NZ238323A - Diverting debris from fluid stream using fluid reflection to clear a mesh screen - Google Patents

Description

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P.O. Journal, iMc: 2 3 8 3 2 3 No.: Date: NEW ZEALAND PATENTS ACT, 1953 COMPLETE SPECIFICATION DEBRIS DIVERTER AND FILTRATION METHOD ** v •- IL . _ '? ml y s+jwe, KEVIN JOHN BANNER, an Australian citizen of Russell Street, mo.

Dennington, Victoria^ Australia and IAN GEOFFREY FLETCHER, an Australian citizen of 23 Donaldson Drive, Warrnambool, Sttfp, VictoriaA Australia hereby declare the invention for which i. / we pray that a patent may be granted to pK^/us, and the method by which it is to be performed, to be particularly described in and by the following statement: - - 1 2 3832 3 DEBRIS DIVERTER AND FILTRATION METHOD This invention relates to a debris diverter and a filtration method. It relates particularly to apparatus and 5 a method for diverting debris and large solids out of a fluid stream.

The invention has relevance to many different situations in which debris or large solids need to be separated from a fluid stream. It will be described with 10 particular reference to the deflection of debris from rainwater during the collection or drainage of the rainwater from a roof, although the invention is equally applicable to numerous other applications such as the _ separation of particles larger than a predetermined mesh size from a 15 stream of particles of small size in the mining industry, the pre-treatment filtering of sewage, some gas filtration systems, the filtering of offal in abbatoirs, and the diverting of debris in storm-water drainage systems.

A normal roof is surrounded at least in part by 20 gutters into which rainwater falling on the roof flows. The gutters are normally connected to downpipes through which water from the gutters flows and the downpipes • are in turn normally connected to a drainage system or to a water collection system.

Because debris trapped within a water collection ' system or drainage system can create substantial difficulties, it is common to provide a filter such as a wire screen at a position near where the downpipe meets the gutter, so that debris from the gutter does not pass through 30 the downpipe and into the drainage or collection system.

However, screens positioned over the top of a downpipe frequently become blocked by debris such as dead leaves, bird droppings, dead birds and tennis balls so that the downpipe and gutter cease to function in their intended 35 manner. It is generally, necessary for a person to clean such gutters and screens periodically, and "this- ■ -d-S- an inconvenient and unpleasant task. if c. ,/ 2 6 a 31 3 There is therefore a need for a debris diversion system which reduces or eliminates the amount of maintenance required by conventional drainage systems.

Various attempts have been made to design an improved 5 system. Great Britain Patent Application 2137657-A describes a rainwater strainer suitable for installation below, a gutter and above a drain pipe. The strainer's screen is inclined at an angle to the horizontal so that debris such as leaves travels down the inclination and falls 10 off the edge. However, it has been found that, even with the screen being at an angle to the horizontal, debris tends to accumulate on the screen. If the angle of inclination is increased substantially in an attempt to overcome this, water tends to flow over the edge of the strainer together 15 with the debris.

Swiss Patent Application 620960-A5 describes a filter arrangement for a pipe, with a filter screen being oriented obliquely to the direction of flow- along the pipe. This arrangement suffers the same disadvantages. 20 Australian Patent Application 29569/89 suggests a possible solution to the problem of debris clinging to an inclined strainer screen, at least for the purposes of rainwater drainage systems. This involves having two or more inclined screens which are thoroughly exposed to the 25 elements, allowing the wind to blow away debris adhering to the screens. However, this is at best a partial solution as it requires the presence of substantial wind, .and even with substantial wind obstinate debris may cling to the screens. Further, an open arrangement increases the likelihood of 30 water spilling over the edge of the strainer with the debris, and an open arrangement is clearly unsuitable for many filtering applications not relating to rainwater.

According to one aspect of the present invention, there is provided an apparatus for deflecting solids larger 35 than a predetermined mesh size from a fluid stream, the apparatus comprising: (a) a screen filter, oriented substantially^-obliquely to the direction of flow of the fluid stream through' the;-.. !<" / l!-' V9J^99^ 11 23832 3 r apparatus, the filter being such that it traps substantially all solids larger than the predetermined size but allows substantially all the remaining fluid stream to pass through it; and (b) a fluid reflecting means located close to the filter on the downstream side • of the filter, the fluid reflecting means being such that it reflects at least 1 a proportion of the fluid back through the filter to dislodge solids trapped on the upstream face of the 10 filter; wherein, by the combined effect of the fluid stream, the ■obliquely angled filter arid the dislodging action of the * reflected fluid, the solids trapped by the filter are caused to migrate across the upstream face of the filter to a 15 location outside the fluid stream.

