This Recommended Practice (RP) covers procedures for calibrating and verifying equipment used in characterizing cleanrooms and for determining intervals of calibration. The RP includes general procedures for calibrating aerosol generators, photometers, anemometers, airflow capture hoods, temperature measurement systems and devices, pressure and vacuum gauges, polymicrosphere (PSL) generators, aerosol diluters, and condensation nuclei counters. Where available, references for calibrating other instruments are provided.