SMART CONTROLS


airflow and IAQ parameters in ventilation and AC systems.


Thermal anemometers


Air velocity is a value which may be of importance in many areas including testing HVAC systems for their suitability during Covid-19. The use of an anemometer of some type will be required to measure this air velocity and display the value. A thermal anemometer is particularly useful for measuring in smaller ductwork as its small size ensures minimum disruption to the airflow, and typically the thermal type anemometer will cover flow ranges from 0.03 to 50 m/s.


Vane anemometers The vane anemometer is a classic way of measuring airflow velocity – however, they do have the technical issue due to the initial air movement needed to get the vane moving. This ‘start-up’ lag means that compared to thermal anemometers the vane type is not particularly suited to low velocity measurement, but typically will work across a flow range of 0.3 to 40 m/s.


Pitot anemometers If the airflow to be measured is of a velocity greater than 50 m/s, or the air itself could contain particles that could damage a thermal or vane type device, then the next measurement technique would be to use a pitot tube and differential pressure meter. This type of anemometer will measure up to 100 m/s easily and can also work with high temperature airflows where both the thermal and vane type products usually have a maximum temperature range of +70°C.


Airflow volume


Usually as well as airflow velocity there will be a requirement to measure the actual volume flow through a duct or at an outlet vent/grill. For duct measurement the internal dimensions can be used to calculate the volume flow and most modern anemometers will allow the user to enter the ductwork configuration to allow calculation of airflow volume. It is currently recommended that in unoccupied buildings to “continue to operate ventilation systems continuously at reduced speed” to


ensure ongoing airflow but to help to “ensure minimal energy usage but will help to remove virus particles out of the building and from surfaces.”


Volume flow hoods make measuring at


ceiling mounted outlets even easier. Volume flow hoods are light, precise and convenient and are designed for precision measurement of volume when balancing a system. It is important that we also “understand


and properly monitor indoor air quality (IAQ) in particular the potential effects on the workforce in enclosed environments” during the Covid-19 pandemic. Indoor air quality can refer to the ambient temperature, relative humidity, airflow, CO and CO2


levels within a building, and appropriate levels will ensure both a safe and comfortable environment for the individuals within it. Studies have repeatedly shown poor air quality can lead to fatigue, poor concentration and even health issues. During the current focus on ensuring


buildings and offices are safe for use it is essential that airflow systems are correctly balanced to ensure safety in air quality.


Take a tour of the Testo 440 T


he testo 440 offers engineers involved in ventilation and climate system commissioning a range of measurement options and here we will highlight just a few! Convenience and maximum flexibility for airflow in duct and outlet measurements When combined with our large range of air velocity probes (sold separately), you can carry out simple and convenient measurements, even at locations that are difficult to access within ventilation ducts or at air outlets. Even greater freedom is provided with our option of Bluetooth probe handles, so no messy cables between probe and instrument are necessary.


Poor indoor air quality due to excessive CO2 can cause tiredness, lack of concentration and even illness. The testo 440 is perfect for measuring and monitoring indoor air quality to ensure appropriate CO2 levels and a more comfortable environment. Determine the degree of turbulence and


the draught risk in the workplace: draught restricts the comfort level and is the most common cause of complaints about the indoor climate. The turbulence probe (sold separately) measures air velocity and air


temperature, and automatically calculates the draught risk and the degree of turbulence in accordance with EN ISO 7730/ASHRAE 55. When in conjunction with a variety of probes


the testo 440 is also ideal for applications in cleanrooms and labs. Our specific fume cupboard probe makes testing for LEV compliance simple.


www.acr-news.com


July 2020 25


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