GB2117496A - Valves - Google Patents

Abstract

An outlet valve for controlling the flow of liquids or semi-liquids such as slurries from a container such as a processing vessel comprises a valve body 10 having an inlet 12 adapted to be connected to a container and an outlet 22 connected to the inlet by a passage 24 in the valve body, a valve stem 30 extending into the passage 24 and movable longitudinally between a closed position in which a valve member 34 at one end of the stem engages a valve seat 16 and an open position in which the valve member 34 is moved from the valve seat 16, and actuating means positioned outside the valve body for moving the valve stem between the open and closed positions. The actuating means comprises an actuating member 54 rotatable, by a handle 90, about an axis perpendicular to the longitudinal axis of the valve stem 30, an actuating arm 66 pivoted at one end to the valve stem 30 and pivoted at the other end to the actuating member 54 for rotation about an axis parallel to and spaced from the axis of rotation of the actuating member. Locking means 102 are provided to hold the actuating member in positions corresponding to the open and closed positions of the valve stem, and in an intermediate position providing a restricted flow from the outlet 22. The position of the handle 90 provides a positive visual indication of the position of the valve stem. <IMAGE>

Description

SPECIFICATION Improvements in valves This invention relates to valves.

More particularly, the invention relates to outlet valves for controlling the flow of liquids or semiliquids such as slurries from a container such as a processing vessel.

There are known valves of this kind, comprising a valve body having an inlet adapted to be connected to a container and an outlet connected to the inlet by a passage in the valve body, a valve stem extending into the passage and movable longitudinally between a closed position in which a valve member at one end of the stem engages a valve seat in the body thereby to close the passage and an open position in which the valve member is moved from the seat, and actuating means positioned outside the valve body for moving the valve stem between the open and closed positions.

In the known valves, the actuating means comprises a hand wheel rotating a nut engaging a screw thread on the end of the valve stem, so that rotation of the hand wheel effects longitudinal movement of the valve stem. This has the disadvantage that operation of the valve is relatively slow and that there is no positive indication of the position of the valve stem.

This invention consists in a valve of the kind referred to, in which the actuating means comprises an actuating member rotatable about an axis transverse to the longitudinal axis of the valve stem, an actuating arm pivoted at one end to the valve stem and pivoted at the other end to the actuating member for rotation about an axis parallel to and spaced from the axis of rotation of the actuating member so that on rotation of the actuating member the valve stem moves between the open and closed position, and means for rotating the actuating member.

The means for rotating the actuating member may comprise a handle secured to or coupled to the actuating member. Alternatively, a power driven mechanism may be provided for rotating the actuating member.

Preferably, stops are provided to limit the angular movement of the actuating member, the end limits corresponding to the closed and open position5 of the valve stem. Suitably, the valve stem is movable vertically, the valve being closed in the uppermost position and open in the lowermost position of the valve stem.

Advantageously, releasable locking means are provided for holding the actuating member in the closed and open positions. The locking means may also be arranged to hold the actuating member in a third position between the closed and open positions, in which the valve member is positioned to allow a restricted flow through the valve body.

The invention provides a valve with a compact and quick-actuating operating mechanism.

One embodiment of the invention will now be described, with reference to the accompanying drawings in which: Figure 1 is a cross-section through a valve in accordance with the invention, and Figure 2 is a fragmentary view in the direction of arrow II in Figure 1, with the casing of the actuating mechanism omitted.

Referring to the drawings, an outlet valve for a container comprises a valve body 10 of stainless steel, a valve stem 30 having a valve member 34, and an actuating mechanism 50 for raising and lowering the valve stem.

The valve body 10 has a cylindrical upper part 12 adapted to fit into a bore in the bottom wall of a processing vessel. The valve body is held in position by a mounting flange 14 bolted to the bottom wall of the vessel. The upper part 12 includes a frustoconical valve seat 16. A cylindrical portion 18 of the valve body 10 extends from the upper part 12 at an angle to the vertical of 45 , and leads to a tapering portion 20 ending in an outlet 22. A passage 24 thus extends from the upper part 12 to the outlet 22.

The valve stem 30 moves vertically in a support member 40 which passes through the wall of the cylindrical portion 18 of the valve body and is welded in position. Movement of the valve stem is guided by upper and lower guide bushes 42 and 44.

A spring-loaded gland packing 46 is housed between the guide bushes and prevents leakage from the interior of the valve body.

Screwed to the top of the valve stem 30 is a head retainer 38 which clamps the loaded p.t.f.e. valve member 34 and a lower retaining member 32 to the valve stem 30. The head retainer 38 has a portion 36 of square section fitting into a square-section bore in the lower retaining member 32, and a threaded portion 35 engaging a threaded bore in the valve stem 30. Spanner flats 31 and 37 on the valve stem 30 and head retainer 38 enable the head retainer to be turned relative to the stem to clamp the valve member 34 in position. This arrangement enables the valve member 34 to be easily replaced if it is damaged in use. The head retainer 38 has an upper flat face 39 which, when the valve stem 30 is raised to bring the fructoconical face 33 of valve member 34 into engagement with the valve seat 16, is flush with the upper face 13 ofthevalve body 10.

