Experimental study of airborne particle transmission through the doorway of a cleanroom due to the movement of a person

Abstract

Impact of a person entering from an airlock to a cleanroom through doorway on airborne particle transmission was investigated experimentally in a full-scaled mockup. Nine experimental cases were setup based on doorway airflow rates 210, 400 and 580 L/s and walking speeds 0.5 and 1.0 m/s. The particles were generated in the airlock. The dynamic particle concentration in the cleanroom during door opening, holding and closing, and the concentration of remaining particles at the moment when the door was closed were measured. It is concluded: (1) the particle concentration in the cleanroom was increased by the entering of the person, especially at a low doorway airflow rate. Human movement at a speed of 1.0 m/s induced more particles compared with that at 0.5 m/s, with the overall concentration ratios of cleanroom to airlock of 2.75% and 1.47%, respectively at doorway airflow 210 L/s; (2) increasing doorway airflow from 210 L/s (0.11 m/s) to 400 L/s (0.22 m/s) greatly reduced the adverse effect caused by the human movement (concentration ratio of 0.49% at walking speed 1.0 m/s); the particle concentration became smaller when doorway airflow was further increased to 580 L/s (0.31 m/s); and (3) the concentration of remaining particles after the door was closed was lower than the transient high concentration during door opening and personnel walking process. The findings could provide guidance for aerodynamic barrier control of dynamic disturbance in cleanrooms or spaces where air cleanliness is of concern, e.g., isolation and operating rooms.