The clean room uses HEPA filters and adopts the principle of laminar flow (unidirectional flow) or turbulent flow (turbulent flow, non unidirectional flow) to control the particles in the air. The laminar or unidirectional air flow system guides the filtered air in a constant flow direction downward or horizontally to the filter on the wall near the floor of the clean room, or recirculates through the raised perforated floor plate. Laminar air flow system is usually used on 80% of the ceiling of the clean room to maintain constant air. Stainless steel or other non shedding materials are used to construct laminar air flow filters and hoods to prevent excess particles from entering the air. Turbulence, or non unidirectional air flow, uses laminar air flow hoods and non-specific velocity filters to keep the air in the clean room moving in a constant direction, although not all directions are the same. Rough air attempts to capture particles that may be present in the air and drive them to the floor where they enter the filter and leave the clean room environment.
Clean rooms require a lot of air and are usually at a controlled temperature and humidity. In order to reduce the cost of changing the ambient temperature or humidity, about 80% of the air will be recycled. The recycled gas will first pass through the filtration system to remove particulate pollution, while maintaining the appropriate temperature and humidity before passing through the clean room. Particles (pollutants) in the air either float around. Most particles in the air will settle slowly, and the rate of settling depends on their size.
A well-designed air treatment system should deliver fresh and recycled filtered clean air to the clean room together, and take particles away from the clean room together. According to the different operating objects, the air taken out from the room is usually recycled through the air treatment system, and the particles are removed by the filter in the air treatment system. If the process, raw materials or products contain a large amount of moisture, the harmful steam or gas cannot be recycled back to the room. This air is usually discharged to the atmosphere, and then 100% of the fresh air is sucked into the clean room system, and then sent to the clean room after treatment. The amount of air entering the clean room is strictly controlled, and the amount of air discharged is also strictly controlled. Most clean rooms operate under pressure by introducing a higher supply of air into the clean room than the supply of air discharged from the clean room.
High pressure will cause air to leak out from under the door or through any unavoidable small cracks or gaps in the clean room. The key to a good clean room design is the proper position of air introduction (supply) and discharge (exhaust). When arranging the clean room, the position of the air supply and exhaust (return) grille shall be given priority. The inlet (ceiling) and return air grille (in the lower position) shall be located on the opposite side of the clean room. If it is necessary to protect the operator from the product, the air flow should be away from the operator. The US FDA and the European Union have formulated very strict guidelines and limits for microbial pollution. The pressurization chamber between the air processor and the fan filter unit and the adhesive pad can also be used. For aseptic rooms requiring class a air, the air flow is from top to bottom and unidirectional or laminar to ensure that the air is not polluted before contacting the products.
If you want to know more about the clean room, please follow the official website of Suzhou Pharma Machinery Co., Ltd. ：www.sz-pharma.com
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