This invention relates to a strainer assembly. The apparatus is for filtering water and in particular, irrigation water. The invention finds specific application in centre pivot irrigation systems. BACKGROUND TO THE INVENTION

Irrigation water invariably carries a relatively large amount of impurities. These range from small stones to organic, plant material. The objects can usually pass through a pump of the kind used with such water. A real problem is caused when the water needs to pass through sprinkler or irrigation equipment.

The obstructions which result adversely affect the spraying of the water from the equipment. Where blockages occur, they must be cleared. This needs to be done manually. The operation of the equipment is impaired and the cost and inconvenience in keeping it clean is significant. The problem is of particular relevance to centre pivot irrigation systems. OBJECT OF THE INVENTION

It is an object of the invention to provide apparatus which can be used to filter water and which will at least partially alleviate the problems referred to.

SUMMARY OF THE INVENTION

In accordance with the invention there is provided a strainer assembly comprising a trap arranged between an inlet and outlet, a strainer which divides the trap and a deflector which is located adjacent the trap and is inclined towards the inlet.

The invention further provides for the strainer to be a perforated plate which is shaped to provide the deflector; and for the inlet and outlet to be aligned.

Further features of the invention provide for the inlet and outlet to be formed from a first pipe and the trap from a second pipe of greater diameter than the first; and for the trap to be fitted with guides to slidably receive side edges of the strainer with the deflector portion of the strainer sized to fit past the guides and having a curved edge to abut the wall inside the first pipe.

Further features of the invention provide for the trap to have a removable end plate; for the end plate to be fitted with a valve controlled discharge port on the inlet side of the strainer; and for the inlet and outlet to each be provided with a flange for connection into a water pipe.

Further features of the invention provide for the strainer assembly to be for use on a centre pivot irrigation system; and for the assembly to be suited for fitment between the last tower and the overhang of the irrigation system. BRIEF DESCRIPTION OF THE DRAWINGS

These and other features of the invention will become more apparent from the following description, made by way of example only, of the embodiment illustrated in the accompanying drawings, in which:

Figure 1 shows a perspective view of a strainer assembly housing and of a strainer for use in the housing; Figure 2 shows an end, cross-sectional view of the strainer;

Figure 3 shows a side and bottom view of a cross-pipe for the assembly;

Figure 4 shows a side and front/rear view of a pipe forming a trap for the assembly;

Figure 5 shows a bottom end view of the strainer assembly; and

Figure 6 shows a side cross-sectional view of the assembly. DETAILED DESCRIPTION OF THE INVENTION

Referring to the drawings, a strainer assembly is indicated generally by reference numeral (1 ). The assembly (1 ) is suited for use with an irrigation pivot system (not shown). More specifically, the assembly (1 ) will be fitted between the last tower of the pivot system and the overhanging sprinkler support.

The strainer assembly (1 ) is provided with a T-shaped housing. The housing includes a trap (2) arranged between an inlet (3) and outlet (4), which are axially arranged in line with each other. The inlet (3) and outlet (4) are formed from a first pipe (5) and the trap (2) from a second pipe (6). The pipes (5) and (6) are provided of suitable steel or metal material.

The second pipe (6) is of slightly greater diameter than the first - the relevance of this will be explained below. In this example, the first pipe (5) will have a diameter "x" of 152mm and the second (6), a diameter "y" of 164mm - see Figure 6.

The pipes (5) and (6) are cut with corresponding openings (7) and (8) to form a join and welded into a T-junction. The openings (7) and (8) which form the join are cut to accommodate the variation between the pipe diameters. The opening (7) in the operatively bottom side of the first pipe (5) is cut to a diameter of 164mm to accommodate the second pipe (6) which provides the trap (2). The top end of the trap (2) is cut with a profiled opening to a diameter of 152mm (seen when viewed from the front/rear) to fit onto the first pipe (5) over the opening (7). The edges of these openings (7) and (8) are appropriately chamfered along the join lines to facilitate the welding of these components.

The ends the first pipe (5) are fitted with annular flanges (9), welded in place at each end. These are for connection into the water line (not shown) of the centre pivot overhang. The outlet (4) end of the pipe (5) together with its flange (9) is inclined to accommodate the inclination of the sprinkler overhang line into which the assembly (1 ) is connected. This is achieved by cutting the end of the pipe (5) at an angled (5.1 ) as indicated in Figure 3. A strainer (10) is in use located to divide the trap (2) into inlet and outlet portions. The strainer assembly (1 ) includes as a feature of the invention, a deflector (1 1 ). The deflector (1 1 ) is arranged to direct water towards the trap (2). In this embodiment, the deflector (1 1 ) extends as part of the strainer (10) and is inclined towards the inlet (3). The strainer (10) is a plate cut from perforated sheet steel or metal. The sprinklers of the overhang (not shown) can accommodate particles in the irrigation water of about 8mm gauge size to pass. The openings (12), which provide the gauge of the strainer plate (10), are of a diameter of 6mm. The gauge of the strainer plate (10) will vary depending on the equipment it serves.

