WO2014064452A1

WO2014064452A1 - Adjustable emitter and preform

Info

Publication number: WO2014064452A1
Application number: PCT/GB2013/052781
Authority: WO
Inventors: Michael Edward Brown
Original assignee: Michael Edward Brown
Priority date: 2012-10-26
Filing date: 2013-10-24
Publication date: 2014-05-01
Also published as: GB2523479A; GB201505921D0; GB2523479B

Abstract

An outflow-purgable and adjustable emitter (1) is described for use in micro-irrigation systems. The emitter (1) comprises; a hollow body (2) defining a flow channel having a fluid inlet, which channel continues towards a fluid outflow in the form of a resilient slitted-aperture (10), which aperture provides a resistance to the flow of fluid from the body (2), the said body having one or more radially displaced projections (7) from the outer surface of the body and adjusting means (5) in mechanical association with the body and assembled to move relative to the body to selectively engage with the projections (7), and with said resilient slitted-aperture (10) also being selectively deformable. An end cap of otherwise similar construction convertible to such an emitter by provision of a slit is also described.

Description

ADJUSTABLE EMITTER AND PREFORM

Field of Invention

The invention relates to an emitter and in particular an outflow-purgable adjustable emitter for example for use in an assembly for the irrigation of plant species via a system of delivery hoses and fittings for example to control/ inhibit the flow of irrigation fluid. The invention further relates to a blind end cap for an irrigation fitting which is adapted to be convertible to an outflow-purgable and adjustable emitter, to act in a first case as a push on seal and after modification as a push on emitter for the irrigation of plant species via a system of delivery hoses and fittings. In a preferred, though not exclusive, embodiment the invention relates to a device and method for controlling and irrigating a small-scale growing environment when fluids are delivered via hoses from a low energy source equal to or less than, three metres of irrigation head pressure. The invention, and the prior art, are largely discussed in this preferred context, but the more general applicability of the invention will be understood.

Background

For the small scale micro-irrigation of plants, trees, shrubs and vines there are at least three classes of labyrinthine type or narrow passageway drip emitter available to Subsistence Farmers, Smallholders and Gardeners alike, for use on plot sizes below 10,000 square metres (approximately 328 ft x 328 ft), and these make up the vast majority of the smaller micro-irrigation installations. None of the current emitter types are dual purpose and suitable to be initially installed as a blind end cap, to cap off a surplus outlet in a hose distribution system in readiness, with minor modification, for a future expansion in the number of emitters, i.e., as plants, especially perennials' grow in size and require more emitters to irrigate them. And none of the current emitter types is capable of a simple and effective front purging action by manually squeezing to increase the outflow and clear out lodged debris. A typical small scale gravity fed system might consist of; an elevated tank having a main line hose outlet with inline valve and mesh filter, an array of sub-main distribution hoses, smaller side lateral hoses, drip emitters and a selection of fittings to connect everything together. In many cases the tanks are refilled manually, by a variety of means and with water from a number of sources. This opportunity for variability in terms of water quality and operational procedure presents a challenge to the Designer of a 'fit for purpose' adjustable and readily cleanable emitter - which ideally must be considered as one component in a system of components, designed to work together in a system.

Emitters (often referred to as Drip Emitters) can be installed 'inline' at intervals in a run around hose system or they can be attached to the free ends of lateral tubes, which are Tee'd off from a supply hose, in which case they are referred to as 'end of line' emitters. Sometimes in this latter arrangement the small bore lateral hose itself, becomes the emitter, and this is then referred to as a micro-tube. Micro- tubes can vary from 1 to 10 millimetres in bore although 1.5 millimetres bore is a common size. And range from a few centimetres in length to upwards of one to two metres. This is in order to create different degrees of resistance to the passage of irrigation fluids.

These three classes of drip emitter rely on small cross-section internal passageways, often extremely convoluted, to drop the pressure of the out flowing water. As a consequence they will only operate for extended periods with clean water, free from particulate matter, and this is rarely available from regular extraction sources. For the most part, when these emitters are employed in a micro-irrigation system the source water has to be filtered before use. Otherwise the emitters become blocked and inoperable and because of their design, have to be detached for cleaning (back flushed) or cleaned out in situ with acids or caustic solutions, depending on the nature of the accumulations which result in blockages. It is not unusual on the larger commercial systems for chemicals to be added to the water to neutralise the effects of reactive compounds and agents present in the water. None of these actions are very practical in the field for the small scale systems being considered.

