11
Membrane cleaning. Working pressure 0 bar!!!
Description:
When the fresh water production decreases more than 15 %, the membrane should be
cleaned chemically.
Caution
:
Cleaning chemical no. 1 is alkaline and cleaning chemical no. 2 is an acid. Please consider
the hazard notes on the canisters. Working with chemicals, please wear protective glasses,
breathing protection and rubber gloves for your own safety. Do must not mix different
chemicals.
Follow instructions below to avoid that chemical get into your fresh water tank.
Cleaning of membranes. Working pressure 0 bar!!!
Instruction for cleaning
Attention:
Make sure that you follow the following instructions carefully so that no cleaning chemical
gets into your fresh water tank.
1) Close the seawater intake valve.
2) Open the
pressure control
valve entirely, turn the product water three-way valve (no. 2)
to position
test-outlet
to avoid that chemicals get into the drinking water tank.
3) Rinse the system with fresh water as described in “Fresh water flushing”.
4) Turn the 3 three-way valve (no. 4) according to the flow diagram “Long term preservation
(mothballing) of the plant”. Open valve (no. 1).
5) Blend about 5 liters warm chlorine-free fresh water, temperature appr. 25° Celsius (77°
Fahrenheit), with chemical no. 1 (Alkaline), according to the instructions on the package.
Since there are about 1,5 liters of water already in each membrane and 1 liter of water in
each filter, please add the according amount of chemical to the water that has to be
blended in every membrane and filter.
6) Switch on the feed pump and the high-pressure pump. The unit is run for an 5 minutes to
circulate the solution through the membrane. Temperature of the solution must not exceed
more then 45° Celsius. Then allowed to rest for an hour, and then run again for 5 minutes.
Perform possibly exiting the test outlet liquid back into the preservative tank.
7) The chemical in the tank can be discharged overboard after turning the three-way valve
(no. 4). It should be noted that the system gets no air.
8) After this, the system is put back into service, unpressurized, and run for 15 minutes or so
to clear out the cleaning solution, before being returned to regular service. Once again, the
initial product water will need to be discharged for 30 minutes over the test outlet.
9) If there is no change in freshwater output, repeat the procedure 1 to 7 with chemical no. 2
(Acid).
Attention:
Prior to a longer period of shutdown, the Aquatec has to be preserved with Biocide after
cleaning and flushing.
Caution
:
At every recommissioning after cleaning or mothballing, divert the product water over the
test-outlet for the first 30 minutes to rinse the chemical completely out of the system.
