Abstract: A valve system can include a valve body having an inlet and an outlet, a valve member moveable between open and closed positions to fluidically couple and decouple the inlet and the outlet, and an actuator. The actuator can include an actuation chamber, an actuator member to move the valve member, ports, and a control system. The ports can be arranged to permit flow from the inlet to first and second volumes of the actuation chamber, and to permit flow from the first and second volumes of the actuation chamber to the outlet. The control system can selectively direct fluid flow through the ports.

Abstract: A valve assembly can include a valve body and a seal ring. The seal ring can be seated in a seal cavity of the valve body. The seal ring can include a base that extends in an axial direction within the seal cavity, a leg that extends from the base, and a foot that extends from the leg. When a disk of the valve assembly is in a closed valve position, a primary seal can be formed between the foot and the disk and a secondary seal is formed between the base and a first wall of the seal cavity. The seal ring can accommodate disk drift at least partly via elastic bending, and can provide disk tracking via lateral movement within the seal cavity.

Abstract: A valve system can include a valve body having an inlet and an outlet, a valve member moveable between open and closed positions to fluidically couple and decouple the inlet and the outlet, and an actuator. The actuator can include an actuation chamber, an actuator member to move the valve member, ports, and a control system. The ports can be arranged to permit flow from the inlet to first and second volumes of the actuation chamber, and to permit flow from the first and second volumes of the actuation chamber to the outlet. The control system can selectively direct fluid flow through the ports.