Apparatus may be constructed according to the present invention for use in deflecting solids from any type of fluid stream including a gas fluid stream, a liquid stream, or a fluid stream of small solid particles. 20 The screen filter may be any suitable screen filter for separating solids larger than the predetermined size from the fluid stream. When the apparatus is used for separating debris from rainwater entering a downpipe, a wire mesh forms a suitable filter. Other suitable filters 25 include a metal or plastic grill and a perforated metal or plastic- sheet. In other applications, the filter may comprise cloth, filter paper, or any other suitable type of ' filter.

It is further preferred, although not essential, that 30 the filter be substantially flat and oriented at a angle of between 5° and 85° to the direction of flow of the fluid. More preferably, the upstream face of the filter will be oriented at an angle of approximately 45° to the direction of travel of the fluid. It is preferred that the 35 orientation of the filter relative to the direction of movement of the fluid be such that trapped solids can migrate across the upstream face of ""'the—frarlt-e-r— —Ul_a downstream direction while substantially a 1 l^gsO^sstJie x 19 JUNJ99IS1 2 3 a j % passes through the filter. As an alternative to a flat filter, the filter may be slightly curved or concave or convex.

The fluid reflecting means may be any means suitable for reflecting at least a proportion of the fluid back through the filter to dislodge solids trapped on the upstream face of the filter. The fluid reflecting means is preferably located close to the filter. The fluid reflecting means may be made from any suitable materials. Suitable materials include substantially rigid metals such as stainless steel, zinc-plated iron, copper and aluminium; plastics such as polyvinylchloride; and rubber.

The fluid reflecting means may be in any suitable configuration. It may have a perforated or unperforated surface. It may have a substantially flat surface arranged substantially parallel to the surface of the filter. However, if the surface of the fluid reflecting means is oriented obliquely to the direction- of flow of fluid, it will have the undesirable tendency to deflect fluid out of the normal path of fluid flow and perhaps also out of the solid matter outlet if one is provided. It is therefore preferred that the fluid reflecting means have a stepped surface configuration so that surface regions substantially perpendicular to the direction of fluid flow alternate with surface regions substantially parallel to the direction of fluid flow.

It is preferred that the apparatus further comprise a fluid stream inlet and a fluid stream outlet. The inlet may be of any suitable size and configuration. It is preferred that the inlet be of sufficient size to allow most of the solids normally encountered in the particular application to enter, so that the solids do not cause blockage at the inlet. The most appropriate size and configuration for the inlet will vary depending upon the application of the apparatus; when the apparatus is used for deflecting debris from a downpipe, it is preferred that the inlet be sufficiently large to accommodate such r^esms-as dead birds and tennis balls. 2 3 O $ The fluid outlet may be any suitable outlet for the fluid, and it is located downstream of the filter and fluid reflecting means.

It is preferred that a solid matter outlet be provided 5 at or near the most downstream part or parts of the upstream face of the filter, to enable solids trapped by the filter to exit. However, in some embodiments the solids may exit through the inlet, or alternatively the debris may be accumulated. As an optional feature, the solid matter 10 outlet may incorporate a door. The door is normally closed, preventing or deterring fluid from exiting through the solid matter outlet. However, the door opens in response to the weight of solid matter, allowing solids to be expelled. As a further optional feature, draining means may be provided 15 near the solid matter outlet. The draining means function to drain excess fluid from solid matter before it is expelled, thus reducing leakage of fluid through the solid matter outlet. Where the fluid is a liquid, the draining means may comprise grooves in the surface of the filter, 20 drawing excess liquid from trapped solids by capillary action.

It is preferred that the solids deflection apparatus be enclosed within a housing having an inlet opening, a fluid outlet opening, and preferably also a solid matter 25 outlet opening. The housing may be made of any suitable * materials. Suitable materials will depend upon the application of the debris deflection apparatus. When the apparatus is being used for separating rainwater from debris, suitable materials include weather-proof wood, 30 plastics such as PVC and metals, such as galvanised iron, stainless steel, aluminium and copper. It is preferred that the use of two or more different metals in a combination which may lead to early corrosion be avoided.

