About clean rooms
Clean Room, also known as clean workshop, clean room or clean room. The main function of clean room is indoor pollution control. Without clean room, pollution-sensitive parts cannot be mass-produced. In FED-STD-2, a clean room is defined as a room equipped with air filtration, distribution, optimization, construction materials, and devices in which specific, regulated operating procedures are used to control the concentration of airborne particulates in order to achieve an appropriate particulate cleanliness level. Cleanliness and continuous stability of pollution control is the core standard for testing clean room quality. The standard is divided into several grades according to regional environment, purification degree and other factors. International standards and domestic regional industry standards are commonly used. Purification capacity and environmental adaptability far exceed international brands.

1 Introduction
Clean room refers to a specially designed room that removes particles, harmful air, bacteria and other pollutants in the air within a certain space range, and controls indoor temperature, cleanliness, indoor pressure, air velocity and air distribution, noise and vibration, lighting and static electricity within a certain range of requirements. That is, no matter how the external air conditions change, the interior can maintain the original requirements of cleanliness, temperature, humidity, pressure and other properties.
The most important role of clean room is to control the clean degree-days and temperature and humidity of the atmosphere exposed to products (such as silicon chips, etc.), so that products can be produced and manufactured in a good environmental space, this space is called clean room. According to international practice, the dust-free purification level is mainly based on the particle diameter per cubic meter of air is larger than the standard to define the number of particles. That is to say, the so-called dust-free is not 100% without a little dust, but controlled in a very small amount of units. Of course, the particles in line with the dust standard in this standard are very small compared with our common dust, but for optical structure, even a little dust will have a very big negative impact, so in the production of optical structure products, dust-free is an inevitable requirement.
Keeping the amount of fine dust smaller than 0.3 microns per cubic meter below 3,500 is A grade A of international dust-free standards. The dust-free standards for chip production and processing have higher requirements for dust than Class A, and such high standards are mainly applied to the production of some higher grade chips. Particulate matter of 0.5uM or less is strictly limited to 1,000 particles per cubic inch, known in the industry as 1K.
Empty: Clean room (facility) that has been constructed and is ready for use. It has all the relevant services and features. However, there is no equipment operated by operators within the facility.
Static: a clean room (facility) with complete functions, properly installed Settings, which can be used or in use according to the Settings, but there is no operator in the facility.
Dynamic: in the normal use of clean room, complete service function, equipment and personnel; Take up normal work if needed.

Unidirectional flow (laminar flow) clean room principle
In the clean room, from the air supply outlet to the air return outlet, there is almost no change in the section of the air flow through the way, coupled with the pressure and flow balancing effect of the air inlet plenum and high efficiency filter, the flow rate on the whole room section is more uniform, and at least in the working area, the flow line is unidirectional parallel, without eddy current. This is the three characteristics of one-way flow clean rooms. The streamline here is unidirectional parallel, which means that the time mean streamline lines are parallel to each other and have a single direction.
The flow mode of one-way flow clean room is turbulent according to Reynolds number, so the so-called laminar flow in clean room and laminar flow in fluid mechanics are completely different concepts. Therefore, the term laminar flow clean room is not appropriate, and some foreign standards and articles also point out this point, such as the British standard BS-5295 has defined the so-called laminar flow clean room as unidirectional flow clean room, but it is used to indicate laminar flow in brackets. The former Federal German standard VDl-2083 uses the term "non-turbulent displacement flow", and points out in the note that the concept of laminar flow is only to distinguish the turbulent (turbulent) flow clean room which appeared earlier than the laminar flow clean room, and the customary term adopted at that time is that "laminar flow system" does not exactly mean stratified flow, but turbulent displacement flow. The concept mentioned in this chapter is a turbulent gradual flow. In fluid mechanics, this state of flow may also be called parallel flow or one-way flow. In 1977, China adopted the term "parallel flow" in the "Technical Measures for Air Cleanliness", after which it also pointed out that the term is commonly called "laminar flow".
In a unidirectional clean room, the clean air is not one or several streams, but filled with the whole room section. Therefore, this clean room does not rely on the mixing and dilution effect of clean air on indoor dirty air, but on the release effect of clean air to exhaust indoor dirty air along the whole section to the outside, to achieve the purpose of purifying indoor air. Therefore, some people in the former Federal Germany called the airflow in the unidirectional clean room "piston flow" and "flat push flow". In the former Soviet Union, they called it "squeezed weak air jet". Clean air is like an air piston, along the "cylinder" of the room, forward (down), and the dust particles can only forward (down) into, not back, the original high dust concentration of air squeezed out of the room.
In the unidirectional flow clean room and unidirectional flow purification equipment, the reverse air flow along the wall and below the lap of two filters can be found. This air stream will carry pollution from below to above and down, disrupting the state of the piston flow and causing great harm. For the local purification equipment that is communicated with the outside, such as the clean table, the air flow will emit the polluted air from the outside. In the design, we must reduce the invalid area of the filter frame space, but also try to make the wall surface of the space as close to the effective air cross section of the filter as possible.

