GB2143307A

GB2143307A - Preventing valve actuation

Info

Publication number: GB2143307A
Application number: GB08418099A
Authority: GB
Inventors: George Gardner
Original assignee: IMI BAILEY BIRKETT Ltd
Current assignee: IMI BAILEY BIRKETT Ltd
Priority date: 1983-07-14
Filing date: 1984-07-16
Publication date: 1985-02-06
Also published as: GB8418099D0; GB2143307B

Abstract

A valve including a spindle 3 and a handwheel 1 and keying means 8 which, in a first position, keys the spindle to the handwheel to allow normal operation of the valve and, in a second position, withdraws the keying between the spindle and the handwheel and allows the handwheel to be rotated without operation of the valve. Security means 4,9,10 are provided to prevent unauthorised movement of the keying means between the two positions. <IMAGE>

Description

SPECIFICATION Valves and mechanism therefor The invention relates to fluid flow control valves and more particularly to mechanismsthereforwhich prevent unauthorised operation of the valve.

In accordance with the invention there is provided a manually operable fluid flow control valve including a valve spindle and a handwheel having a central boss and keying means movable between first and second positions, in the first of which positions the keying means keys the spindle with the handwheel boss so that rotation of the handwheel will effect rotation of the spindle and in the second position of which there is no such key between the spindle and the boss so that rotation of the handwheel does not effect rotation of the spindle, and security means for preventing unauthorised movement of the keying means between the two positions.

Advantageously a groove or recess is present on that part of the spindle adjacent the handwheel and a further groove or recess is present on that part of the handwheel adjacent the spindle and the grooves are alignable by correct positioning of the handwheel relative to the spindle to form a slot with which the keying means can engage in the first position.

Preferably the security means includes an apertured spindle extension and an apertured keying means and relative movement between the keying means and spindle extension is prevented by a locking device passing through the apertures.

Conveniently, the aperture in the keying device is positioned such that relative movement between the keying means and the spindle extension is prevented by the locking device in both the first and second positions of the keying means.

The locking device is preferably a padlock, the arm of which passes through the apertures in the spindle extension and keying means.

The valve keying means can be of any convenient shape, advantageously cylindrical, whose crosssectional size closely conforms to the slot formed between the handwheel and the spindle.

For additional protection against unauthorised operation of the valve, it may in certain circumstances be useful to allow rotation of the spindle extension relative to the spindle itself. This can be achieved, for example, by attaching the spindle extension to the spindle by means of a tension pin.

Such a pin can take the form of a split cylindrical ring which is snapped into position between a lug on the spindle extension and a corresponding hole in the spindle. Alternatively a rotation clip (circlip) can be employed.

Preferably, when using an independently rotatable spindle extension in particular, a washer is available for placing about the spindle extension when the keying means is in the second position so that the washer covers the slot formed between the handwheel and the spindle.

The invention will now be more particularly described and exemplified by reference to the accompanying drawings in which: Figure 1 shows a sectional view of an embodiment of the invention with the keying means in its first position; Figure 2 shows the same sectional view of that of Figure 1 with the keying means in its second position; Figure 3 shows a plan view of the embodiment of Figures 1 and 2 with the keying means in the second position; and Figure 4 shows a sectional view of a further embodiment of the invention in which the spindle extension is rotatable independently of the spindle itself.

Referring to the drawings, a handwheel 1 has a central boss 2 and is mounted about a spindle 3 having an extension 4 integral therewith. That portion of the spindle about which the handwheel is mounted is of smaller cross-sectional area than the main portion of the spindle and the handwheel boss 2 abuts the ledge 5 formed between the two spindle portions.

A groove or recess is formed in the spindle 3 at 6 which extends parallel to the longitudinal axis of the spindle and is of semi-circular cross section. A groove or recess of similar size and shape is found in the handwheel boss 2 at 7 so that, when the handwheel and spindle are correctly positioned, these grooves or recesses co-operate to form a circular slot between the spindle and handwheel.

Keying means in the form of a cylindrica key 8 is provided which, in a first position as shown in Figure 1, engages the slot formed by correct positioning of grooves 6 and 7 and thereby prevents relative movement between the spindle and the handwheel.

In this first position rotation of the handwheel thereby causes consequential rotation of the spindle and hence operation of the valve.

When the cylindrical key 8 is in its second position shown in Figures 2 (in section) and in Figure 3, it is withdrawn from the slot formed between grooves 6 and 7 and the handwheel and spindle are therefore free to rotate about the longitudinal axis of the spindle relative to each other. In this second position, therefore, rotation of the handwheel will not cause operation of the valve.

Security means are provided to prevent unauthorised movement of the keying means between the first and second positions and generally to prevent unauthorised operation of the valve.

In particular, an aperture is provided in the spindle extension 4 and a further aperture is provided in the key 8 so that, in both positions of the key 8, an arm 9 of a padlock 10 can be passed through both the apertures and thereby prevent movement of key 8 between its two positions.

For additional security, it may be expedient to allow movement of the spindle extension 4 relative to spindle 3 itself and, in such cases, the extension 4 may be attached to the spindle 3 as shown in Figure 4. This involves providing the spindle extension with a lug 11 and securing the lug 11 within a hole 12 in the spindle 3 by means of a tension pin in the form of a split cylindrical ring 13 which is snapped into position between the lug 11 and the hole 12. Flange 14 ensures retention of the lug 11 within the hole 12.

Such an arrangement will prevent rotation of the spindle, and hence operation of the valve, by rotation of the key and padlock when the key is in its second positon. This arrangement is preferably complemented by surrounding the spindle extension 4 with a washer sufficiently large to coverthe top of the grooves 6 and 7 in the spindle and handwheel respectively prior to fitting the padlock when the key is in its second position.

Claims

1. A manually operable fluid flow control valve including a valve spindle and a handwheel having a central boss and keying means movable between first and second positions, in the first of which positions the keying means keys the spindle with the handwheel boss so that rotation of the handwheel will effect rotation of the spindle and in the second position of which there is no such key between the spindle and the boss so that rotation of the handwheel does not effect rotation of the spindle, and security means for preventing unauthorised movement of the keying means between the two positions.

2. A valve according to Claim 1 in which a groove or recess is present on that part of the spindle adjacent the handwheel and a further groove or recess is present on that part of the handwheel adjacent the spindle and the grooves are alignable by correct positioning of the handwheel relative to the spindle to form a slot with which the keying means can engage in the first position.

3. A valve according to Claim 1 or Claim 2 in which the security means including an apertured spindle extension and an apertured keying means and relative movement between the keying means and spindle extension is prevented by a locking device passing through the apertures.

4. A valve according to Claim 3 in which the aperture in the keying device is positioned such that relative movement between the keying means and the spindle extension is prevented by the locking device in both the first and second positions of the keying means.

5. A valve according to Claim 3 or Claim 4, in which the locking device is a padlock, the arm of which passes through the apertures in the spindle extension and keying means.

6. A valve according to any preceding claim in which the keying means is of cylindrical shape.

7. A valve according to any one of Claims 3 to 6 in which the spindle extension can rotate about the spindle longitudinal axis independently of the spindle itself.

8. A valve according to Claim 7 in which the spindle extension is attached to the spindle by means of a tension pin.

9. A valve according to any one of Claims 3 to 8 in which a washer is placed about the spindle extension when the keying means is in the second position so that the washer covers the slot formed between the handwheel and the spindle.

10. A valve according to Claim 1 substantially as described herein with reference to any one of Figures 1 to 4.