AU2016204853A1

AU2016204853A1 - Backflow Protection Device

Info

Publication number: AU2016204853A1
Application number: AU2016204853A
Authority: AU
Inventors: Peter John Morris
Original assignee: Australian Valve Group Pty Ltd
Current assignee: Australian Valve Group Pty Ltd
Priority date: 2015-07-10
Filing date: 2016-07-11
Publication date: 2017-02-02
Also published as: AU2016102479A4

Abstract

Abstract Backflow protection device 1 has a casing 10, an inlet 12, an outlet 14, and a cartridge 16. The cartridge 16 is removably insertable into the casing 10 and the cartridge 16 is provided with at least two non-return valves 18. A relief device 44/200 may also be connected to the backflow protection device 1. (-li

Description

2016204853 11 Jul2016

Name of Applicant: 1

ORIGINAL

AUSTRALIA

Patents Act 1990

COMPLETE SPECIFICATION STANDARD PATENT

Australian Valve Group Pty Ltd

Actual Inventor(s):

Peter John Morris

Address for service is:

Golja Haines & Friend

Invention Title:

The following statement i: of performing it known to

Backflow Protection Device ; a full description of this invention, including the best method me:-2 2016204853 11 Jul2016

Title "Backflow Protection Device" [0001] Throughout this specification, unless the context requires otherwise, the word "comprise" and variations such as "comprises", "comprising" and "comprised" are to be understood to imply the presence of a stated integer or group of integers but not the exclusion of any other integer or group of integers.

[0002] Throughout this specification, unless the context requires otherwise, the word "include" and variations such as "includes", "including" and "included" are to be understood to imply the presence of a stated integer or group of integers but not the exclusion of any other integer or group of integers.

Technical Field [0003] The present invention relates to a backflow protection device.

[0004] Backflow protection devices are typically used in plumbing installations.

Background Art [0005] Any discussion of background art, any reference to a document and any reference to information that is known, which is contained in this specification, is provided only for the purpose of facilitating an understanding of the background art to the present invention, and is not an acknowledgement or admission that any of that material forms part of the common general knowledge in Australia or any other country as at the priority date of the application in relation to which this specification has been filed.

[0006] Backflow protection devices are often installed in plumbing installations at or near the boundary of premises. Their purpose is to prevent a backflow condition causing contamination to the municipal water supply, to which the plumbing installation is connected, which could occur if the pressure in the plumbing installation builds up and caused a backflow into the municipal water supply.

[0007] Backflow protection devices must meet the regulatory requirements as set out in published standards. The regulatory requirements also distinguish between backflow 3 2016204853 11 Jul 2016 protection devices that are designed for use in high hazard conditions and backflow protection devices that are designed for use in medium hazard conditions. Backflow protection devices designed for use in high hazard conditions must have two independently operating non-return valves and a relief valve positioned between the two non-return valves and is arranged to be force-loaded to the open position to atmosphere whenever the pressure differential across the upstream non-return valve drops to a preset level, typically 14kPa. Backflow protection devices that are designed for use in medium hazard conditions omit the relief valve. Consequently, manufacturers make backflow protection devices, according to one design, for high hazard conditions, and backflow protection devices, according to a second design, for medium hazard conditions.

[0008] However, whilst such backflow protection devices may meet the regulatory requirements, little or no thought has been given by manufacturers to the needs of the retailer or the installer or service personnel of such devices.

[0009] Typically, a plumber would need to go to a plumbing merchant and purchase a back flow protection device suitable for the particular plumbing installation being undertaken. Whilst the plumber has purchased a suitable backflow protection device, it doesn't end there. The device will normally have female threads at the inlet and outlet but to complete the installation as per the requirements of the plumbing standard, the plumber will have to purchase three threaded nipples, two ball valves, a strainer and two unions to connect to the pipework of the plumbing installation. All these components would then have to be screwed together using thread seal tape or thread sealant which not only takes time but presents six potential leak points on the installation. In addition, thread seal tape and thread sealant can have an adverse impact on the safe operation of backflow protection devices if any excess tape or sealant becomes lodged in the nonreturn valves of the backflow protection device.

[0010] Furthermore, it is a regulatory requirement that backflow protection devices are checked for correct performance and serviced periodically, e.g. at least annually. However, in the case of existing backflow protection devices, this has to be carried out with the backflow protection in situation, i.e. with it connected in the plumbing installation, which in some installations can be in the dirt and/or working upside down as well as being subject to the elements so as to have access to the individually operating non-return valves and the strainer of the backflow protection device. This can make the periodic checking and servicing procedures awkward and time consuming. 4 2016204853 11 Μ 2016 [0011] Should the periodic check of the backflow protection device find that one of more of the non-return valves is defective, it must be separately removed from its housing in the backflow protection device and then replaced; similarly for the strainer should it be found to be defective.