Through the above analysis, it can be considered that there are two important prerequisites for ensuring the characteristics of unidirectional flow clean room (high cleanliness and rapid self-cleaning recovery ability) : (1) the cleanliness of incoming flow; (2) piston flow of incoming flow;
For the cleanliness of the flow, it is not a problem for the unidirectional clean room of air supply through the high efficiency filter, and for the "piston flow" of the flow, it is necessary to make a step analysis.
According to the principle of fluid mechanics, the incoming flow condition will have a direct and important impact on the future flow condition. The outlet air flow of the air supply surface is also the incoming flow in the working area.
The high turbulence of incoming flow will affect the one-way flow characteristics behind it. If the incoming flow does not fill the flow section, it will affect whether the "piston flow" can be formed and the speed of its formation. The inflow flow is not full flow section is also a factor of inflow element movement. Therefore, under the condition of using high efficiency filter, the necessary condition to ensure the characteristics of unidirectional flow clean room is "piston flow", and the necessary condition of "piston flow" is that the incoming flow fills the flow section. However, it is also impractical for a room rather than a pipe to fill the flow section completely from end to end.
Initially, it was indeed thought that this one-way, parallel flow of air should fill the entire clean room, but this was technically and economically unfavorable. With the development of understanding, people also pointed out that this unidirectional flow is only "in a limited field all the air along the parallel flow line at the same speed", and believed that the occurrence of eddy current can be suppressed. A room where the unidirectional flow of clean air through the whole space is dominant is also called a unidirectional clean room. That is to say, the whole room is not required to have one-way parallel flow lines, uniform speed, no eddy current, but only requires one-way parallel flow characteristics to dominate the room, for example, the whole work area of the floor space to ensure unidirectional flow, this room is one-way flow clean room. The high cleanliness of unidirectional flow clean room in the relevant standards and measures introduced earlier at home and abroad refers to the cleanliness achieved in the work area. Therefore, the densely arranged streamline diffuser and full orifice plate are also used as a means to achieve vertical unidirectional flow.
Turbulence principle
According to its airflow state to distinguish the clean room, mainly divided into turbulence (non-one-way flow) clean room, one-way flow clean room and radial flow clean room (also known as vector flow clean room), this section mainly discusses the turbulence clean room. As has been pointed out above, no matter which kind of clean room is turbulent flow mode. Why don't they call them turbulent clean rooms?
The name of turbulence clean room is borrowed from the Japanese word, but the Japanese word turbulence means turbulence, and the word turbulence formally adopted in the Technical Measures for Air Cleaning in China is both turbulent meaning and different from the proper term turbulence in fluid mechanics. It is customary in the world to call this kind of clean room non-unidirectional flow clean room.
The so-called turbulence clean room generally includes the following air supply forms:
⑴ high efficiency filter top delivery (with and without diffusion plate
The streamline diffuser jacking in
⑶ Local orifice plate top feeding
(4) lateral delivery
Clean rooms with these supply air forms, if judged by Reynolds number, clearly belong to turbulent flow mode, but it is not appropriate to call them turbulent clean rooms. Air flow along the entire ceiling, indoor speed reached 0.25m/s above, this indoor flow state is turbulent, but in the back will be clear, although these two air supply methods are caused by indoor turbulent flow, but in terms of its principle of indoor air purification, it is fundamentally different, the latter belongs to the one-way flow or parallel flow clean room purification principle. So if the former is called a turbulent clean room, the latter should also be included.
The main characteristic of turbulence clean room is that the flow section of the air flow from the flow to the outlet (from the air supply outlet to the air return outlet) is changed. The clean room section is much larger than the air supply outlet section, so uniform air flow can not be formed in the whole room section or in the whole room working area section. Therefore, the streamline after the air supply outlet has a large or increasingly large Angle with a small radius of curvature. It is impossible for the air flow to flow in a single direction indoors. It will collide with each other, and there will be backflow and vortex. This determines the flow nature of the turbulence clean room is: abrupt flow; Heterogeneous flow.
This is a more accurate and comprehensive description of turbulence cleanrooms than turbulence. Turbulent flow is mainly determined by Reynolds number, that is, by velocity, but if you use a high efficiency filter top feed, even if the velocity is very low, all of these results will occur because it is a sudden and heterogeneous flow. Therefore, in this case, there is not only the mixing between flow layers caused by turbulent flow, but also the mixing caused by large backflow and vortex in the whole chamber.
So, in a word, the principle of turbulence clean room is: when a clean air flow is sent into the room from the air supply outlet, it rapidly diffuses around and mixes, and at the same time, almost the same amount of air flow is discharged from the return outlet. The clean air flow dilutes the indoor polluted air, diluting the original indoor air with a high dust concentration, and reaching balance all the time. So the faster and more evenly the flow spreads, the better the dilution. So the principle of a turbulence clean room is dilution.
