What is a clean room and clean room standards
NGUYỄN ĐỨC TUẤN - 15/04/2019
Clean rooms are often used in scientific research, medical industry, high-tech production. Clean rooms are a controlled environment with low levels of pollutants such as dust, bacteria, aerosols and chemical vapors in the air. For accuracy, clean rooms are classified by pollution control level, determined by the number of dust particles per cubic meter of air and the specified particle size. The external atmosphere in a typical city environment contains 35 million dust particles per cubic meter of air, 0.5 mm dust particle diameter and may be larger, corresponding to ISO 9 specified for Clean room, is the lowest level of clean room standards.
Overview of clean rooms
Clean rooms are practically used in industry where small dust particles can adversely affect the production process. They vary in size, pollution control level and are widely used in industries such as semiconductor manufacturing, pharmaceuticals, biotechnology, medical equipment and scientific research, as well. as an important production process, popular in aviation, optics, military and energy sectors.
A clean room is any space, where it is specified to perform dust pollution mitigation and control other environmental parameters such as temperature, humidity and pressure. An important component used is the High-Performance Air Filter "High Efficiency Particulate Air HEPA filter used to separate dust particles of 0.3 microns in size and possibly larger. All air delivered to a clean room must go through a filter HEPA, and in some cases require more stringent cleanliness, a "Ultra Low Particulate Air (ULPA) filter" must be used. .
Staff working in clean rooms must undergo training on pollution control theory. They enter and exit clean rooms through pneumatic balancing doors (airlocks), air showers and / or gowning rooms, they must wear clothes designed to separated from natural pollutants such as sweat, created by body skin.
Picture: work in clean rooms
Work in clean rooms
Depending on the classification of the clean room or its function, the staff can wear simply as a lab coat and a hair net, or wear layers of clothing that are completely enclosed like "rabbit clothes." "With a self-breathing machine.
Clean room clothes are used to prevent contamination from evaporating from the wearer's body and polluting the environment. Clean room clothing does not release dust or dust particles to avoid environmental pollution caused by wearers. This type of pollution because wearers can degrade product performance in the semiconductor and pharmaceutical industry and it can cause cross-contamination between health workers and patients in the health care industry. healthy (for example).
A set of clean room clothes including boots, shoes, foot covers, masks, hats, seamless garments, masks, lab coats, gloves, hair nets, covers and covers shoe. The type of clean room clothes used must reflect clean room specifications and products. Low-level clean room may only require special shoes and soles that are completely smooth without dust or dirt. However, shoe soles do not create a danger as slippery should be prioritized. A complete accessory is usually needed to enter a clean room. Low-level clean rooms (Class 10,000) can use simple jackets, hair nets, and boots. For clean rooms (Class 10), wear very carefully and completely sealed gowns, boots, gloves and closed masks are required.
The principle of air in a clean room
Clean rooms maintain a clean air flow through the use of either an air filter HEPA or ULPA that applies the principle of straight air Laminar or turbulent airflow (Turbulent). Straight air flow, or unidirectional air flow, is an airflow system that is delivered directly from the air filter from the ceiling down a line. Straight air flow systems are usually 100% fully used by ceilings to transfer air down and maintain air continuously in one direction. The straight air flow meets the standard level, which is usually focused in the area where workers focus on work, and is specified in ISO-1 to ISO-4 by the principles of classifying clean rooms of international standards. ISO (International Standards Organization).
The standard clean room construction design must include complete gas distribution systems, including appropriate backup options, and calculation of return air flows. In the clean room, the principle of straight air flow is applied, this obviously has to set up the return air chambers in the low area around the perimeter of the clean room. In straight air flow applications, it requires the arrangement of gas recovery at the downstream boundary of the circulation process. The use of ceiling walls in combination with gas recovery is completely in conflict with the appropriate clean room system design.
Classify clean rooms
Clean rooms are classified according to the degree of air cleaning. According to the latest US standard FS 209E (Federal Standard 209E), the number of dust particles equal to and greater than 0.5mm is measured in an air volume whereby this number is used to classify rooms clean. Newer standards are TC 209 of the International Standards Organization (ISO). Both standards classify clean rooms by the amount of dust particles found in the air of the laboratory. The cleanroom classification standards FS 209E and ISO 14644-1 require specific measurement of dust particle counts and calculation of the level classification of a clean room or area. In the UK, the standard (British Standard 5295) is used to classify clean rooms. This standard is applied to replace ISO 14644-1.
Clean rooms are classified according to the number and size of allowed dust particles in an air volume. A large number of dust particles are in "class 100" (ISO 5) or "class 1000" (ISO 6) layers, "refer to the ISO 14644-1 table below", and also specify the number of particles of size 0.5 mm or more allowed in an air volume. The standard also allows for supplementation, (on the basis of "interpolation"), so we can design a clean room with "Class 2000" class, which is not shown in this ISO standard.
A small group is included in the ISO 14644-1 standard, which writes according to the "Logarithmic" base of the number of particles 0.1 µm (micron) or larger within the limit of an air volume. . For example, a clean room class (Class ISO 5) has a maximum number of dust particles of 105 = 100,000 in every m³ of air.
Both ISO 14644-1 and FS 209E demonstrate the relative nature of the particle size and dust particle concentration in the clean room. For that reason, there is no absolute standard for clean rooms without any dust. Air quality in a normal room is approximately (Class 1,000,000) or ISO 9 layer.