Technical Specifications Category Specification Model Type 299H Type Pilot-Operated, Pop-Action Pressure Relief Valve Function Overpressure Protection for pressurized systems. Operation Pilot-Operated. The main valve is held closed by system pressure. The pilot valve senses pressure and, upon reaching setpoint, vents the pressure from atop the main valve piston, causing it to open fully. Action Pop-Action (Rapid Opening) Services Liquid, Gas, and Steam Set Pressure Range Varies with valve size and service. Can be rated for a wide range, from low pressures to over 1000 psig (69 bar). Blowdown Adjustable (typically 2-7% for steam/gas, 5-20% for liquid). Main Valve Sizes Typically available in a range of sizes, e.g., 1" x 2", 1-1/2" x 3", 2" x 3", 3" x 4", 4" x 6" (Inlet x Outlet). End Connections Flanged (ANSI Class 150, 300, 600, etc.) or Butt-Weld. Body Materials Carbon Steel (standard), with other alloys like Stainless Steel available. Pilot Valve Materials Stainless Steel (standard). Standards Compliance Can be designed to meet ASME Boiler and Pressure Vessel Code, Section I and Section VIII.
