- - I also thought you were thinking of a tank with water in it and then pressurizing it to 800-820 psi by injecting air. As stated that would not work
as the air would pass through the water then the membrane leaving the water behind.
- - Using a pump
like the "Clark" pump
that is in the "Spectra" water makers - an opposing dual cylinder piston pump - driven by air pressure if possibly do-able. But any piston system would have to add air to keep the pressure steady at 800-820 psi as the volume of the moving piston changes. Here you are using an intermediate motor
to drive an aircompressor to drive the water piston pump. Why not just drive the water piston pump directly and cut out the "middle man?" The extra step means extra energy (electricity needed).
- - How about switching mediums and eliminating the electricity? Use steam generated by gas flame. The old steam locomotives worked quite well and it might be interesting to hear your boat
go by making the chugga, chugga, whomp, whomp, hsss noise
as you make R.O. water. And having a steam whistle would be neat.
- - The most practical way to power an R.O. system is your engine
. A high pressure pump mounted directly on the engine
with sufficient belts to transfer the power to the pump. Then h.p. hoses to the R.O. Membrane. All the parts
necessary are available either new individually or you can purchase
from the scrap heaps of dead R.O. machines and put a system together.
- - Basic parts needed are 5 mic particulate filter; low pressure pump to suck the seawater through the filter and deliver it to the h.p. pump; R.O. membranes/container units; a h.p. regulator
valve between the output of the R.O. membrane container and the brine discharge line along with a ball valve to bypass the regulator
- - For fresh water rinsing you need a charcoal filter and a valve to supply fresh water to the inlet of the 5 mic particulate filter.
- - Some of these parts are available at your local discount home store and the others off the internet
or boat junk stores (stores selling discarded and old parts from boats).