Air conditioning system
| Type | require important points | Processing method |
| Clean air conditioner | There are certain requirements for the temperature and humidity of the air, and there are strict requirements for the size and quantity of dust in the air. | It is mainly realized by configuring filters, and configuring different levels of filters according to different purification levels. |
| Constant temperature and humidity air conditioner | There are strict requirements on indoor temperature, humidity base and accuracy. | A set of fully functional control system is required to match the air conditioning box. |
Air conditioning system composition
The air-conditioning system consists of a series of devices that drive the flow (such as pumps, fans, and compressors), heat exchangers (such as evaporators, condensers), and channels that connect each device (such as air pipes, water pipes, and refrigerant pipes). It consists of 5 A combination of cycles: A. Indoor air circulation, B. Ice water circulation, C. Refrigerant circulation, D. Cooling water circulation, E. Outdoor air circulation. The flow chart is as follows:
PS: In the flowchart, each device is explained separately, but in actual use, several devices will be combined into “equipment”. For example, the combination of evaporator, compressor, and condenser is the ice water host, indoor windmill and cooling coil It can be combined into an air conditioning box (AHU) or a small blower (FCU).
Air conditioning system classification
The five circulatory systems mentioned above are closely interlinked, and if one of them is changed, it will become another form of air conditioning system. For example, if the cooling water cycle is removed, it becomes an air-cooled ice water main engine. If the cooling water and ice water circulation are removed, it becomes a common window/separate air conditioner in the home. According to different usage requirements, choose equipment with different functions to complete a variety of air conditioning systems, such as household systems, office systems, constant temperature and humidity systems, pressure filtration systems, etc. The configuration examples are as follows:
Clean room airflow method
According to different grades, clean rooms have different airflow designs. They are mainly divided into two categories: turbulent flow and laminar flow. The turbulent flow type, as the name implies, has an irregular or turbulent airflow shape, which is mostly used for low cleanliness requirements. interior space. The laminar flow type is a uniform linear pattern. The airflow enters the room through the filter with high coverage, and the air is returned from the raised floor or the partition wall on both sides. Its advantage is that it will not be disturbed by unstable airflow and is suitable for cleaning. For clean rooms with higher degree requirements, laminar flow clean rooms are further subdivided into two types: “vertical laminar flow” and “horizontal laminar flow”:
A.Turbulent Flow
- Principle of operation:
The air is sent from the air-conditioning box through the air duct to the air filter (FFU) distributed on the ceiling of the clean room to enter the work area, and returns to the air from the suction port installed on the floor or low wall, and circulates repeatedly. - Cleanliness (class): 1000～10,000 above
- Application: In environments with low cleanliness requirements, most clean rooms use this method.
B.VERTICAL UNIDIRECTIN AIR FLOW
- Principle of operation:
The outside air is preliminarily filtered by the combined air-conditioning box (AHU), and then sent to the ceiling (air cabin) of the clean room through the air duct, and then fully cleaned by the high-coverage HEPA filter, blowing in vertically from the ceiling from top to bottom In the operating area, the remaining air is sucked into the return air from the raised floor and circulates repeatedly. - Cleanliness (class): Class 1 to 100.
- Application: Environments requiring high cleanliness.
C.HORIZONTAL UNIDIRECTION AIR FLOW
- Principle of operation:
The outside air is preliminarily filtered by AHU and sent to a single side wall. Through the filtration and promotion of the high coverage HEPA filter or the fan wall, the clean air is sent to the operation area in a horizontal state and in one direction, and then by The return air system to the side wall or ceiling is recycled, and the cycle is repeated. - Cleanliness (class): 100～1000
- Application: operating room, computer room, automated storage system.
Air flow comparison table
The cleanliness, structure, and erection cost of the above three types of clean rooms are different, and each has its own advantages and disadvantages, which are summarized in the following table:
Principles of Clean Room Air Conditioning
The purpose of using air conditioners in clean rooms is to stably control the temperature, humidity and pressure of the indoor environment, and to produce consistent and stable supply of sufficient “clean air” to the operating end (the principle is as follows: First, the outside air , OA), after being processed by various airflow processing units in its system, it is mixed with the circulating air volume (Return, RA) in the clean room to obtain a continuous supply of clean air that meets the demand and can maintain a certain pressure in the room.
