Bureaucrat, staff, administrator
4,335
edits
Changes
m
→Installation and Maintenance
= Watermakers Produce Fresh Water Every Day =
Before the invention of devices to desalinate seawater, sailors had to carry enough water on board for an entire voyage between land-falls. Water stored for long periods attracts bacteria, making it taste sour. Modern watermakers remove this burden, producing fresh water every day. Although there are several means of desalinating seawater, the only practical marine application is a [https://en.wikipedia.org/wiki/Reverse_osmosis reverse-osmosis ] watermaker.
For example, a relatively new watermaker technology uses a type of dehumidifier to condense water from the air. Manufacturers include companies such as Air Eater Proprietary Limited, Hyflux and Vapaire Water Purifier. But the capacity of such systems is limited, around 1 litre/hour (6.25 gal/day), in conditions of 45 to 60% humidity. These systems, while interesting, clearly do not meet the daily output requirements of a boat.
Reverse osmosis is the process of causing pure water to move out of the solution and through the membrane to the other side. To accomplish this, a high-pressure pump must be used, around 800 psi. The process is not very efficient, either. About 90% of the seawater and energy are wasted. In some designs, notably Spectra and Livol, this energy is partially recovered by applying it on the backside of the piston in the pump.
=== Pre-Filtration ===
To prevent clogging the membranes, a pre-filtration system can remove particles of sand and organic matter down to 1 micron in size. Install a back-washed sand filter at the inlet. Use a series of filters (e.g., 50-25-5-1 micron) to remove other particles. If you put the finer filter first, it will clog immediately. Install an oil-water separator to remove oil. An absorption/reactive carbon filter will remove taste, odour, chlorine and organic chemicals.
=== Post-Filtration ===
A second carbon filter can capture chemicals not removed by the reverse osmosis membrane. An ultraviolet lamp can sterilize any microbes that may escape filtering by the reverse osmosis membrane.
== Right Sizing the Capacity ==
Once you have determined the capacity required in GPH, pick a model close to this which has the best GPHA (GPH/AH) rating. Next, analyse the impact on the electrical system. If that doesn’t calculate-out the way you would like, repeat the exercise with a modified scenario.
== Installation and Maintenance == For cold water expeditions, the water intake to the watermaker should be preheated.
See [[WatermakerInstallation]] and [[WatermakeMaintenance]].
[[Category:FreshwaterSystems]]