Summary of Invention [0012] In accordance with one aspect of the present invention, there is provided a backflow protection device comprising a casing, an inlet, an outlet, and a cartridge, wherein the cartridge is removably insertable into the casing and the cartridge is provided with at least two non-return valves.

[0013] Preferably, the cartridge is detachably connected with the casing.

[0014] Preferably, the casing is provided with the inlet.

[0015] Preferably, the cartridge is provided with the outlet.

[0016] Preferably, a portion of the cartridge extends from the casing.

[0017] Preferably, the cartridge is provided with the at least two non-return valves such that the at least two non-return valves are removably retained with the cartridge.

[0018] Preferably, the at least two non-return valves are arranged serially, one after the other, in the cartridge.

[0019] Preferably, the cartridge is provided with a strainer, or filter.

[0020] Preferably, the two non-return valves and the strainer are arranged serially and substantially linearly in the cartridge.

[0021] In one embodiment, the backflow protection device further comprises a relief device.

[0022] The relief device may comprise a valve and a diaphragm such that pressure differential on opposed sides of the diaphragm causes the valve to open or close.

[0023] The relief device may comprise a casing and the casing comprises at least a first part and a second part and the diaphragm is retained in position by the first and second parts of the casing. 5 2016204853 11 Jul 2016

Brief Description of Drawings [0024] The present invention will now be described, by way of example only, with reference to the accompanying drawings, in which: [0025] Figure 1 is a perspective view of a first embodiment of a backflow protection device in accordance with the present invention; [0026] Figure 2 is a side elevation view of the backflow protection device shown in Figure 1; [0027] Figure 3 is a first cross sectional side elevation view of the backflow protection device shown in Figure 1, showing the non-return valves and the relief device in their open conditions; [0028] Figure 4 is an exploded perspective view of the backflow protection device shown in Figure 1; [0029] Figure 5 is an exploded side elevation view of the backflow protection device shown in Figure 1; [0030] Figure 6 is a perspective view of the cartridge of the backflow protection device shown in Figure 1; [0031] Figure 7 is a side elevation view of the cartridge shown in Figure 6; [0032] Figure 8 is a cross sectional side elevation view of the cartridge shown in Figure 6; [0033] Figure 9 is an exploded perspective view of the cartridge shown in Figure 6; [0034] Figure 10 is a perspective view of the relief device of the backflow protection device shown in Figure 1; [0035] Figure 11 is a side elevation view of the relief device of the backflow protection device shown in Figure 1; [0036] Figure 12 is a cross sectional side elevation view of the relief device of the backflow protection device shown in Figure 1; [0037] Figure 13 is an exploded perspective view of the relief device of the backflow protection device shown in Figure 1; 6 2016204853 11 Jul2016 [0038] Figure 14 is a second cross sectional side elevation view of the backflow protection device shown in Figure 1, showing the non-return valves and the relief device in their closed conditions; and [0039] Figure 15 is a third cross sectional side elevation view of the backflow protection device shown in Figure 1, showing the non-return valves in their open conditions and the relief device in its closed conditions; [0040] Figure 16 is a side elevation view of a second embodiment of a relief device for the backflow protection device shown in Figure 1; [0041] Figure 17 is a cross sectional side elevation view of the second embodiment of the relief device shown in Figure 16; [0042] Figure 18 is a first exploded perspective view of the second embodiment of the relief device shown in Figure 16; and [0043] Figure 19 is a second exploded perspective view of the second embodiment of the relief device shown in Figure 16.

Description of Embodiments [0044] In the drawings, there is shown an embodiment of a backflow protection device 1, and various components thereof.

[0045] The backflow protection device 1 comprises a casing 10, an inlet 12, an outlet 14 and a cartridge 16.

[0046] The cartridge 16 is removably insertable into the casing 10.

[0047] The casing 10 is provided with the inlet 12. The cartridge 16 is provided with the outlet 14.

[0048] The cartridge 16 is provided with two non-return valves 18, as will be further described herein. The two non-return valves 18 operate independently. Each non-return valve 18 allows flow of fluid only in the direction from the inlet 12 to the outlet 14 as will be further described herein. The non-return valves 18 may be of conventional form and operation.

