Smoke visualization for the invasion of pollutants during door-opening process in pharmaceutical cleanrooms: Effects of initial pressure differential and airlock barriers

Abstract

Little research has been conducted on containing pollution invasion when the doors of pharmaceutical cleanrooms are opened. In this study, a clean pharmaceutical laboratory was built, and smoke visualization experiments were conducted. The transient effects of the initial pressure differential between rooms, airlock barrier, and time delay of airlock doors on the containment of disturbance by a normal door cycle of 4.5 s and by personnel entry were investigated. The initial pressure differentials were set from 5 to 25 Pa, and the delay time of the airlock doors was set from 6 to 36 s. The results indicated that the door operation and personnel entry caused smoke to invade the cleanroom. An increase in the pressure differential improved the containment of smoke migration. The amount of smoke invasion was lower, and the smoke was almost invisible by 18 s after the door opening at differential pressures of 20 and 25 Pa. An airlock exhibited an effective buffer effect even if the pressure differential across each airlock door was less than 5 Pa. Increasing the time delay was beneficial for eliminating migrated polluted air in the airlock. A delay time of 16 s significantly reduced the pollution for an initial pressure differential of 5 Pa across the airlock door. These findings can provide guidance for the containment of short-term disturbances in pharmaceutical cleanrooms and other controlled spaces.