Integrity Testing: Pressure Hold

Integrity testing is crucial for processes using membrane filters to ensure they meet removal criteria. While bubble point and diffusive flow are common methods, Pressure Hold Test is recommended for multi-round housings. This non-destructive test measures diffusive flow using a gauge to monitor upstream pressure change over time. The Pressure Hold value is unique to each system and calculated based on system volume and time. The formula for Pressure Hold Test is D (T) (Pa)/ Vh = ÄP, where D is diffusion rate, T is time, Pa is atmosphere pressure, Vh is upstream volume, and ÄP is pressure drop. An example calculation is provided for a 30” cartridge with a diffusive flow value of 35 cc/min. If the pressure drop during the test is less than 2.31 psi, the system is considered integral. Upstream system volume is critical and must be accurately determined for the calculation. The volume includes housing volume and piping/tubing from the inlet valve to the upstream gas valve, which can be calculated or empirically derived.

• Integrity testing is essential for processes using membrane filters

• Pressure Hold Test is recommended for multi-round housings

• Non-destructive test based on diffusive flow

• Formula for Pressure Hold Test provided

• Example calculation for a 30” cartridge

• Upstream system volume is critical for accurate testing

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