Drainage Assembly and Method

Abstract

A flow concentrating assembly for connection to a downpipe, the assembly including: a flow concentrating pipe having an upstream diameter equal to that of the downpipe and an outlet section having a diameter smaller than the upstream diameter, the flow concentrating pipe being disposed on the downpipe with an outlet aperture of the outlet section concentric with the downpipe and directed downwardly; and the flow concentrating section providing a fluid path between a location on the downpipe adjacent the outlet aperture and a location external to the downpipe, the flow concentrating section being disposed such that, in use, water flows through the outlet aperture to form an annular space around the water flow, and air in the annular space can be released along the fluid path.

Description

[Technical Field]

[0001] The present invention relates to a drainage system, and more particularly to a drainage system for rainwater to vertical downpipes used for multi-storey / repeated floor drainage (e.g. balconies, walkways). [Background technology]

[0002] Gravity stormwater systems that drain water from multiple / repeated floors (e.g., balconies, corridors, etc.) have a risk of water backflow if the system is not designed correctly. With current gravity stormwater drainage design principles, it is very difficult to predict backflow. The main cause of backflow is air escaping from the gravity stormwater barrel through openings. The worst case scenario for backflow is when the gravity stormwater system's discharge is obstructed, for example, by submerged discharge due to flooding of external drains, or by insufficient size of the discharge pipe.

[0003] To prevent the above uncertainties, the flow rate of the plumbing must be limited to a very low flow capacity, allowing the central core of the space to vent air vertically upwards rather than through drainage openings on the repeating floors.

[0004] Many stormwater drainage standards, such as British Standard and European Standard BS EN 12056-3, recommend that vertical pipes have a fill level between 0.2 and 0.33. This means that the central core of the pipe, which is at least 67% of the cross-sectional area, must be available for air passage. This is to prevent any pressure fluctuations within the gravity system and to ensure that the system pressure is always maintained at atmospheric pressure.

[0005] However, these stormwater drainage standards only address gravity drainage from roofs. They make no mention of drainage from repeated floors. Experiments on drainage from repeated floors have shown that backflow is likely to occur due to the large number of air inlets and vents in the pipes. The most reliable way to reduce the likelihood of backflow is to use a large diameter vertical pipe or to limit the capacity of the gravity system. However, this makes the gravity system inefficient. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Application Laid-Open No. 2007-092296 [Patent Document 2] Japanese Patent Application Laid-Open No. 2008-150785 [Patent Document 3] Chinese Patent Application Publication No. 112031125 [Patent Document 4] German Utility Model No. 29608589 Summary of the Invention

[0007] In a first aspect, the present invention provides a flow concentrating assembly for connection to a downpipe, the assembly including a flow concentrating pipe having an upstream diameter equal to that of the downpipe and an outlet section having a diameter smaller than the upstream diameter, the flow concentrating pipe being positioned on the downpipe with an outlet aperture of the outlet section concentric with and directed downwardly from the downpipe, and the flow concentrating section providing a fluid pathway between a point on the downpipe adjacent the outlet aperture and a point external to the downpipe, the flow concentrating section being positioned such that, in use, water flows through the outlet aperture to define an annular space around the water flow, and air in the annular space can be released along the fluid pathway.

[0008] In a second aspect, the present invention provides a method for releasing trapped air in a downpipe, the method comprising the steps of flowing water annularly around a bore of the downpipe and into a flow concentrating pipe located collinearly within the downpipe, reducing the diameter of the water flow as it flows through the flow concentrating pipe relative to the diameter of the downpipe, exiting the water through an exit aperture located coaxially in the flow concentrating pipe to form an annular space around the exiting water flow, providing a fluid path between a location adjacent the exit aperture and a location exterior to the downpipe, and releasing air trapped in the annular space along the fluid path.

[0009] The present invention provides a flow concentrating assembly that can be incorporated into a piping system at critical points such as the inlet tray where incoming water can impede the release of air from the system.

[0010] Generally, the present invention provides a flow-focusing pipe that acts as a transition from an upstream diameter to a smaller diameter, thus preventing annular flow by concentrating downward flow into a centrally directed column. As a result, an annular space is formed around the column flow in the lower pipe. This has the dual effect of allowing incoming water to enter the system as a downward annular flow and releasing air in the system that would otherwise be trapped by either or both of the upper pipe flow and the incoming flow. [Brief explanation of the drawings]

[0011] It will be convenient to further describe the invention with reference to the accompanying drawings, which show possible arrangements of the invention. Other arrangements of the invention are possible, and consequently the particularity of the accompanying drawings should not be understood as superseding the generality of the preceding description of the invention.

