I JUNCTION DEVICE, SYSTEM AND METHOD FOR FLUID DRAIl AGE Field of the Invention This invention relates to devices for managing fluid flow within fluid drainage systems, 5 and more particularly to junction devices for fluid drainage systems, port units for such junction devices, and methods of managing fluid flow. Background of the Invention The design principle for junctions within conventional gravity rain water down pipe systems (RWDP) is based on the principle of open channel (non-pressured flow). FIG. 10 1 shows a conventional junction 10 commonly used in rain water down pipe systems. The conventional junction 10 has a down pipe 12 and a connecting horizontal pipe 14 .that is joined in a perpendicular orientation. In drainage operation, water flows and clings along the wall of the pipe in a spiral direction indicated by arrows 30, while air flows in the opposite direction indicated by arrow 20 in the center of the pipe. Water 15 also flows along connecting horizontal pipe 14 in the direction indicated by arrow 32. In standard codes of practice such as the British standard and the European standard, for example, BS EN 12056-3:2000, suggests a fill rate of 33% for rain water down pipe systems for vertical pipe 12 and 70% fill rate for horizontal pipes 14. Such guidelines are intended to prevent pressure fluctuations in the rain water down pipe systems 20 which lead to water 36 being pushed out from the horizontal branches 14. The vertical down pipe 12 is typically fluidly connected to the main drainage sources such as the roof top of a building. The horizontal branches typically fluidly connect the secondary drainage sources such as floor outlets, floor wastes, balconies, planter drainage, or the like as shown in FIG. 2 to the vertical down pipe 12. When pressure fluctuation occurs 25 in conventional gravity rain water down pipe systems, a water plug 34 is formed in the down pipe WO 2008/118099 PCT/SG2008/000086 2 12 preventing the flow of air 20 causing the air to back flow 22. The air is then forced to flow back 24 into the connecting horizontal pipe 14 and pushes the water 36 out. This is commonly termed as backflow. This backflow problem has been the uncertainty factor for development, 5 especially for high rise residential buildings where balconies drainage and lobbies drainage are linked to common rain water down pipe systems. However, even in attempting to follow the standard code of practice of 33% fill rate, pressure fluctuations may still occur in the following situations: 10 submerged discharge (for example, flooding in drains), occurrence of bends in the rain water down pipe systems, and/or occurrences when despite trying to comply with the standard code of practice flow rate extends beyond recommended fill rate of 33%. 15 Backflow occurs when the clear air passage in an open channel of a rain water down pipe system is completely filled with water and forms water plugs, thus preventing air from escaping upwards through the center of the pipe. Instead, air escapes through the side branches 14 causing backflow. Escaping air from the branches is known as positive air flow, whereas air 20 being drawn into the pipe from the branches is known as negative air flow. Significant positive and negative pressures which may form inside the pipes during water flow contributes to backflow. In such cases the air that naturally moves upwards in positive air flow is 25 prevented from escaping. The positive air flow is then forced to escape through the nearest passages which are normally the branches linking to floor outlets. When this occurs, air brings along water and both are forced out through the floor outlet. The nature of the problem in pressure fluctuations is due to its uncertainty and unpredictability. 30 In conventional systems where a number of junctions are arranged in a stack configuration, different pressure fluctuations may be experienced at the upper most junctions in the stack compared to the lower most junctions, and backflow may be observed.
3 Additionally, in conventional junctions as described above are not compatible or easily adaptable in siphonic rain water down pipe (SRWDP) systems (siphonic drainage systems). Typically, in high rise buildings with siphonic drainage systems, the main drainage is completely separate from the drainage of secondary drainage such as floor 5 outlets, floor wastes, balconies, planter drainage and the like. The main drainage is not fluidly connected with the secondary drainage because siphonic systems are drainage systems where the pipes are filled with water and contain no air and exhibit full bore water flow. Typically, pipes commonly used in siphonic drainage systems are 1/3 of the size of pipes commonly used in conventional gravity rain water drain pipe systems 10 (non-siphonic drainage systems). For example, in siphonic drainage systems, the down pipe is typically 2" (50mm), and in non-siphonic drainage systems the down pipe typically has a gauge of 6" (150mm). The siphonic outlets feeding the down pipes in the siphonic drainage system are specially designed to prevent air from entering the system, and the pipe gauge or diameter of the down pipe in the siphonic drainage 15 system connected to the siphonic outlets is chosen to be relatively smaller than in non siphonic drainage systems to ensure that the pipe is completely filled with water. It is