Plant circuit having change-over means for changing sequence of flow

摘要

The change-over means employs two three-way valves and two non-return valves for affecting a switch over in the sequence of flow through the four flow elements. Each three-way valve is constructed with a closure member which may only close one of the inlets of a pair of inlets of the valve or one of the outlets of a pair of outlets of the valve. The valves are arranged so as to switch the flow from a sequence of A-B-C-D to a sequence of A-C-B-D.