Abstract: A fluid flow control device (10) has a stack of annular discs (15) defining a central passageway (14) and a plug (16) reciprocable in the passageway for controlling fluid flow. Adjacent discs (15) in the stack have at least one fluid passageway (21A) formed in a major face (22A) of one disc closed by the abutting major face of the adjacent disc. The fluid passageway (21A) extends in a clockwise direction and has a linear inlet portion (23A) and a curved outlet portion (24A). The inlet portion (23A) is of constant cross-sectional area and the outlet portion (24A) is of increasing cross-sectional are in the direction of fluid flow. Other configurations of discs and/or fluid passageways are disclosed.

Abstract: A fluid flow control device (10) has a stack of annular discs (15) defining a central passageway (14) and a plug (16) reciprocable in the passageway for controlling fluid flow. Adjacent discs (15) in the stack have at least one fluid passageway (21A) formed in a major face (22A) of one disc closed by the abutting major face of the adjacent disc. The fluid passageway (21A) extends in a clockwise direction and has a linear inlet portion (23A) and a curved outlet portion (24A). The inlet portion (23A) is of constant cross-sectional area and the outlet portion (24A) is of increasing cross-sectional are in the direction of fluid flow. Other configurations of discs and/or fluid passageways are disclosed.

Abstract: A valve filter is provided particularly for a balanced pressure valve and provides a means of preventing particles passing, through the balance holes of the valve plug.The valve comprises a valve housing and a valve plug movable in the housing to open and close the valve, the valve plug containing at least one balance hole, the balance hole defining a fluid communication channel through the valve plug, the fluid communication channel being provided with a filter, the filter comprising a body member and a plurality of elements, each element having a first end and a second end and being fixed at its first end to the body member and being, free at its second end, whereby the elements can deflect under pressure.

Abstract: A fluid flow control device, sometimes called a variable fluid restrictor control valve or severe service control valve. These valves employ a moveable plug and are used to control high pressure fluids e.g. superheated steam. The valve of the invention provides axial flow passageways for the fluid, which have right-angled turns. The passageways are either on the radially outer surface of the plug or within an annular sleeve through which the plug is moveable.

Abstract: A fluid flow control device for use in a variable fluid restrictor control valve or severe service control valve. These valves employ a moveable plug and are used to control high pressure fluids e.g. superheated steam. The control device of the invention includes annular discs with fluid passageways through them. Pairs of discs together form a radial passageway for fluid between the interior of a stack of discs and its radially outer circumference. The passageways may have a smaller cross-section at a mid-region of the disc than at the radially inner or outer side of the disc.

Abstract: A trim design (40) comprises a housing (42) having a generally cylindrical passage (44) passing therethrough. Disposed between an inlet (50) and an outlet (48) is a stepped plug (52) having an axial length. Telescopically receiving the stepped plug (52) is a stepped first cage (56). A second cage (82) having apertures (84) therethrough is positioned between the outlet (48) and the first cage (56). The first cage (56) has axial channels (80) for the passage of fluid through the trim design (40). As the plug (52) is moved from a closed position to an opened position, fluid enters a tortuous path formed by the stepped plug (52), the first cage (56) and the axial channels (80) to produce a desired flow capacity change. Flow path decreases in tortuosity with increasing plug travel thereby increasing the flow capacity.

Abstract: A fluid flow control device for use in a variable fluid restrictor control valve or severe service control valve. These valves employ a moveable plug and are used to control high pressure fluids e.g. superheated steam. The control device of the invention includes annular discs with fluid passageways through them. Pairs of discs together form a radial passageway for fluid between the interior of a stack of discs and its radially outer circumference. The passageways may have a smaller cross-section at a mid-region of the disc than at the radially inner or outer side of the disc.The questions raised in reexamination request No. 90/004,962 filed Sep. 29, 1998, have been considered and the results thereof are reflected in this reissue patent which constitutes the reexamination certificate required by 35 U.S.C. 307 as provided in 37 CFR 1.570(e).