not recommended to connect a non-siphonic pipe or junction to a siphonic system as it will introduce air into the siphonic system and prevent full bore flow in the siphonic system thereby reducing the drainage capacity of the siphonic system. It is also not 20 recommended for a siphonic system to be connected to a conventional non-siphonic systems as it will introduce more water than what a conventional non-siphonic system can drain. This will result in occurrence of pressure fluctuations. An attempt to overcome this is to enlarge the diameter of the non-siphonic pipe and design the non siphonic pipe with 33% filled. However, having pipes of different diameter is 25 unsatisfactory and not economical as the down pipe required in the non-siphonic components must be enlarged for most applications. In most cases the down pipes in the non-siphonic system are required to be enlarged by 3 times or larger based on the guideline given by the code of practice. For example where the siphonic drainage system components 30 4 are 2 (50mn) and for the sphohc drainage system to connectto a non-siphonc drainage system, the minimum pipe size of the non-siphonic pipes system must be at least 6" , 50mm) Therefore, there is a need for a device and system that addresses a problem S associated with conventional drainage systems, and in particular to solve the backflow problem in horizontal branches linked ito rain water down pipe systems. Summary of the Invention in accordance with an aspect of the invention there is provided a fluidunction device for managing afst fluid flowing from at least two sources and a second fuid from at 10 least one source; the second flid capable of a negative pressure flow and a positive pressure flow, the device comprising a body having a first port adapted for fluid communication with the frst fluid from a first source, a second port adapted for fluid communicatior with the first fluid from a second fuid source, a third port for the discharge of the first fluid received fro firt and second ports, the body forming a 15 junction between the first and second port and thid port, and a diverter formed in the junction defining a nozzle formed in the body at the junction for diverting the flow of the first fluid from fist source from the first port to the third port, with a sidewail of the second port having an escape cutaway, and so forming an escape for the second fliid in eitherapositve pressure flow or negative pressure flow through the second port, 20 wherein the dierteris itegral with a side wai extending from a mouth of the fist port such that the side wal extending from the mouth is continuous and has smooth surface, n ehbodiments, a first port unit is adapted to be connected and n flU communication with a second port uni forming the fluid juntiaon device. The diverter is arranged to 25 divert water in the junction to form a first fuid plug is formed in theproximity of te first port adjacent the rnozze formed at the junction-Te nozle may form ajet of the frst fluid from the first fluid source increasing the pressure andvekicity ofthe discharge fow of the first flud at the third port The body may comprise a second diverter formed at the junction of the second portfor diverting the flow of theist fiui from the first 30 diverter to the third port and forcing. The first port may have a central axis tat is 5 concentriciy aligned with central axis of the third port or the first pot ay have a cental axis that is maligned with a central axis of the third port, ln accordance with another aspect of the presentinvention that is provided a first port unit adapted to be connected andin fluid communication with a second portumit 5 forming a fluid junction device for managing a first fluidflowing from at least two sources and a second fluid from at least one source, the second fluid capable of a negative pressure flow and a positive pressure flow, the fluid function device comprising: a body aing a first port of the first port unit adapted for fluid corrunication with the firs fluid from a first source, a second port of the second port I0 uni adapted for flud communication th the first fluid from a second fudsour-ce, a third port for the discharge of the first fluid received from first and second ports, the body forming a junction between the first and second port and third por and the first port uni comprising a diverter formed in he juncton defining a nozzle formed in the body athe junAtioni for dverting the flow of the first fluid from the first source from the 15 first port to the third port, with a siode wal of the second port having an escape cutaway, and so forming an escape for the second fluid in either a positive pressure flow or negative pressure flow through the second port. 4herein the diveter is integral wth a side wal extending from a mouth of the first port such that the sidewallextending from the mouth is continuous and has a smooth surface 20 In a further aspect the present invention provides a second part unt adapted to be connected and in fuid communication with a first port unit forming a fuid junction device for managig a first fluid flowing from at least two sources and a second fluid fAom at least one source. the second fluid capable of a negative pressure flow and a positive pressure flw, the fuid junction device comprising: a body having a first port of 25 the frst port uni adapted