|
ULTRAFILTRATION CARTRIDGE SANITATION
As part of a weekly scheduled maintenance program, sanitize the UF Cartridge to be certain that the system remains pyrogen-free. If necessary, the system can be tested for the presence of pyrogens using any suitable pyrogens test kit.
The Milli-Q system has a Luer-Lok sanitation fitting and ball valve and it is possible to inject the sanitizing agent onto the UF housing without removing any of the other cartridges. A Luer slip syringe is required for the injection.
Shut off pump
De-activate auto recirculation timer
Close feedwater supply valve
Open 3-way valve, relieving internal pressure. Leave open until no more water exits final filter unit. Leave flush-valve open.
Mix solution of 3-4ml 5.25% sodium hypochorite with 100ml purified water. (Substitute standard household bleach if it has a concentration of 5.25% sodium hypochlorite). This should produce a level of 200 ppm (or less) when mixed the water in the UF cartridge bowl. Damage to the UF membrane may occur if concentration exceeds 200 ppm.
Fill 50ml syringewith solution.
Insert tip of the syringe into the Luer-Lok® fitting, and twist to lock into place.
Open valve on sanitation fitting.
Inject 100ml of chlorine solution.
Using same syringe, flush sanitation fitting with 50-100ml RO, distilled or prefiltered water.
Close sanitation fitting valve. Leave 3-way outlet valve open so that bleach cannot get into the upstream housings.*
Open feedwater supply valve.
Turn on the pump immediately. Run for about 15 seconds until the housing fills with water. Simultaneously shut off feedwater supply valve and the pump.
Leave system standing idle for about 35 minutes.
Leave flush valve open and open the feedwater supply valve. This will allow the bleach to be flushed from the system. Flush for at least five minutes.
Close flush valve and start pump. Continue to flush the cartridge for ten minutes, through the final filter.
Reopen the flush valve and flush the cartridge for an additional one or two minutes.
Close the flush valve.
Check the chlorine level in water taken from the flush valve and the 3-way valve. Should read = 0.1 ppm.
If chlorine level is <0.1 ppm, close the 3-way valve, start the pump and recirculate the water until the proper resistivity level is reached. If the chlorine level is >0.1, repeat the previous two steps.
*To use the Recirculation Timer overnight instead of allowing the system to stand idle for 35 minutes, substitute the following for the next seven steps.
Open the feed valve and activate the timer. Be sure the 3-way valve is open.
Check the residual chlorine level before resuming normal operation, as instructed in remaining instructions.
ULTRAFILTER CARTRIDGE CLEANING
The UF cartridge may become increasingly fouled from colloids or particulate contaminants in the feedwater during normal use, reducing product flow. Sanitation may restore the flow, but if it doesn't, it may be necessary to remove the cartridge from the bowl and clean it as follows:
Prepare a 1 N solution of 40 grams of NaOH (hydroxcide--from pellets) per liter/151 grams per US gallon of Milli-Q feedwater.
Remove UF cartridge and soak it in the solution for at least 12 hours.
After replacing the UF cartridge in its housing. disconnect the outlet tubing to the final filter, take the final filter out of its housing and release the 3-way valve.
For at least five minutes, flush the cartridge, opening and closing the flush valve on the UF housing until the pH of the product water reads <7. When all of the residual NaOH is gone, return the system to normal operation.
|
|
