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Series 2000-M5, 2000S-M5 Hydronic, Two-Way, Universal Flow Check Valves are for use in commercial and residential hydronic heating systems to provide positive shutoff when circulator is not running, preventing flow of water to radiation units. They are easily opened for gravity circulation. Model 2000-M5 combines angle and horizontal checks and consists of an iron body construction with female threaded connections, bronze seat, and brass center guide. Model 2000S-M5 consists of a straight pattern design with a bronze body construction and solder connections, bronze seat, and brass center guide. Sizes 3/4 to 1 1/4 in. (20 to 32mm) Maximum Pressure: 50psi (344.8kPa); Sizes 1 1/2 to 3 in. (40 to 80mm) - Maximum Pressure: 125psi (8.6 bar).