MDRV is angle-way construction defrost relief valve, with variable opening pressure between (ΔP): 29 – 116 psi (2 – 8 bar). The valve is also designed to work as stop valve with metal to metal back seating facility which allows to replace spindle seal even when valves are under pressure. While designing the valve fluttering due to low velocity and low density are also considered. It is possible to use the valves with wide variation in capacity demands, i.e. from maximum efficiency to part load. A special material O-ring gives excellent sealing over the seat area.