Purolite IP4 is an inert polymer in the form of cylinders. It has been especially designed for use in the Fluidlite process (packed or partially packed and fluidised beds operated in the up-flow counter-flow mode). The polymer has optimum specific gravity, which together with its resistance to attrition and its ability to withstand mechanical stress ensures both excellent stability of the ion exchange bed and free flow through the strainers of the collector system during service, by eliminating the possibility of blockage of strainers with traces of resin fines. Another feature of Purolite IP4 is its ability to improve the distribution of regenerants during the downflow regeneration stage. Purolite IP4 can also be used in down flow processes with upflow regeneration, where it protects the strainers during the regeneration and improves the flow distribution during service.