GB2032579A

GB2032579A - Fluid flow control valves

Info

Publication number: GB2032579A
Application number: GB7834583A
Authority: GB
Original assignee: Saunders Valve Co Ltd
Current assignee: Crane Process Flow Technologies Ltd
Priority date: 1978-08-25
Filing date: 1978-08-25
Publication date: 1980-05-08

Abstract

A butterfly valve (1) having a valve body (2) and an operating handle (5) is provided with an adjustable stop (17) for reliably locating the handle (5) in the position corresponding to the optimum closed position of the valve vane. During assembly, the vane is positioned in the optimum closed position and the stop (17) adjusted until it abuts a stop surface (21) on the handle (5). The stop comprises a cam headed screw in the embodiment shown, but in an alternative embodiment it comprises means for adjusting the position of a plate (13) which carries locating slots (12) used to locate the handle (5) against accidental movement. <IMAGE>

Description

-SPECIFICATION Fluid flow control valves This invention relates to a fluid flow control valve, and in particular to the means for determining the relative positions of various components of the valve when the valve is closed to fluid flow.

In a so-called "butterfly" valve a closure vane is mounted in a valve body and is rotatable by an operating member between a closed position in which the vane compietely closes the flow passage of the valve, and an open position in which the edge of the vane is presented to fluid flowing through the valve, and the flow passage of the valve is open. A problem which has arisen with known valves of this type is that of determining the exact correct position of the vane relative to the body of the valve when the valve is fully closed, It is important that the vane effectively closes the flow passage of the valve to fluid flow, and also that the vane is not forced into undesirably tight contact with its seat. These conflicting requirements mean that the positioning of the vane is critical.In prior art valves, the relative position of the vane to the valve body in the closed position has been determined by the abutment of a portion of the operating member with a fixed stop formed on the valve body. In order to carry out the necessary fine adjustment of the position of the vane relative to the valve body it has been necessary either to file away part of the fixed stop on the valve body or to file or bend the co-operating portion of the operating member until the desired relative position is achieved when the operating member is against its stop. This practice is unsatisfactory since it is time consuming, inherently inaccurate, and does not readily lend itself to readjustment to compensate for seat or vane wear, or the replacement of the seat or vane.

According to one feature of the present invention there is provided a fluid flow control valve comprising a valve body; an obturating member mounted in the valve body and rotatable by an operating member between a closed position in which the valve is closed to fluid flow and an open position angularly displaced from the closed position in which the valve is open to fluid flow; and a stop for determining the relative positions of the obturating member and the valve body when the obturating member is in the closed position, the stop comprising surfaces on or secured to the operating member and the valve body which abut when the obturating member is in the closed position, at least one of said surfaces being adjustable in position relative to the member it is on or secured to.

The above and further features and advantages of the invention will become clear from the following description of an embodiment thereof, given by way of example only, reference being had to the accompanying drawings, wherein: FIGURE 1 is an elevational view, partly in section, of a butterfly valve; FIGURE 2 is a plan view of the valve of Figure 1; and FIGURE 3 shows a side elevation and two end elevations of a cam screw.

The valve 1 shown in Figures 1 and 2 comprises a cast iron valve body 2 having a rubber lining 3, and a closure vane 4 rotatably mounted in the valve body and movable between a closed position (as shown in Figure 1) in which the vane closes the flow passage defined by the rubber lining, and an open position spaced 900 from the closed position in which the valve is open to fluid flow.

Rotation of the vane is accomplished by an operating handle 5 keyed to a spindle 6 which is integral with the vane 4. The handle 5 incorporates a retainer 7 in the form of a lever 8 pivotally mounted on the handle for rocking movement about an axis 9 and biased clockwise as shown in Figure 1 by a compression spring 10 such that the innermost end 11 of the lever 8 is normally located in one of a series of slots 1 2 provided on a plate 13 secured to a flange 14 of the valve body by screws 1 5 and nuts 1 6. In order to move the lever to rotate the vane between its open and closed positions, the free end of the handle is manually grasped, and the adjacent portion of the lever is raised by the fingers of the operator.This rotates the lever anti-clockwise as viewed in Figure 1 and removes the end 11 of the lever from its respective slot. The lever can then be rotated and, in due course, the end 11 of the lever located in a different slot 12.

During assembly of the valve 1 it is necessary to rotate the vane 4 in its optimum closed position, and then to ensure that a stop is provided so that during use the vane is reliably moved into its optimum position each time the valve is closed against the stop. To this end a cam-screw 17 having a screw-threaded shaft 1 8 provided with a co-axial collar 19 and an eccentric head 20 is provided extending through the plate 1 3 and the flange 14. The collar 1 9 is a close fit in the bore through the plate 1 3 through which it passes such that rotation of the cam screw 17 by means of a screw-driver rotates the head of the screw eccentrically with respect to the bore in the plate 13.A nut (not shown) is located on the threaded shaft 1 8 and is tightenable against the underside of the flange 14 in order to lock the cam screw in a selected position.

