The new ISO standard increases the repeatability between units as a whole for all manufacturers.

As electronic equipment used within the cleanroom environment has advanced in leaps and bounds, so too has the airborne particle counter. The first particle counters manufactured in the late 1980s and early 1990s were large, bulky, less sophisticated units unable to detect smaller particles, such as 0.3 micron and lower — largely due to the parts and software available. With the developments made in electronics and software, today’s particle counters do not resemble their counterparts of 20 years ago and the advantages of this new breed offer unparalleled cost and time savings.

Airborne particle counters have been used for many years in the life sciences industry and various other manufacturing processes where contamination is likely and may cause a loss of product. But surprisingly, most users are unaware as to how these units actually work. The inner workings of a particle counter can be compared to a flashlight that is used when the power goes out at night. This would be what the particle counter’s lens tube detection chamber resembles and the flashlight would equate to the laser beam. It is pitch black inside until the laser is turned on and a particle passes thru the beam. The light is then scattered off the particle and by the amount of light that is scattered the particle counter’s detection system can tell how large the particle is and place it in the correct bin which is displayed on the screen.

With new, smaller, higher-powered and more reliable lasers, it is easier to design a lens tube to detect microscopic particles within the air. Along the same lines, detection systems, which are more user-friendly and faster than previous designs, are more easily able to detect particles in faster flow rates. These two major advances have made particle counters more reliable and the results obtained more consistent. This is important for manufacturers because of the latest ISO calibration document:

ISO/FDIS 21501, Determination of particle size distribution – single particle light interaction methods. Part 4: Light scattering airborne particle counter for clean spaces.