Environmental Control Concepts for Industrial Clean-Room Facilities

Abstract

Clean rooms rely on the effectiveness of terminal high-efficiency particulate air (HEPA) filters to provide particle-free air to the controlled environment. The filtration modes of HEPA filters are developed to provide insight into filter specification parameters such as minimum and maximum air velocity, filtration effectiveness versus particle size, and desired static air pressure drop. An outline of control of contaminant flow beyond filters is established through a developed hierarchy of pressures within a clean-room facility. Cleanliness levels with heating, ventilating and air-conditioning (HVAC) systems are discussed through strict adherence to ductwork sealing, treatment of large air volumes, and tight specifications for air-volume control. Numerous supplemental devices are compared to assist the architectural engineer in providing a clean-room facility with greater assurance of contamination control such as: air showers, air ionizers, differential pressure sensors, dynamic air-volume control valves and ultraviolet air sterilizers. Global HVAC system concerns are also delineated with typical parameters for clean-room facilities identified.