2 Required Materials
The following equipment is needed in the clean room during the construction of the purification project:
A. Decorative structure class:
1: The purification equipment needed for clean rooms mainly includes: Air shower room cargo shower room laminar flow hood (FFU) transfer window high efficiency air supply port (divided into ordinary high efficiency air supply port, integrated high efficiency air supply port, high efficiency air supply port of replaceable filter screen) pressure relief valve air volume regulating valve, etc. After clean room is done, some local purification level requirements are particularly high, so we recommend customers to use clean workbench, clean shed and other purification equipment.
2: enclosing structure color steel plate (all kinds of aluminum profile groove aluminum T-beam aluminum Angle aluminum shape column aluminum outer plate three-dimensional joint door plug inner arc line door material window material, etc.) Auxiliary materials Angle iron round steel rubber plug white nail tensile blast hook, etc.)
B. Air conditioning ventilation part:
1. The main materials for air conditioning ventilation include air conditioning host, air return pipe, galvanized water pipe (or PVC water pipe) tower gate valve water pump Y-type filter rubber hose check valve water flow switch thermometer pressure gauge water filter of various pipe codes
2: The main materials of the ventilation part are medium effect pressure booster box air valve air volume regulating valve initial effect rain-proof louver air return louver initial effect filter medium effect filter high efficiency filter laminar flow cover (FFU) thermal insulation cotton moisturizing hose various auxiliary materials
C. Electrical part:

1, air conditioning circuit
2, purification equipment circuit
3. Lighting circuit
D. Ground part:
1. Epoxy resin floor
2. PVC flooring
3, elevated floor ground
3 Required Equipment
Air shower
Air shower series products are a kind of local purification equipment with strong universality, installed between clean room and non-clean room. When people and goods want to enter the clean area, they need to be blown by the air shower, the clean air blown out can remove the dust carried by people and goods, and can effectively block or reduce the dust source into the clean area. The front and rear doors of the air shower/cargo shower room are interlocked electronically, which can also act as an airlock to prevent unpurified air from entering the clean area.
Cargo shower room
Cargo shower room, solid name Siyi, that is, for the goods special shower room, also known as the goods shower channel, goods shower door, widely used in electronic, food, packaging enterprises logistics channel, will enter the clean workshop for operation and processing of raw materials and tools for blowing, to filter the removal of dust particles, into the clean effect of raw materials. Because of the site size of each enterprise logistics channel and the need to blow the size of the transportation of goods and raw materials, so there is no unified standard for the goods shower room, all for non-standard products. Cargo shower in the function of both ordinary type of cargo shower room, and infrared voice signal type of cargo shower room, and automatic moving door type cargo shower room.
Transfer window
Transfer window is mainly suitable for the transfer of small goods between clean area and unclean area, or between clean room and clean room, which can effectively reduce the opening times of clean room door and reduce the minimum degree of pollution in clean area. According to the use requirements, the surface of the transfer window box can be sprayed plastic, the inner liner can be stainless steel, beautiful appearance. The two doors of the transfer window adopt electronic control interlocking or mechanical interlocking device, which can effectively prevent the dust in the low clean area from being brought into the high clean area. It is the best product for the purification workshop.
High efficiency air supply port
This product is class ten thousand, class one hundred thousand turbulence clean room new, reconstruction project purification air conditioning system terminal air supply device. Can be widely used with electronics industry, precision machinery, metallurgy, chemical industry and other industries and medical, pharmaceutical, food and other departments of purification air conditioning system. The device is mainly composed of static pressure box, high efficiency filter, aluminum alloy diffusion plate, standard flange interface, beautiful shape, simple structure, reliable use. The air supply outlet is installed under the type, with the advantages of convenient installation and replacement of filter in clean room, high efficiency filter adopts mechanical compression or liquid tank sealing device, to ensure that the tuyere installation without leakage, reliable sealing, good purification effect, can be applied to the general purification project.
Clean table
The clean table in the dust-free workshop can maintain the local purification of high cleanliness on the operating table according to the requirements of the product or other purposes. Clean table can form aseptic and dust-free local purification in the local space of the operation table. Its main components include pre-filter, high efficiency filter, fan unit, shell, static pressure box, table and supporting electrical components.
