Clean rooms are areas that have been designed to keep air particles and other contaminants at a minimum. Clean rooms are common in many industries such as pharmaceuticals and medical device manufacturing, scientific search, chemical processing and electronics manufacturing. Clean rooms should be designed with consideration for their intended purpose, permissible particle concentration, location and manufacturing process. Design and specification of clean rooms require close coordination with all departments and parties involved.
Specifications for Clean Rooms
Federal Standard 209E in the United States defines clean room as one where the concentration of airborne particles can be controlled within certain limits. The International Organization for Standardization (ISO), sets standards and guidelines for clean room construction and operation. ISO 14644-4 outlines the requirements for clean room construction (also known as clean room installations), but it does not specify any contractual or technological means to meet these requirements.
How clean rooms can reduce contaminants
These are the components that combine to create a safe and effective environment for contamination control.
- High-Efficiency Particulate Air (HEPA) filters: These filters are vital for contamination control. These filters filter particles as small and as fine as 0.3 microns, with a 99.97% minimum level of particle-collective efficiency. HEPA filters are used to filter airborne contaminants out of clean rooms and supply fresh air for the occupants.
- Clean Room Architecture: Clean spaces are designed to create and maintain an airflow that allows the entire air body within a small area to move with uniform velocity along parallel flowlines. This is known as laminar flow. Restricted airflow can cause turbulence and particle movement. Laminar flow is important to reduce the possibility of contamination from airborne particles.
- Measurement & instrumentation:Some of the most important measurements for contamination control include particle count, airflow, velocity, temperature, humidity, and surface cleanliness. These factors are often measured by clean room managers using specific standards and/or tools.
- Electrostatic discharge: A charge is created when two surfaces touch each other. Air can create a charge by moving it. A turbo-electric charge can be created by people touching surfaces or walking on the ground. ESD protective materials should be used with care to avoid any damage. Cleaning managers need to work closely with their staff to identify and prevent these conditions.
- Ventilation & Makeup Air: Ventilation & Makeup Air Volumes: Ventilation are determined by the volume of indoor air to maintain indoor quality, replace process exhaust and maintain building pressure. Ventilation refers to air exchange, or the replacement of old air by fresh filtered air. The fresh, filtered air used to replace the exhausted air in a room is called makeup air.
- Pressure: Rooms should be kept at static pressures greater than atmospheric to prevent wind infiltration. Only certain hazardous materials, for which governmental agencies require that the room be maintained at a negative pressure, can be subject to a positive differential pressure.
- Temperature & Humidity:Temperature controls are necessary to maintain stable conditions for materials, instruments and personnel comfort. To prevent corrosion on surfaces and eliminate static electricity, humidity control is essential.