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this market created sophisticated particle counters to measure relatively small quantities of tiny particulates as one would expect to find in cleanrooms and hospital operating theatres . Over time these grew to be rather complex and expensive instruments .
The commercial and residential air quality space by contrast needed products that were much lower in cost and much simpler for the average user ( not an air quality expert ) to use . So , sensors were selected together that gave some measure of air quality , however crude , since something was better than nothing . I ’ ve heard that phrase repeated many times to explain the current state of sensors in this space . The reality is that it is true in cases where you understand the accuracy of the data and make allowances for the uncertainties when making decisions based on that data . However , when sensors are inaccurate and estimating what the air quality might be based on data from external sources then , at best , inferring anything from that data puts you at great risk of making the wrong decision .
The purpose of this article is not to criticise particular companies or products . Discussions with most of the companies offering products in this space globally suggest that they are wellintentioned and trying to do the best they can for their clients , and most are eager to learn and evaluate new technology with an eye to improving products for their clients .
We are at an exciting time in this industry and have seen huge growth as an industry and air quality is increasingly on everyone ’ s mind and being considered more carefully than ever before . The readers of this publication are largely the stewards and experts in this space and as such it is our responsibility to help shape and guide progress in measurement so that we improve the quality of testing and make them as accurate and reliable as we can . In doing so we can safeguard the health and well-being of those who rely on us and the technology we use and provide .
Finally , it is clear from multiple papers that PM measurements only tell a small part of the story and that size distribution , particularly for ultra-fine particles , is increasingly critical in safeguarding health and well-being . 2
A Particle Counter is a device that is used to measure the concentration and size distribution of airborne particles in a cleanroom or other controlled environment . Here ' s a brief overview of how a Particle Counter works : 1 . Sampling : the Particle Counter draws in a sample of air from the environment being monitored , typically at a constant flow rate of 1 cubic foot per minute ( CFM ).
2 . Particle Detection : as the air sample passes through the instrument , it enters a measurement chamber where it encounters a laser beam . The laser illuminates the particles in the sample , causing them to scatter light in different directions .
3 . Light Detection : the scattered light is detected by a set of photodiodes positioned at different angles around the measurement chamber . Each photodiode detects light scattered at a different angle , allowing the instrument to determine the size and concentration of the particles in the sample .
4 . Data Collection : the instrument collects data on the number of particles detected at each size range and calculates the concentration of particles in the air , typically reported as particles per cubic meter or particles per cubic foot .
5 . Data Analysis : the data collected by the Particle Counter can be analysed to assess the cleanliness of the environment being monitored and to identify potential sources of contamination .
Overall , the Particle Counter uses laser light scattering technology to detect and measure airborne particles in realtime , providing accurate and reliable data on the cleanliness of controlled environments .
PARTICLE COUNTING TEST METHOD Particle counts by number and size ( micron ) are determined and conducted to demonstrate compliance in cleanrooms to ISO standards 14644-1:2015 . Table 1 below depicts the maximum allowable concentrations ( particles / m ³) for particles equal to and greater than the considered sizes :
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RACA Journal I July 2023
TEST METHOD FOR AIRBORNE PATHOGEN NEUTRALISATION There are very few laboratories around the world who have the infrastructure and ability to test air cleaning devices for efficacy against airborne pathogens .
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