The actuating mechanism 50 is carried by a mounting bracket 52 fixed to the valve body 10. The mechanism includes an actuating member 54 formed with a boss 56 rotatable about a horizontal axis in a bore in the bracket 52. The boss 56 rotates in a loaded p.t.f.e. bearing bush 58 and is held in place by means of a circlip 60 and thrust washer 64. A connecting arm 66 is pivoted at its lower end to the actuating member 54, for rotation about an axis parallel to and spaced from the axis of rotation of the actuating member. The arm is pivoted on a bearing bush 68 fixed to the actuating member 54 by a shoulder screw 70. At its upper end the connecting arm 66 is pivoted to a connector block 72, the arm pivoting on a bearing bush 74 fixed to the connector block by a screw 76.The connector block 72 is fixed to the lower end of the valve stem 30 by means of a screw-threaded spigot 78 integral with the connector-block and engaging a threaded bore in the valve stem. Two slide pads 80 fixed to the connector block slide against a vertical face of the mounting bracket 52 to guide the vertical movement of the connector block.

The actuating member 54 is shaped to provide two faces 82 and 83 which engage respective opposite faces 85 and 86, a stop member 84, fixed to mounting bracket 52, to limit the angular movement of the member. The limits of angular movement are separated by 1800 and correspond to the uppermost and lowermost positions of the valve stem 30.

An aluminium casing 88, bolted to the mounting bracket 52, surrounds the actuating mechanism.

The actuating member 54 is rotatable by means of a handle 90. The handle 90 has a boss 92 releasably secured to the boss 56 of the actuating member by means of a screw 94, a square parallel key 96 in the handle boss 92 engaging a keyway in actuating member 54. An annular locating member 98 integral with the casing 88 has in its periphery two recesses 99 and 100 separated by 1800 and corresponding to the end positions of the actuating member 54, and a third recess 101 midway between the other two. A spring loaded locking member 102 carried by the handle 90 normally engages in one or other of the recesses to lock the handle in position. The locking member 102 can be pushed inwardly so that a recess 103 in the locking member is aligned with the periphery of the locating member 98 to allow the handle to be turned.

In operation, rotation of the handle 90 from its intermediate position (shown in the drawings) in a clockwise direction, as seen in Figure 2, causes the actuating arm 66 to lift the valve stem 30. The position of the connector block 72 on the valve stem is so adjusted that when the actuating member 54 reaches its limit of movement the valve stem 30 is in its uppermost position with the valve member 34 engaging the valve seat 16. In this position, the pivotal connection of the actuating arm 66 to the actuating member 54 is aligned with the longitudinal axis of the valve stem 30 and with the axis of rotation of the actuating member, so that the pressure of liquid on the valve member does not apply a torque to the actuating member.Rotation of the handle 90 in the opposite direction causes the actuating arm 66 to move the valve stem 30 downwards, first to the intermediate position then to its lowermost position, when the actuating member reaches its limit of movement. In this position of the valve stem the valve is fully open and liquid can flow freely from the container through the outlet passage 24.

The actuating mechanism thus provides a quick acting and positive means for opening and closing the valve. The position of the handle 90 relative to the locating member 98 provides a visual indication of the position of the valve stem.

The handle may be provided with an extension shaft connecting the handle boss to the actuating member, to enable the handle to be positioned at a distance from the valve. In an alternative embodiment of the invention, the handle may be replaced by a power-driven torque actuator, for example an electric or pneumatic actuator.

It will be appreciated that modifications could be made in the described embodiment. For example, the invention could be applied to a valve in which the valve member moves downwards to engage a valve seat when the valve stem is in its lowermost position, the valve stem being moved upwards by the actuating mechanism to lift the valve member from the seat.

Claims (11)

1. An outlet valve for controlling the flow of liquids or semi-liquids from a container, comprising a valve body having an inlet adapted to be connected to a container and an outlet connected to the inlet by a passage in the valve body, a valve stem extending into the passage and movable longitudinally between a closed position in which a valve member at one end of the stem engages a valve seat in the body thereby to close the passage and an open position in which the valve member is moved from the seat, and actuating means positioned outside the valve body for moving the valve stem between the open and closed positions, in which the actuating means comprises an actuating member rotatable about an axis transverse to the longitudinal axis of the valve stem, an actuating arm pivoted at one end to the valve stem and pivoted at the other end to the actuating member for rotation about an axis parallel to and spaced from the axis of rotation of the actuating member so that on rotation of the actuating member the valve stem moves between the open and closed position, and means for rotating the actuating member.

2. A valve as claimed in claim 1, in which the actuating member is arranged to provide a visual indication of the position of the valve stem.

3. A valve as claimed in claim 1 or claim 2, in which the pivotal connection of the actuating arm to the actuating member is aligned with the longitudinal axis of the valve stem and the axis of rotation of the actuating member when the valve stem is in the closed position, so that pressure of liquid on the valve member does not apply torque to the actuating member.

4. Avalve as claimed in any preceding claim, in which the valve stem is movable vertically, the valve being closed in the uppermost position and open in the lowermost position of the valve stem, and the actuating member is rotatable about a horizontal axis below the valve stem.

5. A valve as claimed in claim 4, in which the valve member is releasably secured to the top of the valve stem.

6. A valve as claimed in any preceding claim, in which the means for rotating the actuating member comprises a handle coupled to the actuating member.

7. A valve as claimed in any one of claims 1 to 5, in which the means for rotating the actuating member comprises a torque actuator coupled to the actuating member.

8. Avalve as claimed in any preceding claim, in which stops are provided to limit the angular movement of the actuating member, the end limits corresponding to the closed and open positions of the valve stem.

9. A valve as claimed in any preceding claim, in which releasable locking means are provided for holding the actuating member in the closed and open positions.

10. A valve as claimed in claim 9, in which the locking means are arranged to hold the actuating member in a third position between the closed and open positions, in which the valve member is positioned to allow a restricted flow through the valve body.

11. An outlet valve for controlling the flow of liquids or semi-liquids from a container, constructed, arranged and adapted to operate substantially as described with reference to, and as shown in, the accompanying drawings.