Trotter A M, Meltzer T H
Sartorius Corporation, Edgewood, NY, USA.
PDA J Pharm Sci Technol. 1998 Jul-Aug;52(4):182-5.
The pressure-drop/hold procedure enables the diffusive flow integrity testing of filters to be performed without breaching the system downstream of the filter. It is not necessary to measure volumetrically the diffused gas on the downstream side of the filter. By means of pressure transducers the pressure loss is determined upstream; thus eliminating the threat of sepsis due to down-stream invasions. The pressure decay exercise can be used to characterize the various filter types. A constancy of filter manufacture is required for a given filter type. Unless the pressure drop exceeds the value established as the maximum allowable decay, the filter is judged to be integral. It qualifies as a sterilizing grade filter. Excessive pressure decays will also eventuate from leaks, as from improperly sealed housings. Performed prior to the filtration, the procedure serves to eliminate the wasteful use of an imperfect system, whether caused by faulty sealing, incorrect filter type or flawed filters. Where leaks are detected, the filter can be reexamined for its integrity. To enable the pressure-drop procedure to serve as an integrity test, the measured pressure decays require being correlated with organism retention data. This is made possible by the arithmetic conversion of the pressure decay curve into the conventional diffusive airflow curve established to have such a correlation. The transformation of the pressure-drop curve into the differential airflow plot is automatically performed by certain of the automated integrity test machines. These devices, utilizing pressure transducers, are capable of measuring small pressure drops with requisite sensitivity; gauges commonly are not. Moreover, as previously stated, the measurements are advantageously made on the upside of the filter. The use of automated test machines is, therefore, recommended for the performance of the pressure hold/drop integrity test in furtherance of the practice of filter integrity testing.
压降/保压程序能够在不破坏过滤器下游系统的情况下对过滤器进行扩散流完整性测试。无需对过滤器下游侧的扩散气体进行体积测量。通过压力传感器确定上游的压力损失；从而消除了下游侵入导致败血症的威胁。压力衰减试验可用于表征各种过滤器类型。对于给定的过滤器类型，要求过滤器制造具有一致性。除非压降超过设定的最大允许衰减值，否则该过滤器被判定为完整。它符合除菌级过滤器的标准。密封不当的外壳等泄漏也会导致压力过度衰减。该程序在过滤之前执行，用于消除因密封不良、过滤器类型错误或过滤器有缺陷而导致的不完善系统的浪费使用情况。在检测到泄漏的情况下，可以重新检查过滤器的完整性。为了使压降程序能够用作完整性测试，需要将测得的压力衰减与微生物截留数据相关联。通过将压力衰减曲线进行算术转换，使其成为已建立有这种相关性的传统扩散气流曲线，这一点得以实现。压降曲线到微分气流图的转换由某些自动完整性测试机器自动执行。这些利用压力传感器的设备能够以所需的灵敏度测量小的压降；而普通仪表通常做不到。此外，如前所述，测量最好在过滤器的上游进行。因此，为了推进过滤器完整性测试的实践，建议使用自动测试机器来进行保压/压降完整性测试。
