GB2078909A - Check valve - Google Patents

Abstract

A swing check valve comprises a valve closure member (22) carried by a swinger (24) suspended from a pivot pin (26). So that sealing means are not required at the outer end of a pivot pin receiving bore, the pivot pin (26) is held at its opposite ends in locations in an externally screwthreaded sleeve (20) upstanding from the valve body, and a closure cap (34) is fitted over said screwthreaded sleeve and forms a fluid tight seal against a shoulder (36) at the root end of the sleeve. <IMAGE>

Description

SPECIFICATION Check valve The invention relates to check valves and in particulay to what are called swing check valves in which a valve closure member is carried by a so-called swinger suspended from a pivot pin. It is usual for the pivot pin to be housed in a bore machined from one side of the valve body, and extending through a lug formed within the body casting, and in this case it is necessary to fit some kind of sealing means to seal the outer end of the pivot pin receiving bore against leakage. The valve body is provided with a removable cap giving access to the valve chamber within which the closure member is located, the cap being fitted in a leak proof manner to guard against the leakage at that point.

Such previously known check valves have several drawbacks, in particular in the fact that sealing means are required at the outer end of the pivot pin receiving bore and in the fact that the lug referred to has to be provided within the body casting. The invention seeks to alleviate these disadvantages and to provide a swing check valve which in volume production offers substantial savings in manufacturing costs.

According to the invention, there is provided a swing check valve the closure member of which is carried by a swinger suspended from a pivot pin held at its opposite ends in locations in an externally screwthreaded sleeve upstanding from the valve body and giving access to a valve member in which the swinger is located, a closure cap being fitted over said screwthreaded sleeve and forming a fluid tight seal against a shoulder at the root end of said sleeve, the arrangement being such that separate sealing means at the locations for the opposite ends of the pivot pins are not required. The locations for the opposite ends of the pivot pin in the externally screw-threaded sleeve may be constituted by a pair of diametrically opposed drilled holes. Alternatively, said locations may be constituted by diametrically disposed depressions formed in the top surface of said sleeve.The pivot pin may be a two part fitment, that is to say a pin element with a reduced diameter portion forming a shoulder against which one side of the swinger abuts and a bush element surrounding an end length of the reduced diameter portion of said pin element and abutting againstthe other side of the swinger. Alternatively, the pivot pin may be a plain pin with two equal length bushes, one on each side of the swinger. Inlet and outlet passages at the opposite ends of the valve body may be internally screwthreaded for the connection of externally screwthreaded pipe ends when the check valve is to be connected in a pipeline. On the other hand, the inlet and outlet passages may be provided with compresssion or capillary joint ends.

In order that the invention may be fully understood and readily carried into effect, the same will now be described, by way of example only, with reference to the accompanying drawings, of which Figure 1 is a longitudinal section through a swing check valve embodying the invention, Figure 2 is a sectional view on the line 2-2 in Figure 1,and Figures 3 and 4 illustrate possible modifications.

Referring now to the drawings, the swing check valve there-illustrated includes a valve body 10 provided at its opposite ends with respective inlet and outlet passages 12 and 14 which are internally screwthreaded for the connection of externally screwthreaded pipe ends when the check valve is to be connected in a pipeline. Avalve chamber 16 is provided within the valve body and the inlet passage 12 terminates in a valve seating 18 on one side of the said valve chamber. The valve body is provided with an upstanding externally screwthreaded sleeve 20 which gives access to the valve chamber.

A closure member 22, which is adapted to abut against the valve seating 18 to close the valve, is carried by a swinger 24 suspended from a pivot pin indicated 26 in Figure 1. The shape of the swinger is such that it counterbalances the weight of the closure member 22 acting about the point of pivotal connection. The pivot pin is held at its opposite ends in locations constituted by a pair of diametrically opposed drilled holes 28 in the upstanding sleeve 20 (the opposite ends of the pivot pin being below the root diameter of the screwthread encircling the sleeve).As shown in Figure 2, the pivot pin is a two part fitment and is constituted by a pin element 30 with a reduced diameter portion forming a shoulder against which one side of the swinger abuts, and a bush element 32 surrounding an end length of said reduced diameter portion of said pin element and abutting against the other side of the swinger.

A closure cap 34 is shown to be fitted over the screwthreaded sleeve 20 upstanding from the valve body, said cap forming a fluid tight seal against a shoulder 36 at the root end of said sleeve. Thus the arrangement is such that separate sealing means at the locations for the opposite ends of the pivot pin are not required.

A further advantage of the check valve design just described is that the need for a cast lug within the valve chamber of the valve body and through which a pivot pin receiving bore would normally be drilled is avoided. Furthermore, the drilling of the diametrically opposed holes 28 in the upstanding sleeve 20 is a comparatively simple operation.

Various modifications may be made. For example, it would be quite possible to locate the opposite ends ofthe pivot pin in diametrically opposed depressions formed in the top surface of the screwthreaded sleeve upstanding from the valve body instead of in holes drilled in said sleeve. Other methods of mounting the swinger on said pivot pin could also be adopted. For example, instead of the pin element 30 having a reduced diameter portion on which a bush element is fitted, the pin element could be a plain pin with two equal length bushes, one on each side of the swinger. It will also be understood that the shape of the swinger and the manner in which the closure member 22 is connected thereto may be somewhat different from that illustrated. For example, as shown in Figure 3, the part of the swinger to which the closure member is connected may be more nearly beneath the pivot pin 26 and the closure member provided with a stem portion 38 for connection to the swinger. Alternatively, as illustrated in Figure 4, the swinger may be formed with an upstanding tail portion 40, this form of swinger being thought to have certain advantages in production and in weight distribution.

Claims (8)

1. A swing check valve the closure member of which is carried by a swinger suspended from a pivot pin held at its opposite ends in locations in an externally screwthreaded sleeve upstanding from the valve body and giving access to a valve chamber in which the swinger is located, a closure cap being fitted over said screwthreaded sleeve and forming a fluid tight seal against a shoulder at the root end of said sleeve, the arrangement being such that separate sealing means at the locations for the opposite ends of the pivot pin are not required.

2. A swing check valve according to ciaim 1, in which the locations for the opposite ends of the pivot pin in the externally screwthreaded sleeve are constituted by a pair of diametrically opposed drilled holes.

3. A swing check valve according to claim 1, in which the locations for the opposite ends of the pivot pin in the externally screwthreaded sleeve are constituted by diametrically disposed depressions formed in the top surface of said sleeve.

4. A swing check valve according to any one of the preceding claim, in which the pivot pin is a two part fitment, that is to say a pin element with a reduced diameter portion forming a shoulder against which one side of the swinger abuts and a bush element surrounding an end length of the reduced diameter portion of said pin element and abutting against the other side of the swinger.

5. A swing check valve according to any one of claims 1 to 3, in which the pivot pin is a plain pin with two equal length bushes, one on each side of the swinger.

6. A swing check valve according to any one of the preceding claims, in which inlet and outlet passages at the opposite ends of the valve body are internally screwthreaded for the connection of externally screwthreaded pipe ends when the check valve is to be connected in a pipeline.

7. A swing check valve according to any one of claims 1 to 5, in which inlet and outlet passages at the opposite ends of the valve body are provided with compression or capillary joint ends for the connection of pipe ends when the check valve is to be connected in a pipeline.

8. A swing check valve constructed, arranged and adapted to operate substantially as hereinbefore described, with reference to and as illustrated by the accompanying drawings.