Product Description: ARKOC ARK 973 Series on-off speed controlled check valves are hydraulic control valves that prevent backflow in the system operating with line pressure. When the outlet pressure value exceeds the inlet pressure value, the valve closes itself completely and tightly without causing any impact. When the inlet pressure value exceeds the outlet pressure value, the check valve opens itself slowly; thus, it damps the pressure fluctuations that occur when the pump starts.These valves are used in deep-well pumping stations and city water supply network pumping stations. The fluid sent from the valve inlet signal line to the lower chamber of the valve helps to open, but also provides shock-free closing when closing. The fluid sent from the valve output signal line to the upper chamber of the valve provides slow opening and slow closing.