The construction requirements of the clean table in the dust-free workshop are as follows: table, the wooden plastic veneer is pasted on the laminate to make the table, or the stainless steel to make the table; Box, with hot tie thin steel plate and skeleton gas welding is easy to deformation, can use cold rolled sheet edge lap, large current welding, the inner surface needs to paste noise reduction material, the maximum size should be through the general door is appropriate; The box is sealed, and all gaps are sealed with sealant; The section of the operation area should be the same as the section of the air supply filter as far as possible to reduce the blind area; Fan, motor, choose high pressure low noise small fan, fan and box body connection using soft connection, motor and fan should take vibration reduction measures; Lampshade, fluorescent lamp should be set as far as possible in the lampshade, lampshade through clean air flow; Pre-filter, pre-filter must be set, the capacity should be large, in the use of air volume, the initial resistance should be less than 50Pa; High efficiency filter, as far as possible to use a large area of filter, reduce the number of air filters, the seal between the filter and the frame should use the sealing guide combined with the double ring sealing system.
FFU fan filter unit
The fan Filter unit (FFU) is an air self-cleaning device that can be mounted on an indoor ceiling or placed on a support to achieve local grades of up to 100. It can also be used for air supply at the end of clean room. The product is equipped with primary and high efficiency two-stage filtration device. The fan draws the air from the top and filters it through the primary and high efficiency filter. The filtered clean air is sent out in the whole outlet. There are two kinds of installation: suspension type and floor support.
The fan draws air from the top of the FFU and filters it through the primary and high efficiency filters. The filtered clean air is sent out uniformly at the wind speed of 0.45M/S±20% on the whole outlet surface. It provides high quality clean air for clean rooms and microenvironments of different sizes and cleanliness levels. In the renovation and renovation of the new clean room and clean workshop, it can improve the cleanliness level, reduce noise and vibration, and also greatly reduce the cost. It is convenient to install and maintain, and is an ideal part for clean environment.
Laminar flow hood
Laminar hood An air purification device that provides a locally clean environment. It mainly has a box, fan, primary air filter, high efficiency air filter. Damping layer, lamps and other components, box spray or stainless steel material. The product can be suspended, but also ground support, compact structure, easy to use. It can be used singly or joined to form a banded clean area. Widely used in precision machinery, electronics, pharmaceutical, food, fine chemical and other sectors.
4. Control the project
1. It can remove the fine dust particles floating in the air.
2, can prevent the production of fine dust particles.
3. Control of temperature and humidity.
4, pressure regulation.
5. Removal of harmful gases.
6. Air tightness of structure and compartment.
7. Prevention of static electricity.
8. Electromagnetic interference prevention.
9. Safety considerations.
10, energy conservation considerations.
5 Purification Method
Air purification method
1, overall purification: can be divided into laminar flow type and turbulent type. Laminar flow means that the air flows from one side to the other side at the same speed comprehensively, so that the dust particles or bacteria generated indoors will not spread around and be flat pushed out of the room, and achieve good bactericidal effect.
⑴ High efficiency filtration and sterilization technology: air cleaning mainly depends on high efficiency or super high efficiency filtration equipment to transport clean air to a specific environment and can maintain the cleanliness of the air. Filter clean principle: (1) net interception; ② screen retention; (3) electrostatic attraction retention; Inertial collision and Brownian motion retention. Therefore, filtration cleaning technology is a result of comprehensive effects.
⑵ Filter material structure: Most of the filter materials used in the biological clean room are high efficiency or ultra-high efficiency filter materials. The filter materials used are: glass wool filter material, advanced paper pulp filter material, asbestos fiber filter material, perchloride fiber filter material, etc. The retention rate of 0.5μm particles in the air can reach 90%~99%, and the retention rate of 0.3μm particles can be more than 99.9%.
2, local purification
(1) Clean laminar flow hood: Clean laminar flow hood is a local air purification device for hospitals. Generally can form vertical laminar flow mode, surrounded by transparent curtain. The whole hood can maintain a high degree of cleanliness (class 10 to 100) air. This clean laminar flow mask can be used for the treatment and protection of patients with immunocompromised function, so it is also called aseptic bed laminar flow mask.
(2) Purifying operation table: The air in the box can be purified by horizontal or vertical laminar flow, so that the purification in the operation table can reach a very high level.
(3) Electrostatic adsorption sterilization purification technology: electrostatic adsorption sterilization is the use of industrial electric dust removal principle, in the miniaturization technology has been innovative. (1) Using a fine wire discharge electrode and honeycomb aluminum box collecting pole to form a level line device; (2) Using the mirror image force charge adsorption.
At present, there is a three-stage purification device, that is, pre-filtration, high-efficiency filtration, activated carbon adsorption, combined positive ion electrostatic adsorption to remove bacteria, and adopts high air volume air purification to ensure the frequency of indoor air purification, which better solves the problem of continuous air disinfection in key hospital departments such as operating rooms, ICU, maternal and infant wards, hemodialysis rooms and other crowded conditions. Can make the hospital indoor air purification cleanliness of 100,000 ~ 10,000 level.
