GB2471559A

GB2471559A - Pressure Relief Device

Info

Publication number: GB2471559A
Application number: GB201010867A
Authority: GB
Inventors: John William Proctor
Original assignee: Yorkshire Water Services Ltd
Current assignee: Yorkshire Water Services Ltd
Priority date: 2009-06-29
Filing date: 2010-06-29
Publication date: 2011-01-05
Anticipated expiration: 2030-06-29
Also published as: GB2471559B; GB201010867D0; GB0911187D0; GB2511955B; GB201409649D0; GB2511955A

Abstract

The invention relates to a pressure relief device (10 figure 1) for a mains water system. The pressure relief device (10 figure 1) comprises a housing base (20 figure 1) having an external connection 22 which is removably connectable to a hydrant (90 figure 6), a disc housing (30 figure 1) for housing a bursting diaphragm (40 figure 5), a pressure relief enclosure 50, and a housing top (60 figure 1) with a protrusion 62 for receiving a tool (92 figure 6). The pressure relief device (10 figure 1) may be quickly removed from the hydrant in case of emergency by attaching the tool to the protrusion 62 and using it to rotate the pressure relief device (10 figure 1) and thus remove the pressure relief device (10 figure 1) from the hydrant. Later embodiments relate to a method of attaching and removing the pressure relief valve, and a method of replacing a bursting diaphragm.

Description

Pressure Relief Device

BACKGROUND

Technical Field

The present invention relates to a pressure relief device. More particularly, the present invention relates to a pressure relief device for a mains water system, and a method for using the pressure relief device whilst performing maintenance on the mains water system.

Description of Related Art

In a mains water system the maximum operating pressure varies considerably, ranging from less than 2 Bar up to in excess of 10 Bar. If the pressure exceeds the normal operating pressure regime, the mains water system can burst or become severely damaged. Both of which are laborious to locate and expensive to repair, which leads to high expense for the consumer. It is known to protect mains water systems from excessive pressure by using pressure relief devices which restrict the pressure to below the maximum operating pressure.

One solution known in the art is disclosed in GB 2366830A, which relates to a pressure relief valve in a mains water supply system comprising a pressure relief valve which, in use, opens to release excess water pressure when it exceeds a predetermined level, and a screw fit connection into an existing hydrant in a mains supply. However, fire safety services cannot quickly remove this device in case of emergency.

An objective of the present invention is to provide a pressure relief device to overcome

the above or other problems with the prior art.

SUMMARY OF THE INVENTION

According to the present invention there is provided a pressure relief device, mains water system and methods as set forth in the appended claims. Further, optional features of the invention will be apparent from the dependent claims, and the description which follows.

According to a first aspect of the present invention there is provided a pressure relief device comprising, in general order: a first end having an external connection removably connectable to a hydrant in use; a flange for receiving a bursting diaphragm; a pressure relief enclosure; and at a second end opposite the first end a protrusion for receiving a tool; wherein the pressure relief device defines a longitudinal axis passing from the first end to the second end, and the external connection and protrusion are substantially coaxially arranged along the longitudinal axis.

In this way, the pressure relief device can be quickly removed from the hydrant in case of emergency by attaching a tool to the protrusion and using it to rotate the pressure relief device and thus in use remove the pressure relief device from the hydrant.

Preferably, the pressure relief device comprises a first internal connection between the flange and the pressure relief enclosure, the first internal connection providing a force along the longitudinal axis for sealing a bursting diaphragm in use, against the flange and is rotationally constrainable about the longitudinal axis.

In this way, the bursting diaphragm may be replaced quickly and conveniently.

However, importantly, because the first internal connection is rotationally constrained, the external connection can be removed from the hydrant by rotation imparted by the tool at the protrusion.

Preferably the first internal connection comprises a male and female coaxial screw thread each on opposite sides of the first internal connection, the first internal connection being rotationally constrainable by one or more protrusions that are extendible in the longitudinal axis into corresponding cut-outs, the protrusions and cut-outs being on opposite sides of the first internal connection.

