GB2071821A - Diaphragm valves - Google Patents

Abstract

A weir type diaphragm valve has the valve body formed in two separate parts (10, 11), such parts having walls (12, 13) which form the weir (4) when secured together and the weir (4) has a valve seat (17) formed as a detachable part formed for example from elastomeric material. The valve seat may be clamped between the walls (12, 13) and have a metal insert (1b). The diaphragm (8) Fig. 4a and b, (not shown), is clamped between flanges (7, 20) on the bonnet assembly and the valve body and an elongate sealing element (21 or 22) may be provided between the flanges around the diaphragm. The operating mechanism comprises a hand wheel (24) and an indicator nut (27) is supported on the wheel. As the wheel is rotated a spindle (23) engages the nut and moves it axially relative to the wheel. <IMAGE>

Description

SPECIFICATION Diaphragm valves This invention relates to diaphragm valves of the kind, hereinafter referred to as the kind described, which comprises a valve body shaped to provide fluid inlet and outlet passages with a weir therebetween, a diaphragm mounted on the valve body and movable between an open position at which it is spaced above the weir to permit flow of fluid from the inlet passage to the outlet passage over the top of the weir and a closed position at which it sealingly engages the weir and thereby prevents said fluid flow, and a bonnet assembly mounted on said valve body over the diaphragm and containing an operating mechanism for use in effecting said movement of the diaphragm.

With a known diaphragm valve of the kind described the valve body including the said passages and weir is formed as a one-piece metal cast structure. This known arrangement may be disadvantageous in that manufacture of the one-piece body may be complicated and expensive and one object of the present invention is to overcome or at least apprecia bly reduce this disadvantage.

According to one aspect of the invention therefore there is provided a diaphragm valve of the kind described characterised in that the valve body is formed from two separate structures each providing a respective one of the said passages and having a respective upstanding wall, the structures being adapted to be'secured together with the said walls arranged against each other so as to define together at least part of the said weir.

With this arrangement, the valve body can be manufactured in a simple and inexpensive manner.

The structures may be fixed together by bolts passed thorough bores in abutting flanges of the slquctures. Such flanges may be immediately beneath the said walls. If desired a sealing element may be provided between the structures, particularly between said abutting flanges.

With the aforesaid known diaphragm valve, the metal top surface of the weir forms a valve seat for sealing engagement with the diaphragm, and sealing problems may arise due to wear of this surface in use. A further object of the present invention is to avoid or at least reduce such problems.

According to a further aspect of the present invention therefore there is provided a diaphragm valve of the kind described wherein said weir incorporates a valve seat for sealing engagement with the diaphragm, characterised in that said valve seat is defined by a detachably mounted element.

With this arrangement the valve seat can be replaced when it becomes worn. The detachable element may be moulded from a natural or synthetic elastomeric material, and a metal bar or other reinforcement may be incorporated for stiffening purposes.

Most preferably the second aspect of the present invention is combined with the first aspect of the present invention, the valve seat being clamped between profiled sections of the said walls.

Also with the aforesaid known diaphragm valve, the diaphragm is sealed at its periphery relative to the valve body by clamping such periphery between flanges on the bonnet assembly and on the valve body. With this arrangement the problem arises that it is difficult to ensure that a good seal is maintained at the diaphragm periphery and a further object of the present invention is to overcome or at least appreciably reduce this problem.

According to a yet further aspect of the present invention therefore there is provided a diaphragm valve of the kind described wherein the diaphragm is clamped at its periphery between flanges on the bonnet assembly and on the valve body, characterised in that an elongate sealing element is fixed around the periphery of the diaphragm in a groove in at least one of said flanges.

With this arrangement, good sealing of the diaphragm relative to the valve body can be maintained. The sealing element may be an O-ring seal.

Further, with the aforesaid known diaphragm valve, the operating mechanism is operated by a hand wheel on top of the bonnet assembly. A still further object of the present invention is to provide an indicator device which can give a visual indication of the operational position of such hand wheel.

