Flow Restrictors (FLR) can clog with debris and therefore should be replaced at the same interval as replacing the RO membrane. FLR’s have various flow rates that must be properly sized to the membrane capacity in order for the RO to function properly. When changing the membrane capacity in your RO system, always install a new FLR that is properly sized to yield a proper rinse rate of approximately 3 parts to drain for every part of product water (RO) produced.