Reverse Osmosis

What is the reverse osmosis principle used in your desalinating system?

Sea water is forced at high pressure through the membranes which act as "molecular sieves", only allowing pure fresh water to pass through. Most dissolved solid particles will not penetrate the membranes. This waste, along with the remaining saline solution, will flow on the surface of the membranes and will be rejected.

Not all particles dissolved in sea water can be eliminated. The system is designed to reject 99% of the TDS (Totally Dissolved Solids); approximately 2% of the 35,000 PPM/TDS will pass through the membranes. This guarantees drinking water with a TDS value of 500 (average).

Please note that the drinking water produced by your reverse osmosis system is essentially sterile, however, your fresh water storage should be treated periodically with a slight dose of chlorine (or iodine) to ensure it remains consumable.

Pay attention not to allow pure chlorine (or a too high dose of chlorine) into the desalination system, as this could damage the device.

How does your watermaker work?

Sea water enters the inlet valve which penetrates the hull. This sea water is then routed by the pre-pump through the 25 µm and 5 µm pre-filters. The filtered water is forced through the membrane by the HP pump (operating pressure 60 to 65 bars). The pressurized water passes through the surface holes of the membranes depositing the salt and minerals, which are then rejected into the sea with the remaining solution.
The now fresh water flows over a detector which measures its salt content: If the desalination achieved is satisfactory, the three-way valve automatically directs the fresh water to the tank. If the salinity values measured by the salinity probe are too high (conductivity > 1,000 siemens), the valve will reject the water produced into the sea.

The volume of drinking water being treated at any time is monitored by a flowmeter on the control panel.

Membranes - Delicate Components

Reverse osmosis membranes must be carefully maintained as they are the most delicate elements of the reverse osmosis system. We recommend that the maintenance instructions are carefully followed to prevent the membranes from damage and to ensure the guarantee is not invalidated. Maximum production capacity of the desalinator is achieved with a sea water temperature of 25°C. The functioning of the membranes will vary depending on the temperature of the sea water and on the sailing area. Output drops by approximately 2.5% to 5% for each degree below 25°C.

Extreme temperatures:

The membranes should not be exposed to temperatures below 0°C. Overpressure due to expansion caused by freezing can rupture the membranes and prevent the salt from being filtered out. The membranes must not be exposed to temperatures above 60°C, as high temperatures may also prevent salt from being removed.

Drying out of the membranes:

The membranes should be permanently immersed in liquid: either sea water before treatment, fresh water provisionally stored or sterilizing liquid if the water maker is not used for extended periods of time (Sterilizer is effective for six months and must be replaced after this period of time).

Recommendations for use:

The various quality and salinity grades of sea water affect both membrane efficiency and the working of the desalinator in Marinas. The system is not recommended for use in muddy or polluted water (briny water, river, Red Sea), which can clog and damage the membranes. However, if the desalinator has to be used in such conditions, only run it for very short periods and as soon as clean sea water becomes available clean the membranes and run the system without pressure for 30 minutes with the pressure regulator open.