Sea water entering from the-hull, arrives at the RO desalination unit and will first pass through the water strainer which removes any large suspended matter, and then enters the Booster pump. As the seawater is pushed through the low pressure pump, the low pressure gauge will rise from zero to pressure data. The water discharged by the low pressure pump through prefilter which further reduces all suspended solids to an approximate five micron particle size. A 5 micron filter cartridge is placed before the 1 micron. Prior entering the 5 micron filter, a dosing pump is installed to inject chemical for membrane protection.
The filtered seawater then enters the high pressure pump and is discharged into the inlet of the reserve osmosis membrane module at a pressure of 800psi (55bars). Through the process of reverse osmosis potable drinking water is producted. The impurities containing largely salts (brine) stay behine and are automatically flushed overboard through the reject regulating valve.
The drinking water, also called product water, passes by a conductivity probe that measures the quality of the product water. The conductivity probe gives its signal to the controller.This controller has a green, and amber light. The amber light indicate that the product water quality is low and therefore not acceptable for drinking purpose.The green light indicates that the product water quality is good and acceptable for drinking.
The feed water temperature directly affects the product water output of the reverse osmosis membrane. Generally, as the feed water gets colder, the RO membrane output decreases and vice versa. You can compensate for the decrease in output which is due to the feed water temperature. by increasing the opreating pressure.For the tropical part of the world, the sea water temperature is considered constant through out the year.
Caution: Never exceed 1000psi of operating pressure.
On the front panel of the reverse osmosis, you can find the product water flow meter which indicates in gallons per minute(GPM) or liter per minute(LPM) the rate at which the product water is producted by the RO membranes. The other flow meter indicates reject flow rate.
The high pressure gauge indicates in pounds per square inch(psi) or bar(kg/cm2) of the operating pressure on the membrane modules. The low pressure gauge indicated the pressure discharged by the low pressure booster pump.
The low pressure gauge indicated the pressure after the pre filter this gauge should always indicates positive pressure.
Low pressure cut off is installed for pump protection. The low pressure cut off should be set for pump motor to shut off if the pressure falls below 5 Psi.
High pressure cut off is installed for switch off the high pressure pump’s motor. This is a safety feature. This should be set to switch off the high pressure at 1000psi.
Automatic pop off valve. This is a safety feature. This is should be set to release pressure at 1200Psi.
Caution:
- RO plant must be operated with harbor area or in water polluted with oil and debris.
- Please take care of the feed water quality conditions for the membrane module performance. Ensure a constant of 0.15 to 1.5 bar pressure and flow rate of 5m3/hr.
- Do not allow any back pressure on the permeate outlet, when there is no pressure on the feed supply, otherwise the membrane cushions will be damaged.
- The feed pressure to the high pressure must not fall below 5Psi.If this happens. The pump will be damaged by cavitation.