According to a yet further aspect of the present invention there is provided a diaphragm valve of the kind described wherein the operating mechanism is operated by a hand wheel on the bonnet assembly, characterised in that the hand wheel supports an indicator nut which is movable axially relative to the wheel whilst being retained circumferentially relative thereto, and a spindle of the operating mechanism which is arranged to be rotated by the wheel has a threaded end which engages the nut so that rotation of the wheel effects said axial movement of the nut.

With this arrangement, with a simple and convenient construction, a clear visual indication (corresponding to the axial positioning of the indicator nut) can be given of the operational position of the wheel and hence of the diaphragm of the valve.

The invention will now be described further by way of example only and with reference to the accompanying drawings in which: Figure 1 is a diagrammatic side view of one form of a valve according to the invention; Figure 2 is a section on the line A-A of Fig.

1 with the valve seat shown in full; Figure 3 is a section on the line B-B of Fig.

2; Figure 4 is a plan view from the top of the valve body of the valve of Fig. 1; Figure 4a is a sectional view of a detail of the arrangement of Fig. 1; Figure 4b is a view similar to Fig. 4a of a modification; Figure 5 is a sectional view of the top of the bonnet assembly of the valve of Fig. 1; Figure 6 is an exploded secticnal view of an alternative embodiment; Figure 7 is a plan view of the valve body of the arrangement of Fig. 6; and Figure 8 is a sectional view of a still further embodiment.

The valve is a fluid flow control valve and comprises a valve body 1 providing an inlet passage 2, an outlet passage 3, and a weir 4 therebetween. The ends of the passages 2, 3 are provided with flanges 5 or other fittings for attachment to pipelines as required. The valve body 1 has an upper open top 6 bounded by flanges 7. A flexible diaphragm 8 is fixed across this open top 6 and a bonnet assembly 9 is mounted over the diaphragm 8.

The valve body 1 is formed from two separate cast bodies 10, 11 each providing a respective one of the passages 2, 3 and each having an upstanding wall 1 2, 1 3 and iower flange 14, 1 5. As shown in Fig. 3, the bodies 10, 11 are fixed together with bolts passed through bores 1 6 in the flanges 14, 15, and a valve seat 1 7 is clamped between grooved upper sections of the walls 12, 1 3. The walls 1 2, 1 3 and valve seat 1 7 define together the aforesaid weir.

The valve seat 17, as shown in Figs. 2 and 3, comprises an elongate shaped moulded plastics or rubber element incorporating a central metal reinforcing bar 1 8.

If desired, and as shown in Fig. 3, a sealing element 1 9 may be held in grooves between the flanges 14, 15.

The valve bodies 10, 11 can be separated as desired to permit replacement of the valve seat 17.

The diaphragm 8 may be of square or rectangular form coextensive with the flanges 7 and, as shown in Fig. 4, the open top 6 of the valve body 1 may be circular. If desired however other shapes may be used.

The periphery of the diaphragm 8 is clamped between the flanges 7 of the valve body 1 and flanges 20 at the bottom of the bonnet assembly -9, fixing bolts being passed through bores in the flanges 7. 20 and the diaphragm 8. Such bores in the flanges 7 are indicated by reference numerals 30 in Fig. 4.

The flanges 7 are provided with a peripheral groove 31 which is generally square and, as shown in Fig. 4a, an O-ring seal 21 may be provided in this groove 31 so as to extend around the periphery of the diaphragm and beneath same. Alternatively, and as shown in Fig. 4b, the diaphragm 8 may be set into recessed portions of the flanges 7, 20 and an O-ring seal 22 may be provided in grooves between the flanges 7, 20 beyond the diaphragm 8.

The bonnet assembly 9 contains a spindle 23 which, as shown in Fig. 5, projects beyond the top of the assembly. Inside the assembly 9 the spindle 23 is threaded and engages a nut on the which is mounted a piston device connected to the centre of the diaphragm 8. Externally of the assembly 9 the spindle 23 is secured to a hand wheel 24.

