1" 2-stage regulating valve 6" WC out. The SR Series combines gas pressure regulating and flame staging in a single unit as an ideal replacement for dual manifold systems. Applications include direct-fired heaters with two-speed fans, hi-lo control for outdoor heaters, LP natural gas switchover, and industrial processing. Suitable for natural, manufactured, mixed gases, liquefied petroleum gases, LP gas-air mixtures, and DIN EN 437 gas families 1, 2, and 11