Hydraulically operated pressure holding control valves maintain a small preset upstream (back pressure) pressure regardless of flow fluctuations or downstream pressure changes. Bermad 800 series valves are hydraulic, pilot, piston-driven, oblique globe valves with seat assembly and double chamber combination actuators. The hydrodynamic body of the valve is designed for unimpeded flow paths and provides excellent and efficient regulation for high pressure differential applications. The 800 series operates under difficult operating conditions with low cavitation and noise. They are made of high quality materials suitable for different mining applications.