[0012] [Figure 1] 1 is a cross-sectional elevation view of a gravity stormwater assembly according to the prior art; [Figure 2] FIG. 1 is a cross-sectional elevation view of a gravity stormwater assembly according to one embodiment of the present invention. [Figure 3A] FIG. 10 is an isometric view of a gravity stormwater assembly according to a second embodiment of the present invention. [Figure 3B] FIG. 10 is an isometric view of a gravity stormwater assembly according to a second embodiment of the present invention. [Figure 3C] FIG. 10 is an isometric view of a gravity stormwater assembly according to a second embodiment of the present invention. [Figure 4] 1A-1C are various cross-sectional views of a gravity stormwater assembly according to some embodiments of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0013] FIG. 1 shows a prior art pipe system in which an inlet, such as a balcony drain 25, receives surface flow 8. In this case, the rain section 25 is part of a rain barrel, with an upper pipe 2 directing downward flow 3. The water flow characteristics are such that, at less than full capacity, flow 3 becomes circular, leaving a central void 4. During a rainstorm, when surface flow 8 and pipe flow 3 occur simultaneously, a water curtain 6 forms, which effectively blocks the surface flow from entering the downstream pipe 10, causing flooding of the surface (e.g., balcony). Furthermore, because this water curtain 6 is circumferentially distributed along the pipe bore, it also blocks air 9 in the downstream pipe 10 from escaping, reducing the available capacity of the system. This results in both overall flooding and localized flooding at each inlet / outlet.

[0014] FIG. 2 shows a flow concentration pipe 5 collinearly positioned within a downpipe 10 and having a drainage / water inlet section 25. The water inlet 25 may be located on a balcony, for example, as part of a stormwater pipe barrel for a multi-story building. The flow concentration pipe 5 may be an extension of an existing pipe or a separable element that can be attached to an existing pipe within the stormwater pipe barrel. The flow concentration pipe 5 includes an upper section corresponding to the downpipe system, a transition section 15, and an outlet section. The transition section 15 is an intermediate, reduced-diameter section for concentrating water flow from the diameter of the upper section to a smaller diameter for the outlet section 20. The outlet section 20 has an aperture 30 through which water flow 35 flows from upstream 55 and ultimately exits 40. The flow concentration assembly further includes a downpipe 10 modified to include a flow concentration section 25 that includes an enlarged annular flange.

[0015] As the upstream water 55 enters the transition section, the narrowing diameter reduces the water backup 37, resulting in the entire bore being utilized, eliminating the annular flow pattern of FIG. 1 . As the water flow 35 flows through the transition section 15 and into the outlet section 20, the diameter of the flow 40 exiting the flow concentration pipe 5 causes the water to converge concentrically with the downpipe 10 at a smaller diameter than the downpipe 10. The water then flows through the outlet aperture, forming an annular space 45 around the water flow 40. As the water flow 40 exits, its velocity and pressure increase, forming a concentrically focused jet of water. This prevents the upstream water from forming an annular flow in the downpipe 10 and avoids the water curtain shown in FIG. 1 . The annular space 45 allows air to pass along the fluid path from adjacent the outlet aperture 30 to a location 50 outside the downpipe. This allows the air within the annular section to be released from the flow concentration section 25. Additionally, surface water 47 is collected by the outlet 25 and allowed to pass into the downpipe 10. Because water 47 flows in contact with the surface, it tends to flow downward in an annular flow. The location of the collection pipe 5 allows the surface water 47 to flow in an annular flow because the outlet 25 receives the surface water within its capacity. This means that all three fluid paths (surface water 47, released air 50, and downpipe flow 40) can coexist without impeding the flow capacity of the system.

[0016] 3A-3C show a flow concentration assembly according to a further embodiment of the present invention. In this embodiment, the flow concentration pipe 60 is a separable element that can be attached to an existing downpipe and, for example, soldered, bolted, strapped, clamped, screwed, or welded into place. The embodiment of FIGS. 3A-3C shows a flow concentration pipe 60 with a combined transition and outlet section, as opposed to the separate sections of the embodiment of FIG. 2.