for fluid communication with the first fluid fro a first source, a second port of the secondport unit adapted for fluid conication with the first fluid from a second fid source, a thd port for the discharge of the first fluid received from first and second ports the body forming a junction between the frst and second port and third port and adierter formed inithe inactionn defining a nozzle formed in the 30 body at the junction for diverting the flow ofthe firstfluid from the first source fror the first port to the third part with a side wad of the second port having an escape cutaway, and so forming an escape for the second fluid in either a positive pressure flow or negative pressure w through the second port weren the diAverter is integral with a side wall extending from mouth of the first port such that the side wal extending fron thenuh is continuous:arid has a smooth surface Inaccordance vth an aspect of the invention there is provided a drainage system 5 comprsing a plurality of devices fornin a stack of devices, vherein the output of an upper device in fluid communion with the first port of the lower device Each device in the drainage system may comprise an escape for the second fluid eriher a positive pressure flow or negative pressure flow though the second pod of each device. In accordance with an aspect of theinvention there is provided a method for managing 10 a first fluid flowing rom at least two sources and a second fluid from at leastone source, the second fluid capabne of a negative pressure flow and a positive pressure flow, thee method cspifgrhe firs fromte first fluid source in a fluid junction device having a body having a first port adapted or fluid commnrcationwih the first fluid from a firstsource, a second port adapted for fluid communication with the IS ft fluid from a second fluid source, a third port for the discharge of the first fluid received fJom first and second porthe body forming a junction between thefirst and second port and third port divertng the first fluid wita diverter formedithe junction dinin a nozzle formed in the body at the junction for diverting the flow of the first fluid from the first source from 20 the first port to the thid port: and fo r g an escape for the second fluid in eiher a posive pressure flow or negative pressure flow through the second port. herein the dierterls integral with a side wali extending from a south of the first pot such that the side wal extending from the mouth is ontinoenus and has a smooth surface S nembodimentsa first port unit is connected indflidommunicaion with a second port unit the first port unit composing the first port of the idjunction device, and the second od uni comprising the second port of the flud junctiondevice A pluralon f devices are connected to form a stack of devices the output of an upper device inthe stack of devices isn fluid cor nunicaoi with the iatport of a lower device An 6 escape is forned for the second fluid in either a positive pressurefow or a negative pressure flow through the second port of each device in the stack of devices, The first fluid is diverted to increase the pressure and velocity of the discharge flow of the first fluid front the first port to the third port. Brief Description of the Drawings In order that the present invention may be fully understood and readily put into practical effect, thereshal inow be described, by way of non-linita.ve example only, preferred embodiments of the present invention the description being wth reference to the 10 accompanying ilstative drawings in the drawings FIG. I shows a cross-sectional view of a conventional gravity rain water down pipe junction when property designed and working; FIG 2 shows a cross-sectional view of the conventional gravity ran water down pipe juncton of0d HG1 showing a formation of a water plugduring pressue fluctuations S FIG 3 shows a crosssecional view of n ant-backflow jundion in operation in accordance ith an embodiment of the invention; the crosssectionaview taken along Ine A-A of FG 5,A; FiG. 4 shows the crossectona persoectiveiew of FIG. 3 having a side port exposed on he second pcort in accordance with an enbodiment of the invention; 20 FG. 5A-G show top Views of the antibaNkflow juncton n accordance with an embodimrent of the inventions; FIG. GA and 6B shows rrsetional viewstaken along ines 8-B and C-C, respectivey, of the anilbacflow juntion of G. 4 in accordance with arerbodiment of the invention: 25 WO 2008/118099 PCT/SG2008/000086 7 FIG. 7A shows a side elevation view of the anti-backfiow junction of FIG. 4 having a side port in accordance with an embodiment of the invention, and FIG. 7B shows a side elevation view of an anti-backflow junction in accordance with an embodiment of the invention; 5 FIG. 8 shows a front elevation view of the anti-backfiow junction of FIG. 4 having the second port of the junction with multiple ports in accordance with an embodiment of the invention; 10 FIG. 9A and 9B show a top view of the anti-backflow junction in accordance with an embodiment of the invention, and a cross-sectional view of the anti backflow junction of FIG. 9A taken along line D-D in accordance with an embodiment of the invention, respectively; 15 FIG. 1 0A and 1 OB show a top view of the anti-backflow junction in accordance with an embodiment of the invention, and a cross-sectional view of the anti-backflow