GB2408788A

GB2408788A - Single use diaphragm valve

Info

Publication number: GB2408788A
Application number: GB0325714A
Authority: GB
Inventors: Paul Martyn Williams; Kenneth Louis Bibbo
Original assignee: Crane Process Flow Technologies Ltd; Alfa Laval Biokinetics Inc
Current assignee: Crane Process Flow Technologies Ltd; Alfa Laval Biokinetics Inc
Priority date: 2003-11-04
Filing date: 2003-11-04
Publication date: 2005-06-08
Anticipated expiration: 2023-11-04
Also published as: GB2408788B; CN1902418A; GB0325714D0

Abstract

A diaphragm valve (1) comprising a valve body (2); a diaphragm (12) which is sealed to the valve body (2) to define a flow passage (9) which extends between an inlet port (7) and an outlet port (8), both defined by the valve body (2); and an operating mechanism secured to the valve body (2) for moving the diaphragm (12) into sealing engagement with a seat (11) provided on the valve body (2) in order to close the flow passage (9) to fluid flow. The valve body (2) and diaphragm (12) are formed as a disposable assembly having a relatively less flexible region which forms a valve seat (11) and a relatively more flexible region (12) which forms the diaphragm which may be forced into engagement with the valve seat (11) to close the flow passage (9) to fluid flow, and a housing (3) is provided for mechanically supporting the region of the valve body in which the seat area is defined.

Description

SINGLE USE DL\PHRAGM VALVE BODY This invention relates to a diaphragm

valve, and more particularly to a diaphragm valve having a body which is disposable.

A diaphragm valve comprises a valve body having a diaphragm opening to which a diaphragm is sealed. The valve body and diaphragm together define a flow passage which extends between an inlet port and an outlet port, both defined by the valve body. An operating mechanism is secured to the valve body for moving the diaphragm into sealing engagement with a seat provided on the valve body in order to close the flow passage to fluid flow.

Diaphragm valves have gained wide acceptance in many industries. One reason for the success of diaphragm valves in many industries is the fact that the line content is totally contained within the flow passage defined by the valve body and the diaphragm, and accordingly does not come into contact with any components of the valve other than the diaphragm and this body. This renders diaphragm valves particularly suitable for handling hazardous materials, or for use in applications where high levels of purity are required. For this reason, diaphragm valves have wide acceptance in the biotechnology industry.

It is of critical importance in the biotechnology industry in particular that process equipment can be thoroughly cleaned. Although existing diaphragm valves do admit to thorough cleaning by use of cleaning chemicals and/or steam, ensuring absolute cleanliness with existing diaphragm valves is difficult. It may, for example, be necessary, after initial cleaning, to dis-assemble a diaphragm valves in order to carry out a validity check on the sterility of the system. Such cleaning processes are both time consuming and subject to operator error. Even if, in a particular application, dis-assembly of the valve after initial cleaning is not considered to be necessary, the initial cleaning phase using cleaning chemicals and/or steam cleaning must be carried out thoroughly to achieve a high level of cleanliness. Accordingly, even if valve dis assembly is not necessary high quality cleaning procedures associated with process plant incorporating diaphragm valves are time consuming (and thus costly) and subject to operator error.

Accordingly, the present invention proposes a diaphragm valve in which the body and the diaphragm are "disposable". With such a valve, the valve in its entirety may be removed from a process line and the valve body and diaphragm replaced with a new valve body and diaphragms. Alternatively, only the valve body and diaphragm need be removed and replaced, whilst the remaining components ofthe valve are left in situ. Such replacement may take place instead ofthorough cleaning ofthe valve or at specified intervals in order to prevent the build-up of contaminants within the valve.

Because it is a characteristic of diaphragm valves that the operating mechanism (compressor and actuator) does not come into contact with the line fluid it should not be necessary to dispose of these components when the body itself is disposed of.

Accordingly, it is the primary object of the present invention to provide a diaphragm valve in which the diaphragm and valve body may be disposed of and in which other components of the valve may be re-used in combination with a replacement valve body and diaphragm.

At first sight, the object of the present invention can be achieved simply by replacing a conventional valve body (which is typically of polished forged or cast stainless steel) with a moulded plastics valve body of the same profile. However, this is not possible because the mechanical characteristics of conventional metal valve bodies cannot be reproduced using plastics materials. In particular, the conventional arrangement whereby the closure diaphragm is sealed to the body by clamping the periphery of the diaphragm between respective flanges provided on the body and on the actuating mechanism is not possible if the body is formed of plastics material, in particular flexible plastics material.