[0049] The casing 10 has a (male) screw thread 20 at a first end 22 thereof. The screw thread 20 is provided adjacent to the inlet 12. 7 2016204853 11 Μ 2016 [0050] The casing 10 has a (female) screw thread 24 at the second end 26 thereof. The cartridge 16 is detachably connected to the casing 10 via the female screw thread 24, as will be further described herein.

[0051] The casing 10 is provided with openings 28 into which respective test taps 30 may be connected. A female screw thread 32 is provided adjacent each opening 28 of the casing 10 and a male screw thread 34 is provided on each test tap 30 such that the test taps 30 can be detachably screw threadedly connected into the openings 28 of the casing 10. The test taps 30 are provided with screw threads 36 for connection of a pressure testing device to the casing 10 for periodic checking of the performance of the non-return valves 18. Such pressure testing devices are known in the art, and do not form part of the present invention. The test taps 30 are provided with handles 38 to open (for pressure testing of the non-return valves 18) and close (for the operation mode of the backflow protection device 1) an internal valve 40 in each test tap 30. The test taps 30 may be of conventional form and operation.

[0052] The casing 10 is provided with an additional opening 42. A relief device 44 may be detachably connected to the casing 10 at the opening 42. A male screw thread 46 is provided adjacent to the opening 42 of the casing 10 and a female screw thread 48 is provided on the relief device 44 such that the relief device 44 can be detachably screw threadedly connected to the casing 10 at the opening 42.

[0053] However, if the relief device 44 is not required, it can be removed, or omitted at the time of manufacture or sale, and the opening 42 closed off with a cap (not shown) which screw threadedly connects with the casing 10 via the screw thread 46. When the relief device 44 is provided, the backflow protection device 1 may be described as a reduced pressure zone device (RPZD) as commonly used in the industry.

[0054] Furthermore, whilst the casing 10 of the embodiment of the backflow protection device 1 described and shown herein is provided with an opening 42 for connection of a relief device 44, in an alternative embodiment (not shown) the opening 42 and the relief device 44 may be omitted entirely. In such an embodiment, the casing would not have an opening 42 and instead its surface would be continuous at the location of the opening 42 of the casing 10 of the backflow protection device 1 described and shown herein.

[0055] The cartridge 16 (shown separately in Figures 6, 7, 8 and 9) comprises a housing 50, the non-return valves 18, which are provided in the housing 50, and a strainer, or filter, 52. 8 2016204853 11 Μ 2016 [0056] The cartridge 16 has an inlet 54 at a first end 56 of the housing 50 and an outlet 58 at the second end 60 of the housing 50. The outlet 58 also forms the outlet 14 of the backflow protection device 1.

[0057] The two non-return valves 18 are arranged serially, one after the other, in the housing 50 of the cartridge 16.

[0058] A spacer 51 is provided between the two non-return valves 18.

[0059] The strainer 52 is held in position at the first end 56 of the housing 50, adjacent to the inlet 54 of the housing 50.

[0060] The non-return valves 18 and the strainer 52 are removably retained in the housing 50 by a clip 62, which is provided adjacent the first end 56 of the housing and which engages in a groove, or recess, of the housing 50.

[0061] The two non-return valves 18 and the strainer 52 are arranged serially and substantially linearly in the cartridge 16.

[0062] The housing 50 of the cartridge 16 is provided with an external (male) screw thread 64.

[0063] The cartridge 16 is removably insertable into the casing 10 and the screw thread 64 is able to engage with the screw thread 24 of the casing 10 to detachably connect the cartridge 16 with the casing 10. When the screw threads 64 and 24 are disengaged, the cartridge 16 can be removed from the casing 10.

[0064] An external (male) screw thread 66 is provided adjacent the second end 60 of the housing 50 of the cartridge 16.

[0065] The screw thread 20 of the casing 10 and the screw thread 66 of the housing 50 may be used to connect the backflow protection device 1 into a plumbing installation.

[0066] Flat surfaces 68 are arranged hexagonally around the exterior of the housing 50 adjacent to the screw thread 66. The flat surfaces 68 are spaced from the outlet 58 and the second end 60 of the housing 50 by the screw thread 66.

[0067] The housing 50 is provided with a flange 70. The flange 70 is provided externally of the housing 50. The flange 70 is located between the screw thread 64 and the flat surfaces 68. The housing 50 is provided with a groove 72 between the screw thread 64 and the flange 70. A seal, which may be in the form of an O-ring 74, is located in the groove 72. The housing 50 is provided with two further external grooves 9 2016204853 11 Jul2016 76 and 78 in which respective seals, which may be in the form of O-rings 80 and 82, are located.

