The clean room exhaust of pharmaceutical facility directly affects the fresh air volume of the air conditioning system. Reducing room exhaust can reduce the fresh air volume of air conditioning system, so as to achieve energy saving & emission reduction.
Room air balance: fresh air and clean room return air are mixed in AHU and sent to clean room through the air duct after treatment. Part of the supply air returns to the AHU, part is discharged to outdoor and part is leaked from the clean room.
Reducing the room exhaust is realized by reusing return air and reducing the local exhaust of the process equipment, which are discussed as below.
1.Reuse return air
To prevent cross contamination, reuse return air in clean room is not always acceptable. It is recommended to perform a risk assessment and take the below solutions during the design and equipment selection phase if possible, such as
•Closed material transfer
•Operation with isolator
•The opening operation with dusty materials or bioactivity should be separated from normal one, so as to reduce the full exhaust area
•Reasonable area division to reduce the areas with risk
•Consider delegated air conditioning system for high risk areas
Reduce the system risk by process and layout optimization, and equipment selection. The system optimization and risk assessment can be carried out by cases, and the return air can be reused if the risk is acceptable.
2.Reduce local equipment exhaust
During equipment selection, the following equipment is recommended to reduce local exhaust.
A1 and A2 type BSC should be selected if possible, and the exhaust air can be discharged into the clean room.
The fume hood which is equipped with HEPA for internal circulation can be selected if the process and operation accept.
The isolator exhaust is discontinuous and variable. If the make-up air is taken from clean room, it will affect the stability of the room pressure. The following solutions are recommended during equipment design and selection.
It’s recommended to take the isolator make-up air from CNC area, the air intake and exhaust are handled by isolator without affecting the pressure of the clean room.
Alternatively, if the isolator equipped an exhaust treatment system, the exhaust air can be discharged into the clean room after treatment.
The clean room laundry dryer with HEPA filter can take make-up air from outside, with the application of this machine the room exhaust volume can be reduced.
The HVAC energy consumption of pharmaceutical plants is high. It is recommended to reduce room exhaust by process and layout optimization, equipment selection, and risk assessment during the system design phase to achieve energy saving & emission reduction.