1/2" Model VR, Brass Vacuum Relief Valve The Apollo Model VR Vacuum Relief valve is designed to automatically vent a system should a vacuum occur. It prevents siphoning of water from the system and/or tank collapse. Features: Brass poppet for improved strength Suitable for LP steam (15 PSIG max) ANSI (American National Standards Institute) Z21.22 certified Materials: Bonnet: ASTM (American Society for Testing and Materials) B16 Brass Nozzle: ASTM B16 Brass Poppet: ASTM B16 Brass Seat Washer: EPDM (ethylene propylene diene terpolymer) Spring: Stainless Steel Retainer: Glass filled Noryl Performance Rating: Maximum Pressure: 200 PSIG Maximum Temperature: 250° F