For plot sizes below 1 hectare (10,000 square m, 2.471 acres) and more typically below 1,000 square metres (approximately 105 ft x 105 ft), in many regions of the world it is both impractical and uneconomical to provide the large amount of ground equipment necessary and the energy required to pressure filter water, to be clean enough to continually flow through the current emitter types. And to then distribute this water under pressure, to a relatively small number of emitters, for example less than one hundred in a system - and very often in the region of only twenty or so emitters, quite possibly watering a mixed planting scheme.

A compromise is always reached between how much filtration can be afforded or is practical at the source, for example an elevated tank, and how often and how easy it is to clear blocked emitters by hand in the field. This is the main drawback to much of the prior art when considered for these very small, low cost systems, i.e., the costs of filtering irrigation water prior to distribution, in both Capital and Energy terms, can be disproportionate to the cost of the hose system and emitters and the value of the crops being grown.

Where an irrigation system is hose-fed from an elevated supply tank and has many laterals 'Tee'd off to extend on either side of a main hose line, with each latera l free end fitted with a drip emitter, there will be numerous places where blockages can occur to restrict or entirely stop the flow of irrigation fluid to one or more outlets (emitters). Notably these are at the hose fittings which commonly have smaller bores than the hoses, and inside the emitters themselves, within the tiny labyrinthine channels.

Conventionally every emitter by its very nature has to severely restrict the out flow of irrigation fluid so that all emitters in a balanced system, no matter how far removed from the source, will discharge fluid at a similar rate. This is important for mono-crop growing, i.e., a small grove of citrus, where it may be desirable to achieve uniform fruit from tree to tree. The term 'Balanced system' is used here to describe a conventional optimised system where the emitter out flows are required to be similar and the total outflow from all of the emitters closely matches the capacity available from the source, for example a tank elevated to 2 metres above the ground to be irrigated.

It is not the object of this invention, when converted to an Emitter, for it to be deployed en masse for optimised mono cultivation in balanced systems of hose fed irrigation. Rather the invention is designed for situations where there is currently no suitable emitter available - due in the main to the unavoidable necessity of having to use turbid water (at a very low and also widely varying head pressure) throughout the full extent of a system of distribution hoses (main) and lateral hoses (side branch).

Description of the Prior Art

Irrigation Pipes with Dripper Units and Method of Manufacture - US 3,981,452 - Eckstein

Describes an extruded irrigation hose having 'inline' dripper emitters incorporated at fixed intervals during manufacture, and where these occur the hose is perforated to communicate with the external environment. There are many variations on this design, none of which can be applied with confidence to the small plot sizes referred to, without resort to costly and often impractical pre-filtering and sometimes chemical treatment of the supply water. These precision emitters, ideal for large mono-crop plantings, create the essential back pressure to the flow of irrigation fluid by way of the tiny labyrinthine pathways contained within the emitter inserts, so that the outflows are very uniform and well suited to the application. Despite the many subsequent improvements in the design, these still block up very easily if clean water is not used. Also, as they are integral with the extruded hose (fused to the inside wall) they cannot be removed for cleaning. In practice these types of drip emitter hose have to be periodically chemically cleaned to dissolve internal accumulations or simply scrapped. This type of emitter cannot be forward purged and it is not designed to be. Fluid Flow Regulator Unit - US 4,384,680 - Mehoudar

Describes a button type drip emitter having a ring barbed hollow spigot end for insertion into the side of an irrigation hose (inline) or to equal effect into the open free end of a hose lateral (end of line). Mehouder's Figures 2 and 3 show a short length, circular labyrinthine passageway of small cross-section dictating a torturous path inside the periphery of the emitter. There have been many improvements on this design, none of which can be applied with confidence to the small plot sizes referred to without costly and often impractical pre-filtering of the supply water. This type of emitter cannot be forward purged and it is not designed to be. Emitter for Irrigation Systems - US 3,899,136 - Harmony

