Technical Specifications Category Specification Model Type 4-300 Type Conventional Spring-Loaded Safety Relief Valve Service Air, Steam, and other Compressible Fluids Operation Pop-Action (Rapid Full-Lift) Orifice Designation J (According to API 526. The "300" size corresponds to a "J" orifice). Orifice Area 0.710 sq. in. (458 sq. mm) Inlet Size Varies, but common for this orifice is 2" NPT or flanged. Outlet Size Typically one size larger than the inlet (e.g., 3" NPT for a 2" inlet). Set Pressure Range Available in various spring ranges for different set pressures. The specific range is determined by the spring installed. Blowdown Adjustable (typically 2-7% for steam/air). Maximum Allowable Set Pressure Dependent on the body rating, but typically suitable for several hundred psig. Body Materials Carbon Steel (standard for steam and air), Bronze, Stainless Steel. Standards Compliance Can be designed to meet ASME Boiler and Pressure Vessel Code, Section I and Section VIII.
