Proper start-up of reverse osmosis water treatment systems is essential to prepare the membranes for operating service and to prevent membrane damage due to overfeeding or hydraulic shock. Following the proper start-up sequence also helps ensure that system operating parameters conform to design specifications so that system water quality and productivity goals can be achieved.

Before initiating system start-up procedures, membrane pretreatment, loading of the membrane elements, instrument calibration and other system checks should be completed.
Please refer to the application information literature entitled “Start-Up Sequence” (Form No. 609-02077) for more information.

Operation Guidelines
Avoid any abrupt pressure or cross-flow variations on the spiral elements during start-up, shutdown, cleaning or other sequences to prevent possible membrane damage. During start-up, a gradual change from a standstill to operating state is recommended as follows:
• Feed pressure should be increased gradually over a 30-60 second time frame.
• Cross-flow velocity at set operating point should be achieved gradually over 15-20 seconds.
• Permeate obtained from first hour of operation should be discarded.
Please refer to the product technical manual.

General Information
• Keep elements moist at all times after initial wetting
• If operating limits and guidelines given in this bulletin are not strictly followed, the limited warranty will be null and void. Refer to DOW FILMTEC™ Reverse Osmosis and Nanofiltration Element Three-Year Prorated Limited Warranty (Form No. 609-35010)
• To prevent biological growth during prolonged system shutdowns, it is recommended that membrane elements be immersed in a preservative solution
• The customer is fully responsible for the effects of incompatible chemicals and lubricants on elements
• Maximum pressure drop across an entire pressure vessel (housing) is 50 psi (3.4 bar)
• Avoid static permeate-side backpressure at all times