In this way, the rotational constraint of the first internal connection can be quickly applied by inserting the protrusions into the cut-outs. The converse is true for removing the rotational constraint. Furthermore, the protrusions and cut-outs are integral to the pressure relief device so are not easily lost in practice.

Preferably the pressure relief device has more cut-outs than protrusions. In this way, the axial seal force provided from the first internal connection is variable by selecting from number possible cut-out and protrusion configurations.

Preferably, the pressure relief device comprises a one-way valve disposed between the external connection and the flange. In this way, when the diaphragm has burst, contaminant fluid is prevented from entering the water mains system via the pressure relief device.

Preferably, the pressure relief device comprises a second internal connection between the pressure relief enclosure and a housing top on which the protrusion is mounted, the second internal connection being rotationally constrainable about the longitudinal axis.

In this way, because the second internal connection is rotationally constrained, the external connection can be removed from the hydrant by rotation imparted by the tool at the protrusion. Furthermore, if the protrusion is damaged it can be replaced by replacing the housing top, rather than the entire pressure relief device. Furthermore, the housing top can be replaced without removing the device from the hydrant.

Preferably, the second internal connection comprises a male and female coaxial screw thread each on opposite sides of the second internal connection, the second internal connection being rotationally constrainable by one or more protrusions that are extendible in the longitudinal axis into corresponding cut-outs, the protrusions and cut-outs being on opposite sides of the second internal connection.

In this way, the rotational constraint of the second internal connection can be quickly applied by inserting the protrusions are into the cut-outs. The converse is true for removing the rotational constraint. Furthermore the protrusions and cut-outs are integral to the pressure relief device so are not easily lost in practice.

Preferably, the pressure relief enclosure comprises one or more perforations. In this way, when the diaphragm is burst, water is released from the pressure relief enclosure via the perforations. The perforations prevent any large fragments of diaphragm being dangerously propelled from the enclosure.

Preferably, the perforations are disposed circumferentially with respect to the longitudinal axis. In this way, water flow is dispersed normal to the longitudinal axis, and energy from the water flow is diffused over a wide area, rather than, for example, a high energy jet.

According to another aspect of the present invention there is provided a mains water system comprising the pressure relief device according to the first aspect of the present invention.

According to another aspect of the present invention there is provided a method of attaching a pressure relief device to a hydrant, the method comprising: engaging an external connection, positioned at a first end of the pressure relief device, with a connecting portion of the hydrant; engaging a tool with a protrusion positioned at a second end of the pressure relief device; rotating the tool to cause the external connection to rotate and thereby attach the pressure relief device to the hydrant.

According to another aspect of the present invention there is provided a method of removing a pressure relief device from a hydrant the method comprising: engaging a tool with a protrusion positioned at a second end of the pressure relief device; rotating the tool to cause an external connection positioned at a first end of the pressure relief device and connected to the hydrant to rotate and thereby remove the pressure relief device from the hydrant.

According to another aspect of the present invention there is provided a method of replacing a bursting diaphragm of a pressure relief device, the method comprising removing rotational constraints on an internal connection; separating the internal connection to reveal a flange area against which the bursting diaphragm is positioned; removing and replacing the bursting diaphragm; attaching the internal connection; applying the rotational constraints on the internal connection.

Preferably, the bursting diaphragm is replaced prior to working on a pressurised water system to which the pressure relief device is attached.

BRIEF DESCRIPTION OF THE DRAWINGS

For a better understanding of the present invention, and to show how embodiments of the same may be carried into effect, reference will now be made, by way of example, to the accompanying diagrammatic drawings in which: Figure 1 is a side view of a pressure relief device embodying the present invention; Figure 2 is a cross-sectional view of the pressure relief device of Figure 1 through B-B; Figure 3 is a plan view of a disc housing of the pressure relief device of Figure 1; Figure 4 is a plan view of a pressure relief enclosure of the pressure relief device of Figure 1; Figure 5 is an exploded view of the pressure relief device of Figure 1; and Figure 6 is a side view of the pressure relief device of Figure 1, attached to a hydrant.