(4) Negative ion purification technology: negative ion is a kind of negative chemical groups, reversible changes can occur, existence time is very short, and does not have the ability to kill microorganisms, mainly rely on charged ions and particles in the air, especially microbial particles, the formation of a number of particles condensed to become larger rapidly settlement, so that the air to achieve the purpose of purification. Only when the negative ions in the air have certain chemical properties, such as active oxygen ions, can they have the ability to damage proteins and kill microorganisms. Therefore, the negative ions have a relatively limited ability to purify the air, and the clearance rate of microbial particles in the air can only reach 70%~90%.
6 Working Mode
Turbulent flow
The air enters the clean room from the air conditioning box through the air duct and the air filter (HEPA) in the clean room, and returns the air from the wall panels or elevated floors of the compartments on both sides of the clean room. A state of irregular turbulence or vortex in which the flow of air does not move in a straight line. This type is suitable for cleanroom grades 1,000-100,000.
Definition: A clean room in which air flows at uneven speeds and not parallel, accompanied by backflow or eddy currents.
Characteristics: Turbulence clean room is to achieve cleanliness and cleanliness level by multiple air exchange. The number of air changes determines the purification level in the definition (the more air changes, the higher the purification level)
⑴ Self-cleaning time: refers to the time when the clean room begins to supply air to the clean room according to the design ventilation times, and the indoor dust concentration reaches the designed purification level. It is expected to be less than 20 minutes (15min calculation is preferred) for class 1,000. It is expected to be less than 30 minutes (25min calculation is preferred) for Class 10,000. It is expected to be less than 40 minutes (30min calculation is preferred) for class 100,000.
(2) Air changes (designed according to the above self-cleaning time requirements) 43.5 -- 55.3 times/hour for class 1,000 (specification: 50 times/hour) 23.8 -- 28.6 times/hour for class 10,000 (specification: 25 times/hour) 14.4 -- 19.2 times/hour for class 100,000 (specification: 15 times/hour)
Advantages: simple structure, system construction cost, the expansion of clean room is relatively easy, in some special use places, can use dust-free workbench, improve the grade of clean room.
Disadvantages: Dust particles caused by turbulence float in the indoor space is not easy to discharge, easy to pollute process products. In addition, if the system stops running and reactivates, it often takes quite a long time to achieve the required cleanliness.
Stratified flow
The stratified air flow flows into a uniform straight shape. The air enters the room through the filter with 100% coverage, and is returned to the room by the elevated floor or the partition panels on both sides. This type is suitable for the environment where the grade of clean room needs to be higher. Its type can be divided into two types:
(1) Horizontal layer flow: horizontal air is blown out from the single direction of the filter, returned by the return air system of the opposite wall, and the dust is discharged outdoors with the wind. Generally, the pollution is more serious on the lower side.
Advantages: simple structure, operation after a short time can become stable.
Disadvantages: The construction cost is higher than the chaotic flow, the interior space is not easy to expand.
(2) Vertical layer flow: the ceiling of the room is completely covered by ULPA filter, and the air is blown from top to bottom, so that a high degree of cleanliness can be obtained. The dust generated by the process or the staff can be quickly discharged outside without affecting other working areas.
Advantages: Easy to manage, stable state can be reached within a short time after operation, not easy to be affected by operation state or operators.
Disadvantages: the construction cost is high, the elastic use of space is difficult, the ceiling hanger quite occupies space, the maintenance and replacement of the filter is more troublesome.
Compound type
The compound type is the combination or combination of turbulent flow and stratified flow, which can provide local ultra-clean air.
⑴ Clean Tunnel: HEPA or ULPA filter will 100% cover the process area or working area to improve the cleanliness level to more than 10, which can save installation and operation costs.
This mode isolates the work area of the operator from the maintenance of the product and machine to avoid the impact of machine maintenance on work and quality. Most ULSI processes use this mode.
Clean tunnel has two other advantages: A. Easy elastic expansion; B. Maintenance of equipment can be easily performed in the maintenance area.
(2) Clean Tube: Surround and purify the automatic production line through which the product process passes, and raise the cleanliness level to more than 100. Because the product and the operator and the dust environment are isolated from each other, a small amount of air supply can get good cleanliness, can save energy, do not need manual automatic production line is the most suitable for use. It is applicable to the pharmaceutical, food and semiconductor industries.
⑶ And install local Clean Spot: improve the cleanliness level of the product process area of the turbulence clean room with the clean room grade of 10,000~100,000 to more than 10~1000 for production; Clean workbench, clean working shed, clean air cabinet is such.
Clean workbench: Class 1~100.
Clean working shed: In order to prevent static electricity from forming a small space surrounded by transparent plastic cloth in the free-flow clean room space, independent HEPA or ULPA and air conditioning units are used to make a higher grade clean space. The grade is 10~1000, the height is about 2.5 meters, and the covering area is less than 10m2. The four pillars are equipped with movable wheels, which can be used flexibly.