The following is the basic processing procedure of clean room air-conditioning airflow: outside air (OA) passes through the Make-up Air Unit (MAU) through the primary and bag filter to filter the particles and control its temperature and humidity. Through the return air duct (Mech Chase), the indoor circulating air volume of the clean room is mixed with the supplementary air volume of the external air conditioning box, and then the mixed return air between the return air ducts is cooled to no temperature through the cooling coil (Dry Cooling Coil) The specifications required by the dust room, through the fan filter unit (Fan Filter Unit, FFU) to drive the airflow of the clean room to circulate away the fine dust and heat, and finally through the high/ultra high efficiency filter (HEPA or ULPA Filter) after filtering, supply to Operating Area.
- Differences between temperature and humidity requirements and general air conditioning The temperature of general air conditioner is about 18~26 degrees, while the temperature of clean room air conditioner must be controlled at 22~24 degrees; the relative humidity of general air conditioner is about 40%~65%; the relative humidity of clean room air conditioner is about 45% ~55%.
- Constant temperature and humidity control for special industries Since the semiconductor manufacturing process is extremely sensitive to temperature and humidity changes, most areas of its clean room must be controlled within the original set temperature ± 1°C and humidity ± 3%.
- The air distribution must be even In order to ensure that the air-conditioning system of the clean room can effectively take away the fine dust particles to maintain its cleanliness, in addition to the air velocity must reach a certain standard, the direction of the air flow must also be appropriately controlled according to different clean room levels.
- Supplement the outside air In order to prevent outdoor temperature, humidity and particles from affecting the environmental conditions of the clean room production area, and to extend the life of the clean room air filter, the indoor pressure must be higher than the outdoor pressure, so the clean room needs to be strong Make up the outside air to ensure that the room is under positive pressure. Since semiconductors and some industrial processes produce a large amount of volatile gases, exhaust gases and poisonous gases, these gases must be completely eliminated, so the industrial clean room process exhaust volume is quite large. Therefore, the external air that needs to be supplemented will be more, but it cannot be increased unconditionally, so as to avoid the escape of clean air and increase the operating cost.
- 24/7 operation monitoring Because some process devices in the semiconductor industry are extremely sensitive to temperature and humidity changes, such as the Stepper optical machine in the yellow light zone, as long as there are slight temperature and humidity changes, the accuracy of the device will deviate and the yield will be affected. And some precision components must also be placed in a constant temperature and humidity environment, so the air conditioning system of the clean room must be operated and monitored for 24 hours to ensure a stable working environment.
Dust-free aseptic clean equipment
- Clean room clean equipment function
Dust-free aseptic clean equipment is an indispensable and important component of a clean room. Its function is to help maximize the operating efficiency of its clean working environment. Before entering the clean working area of the clean room, the air shower is the equipment air shower for bathing dust. Its purpose is to treat the dust on the personnel’s clean clothes or tools, or use it between areas of different cleanliness. The Passing Box for transferring items, or the Fan Filter Unit, which is the most terminal equipment for clean room particle pollution treatment, plays a key role in it. - Other clean room construction related equipment
Other clean-related equipment, such as pressure balancer (Damper), automatic hand washing and drying machine, dust-free aseptic operation bench (Clean Bench), dust-free aseptic work booth (Clean Booth), biological safety cabinet (Biological Safety Cabinet), chemical Smoke exhaust cabinet, high efficiency filter net box group (HEPA Box), various primary filters, intermediate bag filters, high/ultra high efficiency filters (HEPA/ULPA), antistatic PVC curtains, ion generation controllers, static electricity Measuring instruments and various types of stainless steel clean equipment, etc.