In use, the cam screw 1 7 is positioned such that the head 20 is at its remotest position from the handle 5. The handle 5 is then rotated to bring the vane into its optimum position, and the cam screw 1 7 ts then rotated to bring the head 20 into abuting contact with an abutment surface 21 formed on the handle 5. The nut on the shaft portion 1 8 of the cam screw 1 7 is then tightened to lock the cam screw in position.

In order to accommodate small variations in tie closed position of the handle the slot 12 corresponding to the closed position is made somewhat over-sized with respect to the width of the end 11 of the lever 8, and accordingly the end 11 can be received in this slot 12 in any of the positions of the handle corresponding to the full range of adjustment provided by the cam screw 17. Once the cam screw 17 has been set as described above, each time the valve is closed the surface 21 is brought into abutment with the head 20 and the vane is reliably returned to its optimum position.

In order to provide a valve to meet customs and excise requirements an additional cover plate 22 is secured to the handle 5 for rotation therewith.

The cover plate includes an arcuate slot 23 to accommodate the head 20 of the screw in all positions of the handle 5, and a cut out 24 through which "OPEN" and "SHUT" markings on the plate 13 are visable when the valve is respectively in its open and closed positions. The cover plate 22 includes a recessed portion 25 which, when in register with an aperture 26 formed in the plate 13 enables a locking pin 27 to be positioned in order to lock the valve in the shut position. The locking pin 27 is suitable for receiving an Excise seal. The plate 13 includes a further aperture 28 in which the locking pin 27 can be stored when not in use.

Although the invention has been described with reference to a particular embodiment, it will be appreciated that other adjustable stop arrangements can be used. For example, the plate 13 may be mounted on the flange 14 in the manner to enable slight variation of its position. In this case, after the spindle 6 and handwheel 5 have been set in the optimum position during assembly the plate 13 is rotated until the slot 12 corresponding to the closed position of the valve is brought into register with the end 11 of the lever 8. In this case, this end slot 12 will not be oversized, but will be working clearance on the end 11, and the optimum position of the vane during subsequent closing operations will be determined by the engagement of the end 11 in the end most slot 12. Advantageously, a cam screw mounted for rotation on the flange 14 can in this case be used to adjust the position of the plate 13. In further alternative arrangement, a cam screw similar to the screw 20 can be mounted on the handle 5 for engagement with a fixed stop provided on the valve body.

Finally, although the invention has been described with reference to a valve having a customs and excise sealable handle, in applications where this facility is not required the cover plate 22 can be omitted and the plate 13 reduced in size accordingly.

Claims

1. A fluid flow control valve comprising a valve body; an obturating member mounted in the valve body and rotatable by an operating member between a closed position in which the valve is closed to fluid flow and an open position angularly displaced from the closed position in which the valve is open to fluid flow; and a stop for determining the relative positions of the obturating member and the valve body when the obturating member is in the closed position, the stop comprising surfaces on or secured to the operating member and the valve body which cooperate when the obturating member is in the closed position, at least one of said surfaces being adjustable in position relative to the member it is on or secured to.

2. A fluid flow control valve according to claim 1 wherein the cooperating surfaces are formed on an adjustable abutment movably positioned on one of the operating member and valve body and on a further abutment positioned on the other of the operating member and the valve body, the abutments being in abutting contact when the obturating member is in the closed position.

3. A fluid flow control valve according to claim 2 wherein the adjustable abutment comprises a screw having a cam head, whereby adjustment of the adjustable surface is achieved by rotation of the screw to present a different portion of the cam surface to the further abutment.

4. A fluid flow control valve according to claim 1 wherein the stop is provided by means for holding the operating member against accidental movement in at least the closed position of the obturating member.

5. A fluid flow control valve according to claim 4 wherein the holding means comprises a plate secured to the valve body and defining a detent, and a locking member mounted on the operating member for engaging the detent to hold the operating member against accidental movement, the stop surfaces being constituted by the detent and the locking member, and the plate being adjustably mounted on the valve body to provide for adjustment of the stop surface formed by the detent.

6. A fluid flow control valve according to claim 5 wherein the plate is adjustable by means of a screw engaged in the valve body and having a cam head located in an aperture formed in the plate.

7. A fluid flow control valve, substantially as hereinbefore described with reference to and as shown in the accompanying drawings.