Watts 0856761 1″ check valve this 1 in two-way universal flow check valve is for use in commercial and residential hydronic heating systems to provide positive shutoff when circulator is not running, preventing the flow of water to radiation units. It is easily opened for gravity circulation. It combines angle and horizontal checks and consists of an iron body construction with female threaded connections, bronze seat, and brass center guide. The maximum pressure is 50 psi (344.8kpa). The maximum pressure is 125 psi (8.6 bar).