50OX relief / holding pressure valve is mainly used for fire or other water systems to prevent system overpressure or maintain fire service pressure. After the fire pump shutdown can also reduce the impact of water hammer. Water hammer is also used to eliminate large-scale water supply system devices. When the water supply pipeline pressure exceeds the set pressure relief valve, pressure relief valves automatically open quick relief to protect the safety of the pipeline can also be used as a pressure valve to protect the main water supply valve upstream pressure.