GB2071815A

GB2071815A - Valves

Info

Publication number: GB2071815A
Application number: GB8008713A
Authority: GB
Original assignee: POWER HOUSE ENG Ltd
Current assignee: POWER HOUSE ENG Ltd
Priority date: 1980-03-14
Filing date: 1980-03-14
Publication date: 1981-09-23
Also published as: GB2071815B

Abstract

A gate valve comprises a housing defined by a pair of plate members 11,12 which are rigidly held spaced apart from one another to define a passageway, one plate member containing the inlet, the other containing the outlet, a planar valve element 14 slidably received between the plate members, the valve element being arranged so that depending on its slidable position it either prevents or permits communication between the inlet and outlet, and a seal assembly located between the valve element and each respective opposed plate member of the passageway, each seal assembly including an annular deformable seal element 32 and compression means, the compression means comprising a rigid annular member 31 which is surrounded by the annular seal element, and contraction means 33 surrounding the annular seal element for compressing the seal element between itself and the rigid annular member to thereby deform the seal element axially to contact opposed respective surfaces of the pair of plate members of the passageway and the valve element, the surfaces of the valve element having a low co-efficient of friction so as to enable the valve element to be slid within the passageway whilst the seal elements are under compression. <IMAGE>

Description

SPECIFICATION Valves The present invention relates to valves of the type which have a planar valve element slidably received in a valve housing between its inlet and outlet parts, the slidable portion of the valve element determining whether communication between the inlet and outlet parts is permitted or prevented. In particular the present invention relates to an improvement in the valve disclosed and claimed in our copending U.K. patent application No.

24161/78.

According to the present invention there is provided a valve having a housing containing an inlet and outlet the housing being defined by a pair of plate members which are rigidly held spaced apart from one another to define a passageway, one plate member containing the inlet, the other containing the outlet, a planar valve element slidably received between a pair of opposed walls of the passageway formed in the housing, the valve element being arranged so that depending on its slidable position it either prevents or permits communication between the inlet and outlet, and a seal assembly located between the valve element and each respective opposed wall of the passageway, each seal assembly including an annular deformable seal element and compression means, the compression means comprising a rigid annular member which is surrounded by the annular seal element, and contraction means surrounding the annular seal element for compressing the seal element between itself and the rigid annular member to thereby deform the seal element axially to contact opposed respective surfaces of the pair of walls of the passageway and the valve element, the surfaces of the valve element having a low co-efficient of friction so as to enable the valve element to be slid within the pasgeway whilst the seal element is under compression.

Reference is now made to the accompanying drawings, in which: Figure 1 is a plan view of a valve according to the present invention; and Figure 2 is a side view, partly in section, of the valve assembly of Fig. 1.

The preferred valve illustrated in the drawings includes a valve housing constituted by a pair of plate members 11, 1 2 spaced apart to form a passageway 1 5 for slidably receiving a valve element 14. The plate members have apertures 16, 1 8 respectively (constituting an inlet and outlet respectively), which are coaxial with one another and the valve element 1 4 has an aperture 20 which, at one end of the slidable movement of the valve element 14 permits communication between the apertures 16, 18 in which case the valve is in an open condition.On sliding the valve element 14 to its opposite end of its slidable movement, the valve element 14 extends completely across apertures 16, 1 8 to prevent communication therebetween, in which case the valve is in its closed condition.

The plate members 11, 1 2 are secured to one another by two rows of bolts 22, 23 respectively located either side of the valve element 1 4. The bolts, 22, 23 are provided with spacing collars 28 which serve to space the plate members apart. Locating dowels 26 are provided either side of the valve element 14 to serve as a guide for the slidable movement of the valve element 14. It will be appreciated that dowels 26 may be dispensed with and that the bolts 22, 23 may be used for guide valve element 14.

Located between the valve element 14 and each plate member 11, 1 2 respectively is a seal assembly 30 which serves to provide a seal between the valve element 14 and plate members 16, 18.

