Expanding Disk Gate Valve

An expanding disk gate valve comprising:

• a) a hollow valve body having an inlet, an outlet, and a gate chamber located between the inlet and the outlet, the gate chamber having an inlet valve seat, an outlet valve seat, and a gate chamber width between the inlet valve seat and the outlet valve seat;
• b) a gate housing defining a gate receiving area with an opening to the gate chamber and having an operating stem coupling;
• c) an operating stem passing through the gate housing, and having a gate housing coupling and a gate disk assembly coupling;
• and
• d) a gate disk assembly comprising:
• i) a first gate disk having a central axis, a face, a back surface, a perimeter, and a first flange extending axially from the back surface of the first gate disk along at least half of the perimeter of the first gate disk;
• ii) a second gate disk having a central axis, a face, a back surface, a perimeter, and a second flange extending axially from the back surface of the second gate disk along at least half of the perimeter of the second gate disk, the first flange and the second flange being sized and located such that when the first gate disk is assembled coaxially with the second gate disk, ends of the first flange and ends of the second flange overlap to define a hollow volume bounded by the back surface of the first gate disk, the back surface of the second gate disk, an inner surface of the first flange, and an inner surface of the second flange;
• iii) an elastomeric disk filling the hollow volume and holding the central axis of the first disk radially offset from the central axis of the second disk when the elastomeric disk is in an uncompressed state;
• iv) an operating stem coupling attached to the first flange for movement of the first flange;
• and
• v) an elastomeric sheath enclosing the first gate disk, the second gate disk and the elastomeric disk;
• such that operation of the operating stem moves the gate disk assembly against a side of the gate chamber, the elastomeric disk is compressed between the first flange and the second flange, causing a width of the gate disk assembly to increase to seal against the inlet valve seat and the outlet valve seat.