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Characteristics of clean room air conditioning system
2024/12/3
Clean room technology starts relatively in our country, but the development speed is extremely fast. Clean Room air conditioning system is the foundation for clean room air control. Therefore, it is really necessary to carry out heavy professionalism and strict system management for clean room air conditioning system from selection to maintenance.
Characteristics of clean room air conditioning system
1, large air volume:The clean room is mainly to filter the dust and bacteria in the air through the circulation of air volume, so as to achieve the control of non-biological particles and biological particles in the air and achieve the clean standard. Therefore, it is necessary to have enough air volume to ensure the cleanliness of the room. The air volume of the clean room is generally calculated according to the number of air changes in the room, usually 10 times, or even dozens of times, especially in the unidirectional clean room, the number of air changes reaches hundreds of times the volume of the room.
The strength of the air handling unit is a test, the current market common air handling units are the use of aluminum alloy frame structure, square steel structure is more, if the thickness of the panel and the strength of the frame is not enough, it is easy to cause the deformation of the air handling unit. Therefore, the strength of the air handling unit is higher.
2, the pressure head of the fan:
Clean room is generally at least the use of primary, middle and high three filter filtration, and the resistance of the three filter added up to about 700 ~ 800 pa, clean room generally also use centralized delivery, return air, to ensure that the clean room to maintain the requirements of positive and negative pressure regulation, so the clean room pipeline resistance is generally more than double that of ordinary air conditioning. To overcome these resistance, it is required that the blower of the air handling unit has enough pressure head, so the air supply unit of the air handling unit in the clean room generally uses a backbent airfoil fan, or a fan without a cavity shell, in order to achieve a high enough return air pressure head.
In this case of large air volume and large pressure head, the air leakage rate of the unit is also a test, and the lower the air leakage rate of the clean room air treatment unit, the more energy will be saved for the customer, and the lower the operating costs.
3, temperature and humidity control precision:
Different from the ordinary comfort air conditioning to meet the requirements of personnel comfort, the precision of temperature and humidity control in the clean room is to meet the process requirements, such as in the manufacture of some electronic products, the control requirements of temperature and humidity are very strict. In order to achieve constant temperature and humidity, it is required that the air handling unit must at least have functional segments such as refrigeration, heating, humidification, and dehumidification, and it needs a precision control method; If the heat exchanger should use high-efficiency hydrophilic fins, and the water flow is controlled by proportional integration, the humidification amount should also be adjusted by proportional integration or PID, in order to achieve higher control accuracy.
4, positive and negative pressure control is strict:
Whether it is an electronic workshop or isolation ward, pharmaceutical factory, laboratory animal room, etc., in order to prevent the spread of dust and bacteria to other clean areas, or to prevent the spread of viruses and bacteria caused cross infection, the positive and negative pressure control of clean rooms is very important, and accurate and effective control of positive and negative pressure is extremely critical. In practical engineering applications, industrial clean rooms are generally maintained by positive pressure, but negative pressure control is used for biological clean rooms that use toxic and harmful gases or use flammable and explosive solvents and other special requirements. In order to have an accurate pressure difference control value, the clean room air handling unit requires a lower air leakage rate in order to have a higher control accuracy.
5, with a good filtration system:
Industrial clean room is mainly to control pollution, to ensure the qualified rate of products, in order to meet the process design requirements of the industrial clean room requirements to strictly control the amount of dust or even to achieve dust-free, which will rely on a set of good air filtration system to complete. The degree of control of clean technology on microorganisms, dust, etc., mainly depends on the performance of the filter. The clean room is generally at least three levels of filtration, the air handling unit is equipped with primary and medium efficiency filters, and the air supply end is equipped with high efficiency filters. The air filter needs to have good quality, and once a leak occurs, it is no longer possible to achieve clean. In addition to not having any leakage itself, the seal of the filter in the air conditioning box should also be noted.
6, considerable stability and reliability:
The high development of modern industry makes industrial products have the characteristics of small size and high value, if the clean air conditioner fails, it will bring thousands of losses, so it requires the air conditioning unit to have considerable stability and reliability, in addition to the requirements for the purchase of every part of the air handling unit with good quality products and careful selection of filters. The inspection and maintenance of the air handling unit and the entire return air system is also a management maintenance that requires professionals in strict accordance with the regulations.
7, meet the requirements of special process:
For example, some products need to use chemical agents, so the unit requires corrosion resistance, and some need to use explosive gases, which requires the air handling unit to be explosion-proof and anti-static, and some processes have high requirements for vibration, so the air handling unit must have better shock-proof measures.
Clean room air conditioning maintenance experience
1, because the dust in the air duct through the filter of the medium efficiency filter has removed 90% of the dust, such as regular replacement of the air duct pollution is much better than the general air conditioning duct, so the internal thorough cleaning of the air duct system is not absolutely necessary, cleaning once every two years is acceptable for clean rooms with higher cleanliness. In addition, the vibration caused by cleaning the air duct will seriously affect the dust amount and working air flow requirements of the clean room, so it is recommended to construction during the maintenance shutdown.2. The PIP(Permanent Inspection Point) air duct inspection system is recommended to be installed to facilitate the monitoring of dust, air volume and wind speed inside the duct.
3, in order to reduce the source of dust, it is necessary to thoroughly clean all surfaces in the upper and lower technical interlayer, and it is also recommended to cause vibration during the work period to avoid affecting the dust volume of the clean room. For clean rooms above the thousand level, the interior of FFU should also be thoroughly and regularly cleaned.
4, pressure difference control is a significant work, frequent testing workload, completely based on experience and feeling is not advisable, it is recommended to use AHU electric air volume regulator. The final resistance of the ultra-high efficiency filter reaches 400-600Pa. It is recommended that the high efficiency filter should be replaced, and the following other situations occur, the high efficiency air filter should also be replaced:
1) The air flow speed is reduced to a minimum, even after the replacement of the primary and medium effect air filters, the air flow speed can not be increased;
2) The air volume of high efficiency air filter is 70% of the original air volume;
3) The high efficiency air filter has irreparable leakage.
5, in general, compared with the general air conditioning metal duct, there are four different requirements for the use of air conditioning metal duct:
1) The air duct should be kept clean;
2) High sealing requirements;
3) High flatness requirements;
4) High static pressure in the air duct.
Clean room air duct system to ensure tightness, strict detection of air duct leakage, it is best to carry out regular light leakage test or air leakage test, monitoring flange or thread tightness, welding or sealant treatment if necessary.
6, the successful completion of clean room air conditioning maintenance and cleaning requires a variety of resources and technology, including the cooperation of manufacturers and component suppliers and personnel with clean room maintenance experience.