junction of FIG. 1 OA taken along line E-E in accordance with an embodiment of the invention, respectively; 20 FIG. 11 A and 11 B show a top view of the anti-backflow junction in accordance with an embodiment of the invention, and a cross-sectional view of the anti-backflow junction of FIG. 11A taken along line F-F in accordance with an embodiment of the invention, respectively; 25 FIG. 12A and 12B show a top view of the anti-backflow junction in accordance with an embodiment of the invention, and a cross-sectional view of the anti-backflow junction of FIG. 12A taken along line G-G in accordance with an embodiment of the invention, respectively; 30 FIG. 13 shows a cross-sectional view an anti-backflow junction having the first port as a separate unit from the second port and the third port in accordance with an embodiment of the invention; WO 2008/118099 PCT/SG2008/000086 8 FIG. 14 shows a cross-sectional view of a stack system comprising a plurality of anti-backflow junctions in accordance with an embodiment of the invention; 5 FIG. 15 shows a cross-sectional view of a hybrid siphonic/non-siphonic stack system comprising a plurality of anti-backflow junctions in accordance with an embodiment of the invention; and FIG. 16 shows a flow diagram of a method in accordance with an 10 embodiment of the invention. Detailed Description FIG. 3 shows a cross-sectional view of an anti-backflow junction device 100 in operation in accordance with an embodiment of the invention. FIG. 4 15 shows the cross-sectional view of the anti-backflow junction device 100 of FIG. 3 with perspective view showing a side port 142 exposed on the second port 104. The cross-sections of FIG. 3 and FIG. 4 are taken along the line A-A shown in FIG. 5A of a top view of the anti-backflow junction. The anti-backflow junction device comprises a body 108 with a cavity or 20 passages having first port 102, a second port 104 and a third port 106. The first port and the second port are in fluid communication with fluid sources (not shown) which may be draining rain water collected from rooftops, balconies, floor wastes, floor outlets, planter drainage and the like. The body 108 is configured with a lip or diverter 112 in the wall that defines a 25 nozzle 110 with the sidewall of the body of the junction device along the wall of the first port and the third port opposite the second port. In an embodiment, a section of the side wall of the second port forms provides as gradual descent, an escape cut away 114, of the branch to the third port. This cut away section 114 maintains the diameter of the pipe size to ensure 30 downward water flow exit from the second port to the third port. Also, between the first port and the second port, a support 136 is provided to provide added structural support for the second port and make the junction device rigid, however, it will be appreciated that such support may not be necessary or other means of support may be envisaged.
WO 2008/118099 PCT/SG2008/000086 9 The diverter 112 is shown in more detail in the top view of the junction device of FIG. 5A and the cross-sectional views of FIG. 6A and 6B taken at different cross-sections of the anti-backflow junction device 100 shown in 5 FIG. 4. The diverter 112 is a protrusion, ramp, channel, lip, bump, latch, ledge, or the like that extends from wall or within the surface of the first port. The diverter is integral with the side wall extending from the mouth of the first port such that the surface of the side wall is continuous with smooth surfaces. In other embodiments, the diverter may be formed as protrusion, 10 ramp, channel, lip, bump, latch, ledge, or the like having smooth and/or angled configuration. It will be appreciated that the diverter may be integral with the side wall, however, the diverter may take other configurations such as structurally added and/or adhered to the side wall of the tubular pipe of the port. In this embodiment shown in FIG. 4-6B, the diverter top length 15 extends about half of the circumference of the wall extending around the perimeter of the first port from a first point 113 to a second point 115 of the diverter as seen in the top view of FIG. 5A to the dashed line 128 of FIG. 4. The bottom length is the distance from point 113 to point 115 around the head of the nozzle in a cross-section (not shown) including the point 124 20 shown in FIG. 4. The depth of the diverter extends from a first point 122 and a second point 124 as shown in FIG. 4. The diverter is sculpted as shown by channel 117, and the resulting diverter width 119 is shown that changes along the length of the diverter. Diverter width is defined by the horizontal distance, relative the central axis of the first port, from point 124 25 to dashed line 128 in FIG. 4. More specifically, diverter width is the distance from the surface of the diverter that is exposed to the water to the first port wall of the pipe as shown in FIG. 6A and FIG. 4. In FIG. 4 the dashed line 128 is an extension of the sidewall 126 of the first port by which the width of the diverter 112 may be seen from dashed line to the surface of 30 the diverter exposed to the interior of the junction device 100. The diverter width is the distance along a radial line diverging from the central axis 180 of the first port from the edge of the ledge of the diverter 112 to the side wall extension as shown as