In accordance with a first aspect of the present invention a diaphragm valve comprising: a valve body; a diaphragm which is sealed to the valve bodyto define a flow passage which extends between an inlet port and an outlet port, both defined by the valve body; and operating mechanism secured to the valve body for moving the diaphragm into sealing engagement with a seat provided on the valve body in order to close the flow passage to fluid flow, is characterized in that the valve body and diaphragm are formed as a disposable assembly having a relatively less flexible region which forms a valve seat and a relatively more flexible region which forms a diaphragm which may be forced into engagement with the valve seat to close the flow passage to fluid flow, and a housing is provided for mechanically supporting the region of the valve body in which the seat area is defined.

The diaphragm valve of the present invention replaces the three main components of the conventional diaphragm valve, namely the body, the diaphragm and the operating mechanism, with three other fundamental components, namely a combined body/diaphragm component, the operating mechanism and a support for the combined body/diaphragm. This fundamental revision of the nature of the components enables the design of a disposable body/diaphragm component to be optimised for production and fluid flow characteristics even if this optimization results in a body the mechanical strength of which would not be sufficient to withstand the forces conventionally applied to diaphragm valve bodies.

The invention will be better understood from the following description of preferred embodiments thereof, given by way of example only, reference being had to the accompanying drawings wherein: Figure 1 illustrates a diaphragm body/diaphragm component and support of a first embodiment of the invention; Figures 2, 3 and 4 show respectively an isometric view, a transverse cross- section, and a longitudinal cross-section of the valve body/diaphragm component of Figure 1; Figure 5 illustrates an alternative valve body/diaphragm component; Figure 6 illustrates an alternative valve body/diaphragm profiled to provide self-draining characteristics; Figure 7 illustrates the components of Figure 1 secured to an operating mechanism; and Figure X illustrates a modified embodiment of the invention in which means are provided for forming a mechanical connection between a flexible portion of the body/diaphragm component and a compressor.

Referring firstly to Figure 1 there is illustrated a diaphragm valve 1 from which the operating mechanism has been removed in the interests of clarity. The remaining components of the valve comprise a combined body and diaphragm member 2 and a support 3 formed by an upper support member 4 and a lower support member 5. The upper support member 4 defines an aperture 6 in which, in use, a diaphragm compressor is located. Means (not shown) are in practice provided for securing the operating mechanism to the support 3.

The body and diaphragm member 2 is illustrated in greater detail in Figures 2- 4. The member 2 is moulded from a synthetic material, for example a synthetic thermo-plastic material. The material may be un-reinforced or reinforced by fibre or other reinforcing materials depending on the circumstances and design in question. It will be seen that the member 2 defines inlet and outlet ports 7, 8 respectively, and a flow passage 9 which connects the inlet and outlet ports. As illustrated, the member 2 is symmetrical about a transverse plane of symmetry and accordingly either of the ports 7, 8 may function as an inlet port whilst the other port functions as an outlet port.

A transverse cross-section in the central region ofthe member 2 is illustrated in Figure 3. In this transverse region the body includes a relatively thick lower portion 10 which defines, on the upper surface thereof, a valve seat 11. The valve seat 11 may be constituted by a portion of a generally smooth flow passage, or may be formed by the upper surface of a weir moulded into the flow passage. Opposite the seat 11 is a relatively flexible portion 12 ofthe body which can be moved, by a suitable operating mechanism into sealing engagement with the seat 11 to close the flow passage 9 to fluid flow. The relatively flexible nature ofthe region 12 is achieved by a combination ofthe profile ofthe member 2 at this region and by a relatively thin section of material at this region. Similarly, the relatively rigid region 10 is formed by a relatively thick section of material and/or reinforcement provided in this region.

It will be noted that wings 13, 14 extend laterally outwardly from the remaining portions of the member 2. The wings at their widest at the central portion at which the cross-section of Figure 3 is taken and reduced in lateral extent towards the opposite ends of the member 2, eventually blending into the profile of the member 2 adjacent the end regions 15, 16 of the body. The purpose of the wings 13, 14 is to provide additional strengthening of the valve body, particularly in the region of the cross- section illustrated in Figure 3.

The thin cross-section of the region 12 blends, in the longitudinal direction, into the full cross-section of the wall of the body, reaching the full cross-section by the end regions 15 and 16, as illustrated in the longitudinal cross-section of Figure 4.

The required contrast between the relatively rigid region 10 and the relatively flexible region 12 may be achieved by use only ofthe shaping ofthese regions, and in particular the thickness of material in these regions, or may be achieved by other means, for example the inclusion of reinforcing material within the relatively rigid regions and/or by differences in the plastics material utilised in the respective regions.