Rotation of the hand wheel 24 effects rotation of the spindle 23 and consequent axial movement of the nut and the piston device and hence of the diaphragm 8. By rotation of the wheel 24 the diaphragm 8 can bèXrnoved between an open position at which it is spaced above the valve seat 1 7 and permits flow of fluid from the passage 2 to the passage 3 over the top of the weir, and a closed position at which it sealingly engages the valve seat 1 7 to prevent such fluid flow.

The hand wheel 24 has a central axial recess 25 and the top end 26 of the spindle 23 projects into this. This top end 26 is coarse threaded and engages a nut 27 which is retained circumferentially, but not axially, relative to the wheel 24 by engagement of an axially extending projection on the outer surface of the nut 26 with an axially extending groove in the inner surface of the wheel recess 25. As the wheel 24 is rotated the spindle 23, which does not move axially, causes the nut 27 to move upwards or downwards within the recess 25 thereby to give a clear visual indication of the operational state of the valve. The nut 27 may be appropriately colour coded.

It is of course to be understand that the invention is not intended to be restricted to the details of the above embodiment which are described by way of example only. Thus, for example, the spindle end 26 may have a multi-start thread.

Further, and as shown in Fig. 6, a circular O-ring seal 32 may be used around the periphery of a diaphragm 33 between a onepiece valve body 34 and a bonnet assembly 35, such body and assembly being joined by screws 36 beyond the seal. The seal 32 fits in grooves 37, 38 in flanges of the bonnet assembly 35 and the valve body 34. Fig. 7 shows bores 39 in the valve body 34 to receive the screws 36.

Fig. 8 shows a modification of the arrangement of Figs. 6 and 7 in which the valve body 34 and bonnet assembly 35 have interfitting threaded circular configurations 40, 41 whereby fixing screws are not required for the joining of such parts.

Claims (14)

1. A diaphragm valve of the kind de scribed wherein said weir incorporates a valve seat for sealing engagement with the diaphragm, characterised in that said valve seat is defined by a detachably mounted element.

2. A valve according to claim 1, characterised in that said detachable element is moulded from a natural or synthetic elastomeric material.

3. A valve according to claim 2, characterised in that a reinforcement member is embedded in the said elastomeric material.

4. A diaphragm valve of the kind described, characterised in that the valve body is formed from two separate structures each providing a respective one of the said passages and having a respective upstanding wall, the structures being adapted to be secured together with the said walls arranged against each other so as to define together at least part of the said weir.

5. A valve according to claim 4, characterised in that the said structures are fixed together by interconnection of abutting flanges of the structures.

6. A valve according to claim 5, characterised in that the said abutting flanges are interconnected by bolts passed through bores therein.

7. A valve according to claim 5 or 6, characterised in that the said flanges are disposed immediately beneath the said walls.

8. A valve according to any one of claims 4 to 7, which is also a valve according to any one of claims 1 to 3.

9. A valve according to claim 8, wherein the said detachable element is clamped between profiled sections of the said walls.

1 0. A diaphragm valve of the kind described wherein the diaphragm is clamped at its periphery between flanges on the bonnet assembly and on the valve body, characterised in that an elongate sealing element is fixed around the periphery of the diaphragm in a groove in at least one of said flanges.

11. A valve according to claim 10, characterised in that the said sealing element comprises an O-ring seal.

12. A valve according to claim 10 or 11, characterised in that the said sealing element extends around a square path.

13. A valve according to claim 10 or 11, characterised in that the said sealing element extends around a round path.

14. A valve according to any one of claims 10 to 13, which is also a valve according to any one of claims 1 to 9.

1 5. A diaphragm valve of the kind described wherein the operating mechanism is operated by a hand wheel on the bonnet assembly, characterised in that the hand wheel supports an indicator nut which is movable axially relative to the wheel whilst being retained circumferentially relative thereto, and a spindle of the operating mechanism which is arranged to be rotated by the wheel has a threaded end which engages the nut so that rotation of the wheel effects said axial movement of the nut.

1 6. A valve according to claim 15, which is also a valve according to any one of claims 1 to 14.

1 7. A diaphragm valve substantially as hereinbefore described with reference to and as illustrated in the accompanying drawings.