PDA TR03-2013 "Various procedures for maintaining hot zone integrity with pressure differentials between the sterile core and the prparation area available. As depicted in Figure 4.1.3-1,continuous sterilizer airflow should be in balance with the exhaust and should move from the cool zone to the entry zone maitaining positive pressure in order to provide a sterile barrier.Differential pressure ranges across these zones will minimize cool zone air entry into the discharge area."
隧道烘箱的压差就是为了防止污染,只要无菌区域对非无菌区域正压即可,有些设备时设计为中间高两边低,也有采用冷却向预热一个方向的压差,都能够避免外部的污染。对应无菌附录征求意见中穿越级别的鼠洞要证明气流流向,只要能保证气流流向,形成正压即可,也没听说哪里有具体的压差值的要求。