It may, for example, be possible to mould a unitary body in which the relatively flexible region 12 is formed from a different polymer or different grade of the same polymer as that used for the relatively rigid regions. This technique may be used in association with the variable wall thick technique referred to above. The important characteristic is that the member 2 defines a relatively rigid region and a relatively flexible region which can be brought into engagement with the rigid region to interrupt fluid flow through the flow passage 9.

The member 2 illustrated in Figures 2-4 may be moulded as a single unitary moulding by use of suitable mould and core tools. In the alternative, the member may be formed by two components, one of which has the form illustrated in Figure 4 and the other of which is a mirror image ofthat component about the longitudinal plane of the section of Figure 4. Two such components can be moulded separately and joined together after moulding by a welding process.

Turning now to Figure 5 an alternative approach to the design and construction of a combined body and diaphragm member is illustrated. In this case, the body 20 is moulded from one synthetic material and the diaphragm 21 is moulded from a different material which is, nonetheless, compatible with the material of the body 20 so that the two components may be welded together to form a unitary body and diaphragm member. The advantage of the Figure 5 arrangement is that the materials from which the body 20 and diaphragm 21 are made may, to an extent, be optimised in light of the respective function these components are to perform, thereby providing a relatively rigid seat area and a relatively flexible diaphragm area. In practice, after the body 20 and diaphragm 21 have been formed and united by an appropriate process the resultant combined member will be used in association with a support appropriately shaped to the profile of the combined member in order to provide the necessary mechanical support in the region of the valve seat 22.

Referring now to Figure 6, an alternative form of combined body and diaphragm member 23 is illustrated. This design generally corresponds to that of the previous embodiments in that it may be a unitary moulding, an assembly of two substantially symmetrical moulded parts, or an assembly of two separate mouldings (body and diaphragm). In this case, however, the body is profiled to provide a substantially flat invert surface 24 so that the valve will have "self-draining" characteristics.

Figure 7 illustrates a complete valve comprising a combined body and diaphragm member 30, a support 31, and an operating mechanism 32. The support 31 comprises a lower support member 33 which offers mechanical support for the relatively rigid portions 34 of the valve body and the wings 35 (only one of which is visible in Figure 7) and an upper portion 36 which serves to locate the component relative to the support 31 and defines a cavity 37 in which the compressor 38 of the operating mechanism 32 is located. Suitable means (for example screws) are provided for attaching the upper part 36 of the support 31 to a flange 39 provided on the operating mechanism 32. The lower portion 33 of the support 31 is secured to the upper portion 36 ofthe support 31 by one or more releasable clamps. For example, the lower portion 33 may be secured to the upper portion 36 by means of a hinge along one edge and by means of a releasable over-centred toggle clamp along the opposite edge. With such an arrangement, the lower portion 33 can be readily separated from the upper portion 36 to permit removal of the body and diaphragm component 30 for appropriate disposal and replacement.

In the arrangement illustrated in Figure 7 the compressor 38 abuts the flexible region of the body and diaphragm member 30, but no mechanical coupling is provided between these respective components. Accordingly, the valve of Figure 7 would be incapable of opening against a sub-ambient pressure within the valve body. To avoid this problem an arrangement for mechanically coupling the flexible portion of the body and diaphragm member to the compressor may be provided. Such an arrangement is illustrated in Figure 8. In this case, a cup 40 is moulded integrally with the body and diaphragm member 41 in the flexible region thereof and is, in use, secured by a snap-fit connection to a button 42 provided on the compressor. With such an arrangement the compressor can readily be coupled to and released from the diaphragm and body member 30.

In the above illustrated embodiments of the invention the body and diaphragm component is illustrated as having plain cylindrical ends. Such ends would, of course, require appropriate coupling to secure them into a pipework system. The exact form of the couplings will depend on the application and many such forms of couplings will be apparent to those skilled in the art.

