Cleanroom Airborne Particle Counters: Certifying Up to ISO Class 5 with Kanomax and other Handheld Particle Counters
In controlled environments, the movement of personnel, equipment, tools, and materials is a direct challenge to aseptic outcomes. Manufacturers of semiconductors, flat panel displays, and hard disk storage units have long recognized the relationship between improved air quality and the increase of final yields. Specifically, the control of air borne particles is essential in achieving ISO Class certification of clean rooms, zones, and spaces. Because work spaces change with production demands, access to localized monitoring equipment is essential for measuring and maintaining desired levels of cleanliness. Handheld airborne particle counters have varying degrees of accuracy, use cases, and detection hardware. The core information of this post is curated from technical documents delivered by Kanomax, but outlines a general process defined by ISO 14644-1 and supports application to ISO Class 5 cleanrooms and above.
How to Certify or Test a Cleanroom with a Handheld Particle Counter
1) Calculate the number of locations that require sampling based on the cleanroom size.
Some particle counters have standard modes which calculate the sampling location map after entering the area of the room in cubic meters. The instrument then calculates the number points with manual customization options for data collection that extends beyond the ISO standard built into the particle counters software.
2)Determine the particle sizes to be measured, max concentrations allowed and the minimum sampling volume at each location.
The cleanroom certifier determines these numbers per the ISO procedure. It’s important to note the flow rate of your equipment at this stage. Handheld units provide the least amount of air flow compared to free standing units and centralized monitoring systems. For example, the Kanomax 3886 is capable of 2.83 L/min, the Kanomax 3905 reaches capacity at 28.3 L/min, and the Kanomax 3910 is capable of 50.0 L/min. Monitoring and testing multiple cleanrooms typically requires high-volume air collection, therefore a high-to-mid volume particle counter is essential. The handheld 3886 or Airy Technology P611 are tools for smaller volume air samples or spot checking. Both instruments can be programmed to sample for a specified length of time making it easy to sample precise volumes of air flow.
3) Measure the particles at each sampling location.
The Kanomax 3887 has an ISO mode that will allow you to program it with the number of sample points and sample duration needed to certify the cleanroom. The 3905 and 3910 have a similar mode called Standard mode which include a configurable setup to certify ISO (as well as other standards such as EU GMP). You can even upload a map of your cleanroom and specify the measuring locations on it in the particle counters.
4) If you are performing multiple samples at each location, take the average of each location.
Step 4 through 6: Average the measurements taken at each location, then average the end results from all locations and calculate the UCL.
Many instruments, like those above will automatically calculate the averages and the UCL for you. These steps are essentially eliminated from your workload.
5) Take an average of the measurements from all the locations.
6) If the number of points sampled was between 2 and 9 then calculate the 95% UCL.
Many instruments like the Kanomax particle counters listed above will automatically calculate the averages and the UCL (Upper Confidence Limit) for you. If you sample 10 or more positions, calculating the UCL is no longer necessary as per ISO 14644-1. If the number of points sampled is more than 1 but less than 10, the UCL must be applied. To calculate this number by hand, see here.
7) Determine if the cleanroom passed or failed by comparing the UCL to the maximum particles per cubic meter as shown on the ISO table.