As an alternative to enclosing the solids deflection 35 apparatus in a housing, it may be installed inside a pipe or in any other suitable location.

According to another aspect of the present invention, there is provided a method of deflecting ^Fi-ids-.^r^er than *9 Jl//v/99yoJ jj 2 3 8 3 2 a predetermined mesh size from a fluid stream, the method comprising: (a) passing the fluid through a screen filter, the filter direction of - flow of the fluid stream, the filter being such that it traps substantially all solids substantially all the remaining fluid to pass through it, and (b) reflecting at least a proportion of the fluid back through the filter to dislodge solids trapped' on the upstream face of the filter, so that, by the combined effect of the fluid steam, the obliquely angled filter and the dislodging action of the reflecting fluid/ the solids trapped by the filter are caused to migrate across the upstream face of the filter to a location outside the fluid stream.

It is preferred that the method of the present invention be accomplished by use of the apparatus provided by the present invention.

The method may further include the step of passing the solids which have migrated across the surface of the filter through a debris outlet.

The step of reflecting at least a proportion of the fluid back through the filter may be done in any suitable manner. The fluid so reflected may be reflected at an angle oblique to the direction of fluid flow, and if the direction of reflection matches the direction of migration of trapped solids across the surface of the filter, the reflected fluid assists further in the migration of the debris. However, oblique reflection of the fluid may also result in undesirable reflection of the fluid out of the fluid stream, and it is therefore preferred that the fluid which is reflected be reflected in a direction substantially opposite to the direction of fluid flow, so that once it has passed back through the filter it will remain within the fluid steam and pass through the filter once again.

The invention will now be describ©3"vi%h..x.eference to being oriented substantially obliquely to the larger than the predetermined size but allows 2 3 8 3 2 fP 8 a preferred embodiment illustrated in the drawings. It is to be understood .that the drawings relate to one embodiment only, and are not intended to limit the scope of the foregoing disclosure. the preferred embodiment.

Figure 2 shows a cross-sectional side view, taken along the line II-II in Figure 1.

The solid matter deflecting apparatus comprises an 10 inlet 1, a filter 2, a fluid reflection means 3 and an outlet 4. All of these components are housed within a housing 5, which further provides a solid matter outlet 6.

The embodiment of the invention illustrated is suitable for use in deflecting debris from rainwater in a 15 - gutter before the rainwater passes down a downpipe.

The inlet 1 is approximately 10cm by 20cm in size, so that it is large enough to allow most of the debris accumulating in gutters to pass through, including tennis balls, dead birds and leaves. The debris outlet 6 is of 20 similar size, , so that the debris may pass straight out through it.

Filter 2 in this embodiment comprises a wire mesh having a mesh size of approximately 1mm. This mesh size allows most of the debris to be trapped by the filter, while 25 allowing most of the rainwater to pass through. Filter 2 is oriented at an- angle of approximately 45° to the direction of flow of the fluid, so that debris can migrate across the face of filter 2 in a downwards direction and out through debris outlet 6. It has been found that if filter 2 is too 30 close to the horizontal (perpendicular to the flow of fluid), the debris will not migrate across the surface of the filter. If, on the other hand, the filter is too close to being vertical (parallel to the' direction of flow of fluid) too much fluid is deflected by the filter and passes 35 out the debris outlet.

In the embodiment illustrated, fluid reflection means 3 is in a stepped or corrugated configuration, having substantially horizontal regions alternating _ .with Figure 1 shows a perspective view of the apparatus of 2 3 8 3 2 substantially vertical regions. Rainwater falling through inlet 1 passes through filter 2 and strikes fluid reflection means 3, which causes at least some of the rainwater to rebound through the filter, dislodging debris which may have 5 accumulated on the surface of the filter and causing the debris to migrate towards the debris outlet. Because the reflecting surfaces of the fluid reflection means are substantially perpendicular to the direction of travel of the rainwater, only a minimal amount of rainwater is 10 reflected out through the debris outlet. Holes 10 allow some rainwater to pass through reflecting means 3 without being reflected. The remainder of the rainwater passes through gap 7 and out- through fluid outlet 4, which may be connected to a downpipe.