The strainer plate (1 0), once it is cut to the required shape, is bent to provide the deflector (1 1 ). The plate (10) has a rectangular wall portion (1 0.1 ). This has two opposite edges (10.2) providing parallel rails. The rails (1 0.2) are spaced apart to provide the plate (10) with a width to fit into the inner diameter of the second pipe (5), about 160mm.

The deflector portion (10.3) of the strainer plate (10) extends as a tongue with a curved edge from the bend line at the operatively top end of the wall portion (10.1 ). Shoulders (10.4) that are operatively upwardly disposed are provided between the deflector portion (10.3) and the rails (10.2).

Oppositely arranged guides (20) are provided along the length of the trap (2). The guides are linear ribs (20) closely spaced to slidably receive the rails (10.2) of the strainer plate (10). The opening (7) between the inlet (3) and outlet (4) extends halfway into the first pipe (5). A portion of the opening (7) is provided by two flats at (13.1 ) along the halfway line of the pipe (5). The second pipe (6) has two oppositely disposed peaks with corresponding flats (13.2). These openings (7) and (8) of illustrated configuration enable the T-junction between the pipes (5) and (6) to be formed.

It is between the bottom of the trap (2) and the flats (13.2) that the ribs (20) extend. This is also the space occupied by the wall portion (10.2) of the strainer plate (10) once it is in place. The deflector portion (10.3) of the strainer is sized to fit past the guides (20) to allow insertion of the strainer plate (10) into the operatively upper half of first pipe (5). It is also shaped with a curved edge to abut the wall inside the pipe (5). The flats (13.1 ) in the opening (7) of the first pipe (5) each provide an inward step in the assembly (1 ). The shoulders (10.4) on the strainer plate (10), to either side of the deflector portion (10.3), locate against or adjacent these steps (13.1 ) when the strainer plate (10) is fitted into the assembly (1 ).

The deflector (1 1 ) operatively occupies the top half of the first pipe (5) at an inclination relative to the axis of the pipe (5) and thus has a corresponding elliptical shape to fit closely against the inner wall, separating the inlet (3) from the outlet (4). The deflector (1 1 ) is inclined with its operatively upper end closer to the inlet (3) and its operatively lower end closer to the outlet (4). In use, the flow of water to the outlet (4) serves to hold the edges of the deflector (1 1 ) against the wall of the first pipe (5).

The free, bottom end of the trap (2) is also fitted with a flange (14). A removable end plate (1 5) is securable to the flange (14). The end plate (15) has a discharge port (16), which will be fitted with a valve (not shown). The port (16) is located on the inlet side of the strainer plate (10) and will be used to flush accumulated material from the trap (2).

In use, the strainer plate (10) collects any solid objects and plant material in the irrigation water which are too large to pass through the openings (12). It has been found that the inclined deflector (1 1 ) at least partially deters against blockage of the strainer plate (10). A component of the water flow is directed downwardly into the trap (2). The flow of water provides a degree of agitation at the upstream side of the strainer plate (10) as opposed to where a strainer (without any deflector) is arranged normal to the flow of water from the inlet to the outlet. While stones and other such solid objects will usually sink in the trap (2), plant material is prone to become enmeshed by the strainer plate (10) where no deflector (1 1 ) is used.

It has also been found that on opening of the port (1 6), a desirable degree of flushing of the strained matter is also achieved. Better flushing and a reduction in the material which becomes lodged in or against the strainer (1 ) means that the end plate (15) need not be removed for manual cleaning of the strainer (1 ) as often as would otherwise be required. To some degree, the assembly (1 ) is thus self-cleaning.

The length of the trap (2) and strainer plate (10) will be varied for different applications. The deflector portion (10.3) of the strainer plate (10) may be provided without openings or with smaller openings than are present in the wall portion (10.1 ).

It will be apparent to a person skilled in the art that the deflector (1 1 ) may be provided in various forms. It could for example be a plate welded in place inside the trap housing, between the inlet and outlet. Alternatively, the deflector could be provided as part of the configuration of the housing; for example, by a bend in the conduit wall opposite the trap (2).

It will further be appreciated that the application of the strainer assembly of the invention, while particularly suited thereto, need not be limited to irrigation pivot systems. An assembly in accordance with the invention can be adapted for use in a wide variety of fluid filter applications.