In Harmony's Figure 1 of the patent, resilient (rubbery) drip emitters are shown that look as though they could be very easily pinched by hand at their outlets to forward flush trapped debris. However in Harmony's Figure 2 of the patent, a sectional view reveals a pressure dropping region comprising two opposing imperforate flexible sheets (labyrinthine like) alongside which run two water inflatable tubes which apply a clamping force to the sheets dependent on the water pressure at the entry to the emitter. Together these features generate back pressure (resistance to fluid flow) to compensate for changes in the supply pressure. The sheets have to be forced apart by the source water for it to escape from the emitter mouth. These features mean that each emitter cannot be quickly cleaned in situ, for example simply by pinching the free end between a finger and thumb whilst the irrigation water is flowing. This is principally because of the pressure inflating features and internal obstructions caused by the presence of the imperforate sheet structure. This type of emitter cannot be forward purged and it is not designed to be. Two further observations are noted in the application of this invention namely, it is designed for larger systems operating with 'clean filtered water' from 'higher supply pressures' than are achievable or required by the average smallholder or gardener employing a gravity-fed tank and hose system, which has to be refilled manually. And each emitter would need to be readily demountable from its hose or Tee connector as shown in Harmony's figure 1., to back flush (backward purge) accumulations in the wider tubular region immediately before the imperforate sheet structure and also those accumulations having entered and lodged in same. The illustrations do not reveal the precise means of attachment to a hose system, which means would add further complication and perhaps prove impractical for use on the small scale systems envisaged. In practice and without the use of very clean water the blind inflated pockets accumulate sediments and biological matter which cannot be forward flushed. Eventually these accumulations prevent the emitter from working properly.

It is noteworthy that in some instances drip emitters are designed to be disassembled, cleaned and then put back together. But the task is often a fiddly one requiring; an eye for detail, dexterity, clean rinsing water, and the use of short- bristle brushes, pins or needles - and this is not readily achieved or desirable as a regular procedure in the field.

Micro-Tubes - Annon

Micro-tubes, being the cheapest and simplest drip emitter type - short of piercing a hole in the sidewall of the delivery hose which affords no flow regulation - are commonly used in the field on small plot sizes by subsistence farmers. They achieve the required degree of restriction to water flow from the combination effect of the bore size and the chosen length of tube and this is usually ascertained at the time of installation by empirical means. From observations, the rate of discharge through a micro-tube bore is directly proportional to the operating pressure and inversely proportional to its length. Typically the essential pressure drop is achieved by selecting various lengths, for example a two metre length of 1.5 mm bore tube and inserting one free end into a hole (usually made with a nail) into the sidewall of a larger supply hose typically of 10 mm bore or larger. In practice, and to avoid tripping, the longer lengths of spaghetti-like micro-tube are often tied up in coils on the ground. When it comes to clearing blockages, which are very common in micro- tube systems, the micro-tube is usually pulled out from its connection and blown though by the operator (back flushed and forward flushed). When that doesn't work the length of micro-tube, is replaced with a new one. Without dismantling this long spaghetti type of emitter cannot be forward purged.

By their very nature all of the emitter types referred to, contain within their structure one or more extended pathways of small cross-sectional dimensions, typically of the order of 1.5 - 2.0 millimetres wide (approximately 60 to 80 thousands of an inch) which have the effect of reducing the supply pressure of the irrigation fluids through the emitter. This explains the need for pre-filtering irrigation fluids which have to pass through these narrow passages. The smaller subsistence farmer and smallholder installations employing an elevated gravity-fed tank supply, containing water and all manner of debris, floating and otherwise, commonly include a tubular inline filter of the order of 150 mesh size, on the outgoing side of the tank, close to the start of the hose network. However in almost every case the irrigation fluids are biologically and chemically active and matter which can pass through a mesh filter can grow and/ or form accumulations over time with metal oxides, lime, etc, throughout the extent of the hose system - including within and around the filter mesh apertures.

Further to this, one simple mistake by an operator, releasing unfiltered fluids into a hose system for only a few seconds - which is currently very easily done - has the potential to block every emitter within minutes. This is a very strong incentive to design a more simple Outflow-purging' emitter (forward flushing), i.e., one that can be purged in an instant outwards through the issuing orifice, as opposed to the current technology which is predominately geared to back-flushing, disassembly, chemical cleaning or replacement.

Preferably a simple emitter is required which can initially be employed as a blind end cap to stop the outflow of the supply fluid from initially surplus hose fitting ends or branches, to later be converted to perform as an adjustable emitter when a system needs to be extended to keep pace with the growth of plants.