7 Wind Speed Control
The airflow in clean room is an important factor in the performance of clean room. The airflow velocity of clean room in general is between 0.25 and 0.5m/s. This airflow velocity is a breeze area, which is prone to interference and chaos by the actions of people and machines. Therefore, when the required cleanliness level is met, the most appropriate wind speed can be supplied to achieve the appropriate wind speed supply to achieve economic effect.
On the other hand, to achieve the stable effect of clean room cleanliness, the maintenance of uniform air flow is also an important factor. If the uniform air flow cannot be maintained, it means that the wind speed is different, especially on the wall, the air flow will have eddy current effect along the wall, and it is actually difficult to achieve high cleanliness at this time.
In order to maintain a uniform flow in the vertical stratified flow direction, it is necessary to: (a) there should be no velocity difference in the blowing wind speed; (b) There shall be no speed difference in the wind speed of the intake surface of the floor return air plate. If the speed is too low or too high (0.2m/s, 0.7m/s), vortex phenomenon occurs, and if the speed is 0.5m/s, the airflow is more uniform. In general clean room, the wind speed is between 0.25 and 0.5m/s.
8 Influencing Factors
There are many factors affecting the air flow of clean room, such as process equipment, personnel, clean room assembly materials, lighting appliances, etc. At the same time, the separation point of the air flow above the production equipment should also be considered.
The air distribution point on the surface of the general operating table or production equipment should be located at 2/3 of the distance between the clean room space and the partition board, so that the air can flow from the inside of the process area to the operation area when the operator is working, and the fine dust can be taken away; If the diversion point is configured in front of the process area, it will become an improper airflow diversion. At this time, most of the airflow will flow to the process area, and the dust caused by the operation of the operator will be taken to the back of the equipment, and the workbench will be polluted, and the yield will be reduced.
The obstacles such as the work table in the clean room will have eddy current phenomenon at the junction, and the relative cleanliness near it will be poor. Drilling the return air hole on the work table will reduce the eddy current phenomenon to the minimum; The proper selection of assembly materials and the perfect layout of equipment also play an important role in determining whether the airflow becomes eddy current.
The composition of clean room is composed of the following systems (one of which is indispensable in the system molecules), otherwise it will not be able to form a complete and good quality clean room:
⑴ Ceiling system: includes Ceiling rod, I-Beam or U-Beam, Ceiling grid or Ceilingframe.
(2) Air conditioning system: including air cabin, filter system, windmill, etc.
(3) Partition wall: including Windows and doors.
(4) Flooring: including elevated floor or anti-static comfort floor.
⑸ Lighting equipment: including fluorescent lamp, yellow lamp, etc.
The main structure of the clean room is generally made of steel or bone cement, but no matter what kind of structure, the following conditions must be met:
● will not crack due to temperature change and vibration;
● It is not easy to produce fine dust particles, and it is difficult to attach particles;
● small hygroscopicity;
● In order to maintain indoor humidity conditions, high thermal insulation.
9 Importance
The cleanliness of clean rooms is often affected by air flow. In other words, the movement and diffusion of dust generated by people, machine compartments and building structures are controlled by air flow.
The clean room uses HEPA and ULPA to filter the air, and the dust collection rate is up to 99.97~99.99995%, so the air filtered by this filter can be said to be very clean. However, in addition to people, there are dust sources such as machines in the clean room. Once the dust spreads, it is impossible to maintain a clean space. Therefore, air flow must be used to quickly discharge the dust.
10 Application Fields
industry
For the control of inanimate particles. It mainly controls the pollution of air dust particles to working objects, and generally maintains positive pressure inside. It is suitable for precision machinery industry, electronics industry (semiconductor, integrated circuit, etc.) aerospace industry, high purity chemical industry, atomic energy industry, optical magnetic products industry (CD, film, tape production) LCD (liquid crystal glass), computer hard disk, computer magnetic head production and other industries.
organism
It mainly controls the pollution of living particles (bacteria) and inanimate particles (dust) to working objects. It can also be divided into:
A. General biological clean room: mainly control the pollution of microbial (bacterial) objects. At the same time, the internal material should be able to withstand a variety of sterilization agent erosion, the internal general guarantee of positive pressure. Essentially its internal materials should be able to withstand a variety of sterilization treatment of industrial clean room. Examples: pharmaceutical industry, hospital (operating room, aseptic ward) food, cosmetics, beverage product production, animal laboratory, physical and chemical laboratory, blood station, etc.
B. Biological safety clean room: the main control object of the pollution of life particles to the outside world and people. The interior should maintain the negative pressure with the atmosphere. Examples: bacteriology, biology, clean laboratory, physical engineering (recombinant genes, vaccine preparation).
Related knowledge
11 Workload
Dust emission
The amount of dust in the clean room can be considered to be eliminated by local exhaust air from the equipment, and does not flow into the room; Products, materials and other dust in the process of transportation compared with the amount of human dust, generally very small, can be ignored; Because the application of metal half wall (color steel sandwich board) from the building surface dust is also very little, generally accounting for less than 10%, dust mainly from people, accounting for about 90%. In the amount of human dust, because of the improvement of clothing materials and styles, the absolute amount of dust has been reduced.
