A four-way selector valve for selecting communications between four pipes (A, B, C, D) comprising:
- a valve case (1) connected to communicate with a first pipe (A),
- a separate chamber formed within said valve case (1) to communicate with a second pipe (B), said separate chamber (2) being separated from a space (100) within said valve case (1),
- a first valve seat ring (3) placed in a communication path between a connecting portion of a third pipe (C) and said space (100) within the valve case,
- a second valve seat ring (4) placed in a communication path between a connecting portion of a fourth pipe (D) and said space (100) within the valve case (1),
- a movable valve element assembly (10) inserted into said valve case (1) for alternating co-operation with said first and second valve seat rings (3, 4),
- and a valve drive means connected to said movable valve element assembly (10) for at least selectively interconnecting said first pipe (A) either with said third pipe (C) or said fourth pipe (D) and simultaneously interconnecting the remaining one of said third or fourth pipes (C, D) which then is not connected with said first pipe (A) with said second pipe (B),
- wherein first and second valve disks (5, 7) are associated to said first and second valve seat rings (4, 3) and arranged to be pressed essentially in the direction of the axis of the respectively associated valve seat ring (3, 4) in closing direction by remanent force of first and second compression coil springs (6, 8), said first and second valve disks (5, 7) facing the corresponding first and second valve seat rings (3, 4) in said valve case (1),
- a first cylindrical and hollow valve (10a) is arranged to move axially and substantially in the direction of the axis of the associated valve seat ring (3, 4) and into lifting engagement with said first valve disk (5), said first cylindrical valve (10a) having a first end (10a') and a second end (10a"), said first end (10a') communicating with said separate chamber (2), said second end (10a") being arranged to depart from or to come into contact with said first valve disk (5) from the side of said connecting portion of the third pipe (C),
- a second cylindrical and hollow valve (10b) is arranged to move axially and substantially in the direction of the axis of the associated valve seat ring (4) and into lifting engagement with said second valve disk (7), said second cylindrical, hollow valve (10b) having a first end (10b') and a second end (10b"), said first end (10b') communicating with said separate chamber (2), said second end (10b") being arranged to depart from or to come into contact with said second valve disk (7) at the side of said connecting portion of the fourth pipe (D),
- said first and second cylindrical, hollow valves (10a, 10b) are provided side by side and parallel to each other with respect to the longitudinal axis of the hollow valves, each first end (10a', 10b') of said first and second cylindrical, hollow valves (10a, 10b) being arranged in said separate chamber (2) communicating with said second pipe (B),
- a link motion mechanism (46) coupling said first and second cylindrical, hollow valves (10a, 10b) for a common reciprocal movement of both cylindrical valves (10a, 10b) in their respective axial directions allowing to interchange at least between two states, namely, one state of interconnecting said first pipe (A) with said third pipe (C) and simultaneously connecting said second pipe (B) with said fourth pipe (D), and another state of interconnecting said first pipe (A) with said fourth pipe (D) and simultaneously said second pipe (B) with said third pipe (C).