DETAILED DESCRIPTION OF THE EXEMPLARY EMBODIMENTS

Referring to Figure 1, a pressure relief device 10 embodying the present invention is shown. The device 10 comprises a housing base 20 having a external connection 22 which is removably connectable to a hydrant 90, shown in Figure 6, a disc housing 30 for receiving a bursting diaphragm, a pressure relief enclosure 50, and a housing top 60 having a protrusion 62 for receiving a tool 92, shown in Figure 6. The pressure relief device 10 defines a longitudinal axis 70 about which the external connection 22 and protrusion 62 are coaxial.

Referring to Figure 2, which is a cross-section through B-B of Figure 1, the disc housing has a flange 32 for receiving the bursting diaphragm 40. The disc housing 30 and pressure relief enclosure 50 are held together via a first internal connection 34. The first internal connection 34 also provides a force along the longitudinal axis 70 for sealing the bursting diaphragm 40 against the flange 32.

Figures 3 and 4 show the disc housing 30 and the pressure relief enclosure 50 in more detail respectively. The first internal connection 34 comprises a male 36a and female 36b coaxial screw thread. The connection 34 is rotationally constrainable by engaging protrusions 52, which are grub screws threaded into holes 54 through a second flange 56 in the pressure relief enclosure 50, into corresponding cut-outs 38 in the disc housing 30. There are three protrusions 52 in the pressure relief enclosure 50, and twenty-four cut-outs 38 in the disc housing 30.

Additionally, the pressure relief device 10 comprises a second internal connection 58 between the pressure relief enclosure 50 and the housing top 60. The second internal connection 58 comprises a male lOOa and female lOOb coaxial screw thread. The connection 58 is rotationally constrainable by engaging protrusions 64, which are grub screws threaded into holes 66 through the housing top 60, into corresponding cut-outs 102 in the pressure relief enclosure 50.

The pressure relief enclosure 50 comprises a number of perforations 104, disposed circumferentially around its exterior.

More specifically as shown in Figure 2 and Figure 5, the housing base 20 is substantially cylindrical comprising a first end 24a, a second end 24b, an axial hole 26 for water passage, and an annular rim 28 inset from the first end 24a and second end 24b. Between the first end 24a and annular rim 28, the external connection 22 comprises and a female thread 140 for connection to a BS750 hydrant. Between the second end 24b and annular rim 28 there is a cavity 142 to receive a one-way valve 80 disposed between the external connection 22 and the flange 32. On the second end's 24b exterior there is a male thread 144 to be screwed into the disk housing 30. The annular rim 28 comprises a female thread 146 receiving an orifice plate 148. A gasket 150 is inlaid to the annular rim 28 for sealing against the hydrant 90.

Furthermore, the housing base 20 comprises, on its exterior, two or more cross flats 152, which enable it to be gripped by a spanner (not shown), for attachment and removal from the hydrant 90.

As shown in Figure 2, Figure 3 and Figure 5, the disc housing 30 is cylindrical and comprises a first end 160a, a second end 160b, an axial hole 162 for water passage, and a annular rim 164 inset from the first end 160a and second end 160b. The internal diameter of the disc housing 30 between the annular rim 164 and first end 160a is less than the internal diameter of the disc housing 30 between the annular rim 164 and second end 160b. Between the first end 160a and annular rim 164, a female thread 168 is provided suitable to receive the corresponding male thread 144 on the housing base 20 to create a connection 166.

The surface of the annular rim 164 facing the second end 160b provides the flange 32 which receives the bursting diaphragm 40. The diaphragm 40 is a disc, made from graphite metal or any other suitable material. The flange 32 comprises a circular channel 170, for inlaying an 0' ring 172 or gasket.

On the exterior of the second end 160b of the disc housing 30 there is the male thread 36a which is screwed into the pressure relief enclosure 50. A face of the second end 160b further comprises the cut-outs 38. The cut-outs 38 are positioned at regular intervals around the face of the second end 160b and are central to the thickness of the disc housing 30.

Further, the cut-outs 38 are about axes which are parallel longitudinal to axis 70.

As shown best in Figure 4 and Figure 5, the pressure relief enclosure 50 is cylindrical and comprises a first end 106a, a second end 106b, an axial hole 108 for water passage, and an annular rim 110 inset from the first and second ends 106. Between the first end 106a and annular rim 110, the first internal connection 34 comprises the female thread 36b which receives the male thread 36a (see Figure 3) of the disc housing 30.

