These carefully designed and manufactured Constant Flow Regulators accurately control the flow rate from refrigerant liquid pumps. They modulate to maintain a precalibrated ideal constant flow of refrigerant independent of pressure changes. A properly-selected flow regulator can minimize the tendency of a pump to operate in a high NPSH pump region of the pump curve and consequently cavitate , and thus possibly lose prime and cease pumping. These Constant Flow Regulators are designed for refrigeration systems. While primarily intended to be installed at the outlet of refrigerant liquid pumps, these versatile regulators can be used to control flow to individual circuits of large evaporators in place of hand expansion valves or other balancing devices in liquid overfeed systems.