Integrity Test is very essential to evaluate whether the module/element’s present state is good or it is going to end of life. Integrity Test is really means of fiber repair procedure.
The test is very useful for OUT to IN Flow style element Like DOW and Hyflux
You will need the following to complete the fiber repair
• Concentrate tube plug
• Air supply apparatus
• Oil-free compressed air [recommended pressure: 3.0 bars (44 psi)]
• Loctite 406 glue
• Repair pins
• Personal protection equipment (gloves, safety glasses, etc.)
• Knife or diagonal cutters
Figure 1. Integrity test Feed Valve (OFF)Con. Valve (OFF)Air Inlet Valve (ON) PI Transparent TubePermeate Valve (ON)Observe whether air bubbles continuously appear
The bubble test using transparent tubes has been selected to illustrate how it is done.
1. Take the module out of the filtration mode.
2. Drain the module from the feed side.
3. Close feed and concentrate valve and keep the permeate valve open.
4. Pressurize the drained side of the module with oil-free compressed air from the air inlet valve, and slowly raise the air pressure to 1.5 bars (21 psi). Some displaced water will flow out the permeate side.
5. If large continuous air bubbles appear in the transparent tube then the module has broken fibers. Smaller and infrequent bubbles are the result of air diffusion through the pores of the ultrafiltration membrane. If leaks are confirmed, move to STEP 2.
1. Drain the module from the feed side.
2. Remove the top end cap. Keep the bottom end cap on.
3. Isolate the module to perform repair by closing valves or sealing remaining openings.
4. Place the positioning block into the concentrate outlet tube. Then put in the fastening nut. Next, put in the cylinder block and screw in the fastening bolt. [Positioning block, fastening nut, cylinder block and fastening bolt are part of the concentrate tube plug assembly.]
5. Connect the air supply line.
6. Supply oil-free compressed air to the module and slowly raise pressure to 1.5 bars (or 21 psi). 7. Provide a water stream to cover the permeate end of the fibers to help locate any leaks.
8. As the air pressure rises, continuous air bubbles will appear at the location of a broken fiber. Mark the broken fiber with a pin.
9. Continue applying air and water until all broken fibers are located and marked.
10. Depressurize the module using the air release valve.
11. If the broken fibers are near the concentrate tube plug then remove the concentrate tube plug to provide room for repair.
12. Take a new repair pin and place a drop of glue on the end of the pin. Use it to replace the fiber- marking pin immediately. Push the pin firmly into the leaking fiber. Let the repair cure for 5 minutes before trimming the extruding portion of the pin with a knife or diagonal cutters. Repeat for all broken fibers.
13. Repeat steps 4 – 8 to make sure all broken fibers are repaired.
14. To complete the repair, depressurize the membrane, remove the concentrate tube plug, and reassemble the top end cap, remove seals, and realign valves for operation.
You have successfully repaired a Ultrafiltration module!