Preferably the then simple emitter is required which obviates the need for a labyrinthine or long and narrow type of flow path and achieves a sufficient back pressure effect (resistance to flow) more simply, for application in the smaller irrigation systems being considered, where the supply pressure is very much lower than for the larger commercial scale irrigation systems, and where the crop uniformity is less crucial or where crops are of mixed species, size and age. Preferably such an emitter would be mechanically adjustable also, and ideal for use in those areas where no current emitter technology is capable of operating with turbid water flows.

Current commercial scale, micro-irrigation hose systems are often rated up to 4 Bar gauge operating pressure (equivalent to 58 psi of pressure or 134 ft or 40.8 metres of water head), with the emitters skilfully designed to deliver a constant and uniform output over a wide range of End User's available supply pressures - principally for mono-crop cultivation. Emitters have also been developed which have integral back flow preventers (to prevent drain out) and these typically require 0.5 Bar gauge of system pressure to open the emitter outflows, before any irrigation can commence. A 1 Bar gauge pressure is often a minimum end of line operating pressure for the larger commercial irrigation systems employing hundreds of emitters (equivalent to 14.5 psi of pressure or 33.5 ft or 10.2 m of water head). This is in contrast to the operational requirements of the smaller low cost and low energy systems where a gravity fed water tank might only be elevated to a height of 3 metres (on a mound, trestle or building blocks) and more commonly in the range 1 to 2 metres of elevation, resulting in a water supply pressure in the region of 0.1 to 0.2 bar gauge (approximately 1.5 to 3 psi or in water head equivalent 3.3 to 6.6 ft) plus the depth of water in the tank (which could potentially double the water head pressure when in a filled condition). Which depth most commonly drops to its minimum depth on these small systems as they are often left to drain out before being refilled manually, for example with buckets from whatever water source is available. The refilling work is often carried out by women and children whom have to be able to pour buckets of water into the open tops of the tanks. In many cases this is the overriding reason for installing tanks only a metre or so above ground level. However this creates a challenge for the equipment designer - i.e., there being no significant water pressure available to undertake conventional pressurised filtering of the irrigation water - especially given the significant head pressure variation between a filled tank and a point in time approaching the drained out condition.

Additionally, the micro-irrigation fittings supplied by the irrigation industry create a further operational problem for low water-head drip emitter systems, as invariably the fittings employed throughout the extent of a system of hoses have smaller bores than the hoses to which they are connected. Thereby creating internal constrictions in; Straight Connectors, Tee's, Crosses, etc, where what would be described as 'normally mobile' debris, can lodge and accumulate at the inbound side of these fittings.

By employing the most up to date polymers available, including thermoplastic elastomers (TPE's), extruded hoses and moulded fittings could be redesigned for 'small scale micro-irrigation systems' so that the bore sizes through the various fittings would never be less than the smallest bore size of the adjacent hoses, and preferably never less than 5 mm bore, to freely pass mosquito larvae and the like. Then with only basic filtration at the exit from the tank (i.e., in the region of 20 to 50 mesh size and up to 150 mesh size if especially preferred) the smaller mobile debris could be propelled swiftly through the extent of a hose system and out through specially designed emitters, with the larger debris coming to rest predominately inside the emitters themselves. By this approach a new emitter type having simple forward purging means, might be designed to exploit this deliberate construct. The majority of subsistence farmers, smallholders and gardeners alike, have little control over the quality of their irrigation water or the essential unending adherence to 'best practice' irrigation procedures. As a consequence blocked emitters continue to be a most urgent and widespread problem, and this problem has yet to be solved by the irrigation industry for small scale, low cost systems of micro-irrigation.

It is desirable to develop a design of adjustable emitter that mitigates some or all of the above disadvantages and in particular that works effectively with water containing debris and/ or supplied with a relatively low head of pressure, which pressure will diminish considerably as the level in the tank falls to its lowest level, tailing off the irrigation supply to all of the emitters in a system.

