FLUSH VALVE THEREFOR

FIELD OF THE INVENTION [001 ] The present invention relates to irrigation systems, in particular, a system for cleaning irrigation piping.

BACKGROUND OF THE INVENTION

[002] Drip irrigation is a technique wherein a network of drip tubes is placed alongside rows of plants, flowers and the like. The irrigation drip tubes deliver liquid to the plants through small openings (emitters) spaced along the drip tube. While this type of irrigation is very water efficient and thus widely used in arid areas, due to their small openings, the emitters are susceptible to clogging. [003] In fact, one of the major problems with drip irrigation is a tendency for the small openings of the drippers/emitters to become clogged with solids such as particles in the water, plant fibers, algae and various micro-organisms characteristic of practically all water sources. Pre-treatment of the water is helpful to filter out relatively large particles; however, particles that are too small to be filtered by the pre-treatment techniques can accumulate at the emitters and reduce their opening size or even clog them.

[004] Periodic flushing of the drip tubes has been found effective in preventing clogging. Flushing involves flowing water at a relatively high velocity and using high pressure to obtain a fully developed flow. As a result, suspended materials can be to be flushed out and clogging can be prevented.

[005] The flushing process can be manually controlled or actuated, however this typically requires dealing with a large number of drip tubes deployed throughout a crop field, making this method inefficient and not economic.

[006] To reduce labor costs, it has been proposed to utilize valves of the pressure-responsive type, which automatically open upon sensing a change in the water pressure present in the drip tube. Specific proposals include using valves that open in response to reduced water pressure.

[007] It should be noted that it is usually costly to increase water pressure, for flushing. On the other hand, flushing with low water pressure is not as efficient since the scrubbing and flushing action in the drip conduit is less intense.

[008] It is believed that the current state of the technology is represented by US 3921905 A (McElhoe et al., 1975-1 1 -25) and US 2008/087749 A1 (Ruskin et al., 2008-04-17).

SUMMARY OF THE INVENTION

[009] The present invention relates to a system for cleaning piping/conduits, in particular irrigation tubes; as well as a flush valve therefor.

[010] In accordance with embodiments of one aspect of the present invention there is provided a tube flushing system for flushing at least one irrigation tube provided with a pressurized fluid (e.g. water) source. The system includes: a flush valve disposed at a far end of each of the at least one irrigation tube; and a flushing sub-system including flush piping and a flush control valve having an outlet vent, the flushing sub-system being disposed downstream of the flush valve. The flush valve includes: a flush valve inlet; a flush valve outlet; a housing and valve end cap combination in which there are formed: an inlet- flanking conduit that is adjacent the flush valve inlet; a valve diaphragm having a higher surface area at its rear side than at its front side; a valve diaphragm biasing spring configured to bias the valve diaphragm to close the flush valve inlet; and a bypass channel. The flushing system is configured such that when the flush control valve of flushing sub-system is actuated open, water enters flush valve, flows via the bypass channel to fill the flush piping and also presses on the front side of the diaphragm thereby initially moving the diaphragm to open the flush valve whereby water also flows through the inlet-flanking conduit to provide an initial flushing of the at least one irrigation tube, and, when water eventually fills the flush piping, the water pressure on the rear side of the diaphragm moves the diaphragm to closed the flushing valve, thus sealing inlet; and when the control valve is again opened and reduced water pressure in flush piping causes the diaphragm to open the flush valve whereby the at least one irrigation tube is flushed.

[01 1 ] In some embodiments, the at least one irrigation tube is a plurality of irrigation tubes and each tube of the plurality of irrigation tubes has one of the flush valves at a far end thereof.

[012] In some embodiments, the flush valve inlet comprises sealing projections corresponding to the distal ends of the at least one irrigation tubes; and the flush valve outlet comprises sealing projections corresponding to the proximal ends of flush piping.

[013] In some embodiments, the housing and the valve end cap are integrally formed. [014] In accordance with embodiments of another aspect of the present invention there is provided a flush valve for use in combination with a tube (e.g. irrigation tube) to be flushed, having a pressurized fluid (e.g. water) source. The flush valve includes: a flush valve inlet; a flush valve outlet; and a housing and valve end cap combination in which there are formed: an inlet-flanking conduit that is adjacent the flush valve inlet; a valve diaphragm having a higher surface area at its rear side than at its front side; a valve diaphragm biasing spring configured to bias the valve diaphragm to close the flush valve inlet; and a bypass channel.