[0068] When the cartridge 16 is inserted into the housing 50 and connected to the housing 50, via the respective screw threads 66 and 24, the flange 70 abuts with the second end 26 of the casing 10. Furthermore, the O-ring 74 forms a seal between the outer surface of the housing 50 of the cartridge 16 and the inner surface of the casing 10, near the second end 26 of the casing 10; no thread seal tape or thread sealant is required to form the seal. In addition, the O-rings 80 and 82 form respective seals between the outer surface of the housing 50 of the cartridge 16 and the inner surface of the casing 10. The O-ring 80 forms the seal near the first end 54 of the housing 50 and the O-ring 82 forms the seal near the mid section of the housing 50. This arrangement of the O-rings 74, 80 and 82 is best seen in Figure 3.

[0069] The housing 50 is substantially hollow and cylindrical with an opening at each end 56 and 60, which form the inlet 54 and the outlet 58, respectively, of the housing 50. The housing 50 is also provided with openings 84 intermediate the O-rings 80 and 82. When the cartridge 16 is located inside the casing 10, the openings 84 are located such that they are in fluid communication with the middle test tap 30, which is identified by reference numeral 30b in Figure 3.

[0070] As previously described herein, the non-return valves 18 may be of conventional form and operation. Accordingly, a non-return valve 18 may comprise a valve seat 86 and a valve stem 88 having a valve head 90. The valve head 90 is movable such that it is in contact with or spaced from the valve seat 86 to respectively close or open the nonreturn valve 18. The valve head 90 is biased by a spring 92 to seat on the valve seat 86 to thereby keep the non-return valve 18 in the closed condition.

[0071] The seals created by the O-rings 74, 80 and 82 separate the inside of the casing 10 of the backflow protection device 1 into three pressure zones, Zl, Z2 and Z3, which are labelled in Figure 3.

[0072] The first pressure zone Zl is on the upstream side of the first non-return valve 18. The first non-return valve has been labelled as 18a in Figure 3, and is the non-return valve 18 that is closest to the inlet 54 of the housing 50. The upstream side of the first non-return valve 18a is the side that is on the inlet side of the valve seat 86 of the first non-return valve 18a. In Figure 3, this is the side to the left of the valve seat 86 of the first non-return valve 18a. 10 2016204853 11 Jul 2016 [0073] The second pressure zone Z2 is the intermediate zone and is between the first non-return valve 18a and the second non-return valve, which has been labelled as 18b in Figure 3. Specifically, the second zone Z2 is the zone between the valve seat 86 of the first non-return valve 18a and the valve seat 18b of the second non-return valve 18b.

[0074] The third pressure zone Z3 is on the downstream side of the second non-return valve 18b. The downstream side of the second non-return valve 18b is the side that is on the outlet side of the valve seat 86 of the second non-return valve 18b. In Figure 3, this is the side to the right of the valve seat 86 of the second non-return valve 18b.

[0075] The first test tap, labelled as 30a in Figure 3, is in fluid communication with the first pressure zone Zl; the second test tap, labelled as 30b in Figure 3, is in fluid communication with the second pressure zone Z2; and, the third test tap, labelled as 30c in Figure 3, is in fluid communication with the third pressure zone Z3.

[0076] The relief device 44 is shown separately in Figure 12. The relief device 44 comprises a casing 94, having an inlet 96 and an outlet 98, and a valve 100 located inside the casing 94. The relief device 44 is also provided with a loose nut 102. The loose nut 102 is provided with the female screw thread 48, which can be engaged with the male screw thread 46 of the casing 10 to connect the relief device 44 with the casing 10. When so connected, the opening 42 of the casing 10 is in fluid communication with the inlet 96 of the casing 94 of the relief device 44.

[0077] The valve 100 has a valve seat 104 and a valve head 106. The valve head 106 is movable such that it is in contact with or spaced from the valve seat 104 to respectively close or open the valve 100. The valve head 106 is mounted on a valve stem 108. The valve head 106 is provided with a seal 106a which sealingly contacts the valve seat 104 in the closed condition of the valve 100 to prevent fluid flow through the valve 100. A stop member 110 is provided on the valve stem 108. A spring 112 is provided around the valve stem 108 and one end of the spring 112 abuts the stop member 110 and the other end of the spring 112 abuts the inside wall surface of the casing 94.

