After choosing the monitoring method, determine how many monitoring locations or particle counters you need. If the area of your cleanroom is 1,000 m2 or less, use Table A.1 provided in ISO 14644-1:2015. If your area is greater than 1,000 m2, first divide the cleanroom area (in m2) by 1,000. Then multiply this number by 27. Remember that this is the minimum number of locations. You can always have more to cover additional critical locations.
For example, a typical cleanroom area of 9290 m2 (100,000 ft2) would have 251 monitoring locations required by ISO. We recommend even distribution and mounting at a work height of 76 cm (30 in).
9290 / 1000 = 9.29 x 27 = 251
Keep in mind the ISO 14644-1:2015 standard only applies to cleanroom certification. Cleanroom operators should evaluate their processes and the sensitivity of their product to contamination to determine the number of sampling locations required. Our advice is to monitor where it counts. Measure where your product is exposed and where contamination will cause damage. The focus should be on where the risk is the highest.
A solution for monitoring a few locations frequently while keeping the option of portability is the Lasair® III Aerosol Particle Counter. For dedicated, continuous sampling of one location where space is a concern, consider the Airnet® II Air Particle Sensor.
Stay tuned for the final blog in this series on monitoring process gases. For more considerations such as filter monitoring and minienvironments, download the full paper.