[015] In some embodiments, the flush valve inlet comprises sealing projections. [016] In some embodiments, the housing and the valve end cap are integrally formed.

[017] The present invention relates to a drip irrigating system that includes a plurality of drip tubes that communicate with a supply of pressurized liquid. The drip tubes include drip orifices (emitters) arranged to dispense a substantially continuous flow of liquid. A plurality of flush valves are connected to the drip tubes at distal ends (far ends) thereof.

[018] As a result, the present system, with incorporation of its flush valve, can remotely control the flushing of a group of drip tubes, without regard another group of drip tubes. It should be understood that individual drip tubes could be flushed using the same principle, mutatis mutandis.

[019] The present system and flush valve can rely solely on the irrigation liquid (typically water) as the actuating power source. Also, the liquid velocity is at its maximum available value for achieving the best cleaning, while using high pressure water from the irrigation system itself (i.e. no outside source of water or water pressure are required).

BRIEF DESCRIPTION OF THE DRAWINGS

[020] The present invention will be understood and appreciated more fully from the following detailed description taken in conjunction with the appended drawings in which:

[021 ] Fig. 1 is a schematic plan view of a drip tube irrigating network including a flushing system and flush valve in accordance with embodiments of the present invention; [022] Fig. 2 is a longitudinal sectional view of the present flush valve in accordance with embodiments of the invention, showing the flush valve in an open position; [023] Fig. 3 is a longitudinal cross sectional view of Fig. 2 (at a different cross-section than Fig. 2) , showing the flush valve in a closed position;

[024] Fig. 4 is an exploded perspective view of the flush valve of Fig. 2.

[025] The following detailed description of embodiments of the invention refers to the accompanying drawings referred to above. Dimensions of components and features shown in the figures are chosen for convenience or clarity of presentation and are not necessarily shown to scale. Wherever possible, the same reference numbers will be used throughout the drawings and the following description to refer to the same and like parts.

DETAILED DESCRIPTION OF EMBODIMENTS OF THE INVENTION

[026] Illustrative embodiments of the invention are described below. In the interest of clarity, not all features/components of an actual implementation are necessarily described.

[027] Fig. 1 shows an irrigation tube network for irrigating a crop field.

The irrigation tube network includes a tube flushing system, in accordance with embodiments of the present invention. The flushing system includes an irrigation tube network 10 with a main distribution line 12 connected to a suitable source of pressurized irrigation liquid, such as water. A network of irrigation tubes or drip tubes 14 extend from main distribution line 12 to convey water to the crop field, typically via a plurality of drippers or emitters 16 (although the invention is not limited thereto). At the distal ends of drip tubes 14 are flush valves 18, in accordance with embodiments of the present invention. [028] Downstream of flush valves 18 is a flushing sub-system 20 including flush piping 22; a flush control valve 24; and a flushing sub-system outlet or vent 26. Flush control valve 24 is controllable to be open to allow water to flow outward via outlet/vent 26, or to be shut and thereby prevent water from flowing out. In some embodiments, drip tubes 14 are divided into groups, for example, with each group including ten to twenty drip tubes to communicate together with respective flushing sub-systems 20.

[029] Figs. 2 and 3 show two different cross sectional views of flush valve 18; and Fig. 4 shows a perspective exploded view of the flush valve. Each flush valve 18 has a water inlet 28 configured to attach to drip tube 14 and a water outlet 30 configured to attach to flush piping 22 of flushing sub-system 20.

[030] Flush valve 18 further includes a diaphragm 32 adapted to seal water inlet 28; a diaphragm biasing spring 34 configured to bias diaphragm 32 in a "closed" position whereby inlet 28 is sealed/closed. Adjacent to water inlet 28 is an inlet-flanking water conduit 36 (which could be constituted by a series of openings or an annular opening). Flush valve 18 further includes a water bypass channel 38 that bypasses diaphragm 32, disposed mainly within a valve housing 40; and an end cap 42 attachable to housing 40, for example threadable thereon, the end cap holding water outlet 30. Alternatively, housing 40 and end cap 42 can be formed as a single piece. Diaphragm 32 is designed to have a higher water-interface surface area on its (downstream) rear side 31 than its (upstream) front side 33, as shown.

