Patent attributes
An apparatus to allow or stop a flow into a piping system or an enclosed environment comprises (a) a housing having an upper flow passage and a lower flow passage; (b) a valve seat, wherein the valve seat is between the upper flow passage and the lower flow passage, wherein at least one opening is formed on the valve seat; (c) at least one rotary valve inside the housing, wherein each of the at least one rotary valve further comprises a main body and two guides mounted to the main body opposite to each other, and wherein the at least one rotary valve can move inside the upper flow passage and above the valve seat; and (d) at least two guide rails inside the upper flow passage for guiding each of the at least one rotary valve between an open position and a closed position.