This may in particular exhibit one or more of the following advantages:an 'extensive elongate resilient slitted-aperture' in place of the current types of 'labyrinthine structure and tiny outflow orifice', to function as a more practical method of creating a 'non-pressure compensating' resistance to fluid flow;

where the elongate configuration of the slitted-aperture is such that the amount of debris that would normally completely block a conventional emitter will only give rise to partial blocking of the outflow aperture and a corresponding attenuation of the outflow; where an emitter can be selectively squeezed in situ and whilst in operation, to forward flush or front-purge any lodged debris from inside the emitter, without any increase in the supply pressure, as opposed to the current back flushing methods which require mechanical interruption and or dismantling; with said selectively squeezable purging facility also enabling an End User to spot water (rinse down) for example foliage and small implements, without any increase in the supply pressure;

and where there is provided the means for a number of mechanical adjustments based upon the configuration of an assembly comprised of at least two parts having scope for any number of incremental settings between these adjustments being so capable of establishing a preferred flow characteristic, largely though not exclusively independent of other emitters in a system. It may further be desirable to develop an end cap adapted as a preform for such an emitter. This may in particular exhibit one or more of the following advantages: a blind end cap having blind end and external features as to facilitate its use as a dual purpose micro-irrigation item of hardware;

modifiable to and having, after modification, a resilient slitted-aperture with one or more of the above advantages.

Summary of the Invention

According to the Invention in a first aspect there is provided an outflow-purgable and adjustable emitter device having: a hollow body defining an internal flow channel therein having a fluid entry passage or inlet at a first end to receive pressurised fluid, which passage continues as the flow channel towards a fluid outflow at a second end in the form of a resilient slitted-aperture, which aperture provides a resistance to the flow of fluid from the body, and the said body having one or a number of, radially displaced projections for example comprising ramped protuberances or profiled lugs projecting from the outer surface of the body and a separate adjusting means assembled to operate in mechanical association with the body which is assembled thereon and for example slidably and/ or rotatably assembled thereon so as to be movable relative to the body in use and for example to slide along and/ or rotate about the body in use to selectively engage with the projection(s) to force the slitted-aperture more tightly closed when so engaged, to attenuate the outflow of fluid from the body as a means of outflow adjustment for normal operation, and with said resilient slitted-aperture also being selectively deformable to vary and in a particular case for example to provide a purging flow to dramatically increase the fluid outflow.

The invention thus lies in the very simple combination of a resiliently slitted aperture for example in a resiliently deformable body and an adjustment means in mechanical association with the body which is assembled so as to move relative to the body to engage with one or a number of, radially displaced ramped protuberances or profiled lugs from the outer surface of the body to force the slitted-aperture more tightly closed as a means of outflow adjustment for normal operation, and with the body being selectively deformed by pinching or squeezing at any time about the slitted-aperture, the outflow slitted-aperture is made to open up to a gaping formation and greatly increase the rate of fluid egress and purge any trapped debris, whilst at any time the same pinching or squeezing action may be employed for the purposes of spot watering or rinsing down a plant or implements by this said forward flushing means. The adjustment means may be slidably assembled as to slide along the body to selectively engage with one or a number of, radially displaced ramped protuberances or profiled lugs and may alternatively or more preferably additionally be rotatably assembled as to rotate about the body to selectively engage with one or a number of, radially displaced ramped protuberances or profiled lugs.

Thus the invention provides two required flow control modes in admirably simple manner. Regular and for example steady state fluid flow is determined in the first place by the resilience of the slit. In normal operation the slit may be forced partially open by the pressure of the supply fluid giving rise to a fan shaped out flowing stream of fluid. The regular flow rate can be adjusted further by sliding and/ or rotating the adjustment means over the outer surface of the body into/ out of selective engagement with the projection(s) on the outer surface of the body to bear down on the projection(s) when so engaged so as to urge the resilient slitted- aperture to a more tightly closed configuration as a means of outflow adjustment for normal operation. This may provide in a most engaged position for complete closure of the resilient slitted-aperture. Thus there is provided the means for a number of mechanical adjustments based upon the configuration of an assembly comprised of at least two parts having scope for a number of incremental settings between these adjustments being so capable of establishing a preferred flow characteristic, largely though not exclusively independent of other emitters in a system. However the resilience of the aperture may be further exploited by pinching or squeezing at any time about the slitted-aperture to cause the aperture to gape open for purging or spot watering for example. Thus the emitter can be selectively squeezed in situ and whilst in operation, to forward flush or front-purge any lodged debris from inside the emitter, without any increase in the supply pressure, as opposed to the current back flushing methods which require mechanical interruption and or dismantling; with said selectively squeezable purging facility also enabling an End User to spot water (rinse down) for example foliage and small implements, without any increase in the supply pressure. To facilitate the second operation (opening the aperture for purging or spot watering for example) it might be desirable in a preferred case for the device adjusting means additionally to be manufactured from a flexibly resilient material so as not to inhibit the action of pinching or squeezing the flexibly resilient slitted- aperture. Preferably the device adjusting means comprises an annular formation surroundingly disposed about the body and is for example a slidable and/ or rotatable ring-like formation slidable and/ or rotatable on the body from a position of neutrality towards the resilient slitted-aperture at the second end of the body for engagement with the one or more radially displaced profiled lugs or ramped protuberances from the body surface, and where said engagement forces the slitted-aperture towards a more closed position attenuating the outflow of fluid.

