Abstract: A valve assembly is disclosed, which includes a valve body defining a valve chamber and a moveable member. The moveable member has a valve element at its first end and an armature at its second end. The moveable member is moveable in an axial direction to selectively open and close the valve. The entire moveable member is spaced from the walls of the valve body when the valve is open or partially open. A flexible membrane forms a seal against the moveable member and the valve body to divide the valve chamber into a flow chamber in which the valve seat and valve element are located and a pressure compensation chamber within which the armature is entirely enclosed. A first fluid port is fluidly connected to the pressure compensation chamber via one or more bores in a pressure compensation flow path with at least one opening extending into the pressure compensation chamber at an axial position between the armature and the flexible membrane.

Abstract: There is provided a method of energising a solenoid of a valve assembly, comprising the steps of applying a positive over boost voltage to the solenoid to actuate a moveable plunger to open or close a flow path through the valve assembly, and then applying a negative braking voltage to brake the movement of the plunger during movement of the moveable plunger. There is also provided a method of energising a solenoid of a valve assembly, the method comprising the steps of receiving a demand signal to actuate the valve, applying a wait time after receipt of the demand signal, applying a positive over boost voltage across the solenoid to actuate a moveable plunger to open or close a flow path through the valve assembly, monitoring the solenoid closure time, and adjusting one or more input variables in order to control the solenoid closure time.

Abstract: A rocker valve comprising a rocker valve mechanism in a valve body. The mechanism comprises a single pivot arm to which first and second plungers are pivotally fixed to act in opposition. The rocker valve includes a flexible seal member extending laterally across the first and second fluid ports and having a first sealing region attached to a plunger head of the first plunger and a second sealing region attached to a plunger head of the second plunger. When the single pivot arm is pivoted relative to the valve body, a rotation of at least one of the first and second plungers about its respective fixed pivot is constrained solely by the flexible seal member such that a lateral position of the plunger head is automatically adjusted by the flexible seal member to balance tensile forces in the flexible seal member around the plunger head.

Abstract: There is provided a fluid sensing apparatus comprising a fluid flow channel, at least one fluid conduit in fluid communication with the fluid flow channel, and a fluid sensor having a casing and at least one sensor port in fluid communication with the at least one fluid conduit and providing access into the casing. The fluid sensing apparatus also includes a pressure compensation chamber in which the casing of the fluid sensor is enclosed. The apparatus further includes at least one pressure compensation conduit in fluid communication with the pressure compensation chamber and with the fluid flow channel. Also provided is a mass flow controller including such a fluid sensing apparatus.

Abstract: A valve assembly is disclosed, which includes a valve body defining a valve chamber and a moveable member. The moveable member has a valve element at its first end and an armature at its second end. The moveable member is moveable in an axial direction to selectively open and close the valve. The entire moveable member is spaced from the walls of the valve body when the valve is open or partially open. A flexible membrane forms a seal against the moveable member and the valve body to divide the valve chamber into a flow chamber in which the valve seat and valve element are located and a pressure compensation chamber within which the armature is entirely enclosed. A first fluid port is fluidly connected to the pressure compensation chamber via one or more bores in a pressure compensation flow path with at least one opening extending into the pressure compensation chamber at an axial position between the armature and the flexible membrane.

Abstract: A valve assembly, comprising a first fluid port, a second fluid port, a valve seat comprising an inner valve seat and an outer valve seat, and a moveable plunger, being moveable between a closed position and an open position arranged to simultaneously seal the inner valve seat and the outer valve seat when in the closed position. A first fluid pathway passes via the inner valve seat, and a second fluid pathway passes via the outer valve seat between the first and second fluid ports when the movable plunger is in the open position. At least one fluid flow path is provided through the body of the moveable plunger. The cross-sectional area of the flow path through the moveable plunger is at least half of the cylindrical cross-sectional area of the gap between the plunger and the respective inner or outer valve seat.

Abstract: A valve assembly having an inner and outer concentric valve seat. The inner valve seat is arranged radially inward of the outer valve seat to provide an annular opening therebetween. A movable plunger moves between a closed position and an open position to vary a flow restriction at the inner and outer valve seats and simultaneously seal the inner and outer valve seats in the closed position. An inner and outer valve member comprise the inner and outer valve seats and are separate components mounted in fixed relation to one another. The inner and outer valves seats are radially aligned to maintain concentricity of the inner valve seat relative to the outer valve seat and axially aligned to maintain axial alignment of the inner valve seat relative to the outer valve along an axis, wherein the axis is substantially orthogonal to a plane of the inner and outer valve seats.

