HD deluge valve is a quick opening, differential diaphragm type valve. Deluge valve is used to control water flow in Deluge, Pre-Action as well as Foam systems. The valve is held closed by system water pressure trapped in the priming chamber thus keeping the outlet chamber and system piping dry. In fire conditions, when the releasing system operates, pressure is released from the priming chamber, resulting in opening of the deluge valve. HD deluge Valve is UL Listed.