Precautions when reverse osmosis system shut down

Precautions when reverse osmosis system shut down

1) By using treated water flush the reverse osmosis system to flush out the concentrated water on the surface of membrane to prevent salt precipitation pollution.

2) During low-pressure flushing do not add other chemicals such as inhibitor.

3) First please open the product water discharge valve to prevent back pressure.

4) The drop of flow rate and pressure shall be slow, pay attention to the feed water flow rate should not excced the limit value.

Management during daily shutdown (0-48 hours)

1) During the daily shutdown period, shuold flush once every 24 hours to prevent the growth of microorganisms.

Management of system shutdown (2-25 days)

1) After shutting down, ensure that the pressure vessel is filled with product water produced by RO, and close all inlet valves, concentrated water valves and product water valves to prevent the membrane elements from drying out and the growth of microorganisms.

2) When the temperature is greater than 20 degrees Celsius, it is necessary to flush once every 12 hours; when the temperature is less than 20 degrees Celsius, flush once every 24 hours.

3) For ground water or water sources with high microbial pollution, the reverse osmosis system shall be flushed with a solution containing 1.0% sodium bisulfite prepared from RO product water. If the membrane elements are soaked with this solution at the same time, the effect will be better. The flushing cycle also shall be extended accordingly.

4) During the system shutdown, the temperature should be kept between 5℃-45℃. Low temperature is conducive for the preservation of membrane elements, but should prevent the reverse osmosis system from freezing.

Management during long-term system shutdown (25 days or more)

1) Follow the normal shutdown procedure and flush the system with product water at low pressure.

2) It is better to perform a chemical cleaning and sterilization treatment process. After cleaning, flush the system with RO product water at low pressure until the conductivity of the concentrated water is same as feed water.

3) Prepare a protective solution containing 1.0% sodium bisulfite with product water produced by reverse osmosis. Rely on the chemical cleaning system to circulate the membrane elements to remove the air from the pressure vessel and completely soak the membrane elements in the protective liquid to prevent the membrane elements from drying. , Close all inlet valves, concentrated valves and product valves, to prevent air from entering and invalidating the protection liquid.

4) Check the pH value of the protection liquid every week. When the pH is lower than 3, please replace the protection liquid timely.

The shutdown sequence of reverse osmosis system

1) Slowly close the inlet water control valve and open the concentrated water control valve to maintain the designed concentrated water flow

2) When the discharge flow of the high pressure pump drops to the minimum flow, stop the operation of high pressure pump

3) Adjust the state of the pretreatment dosing device

4) Flush the system by RO product water, ensure that the concentrated water is completely removed from the pressure vessel (at this time, concentrated water conductivity = flushing water conductivity)

5) When the flushing is completed, close the concentrated water valve and product water valve

6) The back pressure of product water side must not exceed 0.07Mpa, reverse osmosis system shall be filled with water, suggest that install a check valve on the concentrated water and product water pipes, to prevent siphoning.

7) Ensure that the membrane elements have been kept moist, and have undergone proper disinfection and antifreeze protection during the entire shutdown period

8) During the shutdown period, make sure that the temperature and PH value of the preservation solution are in full compliance with the specifications.

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