This Apollo Valve 10-400 series safety relief valve has a bronze body, a 30 pounds per square inch (psi) relief pressure, a 3/4" male National Pipe Thread (NPT) inlet connection, and a 3/4" female NPT outlet. The valve's body and nozzle are bronze for resistance to corrosion, the seat is silicone for resistance to high temperatures, and the spring is stainless steel for resistance to corrosion. The valve can be used in operating temperatures up to 250 degrees F. This safety valve is American Society of Mechanical Engineers (ASME) safety rated for Section IV hot water heating boilers and hydronic heating systems.Relief valves remove excess pressure or vacuum from a system. The valve openings allow fluids or gases to escape to decrease pressure, and then close once the valve reaches the reseating pressure limit. They also relieve excess vacuum by opening to release a gas into the system and then closing after it reaches its low-pressure limit. Some relief valves have an adjustment mechanism to set the pressure where the valve opens, making it suitable for various applications. Relief valves are rated according to the volume of liquid or gas that can flow through them and the material that the valve is constructed from must be suitable for the fluid or gas, which may be corrosive or at an extreme temperature, in which it operates. Relief valves are used in a variety of applications, such as air compressors, petrochemical and chemical manufacturing, natural gas processing, and power generation.Apollo Valves manufactures ball, mixing, and relief valves, actuators, water gauges, marine fittings, heating and plumbing products, and backflow prevention. The company, founded in 1928 and headquartered in Matthews, NC, meets international standard International Organization for Standardization (ISO)/IEC standard 17025:2005.