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Composition and working principle of clean shed
Composition and working principle of clean shed(I) ComponentsThe clean shed is mainly composed of a box, a fan, a primary air filter, a damping layer, lamps, etc., and the outer shell is sprayed with plastic. Its frame materials usually include industrial aluminum, stainless steel square tubes, iron square tubes, and other spray-painted options. The industrial aluminum frame is stable, beautiful, rust-free, and dust-free, and is one of the more common choices. The role of the frame is not only to support the structure of the entire clean shed but also to ensure that it can remain stable in various environments. The primary air filter is the first line of defense for the clean shed, mainly used to filter larger particles of dust, such as dust particles above 5μm. It can effectively block dust, hair, and other impurities in the air, and protect subsequent filtering equipment and work areas. The fan is the core power source of the clean shed, and a centrifugal fan is usually used. This fan has the characteristics of long life, low noise, maintenance-free, low vibration, and stepless speed change. Coupled with the unique air duct design, the efficiency of the fan is greatly improved and the noise is reduced. The fan filter unit FFU is a key component for the clean shed to achieve high cleanliness. The FFU is equipped with a high-efficiency filter inside, which can filter out dust particles below 0.5μm and various suspended solids, ensuring that the air delivered meets the high cleanliness requirements. The damping layer reduces vibration and noise in the clean room, providing a quieter environment for the work area. The lamps generally use purification lamps specially used for clean rooms, which do not produce dust, provide sufficient lighting for the clean room, and do not pollute the clean environment. (II) Working principle The work of the clean room mainly depends on the FFU fan filter unit. The fan draws air from the top of the FFU, first passing through the primary filter for the first filtration to remove larger particles of dust. Then, the air is filtered more finely through the high-efficiency filter. The high-efficiency filter can capture and remove tiny particles, and its dust collection rate can reach 99.97% - 99.99995%. The air filtered by this filter is very clean. The filtered clean air is uniformly delivered to the clean room at a wind speed of 0.45m/s±20% on the entire outlet surface, forming a uniform flow layer, so that the clean air flow is vertical and unidirectional. This vertical unidirectional airflow pattern can ensure the required cleanliness in the work area. In this process, the airflow in the clean room is an important factor affecting the performance of the clean room. Generally, the airflow speed of the clean room is selected between 0.25-0.5m/s. This airflow speed belongs to the breeze area and is easily disturbed by the actions of people, machines, etc., and tends to be chaotic. However, although increasing the wind speed can suppress the influence of this disturbance and maintain cleanliness, it will increase the operating cost due to the increase in wind speed. Therefore, when the required cleanliness level is met, the most appropriate wind speed should be supplied to achieve an economic effect. On the other hand, to achieve a stable cleanliness effect in a clean room, maintaining uniform airflow is also an important factor. If the uniform airflow cannot be maintained, it means that the wind speed is different, especially on the wall, the airflow will vortex along the wall, and it is difficult to achieve high cleanliness at this time. To maintain uniform airflow in the vertical laminar flow direction, there must be no speed difference between the wind speed on the blowing side and the wind speed on the suction side of the floor return air plate. If the speed is too low or too high (0.2m/s, 0.7m/s), eddy currents will occur, while at a speed of 0.5m/s, the airflow is more uniform. In general, the wind speed in clean rooms is between 0.25 and 0.5m/s. |
