Seawater Service Pressure Relief Valve Model 50A-20, UL Listed, Angle pattern, Factory mutual approved, Fast opening to maintain steady line pressure, Accommodates wide range of flow rate, Closes gradually for surge-free operation, Adjustable pressure settings, Not affected by pressure at valve discharge. This valve is designed specially to automatically relieve excess pressure in fire protection pumping systems. Pilot controlled, it maintains constant system pressure at pump discharge within very close limits at demands change. STANDARD MATERIALS: Body & Cover: Ductile iron ASTM A-536, Trim: ASTM B61 Bronze seat - Monel trim, Pilot control system: Cast bronze with monel trim and SS-316 tubing and fittings Other optional materials are available upon request. END DETAILS: 150 and 300 ANSI B16.42 PRESSURE RATINGS: 150 class 250 psi max. OR 300 class 400 psi max, TEMPERATURE: Water to 180 deg F max. ADJUSTMENT RANGE: 20-200 psi (150 class) OR 100-300 psi (300 class)