[0078] A pressure-receiving member is provided such that fluid pressures in the pressure relief device 44 can act on different surfaces of the pressure-receiving member. In the embodiment of the relief device 44 shown in the drawings, the pressure-receiving member is provided as a diaphragm 114 such that fluid pressures can act on the surfaces of the diaphragm 114 on opposed sides of the diaphragm 114. However, the pressurereceiving member may be provided in alternative forms such that fluid pressures can act on different surfaces of the pressure-receiving member. For example, the pressure-11 2016204853 11 Μ 2016 receiving member may alternatively be provided as a piston head, in which case the fluid pressures can act on different surfaces of the piston head. The diaphragm 114 is provided adjacent to the stop member 110, on the side of the stop member 110 that is opposed to the side against which the spring 112 abuts. The diaphragm 114 is secured in the casing 94. A portion 116 of the valve stem 108 extends into a small chamber 117 of the casing 94. The small chamber 117 is provided with breather port 117a. The portion 116 of the valve stem 108 is provided with a seal, which may be in the form of an O-ring 118, to seal against the inside wall surface of the small chamber 117. The valve stem 108 is formed as a combination unit held together by a bolt member 120 extending through the valve stem 108 from the portion 116 of the valve stem 108 and screw threadedly engaging with an end member 122.

[0079] The casing 94 may be in several parts, namely parts 124, 126 and 128, which are connected together. These are best seen in Figure 12 and are indicated by different cross-hatching. The outlet 98 is provided in the casing part 124, which may also be described as the main part of the casing 94. The casing part 126, which may also be described as a cap part, secures the diaphragm 114 in position. The inlet 96 is provided in the casing part 128, which may also be described as an adaptor insert part. The casing parts 124 and 126 keep the diaphragm 114 secured in position, by being sandwiched there between. The casing parts 126 and 128 are detachably connected to the casing part 124 by respective screw threaded engagements 130 and 132 with respective seals, which may be in the form of O-rings 134 and 136 provided there between. Another seal, which may be an O-ring 136a, is provided between the inside surface of casing part 124 and the outside surface of the casing part 128. The casing part 128 is provided with a seal, which may be an O-ring 138, adjacent the inlet 96 to seal against the inside surface of the casing 10, adjacent to the opening 42. The casing part 128 is provided with another seal, which may be in the form of an O-ring 102a, in the loose nut 102, which seals with the casing 10.

[0080] The first pressure zone Z1 is in fluid communication through small waterways 140, 142 and 144 with a first side 146 of the diaphragm 114. The second pressure zone Z2 is in fluid communication with the second side 148 of the diaphragm 114 through waterway 150. This is best seen in Figures 3 and 12.

[0081] Figures 16, 17 and 18 show a second embodiment of a relief device 200 that may be used in the backflow protection device 1 in place of the relief device 44 herein before described. 12 2016204853 11 M2016 [0082] The relief device 200 may be detachably connected to the casing 10 at the opening 42. A female screw thread 202 is provided on the relief device 200 such that the relief device 200 can be detachably screw threadedly connected to the male screw thread 46 of the casing 10 at the opening 42.

[0083] However, if the relief device 200 is not required, it can be removed, or omitted at the time of manufacture or sale, and the opening 42 closed off with a cap (not shown) which screw threadedly connects with the casing 10 via the screw thread 46. When the relief device 200 is provided, the backflow protection device 1 may be described as a reduced pressure zone device (RPZD) as commonly used in the industry.

[0084] The relief device 200 comprises a casing 204, having an inlet 206 and an outlet 208, and a valve 210 located inside the casing 204. The relief device 200 is also provided with a loose nut 212. The loose nut 102 is provided with the female screw thread 202, which can be engaged with the male screw thread 46 of the casing 10 to connect the relief device 200 with the casing 10. When so connected, the opening 42 of the casing 10 is in fluid communication with the inlet 206 of the casing 204 of the relief device 200.

[0085] The valve 210 has a valve seat 214 and a valve head 216. The valve head 216 is movable such that it is in contact with or spaced from the valve seat 214 to respectively close or open the valve 210. The valve head 216 is mounted on a valve stem 218. The valve head 216 is provided with a seal 216a which sealingly contacts the valve seat 214 in the closed condition of the valve 210 to prevent fluid flow through the valve 210. A stop member 220 is connected to the valve stem 218, e.g. by a screw 222. A bushing 224 is provided around the valve stem 218. The bushing 224 abuts with a flange 226 of the valve head 216. A spring 228 is provided around the valve stem 218. A first end of the spring 228 abuts the stop member 220 and a second end of the spring 222 abuts with the bushing 224. A seal, which may in the form of an O-ring 230, is provided between the valve stem 218 and the bushing 224. A seal, which may be in the form of an O-ring 232, is provided between the bushing 224 and the inside wall surface of the casing 204. The O-ring 232 is provided on the outer circumference of a flange portion 234 of the bushing 224. A first face of the flange portion 234 of the bushing 224 abuts with the flange 226 of the valve head 216. The second end of the spring 222 abuts with the second face of the flange portion 234 of the bushing 224. The seal 216a is removably retained in position, e.g. by a screw 236. The valve seat 214 is provided on a seat insert 238. The seat insert 238 is removably connected with the casing 204, inside the casing 204, e.g. by a screw threaded connection 240. A seal, which may be in the 13 2016204853 11 Μ 2016 form of an O-ring 242, is provided between the seat insert 238 and the inside wall surface of the casing 204.