[031 ] It should be noted that flush valve 18 can be retrofitted into an existing irrigation network; e.g. conveniently using a press-fit type arrangement using beveled sealing projections 46 on the outside walls of inlet 28 and outlet 30 to form a seal with the distal ends of the inside walls of drip tubes 14 and proximal ends of the inside walls of flush piping 22, respectfully. It is also notable that spring 34 provides a fail-safe aspect to prevent the outside elements such as ants and the like from entering drip tubes 14 while the spring keeps flush valve 18 is in a closed position (Fig. 3). It is further noted that even though the flushing is performed with the high pressure water of the irrigation system, and while the water velocity is at its maximum, the flushing does not affect (or at least negligibly affects) the normal irrigation pressure in the other groups of irrigation drip tubes 14. [032] Operation [033] At the initial stage, when there is not yet water in irrigation tube network 10, flush valve 18 is in the closed position (Fig. 3; i.e. spring 34 biases diaphragm 32 so that the diaphragm seals inlet 28 closed (to the right in Figs. 2 and 3). Water is then allowed to fill tube network 10, the water eventually arriving to flush valve 18 and flowing via bypass channel 38 to fill flush piping 22 with water. As illustrated, flush piping 22 can be relatively small in diameter so that the flush piping will quickly fill with water, as described below.

[034] The arriving water also presses on diaphragm 32 thereby (initially) moving the diaphragm to a valve-open position (Fig. 2; i.e. to the left) whereby water not only flows to flush piping 22, but also some water flows through inlet- flanking water conduit(s) 36.

[035] The entering water eventually fills flush piping 22 whereby the pressure downstream of flush valve 18 (at its water outlet 30 and inside the flush valve) equalizes with the water pressure at upstream front side 33 of the flush valve (at valve inlet 28). Due to the higher area on the (left / downstream) rear side 31 of diaphragm 32 than on the (right / upstream) front side 33 thereof, the diaphragm moves back to the right (closed position; Fig 3), thus sealing inlet 28.

[036] When the user wants to flush/clean a particular group of drip tubes

14, the respective control valve 24 is opened (manually or automatically, e.g. periodically by a timer) thereby reducing the water pressure in flush piping 22. As a result, diaphragm 32 moves back to the valve-open position (to the left; Fig. 2) and water enters valve inlet 28 and flows through valve conduits 36, whereby the network of drip tubes 14 of irrigation tube network 10 are flushed/cleaned. It should be noted, that with such a flushing, the water at upstream front side 33 of flush valve 18 is at full water pressure and thus provides for a superior flushing. It should be understood that drip tubes 14 are completely full during the flushing so that the flushing cleans the inner surface of the drip tubes over the full cross- section thereof, i.e. the entire inner surface area of the drip tubes, and not just a portion, which would be the case if the drip tubes were not full. It is desirable that control valve 24 be controlled to flush the groups of drip tubes 14 in a sequential fashion, rather than simultaneously, in order that high water pressure from main distribution line 12 will be available to effectively flush drip tubes 14.

[037] After a suitable flushing time, control valve 24 is controlled shut.

As a result, the pressure in flushing pipe 22 begins to build up whereby diaphragm 32 is moved to close flush valve 18 (Fig. 3). The normal irrigation conditions are not impaired and another group of drip tubes 14 can be flushed/cleaned. The typical water pressure of the irrigation system should be sufficient to maintain proper irrigation conditions even during a sequence of flushings. [038] It should be noted that no additional water source is required to produce the aforementioned superior flushing. Further, the system can be remotely controlled, saving labor costs and time. Additionally, the system avoids the need for additional water sources and power sources (e.g. such as for pumps). Moreover, by controlling selected groups of drip tubes 14 using separate control valves 24, one or more groups of drip tubes can be flushed at high pressure, while other groups continue to provide irrigation.

[039] Although the present tube flushing system and flush valve have been described with respect to crop irrigation, it should be understood that it can be used in other applications and implementations as well where pipe flushing/cleaning is required or desired; and with fluids other than just water, and the term "wate herein the specification and claims is intended to denote this. Likewise, the term "irrigation" is used herein the specification and claims to provide context; however no limitation to any implementation of application of the invention is to be understood. [040] It should be understood that the above description is merely exemplary and that there are various embodiments of the present invention that may be devised, mutatis mutandis, and that the features described in the above- described embodiments, and those not described herein, may be used separately or in any suitable combination; and the invention can be devised in accordance with embodiments not necessarily described above.