Each seal assembly 30 includes an annular member 31 which has an external diameter greater than the diameter of apertures 16, 1 8 and is formed from a relatively rigid material which is resistive to radial inward collapse.

Surrounding the annular member 31 is an annular seal element 32 which is formed of a deformable material, e.g. rubber or similar elastomeric material capable of withstanding the working conditions of the valve assembly.

Preferably the deformable material is silicone rubber. The internal surface of annular member 31 may be coated with an abrasive resistant coating in order to prolong its life particularly when the valve is to be used in a pneumatic system for conveying abrasive material.

Surrounding the annular seal element 32 is a band 33 which is arranged so that its diameter can be reduced to compress the annular seal element 32 between itself and the rigid annular member 31 to thereby deform the sealelement 32 axially in opposite directions to abut opposed surfaces on the valve element 14 and plate members 11, 1 2 respectively. Such deformation of seal element 32 ensures a good sealing contact between said opposed surfaces. The outer face 31 a of annular member 31 and the inner face 33a of bank 33 are chosen so as to have a low co-efficient of friction thereby enabling seal element 32 to move freely relative thereto. Accordingly it is possible to apply a uniform compression to the seal element 32.

Annular member 31 and/or band 33 may be formed entirely of a material having a low coefficient of friction or their outer and inner surface may be respectively coated with a suitable material, e.g. polytetrafluoraethylene (P.T.F.E.).

Each seal element 32, in its relaxed state, is received with clearance between the valve element 14 and respective plate member 11, 12.

In the illustrated embodiment, each band 33 is a metallic strip having an inner face 31 a defined by a layer of P.T.F.E. of about 0.015 inches in thickness. Opposite ends of the strip are connected by a tensioning device 40 which includes a boss 34 located at one end of the band and having a diametrically extending internally threaded bore 35, and a boss 36 located at the other end of the hand and having a diametrically extending bore 38 which slidingly receives the threaded portion 39 of a bolt 41; the threaded portion 39 being threadedly received in bore 35. A sleeve 80 is provided through which the bolt 40' extends. The sleeve 80 has a concave end which abuts against boss 36. A second sleeve 81 abuts against sleeve, 80 and also against the head 83 of the bolt 40'.A washer 82 is located between sleeves 80, 81 and is preferably constructed so as to permit sleeves 80, 81 to rotate relative to one another when under axial compression, for instance the washer may be made of a material having a low co-efficient of friction. It is envisaged that in certain instances, for example in cases where the annular member 31 is of large diameter, that the band 33 may be made of separate portions each of which are connected to one another by a tensioning device 40.

Thus the band may be provided with a plurality of tensioning devices spaced about its circumference.

Each bolt 40' is made long enough to extend beyond the plate member 11, 1 2 to permit easy access.

Each annular member 31 is positioned in abutment with a pair of dowels 46 extending through plate members 11, 1 2 respectively.

A pair of removable stops 50 are provided in opposition to the dowels 46 for each seal assembly to thereby retain each member 31 in position, each removable stop being bolted to the associated plate member so as to abut against the outer surface of a band 33.

Replacement of the seal assemblies may be easily achieved by slacking bands 33 and removing stops 50. Each seal assembly may then be slid out whilst the valve assembly is in situ and the replacement seal assemblies inserted.

Each plate member is provided with apertures 60 spaced about their periphery for receiving bolts (not shown) so that the valve assembly may be located between the flanged ends of adjoining pipes.

In the illustrated embodiment, the valve element 14, and plate members 11, 1 2 are provided with alignable apertures 61 through which a bolt can be passed to lock the valve assembly in either its open or closed positions.

It will be appreciated that the seal element 32 need not necessarily be of round-section but may have other shapes, e.g. square or rectangular. Additionally, the seal element 32 may be hollow.

An advantage of the above valve is that if leakage occurs across the seal elements 32 due to creep and stress relaxation then two solutions are possible (a) tighten the adjusting screw and thereby tension the element 33 or (b) remove and replace the whole seal assembly. The latter may be accomplished while the valve is in situ.