[0086] A pressure-receiving member is provided such that fluid pressures in the pressure relief device 200 can act on different surfaces of the pressure-receiving member. In the embodiment of the relief device 200 shown in Figures 17 and 18 of the drawings, the pressure-receiving member is provided as a diaphragm 244 such that fluid pressures can act on the surfaces of the diaphragm 244 on opposed sides of the diaphragm 244. However, the pressure-receiving member may be provided in alternative forms such that fluid pressures can act on different surfaces of the pressurereceiving member. For example, the pressure-receiving member may alternatively be provided as a piston head, in which case the fluid pressures can act on different surfaces of the piston head. The diaphragm 244 is provided adjacent to the stop member 220, on the side of the stop member 220 that is opposed to the side against which the spring 228 abuts. The diaphragm 244 is secured in the casing 204, as will be further herein described.

[0087] The casing 204 may be in several parts, namely a main part 250, an adaptor insert part 252 and a cap part 254, which are connected together. These are best seen in Figure 17 and are indicated by different cross-hatching. The outlet 208 is provided in the main part 250. The adaptor insert part 252 is of similar structure to the part 128 of the casing 94 of the relief device 44 of the first embodiment. The adaptor insert 252 is provided with the inlet 206. The insert adaptor part 252 is detachably connected with the main part 250, e.g. by a screw threaded connection 256. Seals, which may be in the form of O-rings 258 and 260, are provided between the main part 250 and the insert adaptor part 252. The insert adaptor part 252 is provided with a seal 262 in the loose nut 212. The adaptor insert part 252 is provided with a seal 264 adjacent the inlet 206 to seal against the inside surface of the casing 10, adjacent to the opening 42.

[0088] The cap part 254 secures the diaphragm 244 in position with the main part 250, such that the diaphragm 244 is sandwiched between the main part 250 and the cap part 254. In that regard, bolts 266 extend through openings 268 in the cap part 256, openings 270 in the diaphragm 244 and engage in screw threaded holes 272 in a flange 274 of the main part 250 of the casing 204 of the relief device 200. This sandwiches a central portion of the diaphragm 244 between the stop member 220 and the cap part 256.

[0089] The first pressure zone Z1 is in fluid communication through small waterways 276, 278 and 280 with a first side 282 of the diaphragm 244. The second pressure zone 14 2016204853 11 Μ 2016 Ζ2 is in fluid communication with the second side 284 of the diaphragm 244 through waterway 286. This is best seen in Figure 17.

[0090] The manner of use and operation of the backflow protection device 1 will now be described.

[0091] In use, the backflow protection device 1 is installed in a plumbing installation on premises.

[0092] When installing the backflow protection device 1 in a plumbing installation on premises, a respective isolation valve (such as a ball valve) is connected to the inlet 12 and the outlet 14 of the backflow protection device 1 using the screw threads on the loose nuts of the ball valves to engage with the screw thread 20 at the inlet 14 and the screw thread 66 at the outlet 14. Tubing, of the required size/s, is then connected to the other ends of the ball valves.

[0093] Indeed, in accordance with another aspect of the present invention, the backflow protection device may be provided with a respective isolation valve already provided at the inlet 12 and the outlet 14 of the backflow protection device. As an alternative, a kit may be provided with the isolation valves disconnected from the backflow protection device, and able to be connected at the time of installation into a plumbing installation.

[0094] The inlet 12 of backflow protection device 1 is connected (via a ball valve) to a municipal water supply and the outlet 14 is connected (via a ball valve) to the plumbing installation on the premises. The municipal water supply delivers water to the premises, and the water must first flow through the backflow protection device 1 before entering the plumbing installation on the premises. The backflow protection device 1 guards against contamination to the municipal water supply, which could occur if the pressure in the plumbing installation builds up and caused a backflow into the municipal water supply.