A. Material: cotton has the largest amount of dust, followed by cotton, dacron, pure polyester and nylon.
B. Style: large hanging type has the largest amount of dust, followed by upper and lower divided type, and full cover type has the least amount.
C. Activity: the amount of dust generated during movement generally reaches 3-7 times of the rest time.
D. Cleaning: the amount of dust generated by solvent washing is reduced to one-fifth of that by general water cleaning.
The amount of dust generated on the surface of the indoor maintenance structure is subject to the ground. The amount of dust generated on the surface of the corresponding 8 square meters of ground is equivalent to the amount of dust generated by a stationary person.
Amount of bacteria
Pollution caused by workers:
1) Skin: Humans usually complete skin replacement every four days, and shed about 1000 pieces of skin per minute (the average size is 30*60*3 microns).
2) Hair: Human hair (about 50 to 100 microns in diameter) falls out all the time.
3) Saliva: including sodium, enzymes, salt, potassium, chloride and food particles.
4) Everyday clothing: particles, fibers, silica, cellulose, various chemicals and bacteria.
5) Humans produce 10,000 particles larger than 0.3 microns per minute when sitting or sitting.
6) Human head and trunk movements produce 1 million particles larger than 0.3 microns per minute.
7) A human walking at 0.9m/s produces 5 million particles larger than 0.3 microns per minute.
Analysis of foreign test data can be concluded that:
(1) When the staff wear sterile clothes in the clean room:
At rest, the amount of bacteria is generally 10-300 /min
The amount of bacteria in general body activity is 150-1000 /min
The amount of bacteria produced during brisk walking is 900-2500 /min
⑵ Cough is usually 70~700 people/min
A sneeze is usually 4000~62000 persons per min
⑶ The amount of bacteria caused by wearing ordinary clothes is 3300~62000 / min
⑷ Bacteria rate without mask: Bacteria rate with mask 1:7~1:14
⑸ The amount of bacteria: the amount of dust 1:500~1:1000 according to the domestic case:
⑹ 878 cases of bacteria per person per min
Therefore, it is known that the static bacteria amount of sterile clothing personnel in the clean room is generally not more than 300 / min. Human, the amount of dynamic bacteria is generally not more than 1000 / min/ person, so it is feasible to take this as the basis for calculation.
12 Implementation Standards
Domestic standard
(1) Clean workshop design specification GB50073-2001
(2) Technical Code for Construction of Clean Operation Department of hospital GB50333-2002
(3) Specification for Design of clean workshop for the pharmaceutical industry GB 50457-2008
(4) Code for architectural design of hospitals for infectious diseases
-- Test method for suspended particles in clean rooms (areas) of the pharmaceutical industry GB/T16292-1996
⑹ QS Certification Quality Manual
G.GMP for quality control of drug production
⑻ Specification for construction and acceptance of clean room GB 5091-2010
International standard
ISO series
⑴ Classification of ISO14644-1 air cleanliness
⑵ISO14644-2 is the continuous compliance testing and monitoring technical requirements of ISO14644-1 certification
⑶ Test method of ISO14644-3
⑷ISO14644-4 design and construction start
⑸ISO14644-5 operation (Operations)
⑹ISO14644-6 Terms and Definitions
⑺ISO14644-7 separation unit, clean air hood, glove box, separator and microcirculation equipment
⑻ Molecular pollution of ISO14644-8
(9) Longmen ISO14644-9 Clean Chemicals (liquid)
IEST series
Clean air:
RP-CC001 High efficiency and ultra high efficiency filter
RP-CC002 unidirectional flow device
RP-CC006 Clean room test RP-CC007 ultra high efficiency filter test
RP-CC008 gas absorption device
RP-CC021 Filter medium testing for high efficiency and ultra high efficiency filters
RP-CC034 High Efficiency and Ultra High Efficiency Filter Filter leak detection
Clean room and clean environment:
RP-CC006 Clean room test
RP-CC012 clean room design points
RP-CC016 Deposition rate of non-volatile residues in clean rooms
RP-CC018 Clean room management operation and testing procedures
Static electricity in clean rooms and controlled environments in RP-CC022
RP-CC023 Microorganisms in the clean room
Vibration measurement and description of RP-CC024 microelectronic equipment
RP-CC026 Clean room operation
RP-CC027 People and behavior in clean rooms and controlled environments
Special application:
RP-CC029 Pollution control factors to consider when using paint sprayer
Operation guarantee:
RP-CC003 Clean room and Controlled environment apparel system essentials
RP-CC004 Clean room and controlled environment rag material assessment
RP-CC005 Gloves and finger covers for cleaning rooms and controlled environments
RP-CC020 Clean room document materials and format
Equipment:
RP-CC002 unidirectional flow device
RP-CC013 equipment calibration and inspection procedures
RP-CC015 clean room production equipment and auxiliary equipment
Terms:
RP-CC011 Terms and Definitions in the field of pollution control
Literature:
RP-CC009 Overview of standards, guidelines, methods and related documents in the field of pollution control
Detailed parameter
Cleanliness standard and cleanliness grade (ISO international standard)
Maximum allowable Particle Concentration for each Particle Size (per particle /m3)
ISO rating 0.1um 0.2um 0.3um
1 10 2
2 100 24 10 4
Three, one,
4 10,000 2,370 1,020 32 83
5 100,000 23,700 10,
6 1,000,000 237,000 102
Air cleanliness should be divided into four levels as specified in the table below.