dashed line 128 in FIG. 4 of the opening of the first port taken along a desired cross section as shown in FIG. 6A. The WO 2008/118099 PCT/SG2008/000086 10 depth of the diverter is the vertical distance, relative the central axis of the first port, along the surface of the diverter forming the interior surface of the pipe that extends from point 122 and 124 shown in FIG. 4. The length of the diverter is shown in FIG. 5A and extends from the first point 113 to a 5 second point 115. The diverter has configuration such that in operation, the diverter 112 manages to divert the flow of the downward spiraling water entering the mouth of the first port 102 as indicated by arrows, and concentrates the flow of water against the opposite wall 111 of the second port 104 and third port 106, forming a water plug 134 at the first port 10 proximate the diverter, between the diverter in the side wall 111 of the junction device 100 opposite the diverter 112. The diverter 112 in this embodiment has a sloping, gradient or ramping orientation with respect to the side wall of the first port. In this embodiment the diverter width 119 varies along the length of the diverter 112, and remains constant for the 15 majority of the length at each cross section along the length, however, near the point 113,115 the diverter width is tapered. It will be appreciated that the width of the diverter may vary along either the depth or length or both or remain uniform. The length and/or depth of the diverter may also vary or be uniform along the depth and/or length, respectively. Of course, other 20 configurations may be envisaged for the diverter 112, and some variations are shown and discussed in detail below with reference to FIG. 9A-12B. Since the side wall 111 of the wall opposite the diverter is continuous, the configuration of the side wall 111 and the diverter 112 form a nozzle 110. 25 The diverter 112 is in a position having the orientation where the first port cross-sectional area is reduced at the tip, at point 124, of the diverter forming the nozzle head. The diverter 112 is designed to reduce the cross sectional area of the first port within the shortest width and yet has the least resistance to the fluid flow so as to maximize fluid capacity. This desired 30 function is achieved by the shape and angle of the diverter 112 shown. The ratio of distances of the cross-sectional openings of the nozzle head 150, from the opposite wall of the first port 111 to the tip 124 of the nozzle head (shown in FIG. 5B), and the mouth of the first port 102 (shown in FIG. 5C) is shown. Having the nozzle head opening 152 too small will cause the WO 2008/118099 PCT/SG2008/000086 11 fluid capacity to be low and not effective. Having the nozzle head opening 150 too small also increases the potential of having the device blocked by foreign items and debris such as leaves, twigs, soil and the like. If the nozzle head opening 150 is too large, the anti-backflow properties and 5 functions will not be effective, and backflow may still occur. The ratio to achieve is a balance between the maximum capacity of the anti-backflow junction device and the effectiveness of the anti-backflow junction device. For example, the ratio for percentage of reduction may be from approximately 10% to 25%. It will be appreciated that the ratio of the 10 opening of the first port and the opening of the nozzle head may vary for specific applications, and may be less than 10% or more than 25%. Additionally, the junction of the second port 104 with the first port 102 to the third port 106 as shown is a graduated junction with smooth edges and 15 curves with escape cut away section 114. Another function of an embodiment of second port section 114 besides allowing air to escape is to maintain the pipe diameter of the second port. Maintaining the pipe diameter in the second port also helps to prevent blockages by foreign items and debris such as leaves, twigs, soil and the like at the second port. 20 This also allows the overall size of the anti-backflow junction device 100 as small and compact as possible. In operation, the anti-backflow fitting 100 provides a controlled situation at the junctions to prevent uncontrolled pressure fluctuation in rain water down 25 pipe systems that may contribute to back flow. FIG. 16 shows a flow diagram of a method 400 in accordance with an embodiment of the invention. The flow of water 130 from the first source 402 is channeled or diverted by diverter 112 in the side wall which forms the nozzle 110 that increases the velocity of the flow of water 132 downstream of the nozzle 30 110 and out third port 106. The first fluid directed from the first port away from the second port 404. The air flow 120 is left clear for the air to escape 406 through the second port 104.