[0095] The first non-return valve 18a requires a first pressure differential (PI - P2), of at least a first set magnitude, to open, where PI is the fluid pressure in the first pressure zone Z1 and P2 is the fluid pressure in the second pressure zone Z2. For example, the first pressure differential (PI - P2) may be approximately 35kPa. The second non-return valve 18a requires a second pressure differential pressure (P2 - P3), of at least a second set magnitude, to open, where P3 is the fluid pressure in the third pressure zone Z3. For example, the pressure differential (P2 - P3) may be approximately just above 7kPa.

[0096] The spring 112 of the valve 100 of the relief device 44 together with the fluid pressure P2 in the second pressure act on the diaphragm 114, on the side 148 of the 15 2016204853 11 Μ 2016 diaphragm 114, to open the valve 100. On the opposite side 146 of the diaphragm 114, the pressure PI in the first pressure zone Z1 acts in the opposing direction on the diaphragm 114 to close the valve 100. If there appears that a risk that an over-pressure condition may arise in the plumbing installation such that the difference between the inlet pressure PI and the intermediate pressure P2 drops to a level below, for example, approximately 20kPa, the valve 100 will start to open. This means that the valve head 106 unseats from the valve seat 104, and water is able to flow through the open valve 100 and exit the relief device 44 via the outlet 98. This prevents a situation arising in which water from the plumbing installation on the premises may backflow through the inlet 12 into, and potentially contaminate, the municipal water supply.

[0097] The relief device 200 operates in a corresponding manner to the relief device 44 as herein before described.

[0098] There are three basic scenarios that may occur in the backflow protection device 1. These are the normal operation scenario, malfunction of the first non-return valve 18a, and malfunction of the first non-return valve 18b.

[0099] In the normal operation scenario (shown in Figure 15), for example, a tap in the plumbing installation on the premises may opened and water then flows from the municipal water supply through the backflow protection device 1, from the inlet 12 through the first, second and third pressure zones Zl, Z2 and Z3 to the outlet 14 (including through open first and second valves 18a and 18b), and then through the plumbing installation to the opened tap. The fluid pressure in the second pressure zone Z2 will be approximately 35kPa less than the fluid pressure in the first pressure zone Zl because of the 35kPa pressure needed to open the first non-return valve 18a. The third pressure zone Z3 will have a pressure about 7kPa less than the second pressure zone Z2 because of the second non-return valve 18b and the pressure needed to open it. In the normal operation scenario, the valve 100 of the relief device 44 is closed, such that no water exits from the outlet 98 of the relief device 44. When the tap in the plumbing installation on the premises is returned to the closed position, the first and second valves 18a and 18b will return to their closed positions, which is shown in Figure 14.

[00100] In the scenario that the first non-return valve 18a malfunctions, such that it is unable to close, the pressure difference between PI and P2 will be less than the 20 kPa needed to open the valve 100 of the relief device 44. The valve 100 of the relief device 44 will then empty all water via the outlet 98 since the pressure P2 acts on the diaphragm 114 to cause the valve 100 of the relief device 44 to open, preventing water 16 2016204853 11 Jul2016 flowing from pressure zone Z2 into pressure zone Z1 and into the municipal water supply.

[00101] In the scenario that the second non-return valve 18b malfunctions, the second and third pressure zones Z2 and Z3 will be in fluid communication with each other but the valve 100 of the relief device 44 will open only if there is a backpressure from the water, downstream of the outlet 14, that is greater than PI - 20kPa.

[00102] Figure 3 shows the valve 100 of the relief device 44 in the open position in which the valve head 106 is unseated from the valve seat 104 such that water can pass through the open valve 100 and exits to atmosphere via the outlet 98 of the relief device 44. The flow of water from the casing 10 through the relief device 44 is shown by the flow arrows in Figure 3. Similarly, Figure 17 shows the valve 210 of the relief device 200 in the open position in which the valve head 216 is unseated from the valve seat 214 such that water can pass through the open valve 210 and exits to atmosphere via the outlet 208 of the relief device 200.

[00103] If the relief device 44 or 200 is not provided, the backflow protection device 1 operates as herein before described, except that water is not diverted and discharged from the relief device 44/200 in an over-pressure condition. Instead, in such a condition, the over-pressure on the downstream side of the backflow protection device 1 only causes the valves 18a and 18b to move to their closed condition to prevent water flowing back out through the inlet 12 into the municipal water supply.

[00104] The backflow protection device according to the present invention may have several advantages over backflow protection devices of the prior art.

[00105] Firstly, the backflow protection device according to the present invention comes pre-assembled, without the need for thread seal tape or thread sealant, and is ready for the connecting pipework to be installed. This not only saves time and money but also avoids the potential for leaks from the multiple connections that are required in prior art backflow protection device installations.

