The Top 5 Mistakes Made In Particle Testing Cleanrooms

Cleanroom particle testing standards are set by ISO-14644-1 and 2. Make sure you follow these standards when particle testing your cleanroom. The IEST (the Institute of Environmental Sciences and Technology) works with ISO to write the testing standards. Regular correctly executed particle tests are necessary to ensure the proper operation of your cleanroom. This blog covers commonly made mistakes in cleanroom particle test.

Mistake #1:  Not taking enough sample locations in your cleanroom

ISO-14644-1 2015 significantly increased the number of sample locations required to test a cleanroom.   Be sure you are taking the correct number of sample locations.

For rooms large than 1000 m² use the following formula:

N_L = 27 x (Area m² / 1000)

Mistake #2: Using the wrong type of particle counter to test your cleanroom

Handheld particle counters should only be used to look for particle sources. They do not test a large enough volume of air to accurately measure particle density in a cleanroom.

Bench top particle counters should be used to measure particle density in cleanrooms. Benchtop particle counters typically measure. Lower flow rate (0.1 cfm) cleanroom particle counters can be used for lower class ISO-7 cleanrooms and ISO-8 cleanrooms. Higher flow rate  (1.0 cfm) cleanroom particle counters are required for higher class ISO-5 cleanrooms and ISO-6 cleanrooms.

Mistake #3:  Not getting your particle counter calibrated annually

Particle counters should be calibrated annually by manufacturer or licensed 3^rd party service with  NIST traceable standard. Properly calibrated equipment is a requirement to obtain an accurate particle count measurement.

Mistake #4: Taking the correct particle test measurement

As-built cleanroom particle test is testing when cleanroom has just been completed. It typically does not have equipment or personnel in the room. At-rest cleanroom particle test is testing when the cleanroom has been in use and has equipment but no personnel are present and no operations are on-going. Operational cleanroom particle test is testing when personnel are in the cleanroom working and operating equipment. Your company QA / ISO / CGMP procedure will dictate which cleanroom particle test is required.

Mistake #5: Assuming continuous measurement particle measurement systems eliminate need for annual particle test

Some cleanrooms have continuous measurement particle measurement systems. These systems only take samples at a few fixed locations in each room. To meet  ISO-14644 and do an effective cleanroom particle testing requires more test locations than the fixed locations. So manual cleanroom particle tests should still be done on a regular basis to ensure your cleanroom is meeting its designed cleanroom classification.

Summary:

Regular and effective cleanroom particle testing is critical to keep your cleanroom operating properly. ISO14644-1 and 2 are the ISO standards for cleanroom classification and cleanroom particle testing. The 5 most common mistakes made in cleanroom particle testing are: 1) not enough sample locations 2) not using the correct particle counter 3) not having your particle counter calibrated regularly 4) not selecting the requirement cleanroom particle test and 5) relying on continuous measurement systems instead of regular cleanroom particle tests.