In a particularly preferred embodiment ofthe invention arrangements are put in place to permanently mark each body and diaphragm assembly as it is placed within the support. Such means may, for example, comprise a knife blade provided on the support which cuts a notch or makes an incision in one of the wings of the body and diaphragm member. The object ofthis arrangement is to ensure that a previously used component will not accidentally be re-used. x

Whilst the invention has been described in the context of a 2-port valve it is to be understood that the present invention is applicable to other forms of valve, for example valves with three or more ports controlled by one or more diaphragms. The exact arrangements of the valve body, diaphragm and operating mechanism will, of course, be determined by the number of ports present in the valve, but the general concepts of the present invention may be applied to such multi-port valves and the present application is to be construed as encompassing such multi-port valves. q

Claims

Claims 1. A diaphragm valve comprising: a valve body; a diaphragm which is

sealed to the valve body to define a flow passage which extends between an inlet port and an outlet port, both defined by the valve body; and an operating mechanism secured to the valve body for moving the diaphragm into sealing engagement with a seat provided on the valve body in order to close the flow passage to fluid flow, characterised in that the valve body and diaphragm are formed as a disposable assembly having a relatively less flexible region which forms a valve seat and a relatively more flexible region which forms the diaphragm which may be forced into engagement with the valve seat to close the flow passage to fluid flow, and a housing is provided for mechanically supporting the region of the valve body in which the seat area is defined.
2. A diaphragm valve according to claim 1, wherein said housing has a longitudinal through opening formed therein in which at least the region of the valve body in which the seat area is defined in mounted so as to support said region.
3. A diaphragm valve according to claim 1 or claim 2, wherein said housing includes an aperture in the region of the diaphragm in which said operating mechanism engages.
4. A diaphragm valve according to any of the preceding claims, wherein said housing is formed by an upper support member having a lower surface which engages an upper surface of said region of the valve body, and a lower support member having an upper surface which engages a lower surface of said region ofthe valve body, said upper and lower surfaces of said support members being of complementary shape to the respective upper and lower surfaces of the said region.
5. A diaphragm valve according to claim 4, wherein said support members define between each other a through opening through which said valve body extends.

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6. A diaphragm valve according to any of the preceding claims, wherein the region of the valve body in which the seating area is defined has an upper wall and a lower wall, the upper wall being flexible and forming the diaphragm, and the lower surface being rigid and its inner surface forming the valve seat.
7. A diaphragm valve according to claim 6, wherein said upper wall is thinner than said lower wall so as to be more flexible.
8. A diaphragm valve according to claim 6 or claim 7, wherein said upper wall is of a different shape to said lower wall such that said upper wall is more flexible than said lower wall.
9. A diaphragm valve according to any of claims 6 to 8, wherein said lower wall includes reinforcing means which increases its stiffness.
10. A diaphragm valve according to any of claims 6 to 9, wherein said upper wall is fonned of a more flexible material than said lower wall.
11. A diaphragm valve according to any ofthe preceding claims, further including a pair of wings which extend laterally outwards from opposite sites of the valve body in the region of the valve seat.
12. A diaphragm valve according to claim 11, where said wings extend longitudinally along the valve body and taper laterally towards said valve body towards each end thereof so as to have a maximum width in the region of the valve seat.
13. A diaphragm valve according to any ofthe preceding claims, wherein the valve body is of uritary construction, preferably a unitary moulding, such that the diaphragm is integrally fonned therewith. a.e

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14. A diaphragm valve according to any ofclaims 1 to 12, whereinthediaphragm is formed separately to and is sealingly welded to valve body, in particular by welding.
15. A diaphragm valve according to any of the preceding claims wherein the diaphragm is formed of a different material or different grade of material, in particular a different polymer or different grade of polymer, than at least the region ofthe valve body which fonns the valve seat.
16. A diaphragm valve according to any of the preceding claims, wherein said housing includes marking means which permanently marks the valve body upon mounting of the valve body therein so as to identify the valve body as having been used.
17. A diaphragm valve according to claim 16, wherein marking means damages said valve body so as to prevent its reuse.
18. A diaphragm valve according to any of the preceding claims, wherein said operating means is mechanically coupled to said diaphragm such that upon movement of the operating means towards the valve seat the diaphragm is pressed by the operating means against said valve seat and upon movement of the operating means away from the valve seat the diaphragm is pulled away from the valve seat.
19. A diaphragm valve according to claim 18, wherein a coupling means, in particular a cup, is formed, in particular integrally formed, on said diaphragm, which couplingly engages, in particular is a snap fit, with complementary coupling means, in particular a button carries on the operating means.
20. A diaphragm valve according to claim 19, wherein said diaphragm is coupled to the operating means in such a manner that the coupling means formed on the . . . . ..

. . . . . a > (Z diaphragm is damaged upon uncoupling the diaphragm from the operating means, thereby prevent reuse of the valve body.
21. A diaphragm valve according to any ofthe preceding claims, wherein the valve body is profiled to include a flat invert surface extending through the body from the inlet port to the outlet port such that the valve body is self draining.
22. A diaphragm valve substantially as herein described with reference to the accompanying drawings.

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