[00106] Secondly, the backflow protection device according to the present invention can be easily removed from the plumbing installation for servicing in a clean and dry work environment. The cartridge 16 containing the two independently operating non-return valves 18 and the strainer 52 can then be easily removed for inspection and servicing.

In the case of a defective non-return valve 18 or defective strainer 52, it can be readily replaced by removing the clip 62 from the cartridge 16 and replacing the defective nonreturn valve 18 or defective strainer 52 with another non-return valve 18 or strainer 52, 17 2016204853 11 Μ 2016 and then again retaining the non-return valves 18 and the strainer 52 in place in the cartridge 16 with the clip 62. A further option available, in the case of a defective nonreturn valve 18 or defective strainer 52, is to replace the entire cartridge 16.

[00107] Thirdly, the cartridge 16 is simply screwed into the casing 16 of the backflow protection device and seals into position with an (elastomeric) O-ring seal 74; no thread seal tape or thread sealant is required. The one-piece cartridge 16 incorporates an integral strainer 52 to prevent any debris from fouling the waterways and the two independently operating non-return valves 18 are all housed within a corrosion resistant housing 50. All the components are retained by a corrosion resistant clip 62 and can be easily removed for servicing or replacement.

[00108] Unlike some prior art backflow protection devices, the independently operating non-return valves 18 incorporated in the cartridge 16, of the backflow protection device according to the present invention, are in a one-piece cartridge (16) configuration and do not require individual components when servicing is required. It is simply necessary to clean or replace the non-return valves 18 and/or the cartridge 16 as required.

[00109] Another significant advantage with the backflow protection device according to the present invention is that it allows for the optional attachment of the relief device 44 for high hazard conditions. This is a significant advantage because it can greatly assist with economies of scale for the manufacturer and the retailer since there is no need to make backflow protection devices according to two different designs. Instead, the backflow protection device according to the present invention is made according to only a single design, with the relief device 44 added or omitted as required for the particular installation. The advantage extends to the retailer or merchant and even the plumber because their stock inventory is smaller thereby saving cash flow and space.

[00110] By way of specific example, one version of the backflow protection device according to the present invention may have 1" male inlet and outlet connections that can be adapted for use with ball valves of V2", 3A" and 1" size (the sizes referring to the tubing sizes that can be connected to the ball valves). A second version of the backflow protection device according to the present invention may have 2" male inlet and outlet connections that can be adapted for use with ball valves of Vk", IV2" and a 2" size (the sizes referring to the tubing sizes that can be connected to the ball valves). Both these versions can be used with or without a relief device 44.

[00111] Whilst preferred embodiments of the present invention have been herein before described, the scope of the present invention is not limited to those specific 2016204853 11 Jul2016 18 embodiments, and may be embodied in other ways, as will be apparent to a skilled addressee.

[00112] Modifications and variations such as would be apparent to a skilled addressee are deemed to be within the scope of the present invention.

Claims

The claims defining the invention are as follows:

1. A backflow protection device comprising a casing, an inlet, an outlet, and a cartridge, wherein the cartridge is removably insertable into the casing and the cartridge is provided with at least two non-return valves.
2. A backflow protection device according to claim 1, wherein the cartridge is detachably connected with the casing.
3. A backflow protection device according to claim 1 or 2, wherein the casing is provided with the inlet.
4. A backflow protection device according to any one of the preceding claims, wherein the cartridge is provided with the outlet.
5. A backflow protection device according to any one of the preceding claims, wherein a portion of the cartridge extends from the casing.
6. A backflow protection device according to any one of the preceding claims, wherein the cartridge is provided with the at least two non-return valves such that the at least two non-return valves are removably retained with the cartridge.
7. A backflow protection device according to any one of the preceding claims, wherein the at least two non-return valves are arranged serially, one after the other, in the cartridge.
8. A backflow protection device according to any one of the preceding claims, wherein the cartridge is provided with a strainer or filter.
9. A backflow protection device according to claim 8, wherein the two non-return valves and the strainer are arranged serially and substantially linearly in the cartridge.
10. A backflow protection device according to any one of the preceding claims, further comprising a relief device.
11. A backflow protection device according to claim 10, wherein the relief device comprises a valve and a diaphragm such that pressure differential on opposed sides of the diaphragm causes the valve to open or close.
12. A backflow protection device according to claim 11, wherein the relief device comprises a casing and the casing comprises at least a first part and a second part and the diaphragm is retained in position by the first and second parts of the casing.