The KVP is mounted in the suction line aftr the evaporator:

1. Maintain a constant evaporating pressure and therby 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 too low an evaporating pressure (e.g. as protection against freezing in awater chiller). The regulator closes when the pressure in the evaporator falls below the set value.

3. The KVP are also used to differentiate the evaporating pressures in two or more evaporators in systems with one compressor.