1. Installation

Install the hollow fiber module and connect all tubing. Place the feed tubing into purified water, and place both the retentate tubing and permeate tubing into a waste container.

 

 

2. Cleaning

Start the peristaltic pump. Once the retentate tubing is completely filled with liquid, adjust the retentate valve to establish an appropriate transmembrane pressure (TMP) throughout the system.

Measure the pH of the liquid discharged from both the retentate and permeate outlets until the pH values become neutral.

 

3. Wetting

Stop the peristaltic pump. Immerse the feed tubing, retentate tubing, and permeate tubing in purified water.

Restart the peristaltic pump. After the retentate tubing is filled with liquid, adjust the retentate valve to maintain an appropriate transmembrane pressure (TMP), and thoroughly wet the hollow fiber membrane for 15 minutes.

After wetting, stop the peristaltic pump and fully open the retentate valve.

 

4. Draining

Remove the feed tubing from the purified water.

Start the peristaltic pump to drain all remaining liquid from the feed tubing and retentate tubing.

 

5. Integrity Test

Completely close the retentate valve and immerse the permeate tubing outlet in water.

Start the peristaltic pump to introduce compressed air until the feed pressure reaches 0.65 bar.

Stop the peristaltic pump and maintain the pressure for 10 minutes.

 

6. Measurement of Air Diffusion Flow

During the 10-minute holding period, observe whether the pressure decreases and whether bubbles emerge from the permeate outlet.

• If the pressure remains stable and no bubbles are observed, the hollow fiber module passes the integrity test.
• If pressure drops and bubbles are present, measure the air diffusion flow rate at the permeate outlet using either a flow meter or an inverted graduated cylinder filled with water.

Compare the measured air diffusion flow rate with the manufacturer's reference value to determine whether the hollow fiber module meets the integrity acceptance criteria.

Since the acceptable air diffusion flow values vary among different manufacturers, the final acceptance criteria should always follow the specifications provided in the corresponding product manual.

 

7. Air Release

Fully open the retentate valve to release all residual air from the system.

 

 

 

Potential Causes of Failed Integrity Testing and Corrective Actions

1. Has the Membrane Module Been Fully Wetted?

Before performing an integrity test, the hollow fiber membrane must be completely wetted with water.

It is recommended to circulate purified water through the hollow fiber module for 5–10 minutes before testing.

Insufficient wetting may significantly affect the integrity test results.

Because ultrafiltration hollow fiber membranes have very small pore sizes and extremely high bubble point pressures, the air diffusion flow method is generally preferred for integrity testing.

 

 

2. Is the Installation Correct?

A. Gasket Condition

Gaskets should be replaced regularly.

Long-term use may reduce gasket elasticity, resulting in poor sealing performance and causing integrity test failure.

B. System Leakage

Inspect the pressure gauge, clamps, and all connection points for possible air leakage.

Ensure the entire system is properly sealed, as leakage may prevent pressure holding and lead to inaccurate test results.

 

 

3. Are There Any Residual Process Fluids, Cleaning Agents, or Storage Solutions?

Residual process fluids, cleaning agents, or preservation solutions may prevent the membrane from being completely wetted.

It is recommended to thoroughly clean the hollow fiber module again, increase the rinsing volume, extend the cleaning time, and raise the cleaning temperature when appropriate to improve cleaning effectiveness.

 

 

4. Hollow Fiber Membrane Damage

If all of the above factors have been eliminated, the hollow fiber module itself may have failed the integrity test.

Possible causes include:

A. Physical damage caused by dropping or impact during transportation.

B. Hard particles in the system, such as metal debris from a new system or solid contaminants in the process fluid, may scratch or puncture the membrane.

C. Excessive force applied during installation may damage the membrane structure.

D. Inappropriate cleaning chemicals or storage solutions may damage the membrane material.

E. Severe membrane fouling or irreversible blockage that cannot be effectively cleaned may gradually compromise membrane integrity over prolonged use.

If the hollow fiber module fails the integrity test due to membrane damage, replacement with a new hollow fiber module is recommended.