Through the annular rim 110 there are three holes 54, although the quantity of holes may be one or more. The holes 54 each have an axis which is located to coincide with the axis of corresponding cut-outs 38, of the disc housing 30. As shown there are fewer holes 54 than cut outs 38. The holes 54 support protrusions, which are able to move into the cut-outs 38. In this example, the protrusions are grub screws threaded into the holes 54 which when screwed move axially into the cut-outs 38. In this instance the hole diameter of each cut-out 38 is greater than the maximum thread diameter of each grab screw. In another embodiment not shown, the protrusions are pins.

The pressure relief enclosure 50 comprises a number of perforations 104 for expelling water. The perforations 104 are circular, with axes normal to the longitudinal axis 70, and are spaced around the circumference of the enclosure 50 at several axial locations. In a further embodiment not shown the perforations may have axis tangential to the enclosure's 50 cylindrical body. In yet a further embodiment not shown the perforations may be located on the housing top 60, at a plurality of radial locations.

On the exterior of the second end 106b (see Figure 2 and Figure 5) there is the female thread lOOb to be screwed into the housing top 60. A face of the second end 160b further comprises the cut-outs 102. The cut-outs 102 are positioned at regular intervals around the face of the second end 106b, and are central to the thickness of the device housing 30. The cut-outs 102 have axis which are parallel to the longitudinal to axis 70.

As shown in Figure 2 and Figure 5, the housing top 60 is cylindrical and comprises a first end 120a, and a second end 120b. The first end 120a comprises the male thread lOOa which receives the female thread lOOb of the pressure relief enclosure 50.

Through the housing top 60 there are three holes 66, although the quantity of holes may be one or more. The holes 66 each have an axis which is located to coincide with the axis of the cut-outs 102 of the pressure relief enclosure 50. The holes 66 support protrusions, which are able to move into the cut-outs 102. In this example the protrusions are grub screws threaded into the holes 66 which when screwed move axially into the cut-outs 102, in this instance the hole diameter of each cut-out 102 is greater than the maximum thread diameter of each grub screw. In another embodiment not shown, the protrusions are pins.

The second end 120a comprises the protrusion 62, which extends outwardly from the pressure relief device 10, and which can be gripped by a hydrant key 92 shown in Figure 6, for attaching and removing the pressure relief apparatus 10 to and from the hydrant 90.

The housing base 20, disc housing 30, pressure relief enclosure 50, and housing top 60, can be made from metal, plastic, resin or any other suitable material. The components can either be cast, machined or made by any other suitable method.

With reference especially to Figure 5, a general method of assembly is described.

The one-way valve 80 is inserted into the cavity 142 of the housing base 20. The first end 82a of the one-way valve is sealed against the annular rim 28 of the housing base 20 either by an 0-ring or gasket 84. In this state the second end 82b of the one-way valve protrudes from the cavity 142.

The second end portion 24b of the housing base 20 is inserted into the first end 160a of the disk holder 30. As threads 144 and 168 are engaged rotationally, the annular rim 164 of the disk housing 30 engages the protruding second end 82b of the one-way valve 80, thereby providing an axial sealing force. The connection 166 between the disc housing 20 and disk holder 30 is constrained rotationally by a thread locking adhesive. Alternatively, an arrangement of protrusions and cut-outs may be utilised.

The bursting diaphragm 40 is positioned onto the flange 32 and corresponding 0-ring 172 of the disc housing 30. The disc housing 30 and pressure relief enclosure 50 are connected using the first internal connection 34. As threads 36a and 36b are engaged rotationally, the flange 34 and annular rim 110 clamp the bursting diaphragm 40, thereby providing an axial force to seal the diaphragm 40 against the flange 34 and corresponding 0-ring 172. The seal force is therefore adjusted by the torque applied to the first internal connection 34. When the desired axial seal force is achieved, the first internal connection 34 is rotationally constrained, by screwing grub screws 52 the through threaded holes 54 in the pressure relief enclosure 50, into cut-outs 38 in the disk housing 30. There are more cut-outs 38 than grub screws 52, hence a range of rotational constraint positions are possible.