Such adjusting means may be manufactured from either a rigid or resilient material. Preferably the adjusting means is manufactured from a flexibly resilient material and for example comprises a flexibly resilient ring-like formation slidable and/ or rotatable on the body to be selectively engageable as above described.

A particular advantage of the use of a resilient material for the ring or other adjusting means accrues in relation to the second operation (opening the aperture for purging or spot watering for example). If a resilient ring or other adjusting means is used the device can be pinched with the ring in situ and engaged upon the projections at the second end of the body having the resilient slitted-aperture. If a rigid ring or other adjusting means is used it is likely to be necessary to disengage it for example by sliding away from the second end of the body before deforming the second end to open the resilient slitted-aperture.

Preferably the body is generally cylindrical or otherwise rotationally symmetrical about an elongate axis. Preferably a plurality of radially displaced projections for example comprising ramped protuberances or profiled lugs projecting from the outer surface of the body, conveniently generally evenly radially spaced therearound.

Preferably the resilient slitted-aperture takes the form of an elongate slit in a flexibly resilient formation, comprising at least an end portion at the second end of the body. At least the said end portion of the body is manufactured from a flexibly resilient material. Conveniently the entire body may be a resilient body manufactured from a flexibly resilient material. The material of the body may for example have a Shore A Scale value of between 35 and 60 and for example from 40 to 50. Preferably both the body and the adjusting means such as the ring are manufactured from a resilient material. In such a case the material of the adjusting means such as the ring may be more rigid than the material of the body and may for example have a Shore A Scale value of between 65 and 80. Preferably the resilient slitted-aperture would take the form of a wrap around slit in the range of 8 to 20 mm, and more particularly in the range of 12 to 16 mm in extent, to present a long narrow slit for fluid outflow. In normal operation the slit would be forced partially open by the pressure of the supply fluid giving rise to a fan shaped out flowing stream of fluid. By this arrangement the smaller mobile debris would pass through the slitted-aperture in the fluid stream, with only those larger objects (debris) - of a size that would normally completely block a conventional drip emitter - becoming lodged behind the slitted-aperture to only partially interrupt and attenuate the fan shaped outflow rather than cause a complete stoppage. When the inflowing open end of the body is connected to the open free end of an irrigation hose lateral via, for example, a straight connector means, the slitted- aperture in the out flowing end of the device presents a resistance (attenuation) to the free passage of fluid through the body of the emitter for the hose supply pressures envisaged (up to 3 metres of water head and preferably in the range of 1 to 2 metres) obviating the need for an internal conventional labyrinthine or long narrow passage structure. By the careful selection of the material properties and the dimensions of the resilient body and the use of the externally fitted mechanical adjustment means, an operator would be able to fine tune each emitter of the present invention to ensure that those emitters positioned closest to the source (i.e., an elevated tank of water) will not expel significantly more fluid than those positioned furthest away - unless the planting arrangement calls for such a gradient of outflows.