WO 2008/118099 PCT/SG2008/000086 12 The configuration ensures a controlled situation at every junction within the body of the device. The nozzle 110 formed by the diverter 112 at the junction ensures the formation of the water plug 134 and therefore ensures that the pressure build up at above the nozzle. The forming of the pressure 5 above the nozzle 110 creates a pressure jet which passes through the nozzle at increased velocity. Pressure is released after the nozzle 110. In a system comprising multiple or a plurality of such anti-backflow fittings, the pressure builds and increases again above the next downstream nozzle. This situation is repeated at every junction and may be predicated and 10 controlled. The pressure jet that is formed by the nozzle 110 may cause a high velocity pressure jet that accelerates the water beyond the junction, thereby ensuring a clear air passage at the junction. The anti-backflow fitting works 15 in both negative and positive pressure which is a phenomenon that occurs with water and air flowing in pipes and drainage systems. In most cases the air inside the anti-backflow fitting 100 is forced downwards through the next nozzle together with water traveling at high velocity. In such cases the high velocity pressure jet causes the junction to be under negative 20 pressure. In cases where the discharge is submerged or where the nozzle do not allow sufficient amount of air discharging downwards, the junction of the anti-backflow fitting is under positive pressure. Air escapes through the clear air passage created by the nozzle. 25 In either positive or negative pressure situations, the configuration of the anti-backflow fitting 100 in accordance with an embodiment of the invention ensures a clear air passage is maintained at each junction of the anti backflow fitting, such that water is being prevented from being brought up through the passage by the downward pressure jet. 30 The device 100 having this configuration provides predictability and controllability. The flow capacity of the anti-backflow fitting can be determined by physical testing. Empirical testing has shown that a flow rate of 20 I/s without any backflow, whereas conventional junctions WO 2008/118099 PCT/SG2008/000086 13 experience backflow at as little as 2-3 Vs. Due to the principle that each junction forces the formation and release of pressure, there are no unpredictable pressure fluctuations at the junctions. 5 The action of the nozzle configuration 110 increases the velocity of the fluid to jet flush the junction and the entire system. This jet action enables the self-cleansing of the pipe interior and minimizes blockages. With this configuration, the pressurized system allows a significantly higher 10 flow rate through a pipe as compared to the conventional gravity system. It will be appreciated that the junction may be fitted for pipes of any number of dimensions and cross-sections. For example, the ports of the junction may be adapted for a gauge of 3" (75mm) for the first port and 2" (50mm) 15 for the second port, 4" (100mm) for the first port and 3" (75mm) for the second port, and the like. Other gauges or sizes are contemplated for example the 6" (150mm) first port and 4" (100mm) second port, 6" (150mm) first port and 3" (75mm) second port, 4" (100mm) for the first port and 2" (50mm) for the second port, or the like. The ports may be adapted to 20 receive the same or different sized pipes. For example, the first port may be adapted to receive larger dimensioned pipe than the second port and/or the third port. The third port may have a dimension that is equal to the first port and/or second port, or may have a different gauge than the first and second ports. Additionally, the pipes may be tubular and the cross-section 25 of the pipe may be circular or any number of other cross-sections, such as rectangular, square, oval or the like. The thickness of the pipe walls may be any thickness conventionally used, for example, about 2-3mm. The anti-backflow junction device 100 may be manufactured from polyvinyl 30 carbonate (PVC), high density polyethylene (HDPE), hubbless, cast iron, metallic materials and other such materials. The manufacturing process may be by any conventional pipe manufacturing process such as by PVC extrusion or the like. It will be appreciated that the manufacturing process depends on the particular material selected.
WO 2008/118099 PCT/SG2008/000086 14 In another embodiment, multiple connections to the same anti-backflow fitting are possible, as shown in FIG. 4, 5, 6A, 6B, 7A, 7B, and 8. FIG. 7A shows a side elevation perspective view of the anti-backflow junction 5 having a side port 144 in accordance with an embodiment of the invention, and FIG. 8 shows a front elevation perspective view of the anti-backflow junction having the second port of the junction with multiple ports in accordance with an embodiment of the invention. FIG. 8 specifically shows at multiple ports at the second port 140 having ports 104, 142 and 144. It 10 will be appreciated that any of the ports may be configured with one, two or multiple ports. Each of the ports may be in fluid connection with the same source or different sources of fluid. It will be appreciated that the connection between the ports may be made with a pipe, connecting pipe, another junction or fitting, or the like. The port may form a socket, straight 15 or plain end pipe, or the like, and may be fitted and joined together in any manner. FIG. 7B shows a side elevation perspective view of the anti backflow junction 292 that may be adapted to receive a separate accessory 294 fitting or pipe that may contain an additional or multiple ports. 