liquid relief valves Kunkle valve Kunkle LIQUID RELIEF VALVES Liquid relief valves enable the valve to open proportionally to an increase in pressure over the normal operating pressure. Liquid relief valves are made mainly to get rid of large volumes of steam that will nroamlly pop open to top capacity. When overpressure occurs, liquid relief valves open to where large-volume discharge is not required as the valve rises due to hightened spring resistance. Liquids that are not volatile normally are injected to separating oil - water and recovery systems, and lower pressure units receive volatile liquids.