Abstract: A force actuated modulating control valve such as a direct acting solenoid valve or pilot actuated bellows valve with a knife edge seat so that the metering location on the seat is at the very outer diameter. In one embodiment, a portion of the valve seat outside of the metering edge is removed to substantially the outside diameter to reduce contact with high velocity fluid flow. In certain embodiments, a flow shield may be positioned just outside of the metering edge of the seat to prevent the high velocity fluid from circulating toward parts of the spool assembly. In some embodiments, the flow shield may be fixed to the body of the instrument so all fluid forces are transmitted to the body. Embodiments of the force actuated modulating control valve may be employed in a mass flow controller for controlling fluid flow.

Abstract: The disclosed embodiments include a force actuated modulating control valve such as a direct acting solenoid valve or pilot actuated bellows valve with a knife edge seat so that the metering location on the seat is at the very outer diameter. In one embodiment, a portion of the valve seat outside of the metering edge is removed to substantially the outside diameter to reduce contact with high velocity fluid flow. In certain embodiments, a flow shield may be positioned just outside of the metering edge of the seat to prevent the high velocity fluid from circulating toward parts of the spool assembly. In some embodiments, the flow shield may be fixed to the body of the instrument so all fluid forces are transmitted to the body. Embodiments of the force actuated modulating control valve may be employed in a mass flow controller for controlling fluid flow.

Abstract: A flow control valve includes an inlet and an outlet through which fluid enters and exits the valve. A valve plunger has a guide spring attached thereto, such that the guide spring is situated between the plunger and a valve orifice. The plunger, and thus the guide spring, is movable relative to the orifice to control fluid flow through the valve. The guide spring and the orifice surface adjacent the guide spring define coplanar surfaces that seal against each other when the valve is closed.

Abstract: A flow control valve includes an inlet and an outlet through which fluid enters and exits the valve. A valve plunger has a guide spring attached thereto, such that the guide spring is situated between the plunger and a valve orifice. The plunger, and thus the guide spring, is movable relative to the orifice to control fluid flow through the valve. The guide spring and the orifice surface adjacent the guide spring define coplanar surfaces that seal against each other when the valve is closed.