Library board compartment system
The function of the partition system is not only to separate working environments of different dust-free levels, but also professional partition system planning, which not only supports the standardization and precision of the partitions at the industrial end, the efficiency of the partition area, and the solid board The internal structure design and material selection can also resist earthquake, noise and heat insulation, thereby achieving energy saving of the enterprise. The warehouse board compartment is mainly composed of steel frame, filled with various materials, such as PU foam, rock wool, paper honeycomb, aluminum honeycomb, and the outer surface is made of metal materials, such as galvanized paint steel plate, stainless steel plate, antistatic steel plate, etc. Encapsulation. In accordance with the needs of the industry, we also provide MIT-manufactured high-quality warehouse boards with the green building materials mark or the CNS14705 flame-resistant grade II, the flame-resistant grade one, and the CNS12514 fire protection for one hour and two hours.
In addition, there is also a modular design system (Modular design) that can not only be quickly assembled and disassembled, but also compatible with clean room-related equipment such as air showers and pass boxes, except for fire-fighting weak current pipelines (Fire Various systems such as weak electricity) and automated conveyor belt (Automated conveyor belt) can also be integrated together to effectively achieve temperature and humidity control between different compartments and prevent cross-contamination of particles in the air, ensuring that the original settings are maintained in the compartment area Requirements, comply with clean room specifications and meet the needs of compartments at the industrial end.
Based on materials and functions, Huayong’s warehouse board compartment system can be divided into the following four categories according to the needs of different industries:
| Flame-resistant PU foam compartment board | Fire-resistant paper honeycomb compartment board | Fire-resistant aluminum honeycomb compartment board | Fireproof rock wool compartment board | |
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| Sound insulation coefficient | 35dB | 28dB | 18dB | 30dB |
| Applicable place | Insulation room, soundproof room, machine room | Applicable to various places | Applicable to all places (especially electronic fabs) | All applicable (especially space for sound insulation, heat preservation and fire protection) |
| Certification | CNS-14705 Flame Resistant Grade Two | CNS-14705 Flame Resistant Grade Two | CNS-14705 Flame Resistant Grade Two | CNS-12514 Fire for one hour |
The peripheral equipment of the clean room is installed on the floor system, and when Taiwan is located in the Taiping area, there is an earthquake. Therefore, a stable clean room structure, except for the ceiling bracket (Ceiling Grid), the partition system (Partition System), and the floor The system is also the decisive key. According to the needs of the industry, clean room floor systems in the industry are mainly divided into the following three categories:
- Raised Floor System:
The structure is mainly constructed by aluminum alloy plus truss beams. The aluminum alloy has the characteristics of corrosion resistance, high tension, and strong support. The surface is pasted with conductive floor tiles or anti-static tiles. The floor tiles are precisely inlaid, walking quietly and silently, and the floor surface can be washed into 20%~40% of the ventilation holes, all floor components such as conductive panel coefficient, opening rate, etc., are precisely calculated by the engineers and matched with the air flow to achieve the effect of high purification laminar flow. - PVC antistatic/conductive seamless floor (Antistatic Seamless Floor):
The main body of the floor tile is thermoformed with PVC resin and mixed color materials. The PVC particle interface forms an electrostatic conductive network. The proportion is scientifically proportioned, and it has the characteristics of wear resistance, flame retardant, low dust generation and static electricity. The success or failure of the residual electricity treatment of the floor system is not only the quality control of the floor tiles itself, but also the pre-manufacturing industry of the original floor treatment before construction. In the case of conductive floor tiles, after cleaning the ground, it is necessary to first use special conductive adhesive to make the bottom, and to lay copper or aluminum foil with a professional method. Use the copper aluminum foil and conductive adhesive as the medium to conduct the residual electricity received by the surface floor tiles. To the secondary side grounding target designated by the owner to make it have a safe conductive effect. The antistatic seamless floor has good stability, low initial construction and maintenance costs, and does not require frequent use of conductive wax to maintain its effect. - Epoxy anti-acid and alkali/conductive floor:
Epoxy is a two-component material that is widely used in industrial applications. It has the advantages of abrasion resistance, pressure resistance, high toughness, strong adhesion, and convenient maintenance. It also adopts different construction methods to complete smooth and bright surfaces. Various finished products such as flow spreading mortar and glass fiber stacking method can also be applied according to the owner’s requirements. Epoxy flooring can have different characteristics by using primers of different materials before construction. For example, if you apply an acid- and alkali-resistant primer, the floor has the characteristics of acid and alkali resistance. It is widely used in laboratories or food, medicine, and biotech factories. If a primer with a conductive medium is used, the electrostatic charge can be quickly eliminated and the surface resistivity can reach 106Ω-109Ω. There are also many types of conductive materials, such as carbon-based conductive materials, metal conductive media, metal oxide composite conductive powders, etc., which can achieve different antistatic resistivities.