Typically, the correct axial seal force is achieved by hand tightening the first internal connection 34, and matching up the grub screws 52 with the nearest cut-outs 38.

The housing top 60 is connected via the second internal connection 58 to the pressure relief enclosure 50, by rotationally engaging threads lOOa and bOb. The second internal connection 58 is rotationally constrained, by screwing grub screws 64 the through threaded holes 66 in the housing top 60, into cut-outs 102 in the pressure relief enclosure 50. It is not necessary to seal the second internal connection 58, hence there are the same number of cut-outs 102 as grub screws 64.

The assembled pressure relief device is connected via the external connection to a hydrant by rotationally engaging the female thread 140 with the male thread of the hydrant 90.

With reference to Figure 6, several methods of use will now be described.

The pressure relief device 10 is attached to a hydrant 90 by engaging the external connection 22 with a connection portion 91 of the hydrant. A tool is engaged with the protrusion 62 on the pressure relief device 10. In this example the tool is a hydrant key 92, although any other suitable tool may be used. The tool is rotated to cause the external connection 22 to rotate and thereby attach the pressure relief device 10 to the hydrant 90.

Similarly the pressure relief device 10 is removed from the hydrant 90 by engaging a tool with the protrusion 62 on the pressure relief device 10. The tool is rotated to cause the external connection 22 to rotate and thereby remove the pressure relief device from the hydrant 90.

The bursting diaphragm 40 of the pressure relief device 10 is replaced firstly by separating the second internal connection 58. This comprises removing the rotational constraints on the second internal connection 58 and is achieved by unscrewing the grub screws 64 from the cut-outs 102, and rotating thread lOOa on the housing top 60 against thread lOOb on the pressure relief enclosure 50. Secondly, the first internal connection 34 is separated, this comprises removing the rotational constraints on the first internal connection 34 and is achieved by unscrewing the grub screws 52 from the cut-outs 38, and rotating thread 36a on the disc housing 30 against thread 36b on the pressure relief enclosure 50, to reveal the bursting diaphragm 40 positioned against the flange 32. The bursting diaphragm 40 is removed and replaced. The first internal connection 34 is re-attached by engaging threads 36 and its rotational constraints are applied by screwing grub screws 52 into cut-outs 38. Finally, the second internal connection 58 is attached by engaging threads 100 and its rotational constraints are applied by screwing grub screws 64 into cut-outs 102.

The bursting diaphragm 40 can be replaced when the device is detached from or attached to the hydrant 90. Further, the pressure relief device 10 may be operated in conjunction with any of the methods discussed above as preparation for maintenance of the water mains system when the water mains system is live. In other words, the bursting diaphragm 40 may be replaced by a lower rated bursting diaphragm 40, rated at just above the normal operating pressure of the mains water system, to protect workers operating live on the system.

The invention described brings forth many advantages over the prior art. Not least, the pressure relief device 10 can be quickly removed from the hydrant 90 in case of emergency using the hydrant key 92. Hydrant keys 92 are normally carried by the fire services thereby allowing them, in particular, to remove quickly the pressure relief device 40. This is achieved firstly by lining up the external connection 22 with the protrusion 62 along a common axis of rotation. Previously, this has not been possible in the art due to the specific design of pressure relief valves. Surprisingly, the pressure relief device 10 is designed and arranged to allow this advantage to flow.

Also, the design of the pressure relief device 10 of the present invention, allows easy maintenance and allows for live working on a mains water system.

The skilled person would understand that the pressure relief device could be modified for attachment to a hydrant other than a B5750 hydrant, where appropriate.

Attention is directed to all papers and documents which are filed concurrently with or previous to this specification in connection with this application and which are open to public inspection with this specification, and the contents of all such papers and documents are incorporated herein by reference.

All of the features disclosed in this specification (including any accompanying claims, abstract and drawings), and/or all of the steps of any method or process so disclosed, may be combined in any combination, except combinations where at least some of such features and/or steps are mutually exclusive.