20 Other configurations of the diverter as discussed above with reference to FIG. 4 are shown in FIG. 9A-12B. For example, FIG. 9A-B shows a diverter 220 having a configuration that is a protrusion that extends perpendicular to the first port wall 222 forming a ledge. In this configuration there is no gradient or sloping of the protrusion relative to the first port wall, 25 or the opposing side wall 224 and the protrusion has a perpendicular orientation with respect to the first port wall. The diverter 220 protrudes about the first port wall 222 having a length from a first point 223 to a second point 225 in a straight configuration 227 (not indicated in drawings) edge of the diverter ledge. The diverter is not sculpted and no channel is 30 formed in the diverter, resulting in different diverter width along the length of the diverter. However, this basic diverter configuration still achieves diversion of the water to form the water plug as desired, although in this embodiment higher resistance is observed in operation when the fluid runs WO 2008/118099 PCT/SG2008/000086 15 through. Also, this embodiment reduces the cross-sectional area of the first port, which also lowers drainage capacity. Additionally, in FIG. 9A and 9B the junction of the second port 104 with the 5 first port 102 to the third port 106 as shown is a graduated junction with smooth edges and angle cut away section in the second port section 114. The second port has a horizontal orientation with respect to the first port and third port that have central axis in alignment. 10 FIG. 10A and 10B show an embodiment of the anti-backflow junction device 100 having another configuration of diverter 230. The diverter in this configuration is more like the diverter shown in FIG. 5, 6A and 6B, than FIG. 9A and 9B, since the diverter is sculptured resulting in a smaller diverter width that is uniform across the length of the diverter and the 15 surface of the diverter forms a cut away or channel 236. The diverter extends about half the circumference of the wall forming the first port. Similar to the diverter of FIG. 9A and 9B, the diverter 230 is a protrusion that extends perpendicular to the first port wall 232. In this configuration there is no gradient or sloping of the protrusion relative to the first port wall 20 232 or the opposing side wall 234. The nature of the diverter being perpendicular to the side wall of the pipe also yields an increased resistance to the fluid flow similar to the embodiment shown in FIG. 9A and 9B, however the resistance observed is less than the embodiment shown in FIG. 9A and 9B. 25 FIG. 11A and 11B show an embodiment of the anti-backflow junction device 100 having another configuration of diverter 240. The diverter in this configuration is more like the diverter shown in FIG. 5, 6A and 6B, than FIG. 9A and 9B or FIG. 1OA or 1OB, since the diverter is sculptured forming 30 a cut-out or channel 246 resulting in a smaller diverter width that is uniform across the length of the diverter, and the diverter is graduated along the length of the diverter. The diverter extends about half the circumference of the wall forming the first port. The diverter in this embodiment has a sloping, gradient or ramping orientation with respect to the side wall of the WO 2008/118099 PCT/SG2008/000086 16 first port. This embodiment has a fluid capacity that results from the reduction of the cross-sectional area of the first port that is gradual along the depth of the diverter, i.e. the ratio between the first port opening mouth 152 and the nozzle head opening 150 at point 124 along the depth of the 5 diverter. Additionally, in FIG. 11A and 11B the junction of the second port 104 with the first port 102 to the third port 106 as shown is a graduated junction with smooth edges and curves with escape cut away 114, with the second port 10 having a vertical orientation. FIG. 12A and 12B show another embodiment of the anti-backflow junction device 160 having a double or multiple diverter configurations. The first diverter 162 is shown and is similar to the diverters discussed previously 15 with respect to FIG. 3 to 11B. The second diverter 164 is formed in the side wall 264 opposite the first port wall 262 that the first diverter 162 protrudes. The water is diverted twice in this configuration to form a water plug and resulting air flow 170 as shown and the water is diverted toward the second port wall 268. 20 Additionally, in FIG. 12A and 12B the junction of the second port 104 with the first port 102 to the third port 106 as shown is graduated junction with escape cut away or gradual part 114 and a sharp edge join between the second and third port walls. The second port 168 is shown with pipe 25 having rectangular cross-section. FIG. 12A and 12B show that the first port and third port do not necessarily need to be aligned. The central axis of each of the ports, first, second and third ports 166,168,167 is shown by dashed lines 272,274,276. In this 30 embodiment, the first, second and third ports have central axis that are in misalignment. The sidewall 264 of the first port is misaligned with the sidewall 266 of the third port. Likewise, the sidewall 268 of the third port 167 is misaligned with the sidewall of the second port 168. Whereas the embodiment shown in FIG. 4, the first port and third port share a common WO 2008/118099 PCT/SG2008/000086 17 central axis 180,186 and are concentric. Additionally, in FIG. 4 the central axis of each port 180,184,186 is shown in parallel orientation with each other. The junction between the second port and the third port is in an unparallel orientation as shown in FIG. 4 by dashed lines 182. Of course it 5 will be appreciated that other orientations may be configured, such as the central axis of the first port, central axis of the second port, and central axis of the third port are in parallel or non-parallel orientation and vertical, non vertical or horizontal alignment or misalignment. 