Opens quickly when the pneumatic supply pressure is removed. Open quickly when the solenoid valve is activated. Manual override to open the valve regardless of pneumatic pilot or solenoid valve position. Visual indicator for indication of valve position. Large supply drain port to drain inlet side piping. Pilot operated main valve. No adjustment necessary. Sizes: UL listed for deluge service in sizes 3 - 10 inches. ANSI flanged Class 150 or 300. Wide range of material available.