CLEANROOM TESTING

A cleanroom is a chamber where the concentration of airborne particles is controlled, constructed and operated in such a way as to minimize the introduction, generation, and retention of particles within it, and in which other relevant parameters, e.g., temperature, humidity, and pressure, are controlled as required. A fundamental role in the control of particulate matter in the cleanroom is played by the ventilation of the rooms through the introduction, distribution in the room, and extraction of adequate flow rates of suitably filtered air with the function of both diluting the ambient concentration of contaminants and removing them. Also of particular importance is the pressurization of the environment, achieved by controlling the flow rates of injected and extracted air, to prevent or limit the entry of uncontrolled outside air both through openings for the access of people and materials and through discontinuities in the envelope, cracks and other air-tightness defects.

ISO 14644-1:2015 concerns the classification of air cleanliness in cleanrooms and associated controlled environments performed as a function of airborne particle content only expressed by means of reported concentrations, cumulatively, to particle diameters.

It is good practice, before proceeding to determine the concentration of airborne particles, to verify that all aspects of the cleanroom that contribute to the operational integrity of the cleanroom are complete and functioning in accordance with its performance specifications.

Such preliminary verifications may include, for example:

• Air flow and velocity tests;
• Differential pressure testing;
• Leakage testing of the upright filters;
• Achievement of thermo-hygrometric operating conditions;
• Checking the validity of calibration certificates of instruments used during the tests.