The rate of outflow will be determined by a number of factors including the pressure generated by the water head, the bore sizes of the supply hoses the number of emitters in a given system and the dimensions of the emitter and its material properties. An 'extensive resilient slitted-aperture' is a more practical means of creating the required resistance to fluid flow than the labyrinthine or long narrow passage path means of the current emitters, which emitters cannot be forward purged. To create a resistance to the flow of fluids the outflow aperture is in the form of a normally closed extensive slit formation wrapped around a domed outflow end of the emitter body and where the body is selectively deformable by squeezing or pinching, adjacent to the ends of the slitted-aperture, so as to change the outflow aperture from a normally narrow slitted state to a gaping state to dramatically 'increase' the fluid outflow. And where the mechanical adjusting means is in the form of a narrow encompassing ring, slidable and lockable, by jamming onto the one or more ramped protuberances (radially displaced profiled lugs) on the resilient body so as to 'attenuate' the fluid outflow or stop it entirely. Preferably the device includes a resilient body which is for example an elongated cap shaped body having an opening at one end to receive fluid under pressure and a slitted-aperture at the other end to provide a means for fluid egress, with said slitted-aperture providing a resilient resistance to the passage of fluid, and the body so engaged in mechanical association with an adjusting means as to attenuate the normal fluid outflow, said resilient body also being selectively deformable, such that the slitted-aperture may be changed from a narrow slitted state to a gaping state to significantly increase the egress of fluid and purge entrapped debris.

Preferably the resilient body is manufactured from a thermoplastic elastomer or a thermo-setting compound such as a rubber compound by a process of moulding. In a possible case the resilient or other body is manufactured without the slitted- aperture so that the body can be installed onto the end of an irrigation hose fitting to provide a blind end cap, for example to seal off a surplus side branch of a Tee fitting. After which a slit of any chosen length within the design range may be cut into the blind end of the body to suit a particular or general watering need to cater for an expansion of the irrigation system.

In this case the invention comprises what is in practice a preform for an emitter device in accordance with the disclosure of the present invention, and is provided as a blind end cap component for sealing off a fluid passage, with said component being convertible to an emitter device as above described for example once in situ. The end cap component can thus initially be employed as a blind end cap to stop the outflow of the supply fluid from initially surplus hose fitting ends or branches, to later be converted to perform as an adjustable emitter when a system needs to be extended to keep pace with the growth of plants.

The end cap component thus comprises a hollow body defining a flow channel having a fluid inlet, which channel continues towards a second end having a closed end cap convertible to a resilient slitted-aperture to provided an emitter as described herein, the said body having one or more radially displaced projections from the outer surface of the body and adjusting means in mechanical association with the body and assembled to move relative to the body and for example slidably assembled to slide along the body and/ or rotatably assembled to rotate about the body to selectively engage with the projection(s).

Preferably the resilient or other body is adapted to facilitate its conversion to an emitter and for example has one or more integral cutting guides projecting in a wrap around formation around the blind end of the body to assist in cutting the slitted-aperture to convert a blind cap end device into an emitter device for the purposes of irrigation. Preferably the cutting guides in the form of two closely spaced parallel wings projecting from the body are made of resilient material, which resilience enables the guides to act as stand-offs when the device is selectively squeezed to reduce the incidence of an operator's finger and thumb from obscuring the gaping aperture as it is being formed for front purging, with said resilience also enabling the guides to bow away from each other during the squeezing action so further assisting the formation of the gaping aperture.

Preferably the body adjacent to the ends of the slitted-aperture may at any time be selectively pinched or squeezed to form a gaping aperture, to increase the fluid outflow for the purpose of spot watering or rinsing.

The invention in a further aspect will function with a similar effectiveness if the slitted-aperture is positioned only across an end of the body provided that the engaging relationship between the adjusting means in the form of a narrow ring and one or more radially displaced ramped protuberances is maintained.

The Invention provides in a preferred embodiment of a new type of emitter there is provided, an outflow-purgable and adjustable emitter device having: a hollow body having a fluid entry passage to receive pressurised fluid, which passage continues towards a fluid outflow in the form of a resilient slitted-aperture, which aperture provides a resistance to the flow of fluid from the body, and the said body having adjusting means in both slidable and rotatable mechanical association, to incrementally attenuate the outflow of fluid from the body, and with said resilient slitted-aperture also being selectively deformable by other means to increase the fluid outflow.

In a preferred case as has been described above the device adjusting means comprises an adjusting slidable and/ or rotatable ring-like formation slidable and/ or rotatable on the body from a position of neutrality towards the resilient slitted- aperture at the second end of the body for engagement with the one or more radially displaced profiled lugs or ramped protuberances from the body surface, and where said engagement forces the slitted-aperture towards a more closed position attenuating the outflow of fluid. Preferably the adjusting ring would be a slidable push fit on the preferably resilient preferably tubular body of the device, so as not to slide about freely on the plain tubular portion.