The configuration of reflection means 3 may be varied to suit the volume of water likely to be encountered in any particular application. The likely volume of water will, of course, depend upon established rainfall patterns in the region and the roof area serviced by each down-pipe. Holes 20 10 may be enlarged and the length and area of reflection means 3 may be varied for high volume applications. Holes 10 may be reduced or eliminated for low volume applications, and reflection means 3 may be varied in length or area.

Door 8 is provided over debris outlet 6. Door 8 may 25 extend the whole way down to filter 2, or it may leave a small gap, as illustrated. Door 8 serves to prevent water from splashing out through debris outlet 6. Because door 8 is freely hinged, it opens easily in response to the weight of large debris to allow the debris to escape. 30 Grooves 9 are provided in filter 2 near outlet 4.

These grooves serve to drain excess water from debris accumulated on the filter, so that' the water does not exit through debris outlet 6.

The bottom wall of housing 5 may be angled down 35 towards outlet 4, although it is preferred that the portion of the bottom wall to which the outlet pipe connects be substantially horizontal, so that if the horizontal pipe is circular in cross-section a circular hole can be~~ma.de.in the l 19 JUHl99l!& 2 38 3 bottom wall to accommodate the outlet pipe. If the bottom wall were not horizontal, the hole required to accommodate a pipe of circular cross-section would need to be elliptical, and this is more difficult to achieve.

. It is to be understood that various modifications, alterations and/or additions may be made to the parts previously described without departing from the ambit of the present invention. 9 3 8 ! 2 3 3 ' - -V

Claims (10)

WHAT WE CLAIM IS:

1. Apparatus for deflecting solids larger than a predetermined mesh size from a fluid stream, the apparatus comprising: 5 (a) a screen filter, oriented substantially obliquely to the direction of flow of the fluid stream through the apparatus, the filter being such that it traps substantially all solids larger than the predetermined size but allows substantially all the fluid 10 stream to pass through it; and (b) a fluid reflecting means located close to the filter on the downstream side of the filter, the fluid reflecting means being such that it reflects at least a proportion of the fluid back through the filter to 15 dislodge solids trapped on the upstream face of the filter; wherein, by the combined effect of the fluid stream, the obliquely angled filter and the dislodging action of the reflected fluid, the solids trapped by the filter are caused 20 to migrate across the upstream face of the filter to a location outside the fluid stream.

2. Apparatus according to claim 1 wherein the fluid reflecting means is stepped or corrugated, so that it comprises a series of surfaces perpendicular to the 25 direction of fluid flow.

3. Apparatus according to claim 1 or claim 2 wherein the fluid reflecting means has holes which allow part of the fluid stream to pass without being reflected.

4. Apparatus according to any one of claims 1 to 3 30 further comprising a fluid stream inlet, a fluid stream outlet and a solid matter outlet.

5. Apparatus according to claim 4 wherein the solid matter outlet has a door which is normally closed to prevent fluid from exiting through the solid matter outlet, but 35 which opens in response to the weight of solid matter to allow the solid matter to exit.

6. Apparatus according to claim 4 or claim including draining means near the solid matter - 7 SEP W92 / - 12 - 8123 remove excess fluid from solids trapped by the filter before the solids are expelled through the solid matter outlet.

7. Apparatus according to any one of claims 1 to 6 wherein the apparatus is a rainwater strainer.

8. A method of deflecting solids larger than a predetermined mesh size from a fluid stream, the method comprising: (a) passing the fluid through a screen filter, the filter being oriented substantially obliquely to the direction of flow of the fluid stream, the filter being such that it traps substantially all solids larger than the predetermined size but allows substantially all the — fluid to pass through it, and (b) reflecting at least a proportion of the fluid back through the filter to dislodge solids trapped on the upstream face of the filter, so that, by the combined effect of the fluid steam, the obliquely angled filter and the dislodging action of the reflecting fluid, the solids trapped by • the filter are caused to migrate across the upstream face of the filter to a location outside the fluid stream.

9. Apparatus for deflecting solids from a fluid stream substantially as herein described with reference to the drawings.

10. A method for deflecting solids from a fluid stream substantially as herein described with reference to the drawings. , . TH!S DAY CF"3b^B~WI19 A J. PARK £ FOR THE APPLICANTS A* C A 7 SEP 1992 "'J ' , .J