Each feature disclosed in this specification (including any accompanying claims, abstract and drawings) may be replaced by alternative features serving the same, equivalent or similar purpose, unless expressly stated otherwise. Thus, unless expressly stated otherwise, each feature disclosed is one example only of a generic series of equivalent or similar features.

The invention is not restricted to the details of the foregoing embodiment(s). The invention extends to any novel one, or any novel combination, of the features disclosed in this specification (including any accompanying claims, abstract and drawings), or to any novel one, or any novel combination, of the steps of any method or process so disclosed.

Claims

CLAIMS1. A pressure relief device comprising, in general order: a first end having an external connection removably connectable to a hydrant in use; a flange for receiving a bursting diaphragm; a pressure relief enclosure; and at a second end opposite the first end a protrusion for receiving a tool; wherein the pressure relief device defines a longitudinal axis passing from the first end to the second end, and the external connection and protrusion are substantially coaxially arranged along the longitudinal axis.
2. The pressure relief device of claim 1, comprising a first internal connection between the flange and the pressure relief enclosure, the first internal connection providing a force along the longitudinal axis for sealing a diaphragm in use, against the flanged area, and is rotationally constrainable about the longitudinal axis.
3. The pressure relief device as claimed in claim 2, wherein the first internal connection comprises a male and female coaxial screw thread each on opposite sides of the first internal connection, the first internal connection being rotationally constrainable by one or more protrusions that are extendible in the longitudinal axis into corresponding cut-outs, the protrusions and cut-outs being on opposite sides of the first internal connection.
4. The pressure relief device as claimed in claim 3, wherein there are more cut-outs than protrusions.
5. The pressure relief device as claimed in any preceding claim, comprising a one-way valve disposed between the removable connection and the flange.
6. The pressure relief device as claimed in any preceding claim, comprising a second internal connection between the pressure relief enclosure and a housing top on which the protrusion is mounted, the second internal connection being rotationally constrainable about the longitudinal axis.
7. The pressure relief device as claimed in claim 6, wherein the second internal connection comprises a male and female coaxial screw thread each on opposite sides of the second internal connection, the second internal connection being rotationally constrainable by one or more protrusions that are extendible in the longitudinal axis into corresponding cut-outs, the protrusions and cut-outs being on opposite sides of the second internal connection.
8. The pressure relief device as claimed in any preceding claim, wherein the pressure relief enclosure comprises one or more perforations.
9. The pressure relief device as claimed in claim 8, wherein the perforations are disposed circumferentially with respect to the longitudinal axis.
10. A mains water system comprising the pressure relief device as claimed in any preceding claim.
11. A method of attaching a pressure relief device to a hydrant, the method comprising: engaging an external connection, positioned at a first end of the pressure relief device, with a connecting portion of the hydrant; engaging a tool with a protrusion positioned at a second end of the pressure relief device; rotating the tool to cause the external connection to rotate and thereby attach the pressure relief device to the hydrant.
12. A method of removing a pressure relief device from a hydrant the method comprising: engaging a tool with a protrusion positioned at a second end of the pressure relief device; rotating the tool to cause an external connection positioned at a first end of the pressure relief device and connected to the hydrant to rotate and thereby remove the pressure relief device from the hydrant.
13. A method of replacing a bursting diaphragm of a pressure relief device, the method comprising: locating a hydrant to which the pressure relief device is attached; removing rotational constraints on an internal connection of the pressure relief device; separating the internal connection to reveal a flange area against which the bursting diaphragm is positioned; removing and replacing the bursting diaphragm; attaching the internal correction; applying the rotational constraints on the internal connection.
14. A method of replacing a bursting diaphragm of a pressure relief device, the method comprising: removing rotational constraints on an internal connection; separating the internal connection to reveal a flange area against which the bursting diaphragm is positioned; removing and replacing the bursting diaphragm; attaching the internal connection; applying the rotational constraints on the internal connection.
15. A method as claimed in claims 13 or 14, wherein the bursting diaphragm is replaced prior to working on a pressurised water system to which the pressure relief device is attached.
16. A pressure relief device substantially as described herein, with reference to the accompanying drawings.
17. Methods of using a pressure relief device in a water system substantially as described herein, with respect to the accompanying drawings.