Energy Recovery Devices (ERD) are used in reverse osmosis (RO) systems to recycle the energy held in discharged brine from the membranes. This, iSave 50 and iSave 70 are designed for use with low viscosity and corrosive fluid such as sea water. The Danfoss iSave Energy Recovery Devices all consist of an isobaric pressure exchanger and a positive displacement pump combined into one compact unit. The high-pressure booster pump is based on the vane pump principle enabling a very light and compact design. The vane pumps are fixed displacement pumps in which the flow is proportional to the number of revolutions (rpm) of the driving shaft – enabling flow control. Speed control is made by a VFD. The iSave design ensures lubrication of the moving parts by the fluid itself. All parts included in the iSave 50 & 70 are designed to provide long service life with a constant high efficiency and minimum service required.