Abstract: A fluid sensing apparatus is provided having a fluid flow channel having a flow restriction. A fluid sensor is in fluid communication with first and second fluid ports, and a laminar flow element. The laminar flow element includes a flow stabilisation rod which defines a fluid sensing portion of the fluid flow channel. The flow restriction comprises a reduction in the hydraulic diameter of the fluid sensing portion of the fluid flow channel which is caused by a decrease in diameter of the fluid flow channel, or by an increase in the diameter of the flow stabilisation rod, or by both a decrease in diameter of the fluid flow channel and an increase in the diameter of the flow stabilisation rod. Also provided is a mass flow controller including such a fluid sensing apparatus.

Abstract: There is provided a method of energising a solenoid of a valve assembly, comprising the steps of applying a positive over boost voltage to the solenoid to actuate a moveable plunger to open or close a flow path through the valve assembly, and then applying a negative braking voltage to brake the movement of the plunger during movement of the moveable plunger. There is also provided a method of energising a solenoid of a valve assembly, the method comprising the steps of receiving a demand signal to actuate the valve, applying a wait time after receipt of the demand signal, applying a positive over boost voltage across the solenoid to actuate a moveable plunger to open or close a flow path through the valve assembly, monitoring the solenoid closure time, and adjusting one or more input variables in order to control the solenoid closure time.

Abstract: There is provided a valve assembly (100). The valve assembly comprises a valve seat comprising an inner concentric valve seat (104) and an outer concentric valve seat (105), the inner concentric valve seat being arranged radially inward of the outer concentric valve seat to provide an annular opening therebetween. The valve assembly also comprises a movable plunger (107), being movable between a closed position and an open position to vary a flow restriction at the inner and outer concentric valve seats, and arranged to simultaneously seal the inner concentric valve seat and the outer concentric valve seat when in the closed position. The valve assembly also comprises an inner valve member (124) comprising the inner concentric valve seat and an outer valve member (125) comprising the outer concentric valve seat. The inner valve member is a separate component from the outer valve member and is mounted in fixed relation to the outer valve member via mounting means.

Abstract: There is provided a fluid sensing apparatus (120) comprising a fluid flow channel (121) having a flow restriction (125), a first fluid port (132) at a first location (131) upstream of the flow restriction, a second fluid port (134) at a second location (133) downstream of the flow restriction, a fluid sensor (130) in fluid communication with the first fluid port and second fluid port, and a laminar flow element (150). The laminar flow element includes a flow stabilisation rod (151) which extends along the fluid flow channel at least from the first location to the second location to define a fluid sensing portion of the fluid flow channel between the outer wall (122) of the fluid flow channel and the outer surface (153) of the flow stabilisation rod.

Abstract: There is provided a fluid sensing apparatus comprising a fluid flow channel, at least one fluid conduit in fluid communication with the fluid flow channel, and a fluid sensor having a casing and at least one sensor port in fluid communication with the at least one fluid conduit and providing access into the casing. The fluid sensing apparatus also includes a pressure compensation chamber in which the casing of the fluid sensor is enclosed. The apparatus further includes at least one pressure compensation conduit in fluid communication with the pressure compensation chamber and with the fluid flow channel. Also provided is a mass flow controller including such a fluid sensing apparatus.

Abstract: The present invention provides a rocker valve comprising a valve body including first and second fluid ports and a rocker valve mechanism in the valve body. The mechanism comprises a single pivot arm rotatable relative to the valve body, and first and second plungers pivotally fixed to the single pivot arm. The second plunger acts in opposition to the first plunger when the single pivot arm is pivoted relative to the valve body. The rocker valve includes a flexible seal member extending laterally across the first and second fluid ports. The flexible seal member has a first sealing region attached to the first plunger and a second sealing region attached to the second plunger and is movable by the first and second plungers between a first position in which the first fluid ports is closed by the first sealing region, and a second position in which the second fluid port is closed by the second sealing region.

Abstract: There is provided a valve assembly, comprising, a first fluid port, a second fluid port, a valve seat comprising an inner valve seat and an outer valve seat, the inner valve seat being arranged within the outer valve seat, and a moveable plunger, having a body and being moveable between a closed position and an open position to vary a flow restriction at the valve seat, and arranged to simultaneously seal the inner valve seat and the outer valve seat when in the closed position. A first fluid pathway is provided between the first fluid port and the second fluid port passing via the inner valve seat when the movable plunger is in the open position, and a second fluid pathway is provided between the first fluid port and the second fluid port passing via the outer valve seat when the movable plunger is in the open position. At least one fluid flow path is provided through the body of the moveable plunger comprising an opening configured to form part of the first fluid pathway or the second fluid pathway.