[0017] In this embodiment, the flow concentration pipe 60 includes a contoured outlet section 70. The contoured outlet section 70 has a recessed portion 75 circumferentially disposed around the flow concentration pipe 60. The recessed portion 75 both transitions the diameter of the water flow and provides a profile for the water flow to confine it to the central axis of the flow concentration section 65. That is, water exits through an aperture 90 and enters the downpipe 65, forming an annular space 95. Note that the drain outlet 85 is similar to the drain outlet 25 of FIG. 2. It will be appreciated that by applying the concentration pipe of the present invention, drain outlets of different configurations can operate in the same manner to accommodate the three fluid paths described above.

[0018] The relationship between the downpipe and the outlet diameter may be a function of several parameters including the flow rate, the length of the downpipe, the height of the downpipe above the flow concentrator pipe, and secondary factors that affect these parameters, such as the size and number of upper and lower branches of the flow concentrator assembly 60, 65. That is, for very high flow rates, the diameter of the outlet aperture relative to the downpipe diameter may be in the range of 50% to 90% of the downpipe diameter to provide a sufficient annular space to efficiently discharge the air.

[0019] Figure 4 shows various embodiments of the shape of a flow-concentrating pipe exit aperture. Four shapes 125-140 are provided, with various cross sections shown at 105-120. As will be appreciated, the applicable shapes that fit within the present invention can be extended beyond those shown in Figure 4. Figure 4 shows a non-exhaustive list of possible shapes for a flow-concentrating pipe. Other shapes, such as cylindrical shapes, that provide a constriction in the pipe to generate pressure to expel water upstream while simultaneously allowing air to escape and additional water to enter the system also fit within the present invention.

[0020] The first section 105 provides a cross section through the flow concentrating pipe, the second section 110 is a plan view of the flow concentrating assembly, the third section 115 is the downpipe, and the final section is a cross section of the exit aperture of the flow concentrating pipe.

[0021] Each of the shapes shown is a concave polygon with three or more degrees of rotational symmetry. It will be appreciated that shapes with one or two degrees of rotational symmetry may also be possible if concentric water flow is achieved. The concave portion of the flow concentrator pipe serves to aid in the transition of the flow from the upper downpipe diameter to the aperture diameter. The octagonal 135 and hexagonal 140 convex polygons simulate a more circular exit flow, while the three-pointed star-shaped concave polygon 125 and four-pointed star-shaped concave polygon serve as more rigid transitions. A longer transition may be required for the star-shaped aperture compared to the more open shapes 135, 140 to reduce shock losses during the transition.

[0022] In each case, each shape may create different flow patterns upon exiting the flow concentrating pipe, while each has advantages depending on the flow rate and transition length, which may also be a function of the relationship between the diameter of the aperture and the diameter of the flow concentrating pipe.

Claims

1. 1. A flow concentrating assembly for coupling to a downpipe, comprising: a flow concentrating pipe having an upstream diameter equal to that of the downpipe and an outlet section having a diameter smaller than the upstream diameter, the flow concentrating pipe being disposed on the downpipe with an outlet aperture of the outlet section concentric with the downpipe and directed downward; a flow concentrating section in the downpipe that provides a fluid path between a location adjacent the outlet aperture and a location external to the downpipe; Including, The assembly, in use, is arranged so that water flows through said outlet aperture, forming an annular space around the water flow, and air in said annular space is able to be released along said fluid path.

2. The assembly of claim 1 , wherein the cross-sectional shape of the exit aperture is a concave polygon.

3. The assembly of claim 2 , wherein the concave polygon includes at least three degrees of rotational symmetry.

4. The assembly of claim 2 , wherein the concave polygon has arcuate sides.

5. 5. The assembly of claim 1, wherein the flow concentrating pipe includes a transition intermediate the downpipe section and the outlet section, the transition providing an intermediate diameter reduction.

6. 1. A method of releasing trapped air in a downpipe, comprising: flowing water annularly around the bore of the downpipe and into a flow concentrating pipe collinearly disposed within the downpipe; reducing the diameter of the water flow as it flows through the flow concentrating pipe relative to the diameter of the downpipe; allowing water to exit the concentrically arranged outlet apertures of the flow concentrating pipe to form an annular space around the exiting water flow; providing a fluid path between a location adjacent the outlet aperture and a location external to the downpipe; releasing air trapped in the annular space along the fluid path; A method comprising:

Images