Recently, due to the combination of fan filter unit (FFU) and secondary ice water system dry coil (DCC), it has been applied in clean rooms as a ventilation cycle for internal cleanliness. Due to its considerable flexibility and stability in use, as well as relatively stable temperature control, and the increasingly low price of FFU, this system has been widely used in clean rooms above 209E-CLASS-100. However, there are still some objective limitations to this construction method on site, especially in Class-1000 level clean rooms, where the ventilation rate is designed between 50 and 150 times per hour. Therefore, if FFU/DCC is used, Both AHU/DUCT systems have their relative advantages and disadvantages, so for cleanrooms with a cleanliness level of CLASS-1000, if AHU/DUCT systems are used in their construction, In terms of traditional construction practices, the cost is relatively low.
3.1.1.1 AHU/DUCT system:
A. The ceiling using this system is a single-layer PU ceiling, so its air ducts and related process pipelines can be installed above the PU ceiling, and the maintenance space of FFU in PLENUM of FFU/DCC system and the air duct for circulating air volume are not considered. Therefore, the height of its wall panels only considers the height required for the internal process of C/R, so its net height of C/R is relatively low.
B. Due to the lack of consideration for the installation size and area of DCC, the size of its return air wall is relatively small, which can reduce the use of storage boards and the area occupied by the return air wall within the C/R.
3.1.1.2 FFU/DCC system:
A. Using this system, in order to evaluate the installation of FFUs and the future maintenance space and circulating air ducts of FFUs, it is recommended to maintain a height of 1.5M on the upper PU ceiling of C/RCEILINGT-GRID. This space is called PLENUM because the net height required for general C/R processes is between 3M and 3.5M. If the PLENUM 1.5M height is added, the maximum indoor height of a typical building is reached. Therefore, the air ducts and related process ducts of this system are installed in the space that passes through PLENUM. Therefore, the height of the full height wall panel of this system is approximately 5.2M, which increases the use of storage panels. Higher construction is also more difficult; Due to the related process management systems passing through partition walls, there have been many issues with the airtight edge closure of warehouse board openings.
B. In order to measure the area of DCC and the pressure loss of FFU, the width of the return air wall needs to be matched with the size of DCC. Therefore, the size of the return air wall cannot be too narrow, which will inevitably increase the size of the return air wall, resulting in an increase in the use of storage boards and a relative increase in their occupancy of C/R space.
Suzhou Pharma Machinery Co.,Ltd.
2024/11/11
Gino
