo Smart App for all your refrigeration, air conditioning, heating and ventilation applications with the Bluetooth measuring instruments from Testo. The app is available as a free download and features intuitive measurement menus and smart functions such as creating and sending digital measurement reports.

Download the Testo Smart App for your Android or iOS devices

Google Play Google Play
  • For operating all testo Smart Probes
  • Allows you to use your tablet/smartphone as a second screen when taking measurements with compatible measuring instruments, e.g. the Testo digital manifolds with Bluetooth, the testo 770-3 clamp meter, the testo 552 vacuum gauges or the testo 420 volume flow hood
  • Intuitive measurement menus, easy documentation, sending of measurement reports as PDF or Excel
  • For all refrigeration, air conditioning, heating and ventilation applications
  • Available as a free download with the full range of functions
  • Clever: Data exchange between app and PC in conjunction with the PC software testo DataControl. With both applications, you can create customers and measuring points, draw up reports and lots more, and synchronize your data easily
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