Abstract: Either of the two relatively large capacity tanks can be connected in a high pressure loop or system including a reverse osmosis membrane vessel and a circulating pump. When the pressure is high enough in this loop, product is drawn from the vessel. A feed pump supplies fluid to the tank not in the high pressure system for flushing that tank. The feed pump also supplies fluid to the input of a high pressure pump which provides make-up fluid to the high pressure system at a pressure sufficient to sustain reverse osmosis. The tanks are interchanged periodically. This system only has to provide high pressure fluid at a rate equivalent to the rate of withdrawal of product from the system.

Abstract: The reverse osmosis membrane is mounted inside a tubular container and has a central passage which connects at each end to a central conduit in the associated end cap. One conduit is plugged and the other is the clear product outlet. Sea or brackish water enters an inlet in one end cap and passes through the membrane to leave via an outlet in the other end cap. The end cap in the inlet end of the container is sealed with respect to the container so sea water must flow through the RO membrane rather than between the membrane and the container. The other end cap is not so sealed and outlet sea water can flow into the space between the RO member and the tubular container. A very small bleed hole allows inlet sea water to by-pass the RO member and flow from the inlet into the space between the member and the container. The low volume flow flushes the space to prevent build-up of algae and the like.