Planning process
| Basic clean room design principles< /td> | Other considerations |
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Planning elements of clean room
Site specification
(Floor area. Regulations. Fire protection)
Job requirements
(Temperature, humidity, pressure, vibration amplitude, noise)
Air conditioning, filtration
(Air conditioning load)
Water Supply and Sewerage
(Production line)
electrical equipment
(Power. Receiving)
Waste disposal
(Waste water. Exhaust gas)
- Basic design illustration completed
- Complete the detailed design drawing
- Construction according to design drawings
- Completion and acceptance
Testing and validation
A dust-free environment is extremely important for industries that require cleanliness. If this cleanup condition is not met, it is very likely to contaminate products or cause equipment failures. Therefore, after its construction is completed, various tests and effect confirmations are required to ensure that it functions normally and meets the relevant specifications and cannot be ignored.
Clean room test
The clean room test can be roughly divided into the following three time points.
1. As-built stage: The clean room is completed, and the equipment and personnel have not yet been stationed.
2. Static test phase (At-rest): After the clean room is completed, the equipment has been moved in but the personnel have not yet been stationed.
3. Dynamic testing stage (Operational): Equipment and personnel are produced and operated in a clean room.
PS: Not every project needs to be tested at three points in time, but depends on its type and design requirements:
The main test items of the clean room are as follows (according to the contract): airflow velocity test, leak test, cleanliness test, indoor positive pressure test, temperature and humidity test, noise test, lighting test, static electricity (ESD) test, clean room airflow parallelism Test…etc. All tests are in accordance with the two major specifications of “US Federal FS-209E” and “ISO-14644-1”, supplemented by various precision measuring instruments, to obtain the most accurate data.
Among the clean room testing items, “Cleaniness Classification Testing” is the most important. It must meet the standard range in all three working stages, and certain items must be tested before testing the cleanliness to confirm the clean room The test of the system in operation mode can reach the standard range. The forecast items include:
1. Airflow Volume or Velocity Tests of the filter screen
2. Air Pressure Difference Test
3. Installed Filter Leakage Test (Installed Filter Leakage Test).
Clean room validation
The purpose of the Cleanliness Sure effect is to ensure that the system can continuously and steadily control the air quality in the workplace, so that the finished product can maintain the established quality without contamination. Cleanroom effectiveness is especially important for the pharmaceutical industry
Validation steps and purpose:
| Order | Steps | Purpose |
| 1 | Air volume ventilation test | Confirm the air volume of the air outlet in each clean room, and count the number of air changes to verify whether it meets the design value of the clean room. |
| 2 | PAO leak test | PAO test is a very efficient test procedure. It uses smoke-like molecules (>0.3 micons) to know if the equipment or filter is leaking. |
| 3 | Cleanliness test | Check whether the clean room meets the standard value of the class area by the instrument of the particle counter. |
| 4 | Temperature and humidity test | Confirm whether the temperature and humidity of each clean room in the clean room meet the design value and are within the specification. |
| 5 | Airflow direction test | Confirm whether the pressure difference of the clean room meets the specifications, and at the same time confirm the air flow direction to avoid cross contamination and contamination of cleanliness. |
Validation project
According to the designed clean room system specifications, the main inspection items are as follows (subject to the contract):
- Wind speed, air volume (uniformity) and air exchange rate test
- HEPA filter leak test
- Airborne particulate count
- room pressure test
- airflow parallelism test
- temperature and humidity uniformity test
- clean compartment integrity test
- Recovery test: Determine whether the clean room can be restored to the existing cleanliness within a limited time (only applicable to turbulent clean room) after a brief exposure to pollution by means of smoke or random spraying of airborne particles.