A valve device includes a shaft, a valve body, and a housing including a valve opening. An outwardly facing surface of the valve body is out of contact with the housing and a valve-facing surface is in contact with the housing in a fully closed state in which the valve body closes the valve opening. A valve seal surface includes a first valve seal surface protruding in a valve closing direction and a second valve seal surface recessed in a valve opening direction. A first seal distance in a radial direction from an outer diameter end of the first valve seal surface to a rotation axis is shorter than a second seal distance in the radial direction from an outer diameter end of the second valve seal surface to the rotation axis. The first valve seal surface and the second valve seal surface each have at least a curved surface.

Anti-rotation assemblies for use with fluid valves are disclosed. An example apparatus includes a retainer collar coupled at an end of a plug, the plug including a plug collar around which the retainer collar is disposed, the plug and the retainer collar being substantially flush at an interface between the plug and the retainer collar, a fastener extending transversely through the retainer collar and the plug collar to couple the retainer collar at the end of the plug, when the retainer collar and the plug are disposed within a valve body, a stem extends through the retainer collar and the plug to enable the plug to be moved within the valve body; and an anti-rotation collar to receive the retainer collar, the anti-rotation collar coupled at an end of a cage, the anti-rotation collar and the retainer collar having corresponding non-circular cross-sections to inhibit rotation of the retainer collar and the plug when the plug is moved within the valve body.

Valve plugs having curved notches are described herein. An example valve plug includes a first section defining a first end, a second section defining a second end opposite the first end, and a third section located between the first and second sections, the third section including a curved notch formed inwardly from a periphery of the third section toward a longitudinal axis of the valve plug defined by the first, second and third sections.

Valve plugs having curved notches are described herein. An example valve plug includes a first section defining a first end, a second section defining a second end opposite the first end, and a third section located between the first and second sections, the third section including a curved notch formed inwardly from a periphery of the third section toward a longitudinal axis of the valve plug defined by the first, second and third sections.

A variable flow rate valve mechanism of the present disclosure includes a stem which is rotatably supported by a housing, a bearing which is inserted through a through-hole of the housing and supports the stem to be rotatable about an axis of the stem, and a valve portion which is provided at one end side of the stem and covers an opening. The stem is disposed so that the axis of the stem crosses the opening. The valve portion rotates about the axis of the stem and opens and closes an opening of a variable gas flow rate passage.

A cone type control valve comprising a cone shaped valve plug movably retained in an similarly shaped opening of a valve housing having horizontal inlet and outlet ports and wherein any reciprocal movements of the conical plug can control fluid flow from the inlet to the outlet port. The cone shaped opening furthermore has cavities located perpendicular to the ports, capable to accelerate and de-celerate fluid passing between the two ports.

A cone type control valve comprising a cone shaped valve plug movably retained in an similarly shaped opening of a valve housing having horizontal inlet and outlet ports and wherein any reciprocal movements of the conical plug can control fluid flow from the inlet to the outlet port. The cone shaped opening furthermore has cavities located perpendicular to the ports, capable to accelerate and de-celerate fluid passing between the two ports.

To prevent nuisance marine growth in a valve, particularly a ball valve, used to regulate a flow of seawater, a compound for lubricating and preventing nuisance marine growth is provided in the valve. The nuisance marine growth preventing compound includes a substantially uniform mixture of marine grease and an antifouling agent. The compound is introduced into the valve such that the compound is provided between and contacts a valve body and a ball that regulates the flow of seawater within the valve, and inhibits nuisance marine growth at a space between the ball and the valve body which is occupied by the compound.

To prevent nuisance marine growth in a valve, particularly a ball valve, used to regulate a flow of seawater, a compound for lubricating and preventing nuisance marine growth is provided in the valve. The nuisance marine growth preventing compound includes a substantially uniform mixture of marine grease and an antifouling agent. The compound is introduced into the valve such that the compound is provided between and contacts a valve body and a ball that regulates the flow of seawater within the valve, and inhibits nuisance marine growth at a space between the ball and the valve body which is occupied by the compound.

Slit valve apparatuses are described. In one aspect, a slit valve apparatus is disclosed having a gate with at least one sealing surface, a blocker element, and a connector member that structurally connects the gate and the blocker element. Systems and methods including the slit valve apparatus are also disclosed, as are numerous other aspects.