Sterilizing filterBefore use, it must undergo sterilization treatment (such as online or offline steam sterilization, radiation sterilization, etc.). The design and operation process of online steam sterilization should focus on the high pressure difference and temperature that the filter element can tolerate. Before sterilization begins, non condensable gases and condensed water in the system should be discharged from the filter and pipeline equipment. During the sterilization process, the internal cold point of the filtration system should reach the set sterilization temperature. During the entire sterilization process, the pressure difference between the upstream and downstream of the filter element should not exceed the large pressure difference that the filter element can withstand at a specific temperature. After sterilization, clean air or other suitable gases can be introduced to cool down the system. During cooling, a certain positive pressure should be maintained to maintain the sterile state of the system.
When using a sterilizer for sterilization, the pulsating vacuum sterilization method is usually used. The sterilization process should ensure that the filter can be penetrated by steam, thereby sterilizing the filter. Whether using a filter element with a stainless steel sleeve or a bag filter, both the inlet and outlet ends of the filter should be able to pass through steam. Sterilization should refer to the sterilization parameters provided by the filter manufacturer. Excessive temperature may lead to unstable properties of the polymer material on the filter, and may affect the physical integrity of the filter or increase the extractable level.
Filters, disposable bags, hoses, and other devices may be used in sterilization filtration, which can be sterilized using radiation sterilization. Filters, bags, and hoses that have been sterilized by radiation should not be sterilized multiple times due to cumulative dose effects. If steam sterilization is further applied, it may increase the level of extractable substances, unless the irradiation and steam sterilization of the sterilization filter have been validated.
When online steam is used for sterilization of tank respirators, the reverse steam inlet method can be adopted, that is, steam is directly introduced into the tank, then passes through the filter element downstream of the respirator and is discharged upstream. But the reverse pressure difference during sterilization of the filter element should be controlled. This pressure difference should be maintained within the tolerance range of the filter element. It is recommended to use a filter element with a snap in interface during reverse sterilization, and it is not recommended to use a direct insertion filter element.