Additionally the whole valve assembly may be totally dismantled in order that any maintenance work may be carried out on the external flanges where the seal element 32 abuts.

This may be necessary if corrosion take place at this point. In order, to avoid corrosion at these locations, the inside faces of the plate members may be coated with a suitable finish i.e. paint plating or lining with corrosion resisting materials e.g. stainless steel.

The valve element 14 is provided with opposed faces 14a, 14which have a low coefficient of friction and thereby enable the valve element 14 to be slid between the open and closed positions whilst the seal assemblies are under compression. Accordingly, it is possible to provide mechanical means, for example a pneumatic cylinder or an electric drive motor, for moving the valve element between open and closed position.

To provide the valve element 14 with opposed faces 14a, 1 4b having a low co-efficient of friction, the valve element may be constructed from a low co-efficient of friction material such as stainless steel or it may be coated metal, e.g. a steel element coated with P.T.F.E. or aluminium coated with molibdunum disulphide.

Claims

1. A valve having a housing containing an inlet and outlet the housing being defined by a pair of plate members which are rigidly held spaced apart from one another to define a passageway, one plate member containing the inlet, the other containing the outlet, a planar valve element slidably received between a pair of opposed walls of the passageway formed in the housing, the valve element being arranged' so that depending on its slidable position it either prevents or permits communication between the inlet and outlet, and a seal assembly located between the valve element and each respective opposed wall of the passageway, each seal assembly including an annular deformable seal element and compression means, the compression means comprising a rigid annular member which is surrounded by the annular seal element, and contraction means surrounding the annular seal element for compression the seal element between itself and the rigid annular member to thereby deform the seal element axially to contact opposed respective sufaces of the pair of walls of the passageway and the valve element, the surfaces of the valve element having a low coefficient of friction so as to enable the valve element to be slid within the passageway whilst the seal element is under compression.

2. A valve according to Claim 1 wherein the surfaces of the annular member and the contraction means which contact the seal element have a low co-efficient of friction.

3. A valve according to Claim 1 or 2 wherein each seal assembly when the annular seal element is in a relaxed state, is receivable with clearance in the space defined between respective opposed walls of the passageway and the valve element.

4. A valve according to Claim 1, 2 or 3 wherein the seal assemblies are removably held in position by dowels extending therethrough and through respective plate members, and by removeable stops.

5. A valve according to any of Claims 1 to 4 in which the plate members are secured to one another in spaced relationship to define said passageway by means of a pair of rows of bolts having spacing collars, the rows of bolts being located on opposite sides of the valve element.

6. A valve according to claim 5 wherein the pair of rows of bolts define a guide for the slidable movement of the valve element.

7. A valve according to Claim 5 wherein a pair of rows of dowels are provided on opposite sides of the valve element to define a guide for the slidable movement of the valve element.

8. A valve substantially as described with reference to the accompanying drawings.

CLAIMS (30 Mar 1981)

1. A valve having a housing containing an inlet and outlet the housing being defined by a pair of plate members which are rigidly held spaced apart from one another to define a passageway, one plate member containing the inlet, the other containing the outlet, a planar valve element slidably received between a pair of opposed walls of the passageway formed in the housing, the valve element being arranged so that depending on its slidable position it either prevents or permits communication between the inlet and outlet, and a seal assembly located between the valve element and each respective opposed wall of the passageway, each seal assembly including an annular deformable seal element and compression means, the compression means comprising a rigid annular member which is surrounded by the annular seal element, and contraction means comprising a flexible band surrounding the annular seal element, the band being adjustable in length for compressing the seal element between itself and the rigid annular member to thereby deform the seal element axially to contact opposed respective surfaces of the pair of walls of the passageway and the valve element, the surfaces of the valve element having a low co-efficient of friction so as to enable the valve element to be slid within the passageway whilst the seal element is under compression.