The KVP is mounted in the suction line after the evaporator and is used to: 1. Maintain a constant evaporating pressure and thereby a constant surface temperature on the evaporator. The regulation is modulating. By throttling in the suction line, the amount of refrigerant gas is matched to the evaporator load. 2. Protect against an evaporating pressure that is too low (e.g. as protection against freezing in a water chiller). The regulator closes when the pressure in the evaporator falls below the set value. 3. Differentiate between the evaporating pressures in two or more evaporators in systems with one compressor.