10 FIG. 13 shows another embodiment of the anti-backflow junction 280 having the first port 282 as a separate unit from the second port 284 and the third port 286. The first port unit 283 has a diverter 283. The first port unit 288 may be fitted or joined with the second port unit 284 to form a junction device 280. Additionally, a third port unit 286 may be fitted or 15 joined to the second port junction unit 284. In this embodiment the first port unit 282 may be a reducer and the second port junction unit 284 may be a y-tee that are standard in the industry. The units are fitted together and are concentrically aligned as shown by dashed line 288. The third port unit 286 may also be a reducer that is standard in the industry. This is also shown 20 in the flow diagram of method 400 FIG. 16 as an embodiment in dashed box 408. It will also be appreciated that the anti-backflow junction device may be adapted to receive a separate accessory 294 fitting or pipe that may contain an additional or multiple ports as shown and discussed with reference to FIG. 7B. 25 In another embodiment, a stack 200 is a drainage system with a plurality of junctions 100 connected in a series configuration joined by connecting piping 202, as shown in FIG. 14. The stack 200 is in fluid communication with a rainwater outlet 204 and rainwater pipe 214 at the top of the stack 30 and a drain pipe 206 and drain 208 at the bottom of the stack. The junction device 100 is in fluid communication with other junction devices 100 in the stack such that the third port of an upper junction device is in fluid communication with the first port of the junction device positioned below the upper junction device. In an embodiment a horizontal pipe 210 and source WO 2008/118099 PCT/SG2008/000086 18 212 is also in fluid communication with each junction device 100. Although it is preferred that all junctions in the stacks be the anti-backflow junctions 100, the inclusion of one or more in a conventional gravity rain water down pipe configuration may improve the system at that junction. It will be 5 appreciated that a stack designed to function with the anti-backflow fitting may be mixed with conventional junctions. This is also shown in the flow diagram of method 400 of FIG. 16 as an embodiment in dashed box 410. Additionally, it will be appreciated that the dimensions of the anti-backflow 10 junction device 100 may be sized to maximize overall flow rate while remaining within the certified flow rate of the anti-backflow fitting. It will be appreciated that the anti-backflow fitting may be implemented in a fully conventional gravity RWDP systems, as well as to connect to siphonic 15 and non-siphonic systems. Siphonic systems are drainage systems where the pipes are filled with water and contain no air and exhibit full bore water flow. Typically, in high rise buildings with siphonic drainage systems, the main drainage is completely separate from the drainage of balconies. In an embodiment shown in FIG. 15, the junction device allows the combination 20 of both siphonic drainage systems and non-siphonic drainage systems to form a hybrid system 300 without significant enlargement in pipe size that would have been required in the conventional non-siphonic drainage system while controlling the pressure fluctuation and preventing any backflow. The pipe size or gauge may be maintained on either side of the 25 junction 320. For example in one embodiment the siphonic outlet may be in fluid connection with rainwater pipe 314, and connecting pipe 302 having a gauge or dimension of 2" (50mm), and after junction 320 and anti backflow junction 100 the connecting pipe 302 may have a gauge or dimension of 3" (75mm) where without the anti-backflow junction the 30 connecting pipe 302 would need to be enlarged at least 3 times this size. Of course it will be appreciated that the anti-backflow junction device 100 may have ports ready to receive the different dimensioned pipes at different ports, such that junction 320 would not be required.
19 Whilst there has been described in the foregoing description preferred embodiments of the present invention, it will be understood by those skilled in the technology concerned that many variations or modifications in details of design or construction may be made without departing from the present invention. 5 The reference in this specification to any prior publication (or information derived from it), or to any matter which is known, is not, and should not be taken as an acknowledgment or admission or any form of suggestion that the prior publication (or information derived from it) or known matter forms part of the common general 10 knowledge in the field of endeavour to which this specification relates. Throughout this specification, unless the context requires otherwise, the word "comprise", and variations such as "comprises" and "comprising", will be understood to imply the inclusion of a stated integer or step or group of integers or steps but not the 15 exclusion of any other integer or step or group of integers or steps.