Air cleanliness rating scale
grade
Per cubic meter (per liter) of air
≥0.5 micron dust particle number
Per cubic meter (per liter) of air
≥5 micron dust particle number
Level 100
35 x 100 or less (3.5)
Class 1000
35 x 1000 or less (35)
2500 (0.25) or less
Class 10000
35 x 10000 or less (350).
25000 (2.5) or less
Class 100000
35 x 100000 or less (3500).
25000 (25) or less
Note: For the calculation of dust particles greater than or equal to 5 microns in the clean room with air cleanliness of 100 grade, multiple sampling should be carried out. When it occurs more than once, the test value can be considered *.
13 Application Scope
Purification engineering is a very wide range of basic supporting industries in the application industry, in electronic information, semiconductor, optoelectronics, precision manufacturing, medicine and health, biological engineering, aerospace, automotive spraying and other industries are used, and according to the precision and dust-free requirements of the industry, the grade difference is also large.
At present, the highest level is the aviation warehouse of aerospace, which basically belongs to the first level, belongs to the special field, and the area is relatively small.
In addition, biochemical laboratories and high-precision nanomaterials production workshops have higher requirements for the level. The development of Internet chips will be a major direction of future demand.
14 Eight Features
First, the arc Angle is more suitable for the principle of clean room;
Second, the system automatic control operation, double door electronic interlock, and a photoelectric sensor, one-way channel air shower, from the unclean area into the door, after the infrared induction of someone on the shower, after the door is locked, only from out of the air shower room;
The third point, the whole cold-rolled steel plate production, the external surface of electrostatic spray treatment;
Fourth, the door, bottom plate, nozzle are made of stainless steel, beautiful and generous;
Fifth, soft key touch type time relay, LED display and set the shower time, the range is adjustable in 10-99s, the double doors automatically lock when the shower;
Sixth, the use of initial, high efficiency two-stage filtration system, with a diaphragm high efficiency filter, filtration efficiency is 99.99%, to ensure the purification level;
Seventh, the wind speed of the air nozzle outlet is up to more than 25m/s, and the wind speed of blowing on the human body is more than 18m/s;
Eighth, the use of EVA sealing material, high sealing performance.
15 Personnel Specifications
In order to avoid and reduce clean room practitioners to clean room pollution. Any personnel outside clean room work should turn their back to clean room staff when talking to Jetstar, because the nose and mouth will emit pollution to the watching party.
Do not make the mouth and nose clean room working area.
If you cough or sneeze, cover your back to the cleanroom area with gloves and change them promptly. Those in serious condition should leave the clean room area immediately and report to the leader.
The clean room shall not be placed in the clean room work unrelated items. Clean room work items to discharge orderly.
When the equipment can not operate normally, do not repair privately, to report to the leader, such as professional maintenance of clean room.
In addition, the cleanliness of the clean room has too high requirements. Therefore, the requirements of the physical condition of the clean room staff are very strict.
People suffering from respiratory diseases cannot work in clean rooms because they will pollute the air in clean rooms
People with conjunctivitis or other secretions, or people with skin diseases are not suitable to work in the clean room.
In addition, the staff of the clean room should pay attention to their oral hygiene. Clean room staff should have regular physical health checks
16 Energy Saving in Operation
● Clean room air supply, exhaust air, fresh air should be switched freely, such as production stops, exhaust cabinet should also stop or reduce the air volume, fresh air should also be reduced.
● The process is not absolutely required to protect the operation of the fan on duty, should be started in advance of the method of self-cleaning.
● Clean room fan speed so that its pressure head can be controlled, not always in the maximum pressure head or maximum air volume operation condition.
● Operation should maximize the use of outdoor air cooling effect, and increase the fresh air ratio at this time.
● Clean room should be according to the change of outdoor meteorological conditions, through automatic control or manual control can adjust the output of equipment.
● Reduce the volume of clean space, such as clean tunnel or tunnel clean room, according to the production requirements, the clean space is divided into different cleanliness levels of the process area, operation area, maintenance area and channel area.