Measuring volume flow in public and commercial buildings

In order to feel comfortable in a room, the air quality, amongst other factors, must be ensured. Assuming the room is closed, this quality results from the volume flows of the installed VAC system. In order to respect the regulations for Indoor Air Quality, you must regularly check the total volume flow of the VAC system. It is not uncommon for an air conditioning technician to conduct up to fifty measurements at different air outlets in several rooms.


The challenge

High CO2 concentration in a room causes fatigue, and in some cases makes people ill. For this reason, sufficient oxygen must be introduced by an exchange of fresh air, especially in commercial buildings, offices and schools. The workplace directive DIN EN 13779 even requires certain outside air flows, depending on the activity of the persons in the room: – 20-40 m3/h per person with a predominantly sitting activity – 40-60 m3/h per person with a predominantly non-sitting activity – over 65 m3/h per person with a heavy physical activity.

In order to meet these standards, the air conditioning technician regularly tests the total volume flows of the VAC system. To do this can take multiple measurements, sometimes at up to fifty different outlets, which means a high physical burden. In addition to this, these rooms have large swirl outlets installed as standard, which do not blow the air into the room straight, but instead continually swirl it. The consequence of this swirl is that air flows are often incorrectly measured at these locations. This also complicates the determination of the volume flow substantially.


The solution

The testo 420 sets new standards regarding weight and precision. It is incredibly lightweight, making transportation of the instrument very easy. Thanks to its ergonomic handles, frequent or difficult measurements are no longer a problem. Measurements can be carried out safely and comfortably, without inducing fatigue. It also has an integrated flow straightener, which allows a more precise measurement result to be achieved at larger swirl outlets.



This diagram outlines the principle function of the flow straightener


The innovative flow straightener converts the turbulence at the swirl outlets into an almost uniform air flow, leading to a considerably more accurate measurement. In addition to this, the hood records the ambient climate using an integrated temperature and humidity sensor as well as an absolute pressure sensor.



Track your measurements using the testo 420 App



The application is simple too: Funnel-shaped tension rod sockets support easy and quick set-up, and the trolley included in delivery ensures safe transport. Via Bluetooth App integration, smartphones and tablets can be used as a second display and remote control.

After the measurement, the App allows you to finalise and send the measurement protocol directly on site. Differential pressure or Pitot tube measurements are also possible with the removable measuring instrument by simply entering the duct geometry.

With the testo 420, the user can quickly and accurately fulfil the legal regulations on Indoor Air Quality for ventilation and air conditioning systems in commercial buildings and schools.


Testo 420 – Advantages at glace

– More precise measurement of volume flow at larger swirl outlets

– Uniquely light, with only 2.9 kg

– Fast set-up, easy handling and convenient operation thanks to mobile App


For more information on the testo 420 or any of our products visit our website Alternatively if you have a potential requirement you would prefer to discuss you can call us on 01420 544433 and we’ll be happy to help.




About Testo Limited

We offer an extensive range of instruments for many parameters and applications including; Temperature, Humidity, Velocity, Gas analysis, RPM, Pressure, Light, pH, Sound. testo instruments are widely used in the following sectors: HVAC-R: heating, ventilation, air conditioning and refrigeration. Process Industry: manufacturing industries, service companies and utilities. Food Sector: including food manufacture, transport, storage, distribution and retail. Thermal Imaging: for building surveys, maintenance, electrical inspections and production monitoring.

Posted on February 4, 2016, in Commercial, Environmental, Facilities Maintenance, Facilities management, Latest News, News, Online, Product Launches and tagged , , , , , , , , , , , , . Bookmark the permalink. Leave a comment.

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