In a possible embodiment, the ring-like formation may have one or more tabs projecting perpendicularly from one of its end faces, complementarily arranged with respect to the one or more ramped protuberances or other projections so that when the ring is assembled with the tabs facing and aligned directly with the one or more ramped protuberances or other projections on the body surface. For example a plurality of generally evenly radially spaced projections for example comprising ramped protuberances or profiled lugs project from the outer surface of the body, and projecting tabs are disposed about one of the end faces of the ring in such manner as to correspond in complementary manner to at least some of the projections and/ or gaps defined between the projections. In this way, the ring is additionally adjustable rotationally between a configuration where the projecting tabs tend to bear directly on the corresponding projections on the body and a configuration where the projecting tabs tend to lie between the corresponding projections on the body.

Additional functionality is conferred if the ring is then both slidable to and fro relative to the end with the slitted-aperture and rotatable about the end with the slitted-aperture. In particular in this way, the clamping force could be increased over the maximum condition achieved in the first embodiment above described for the same degree of slidable movement as in the first embodiment, when the slidable ring is slid to engage to its fullest extent with the ramped surface or protuberances, the cutting guides not interfering with this action by their being positioned in the gaps between the tabs with their rear facing edges acting as end stops to the movement necessary to apply the maximum clamping force to the slitted-aperture arrangement. In this second embodiment, the tabbed adjusting ring could be positioned in four different ways to produce four different outflow effects, and in any intermediate position in between, to benefit the User.

1. For example the assembled tabbed adjusting ring could be slid along the body to a 'parked' position away from the out flowing end so that there would be NO ATTENUATION of the out flow. In this situation the tabbed ring could be assembled with the tabs facing in either direction along the body, a position which would favour the furthest away outflows in an irrigation system.

2. The tabbed adjusting ring could be assembled on the body with the tabs facing the inflow end of the body so that when slid along the body to fully engage with the ramped protuberances the attenuation to the fluid outflow would be the same as in the case of the first embodiment and could be referred to as INTERMEDIATE ATTENUATION for general irrigation use.

3. Alternatively the tabbed ring could be assembled on the body with the tabs facing the out flow end and with the tabs aligned to engage with the ramped protuberances, in which case were the tabbed ring to be slid to its full extent along the body to engage with the ramped protuberances the attenuation would achieve its MAXIMUM ATTENUATION value, the setting being useful for outflows close to the supply tank in an irrigation system.

4. Further, from the starting position in 3 above, the tabbed ring could be rotated on the body typically through 90° (in the case of a two tab assembly) and then slid towards the outflow end to reach its full engaging extent, so that the ramped protuberances would be aligned in the gaps between the tabs, and the attenuation force would be less than for position 2 above - and due in the main to the degree of overlap of the adjusting ring over the ends of the wrap around slitted aperture (the aperture length would be effectively shortened and the flexural ability of the slitted-aperture would be reduced), providing a User with further scope for flow adjustment referred to as PRIMARY ATTENUATION especially on the smaller irrigation systems. Preferably an emitter body would be injection moulded as a blind component so that initially the component could, in a first instance be used, as blind end caps to close off irrigation fittings. After which, when plants grow and the need arises, an operator would be able to cut the necessary slit - to create the essential slitted- aperture with a sharp knife, Stanley® blade or similar, and add a ring-like adjusting means to create a practical cap valve emitter. With some basic knowledge an End User might also be able to decide how extensive to make the wrap around slit (cut) within the designated portion of the body (2) for example from 8 to 16 millimetres in wrap around extent, to suit a particular irrigation need, or when conditions merit it, only a short slit across the domed end of the body.

The device or multiples thereof may be employed in a first application when plants are irrigated on mass via a distribution network of irrigation hoses fed ultimately from a source of irrigation fluid for example an elevated tank, and where the tank is installed to deliver fluids for the periods when a tank outflow valve to the hoses is in the open position and before the valve is closed again, or when the valve is left open until the tank supply is exhausted, or where there is no valve and the system is continuously open. Irrigation fluid will typically be water, optionally including suitable horticultural or agricultural additives, such as a plant feed compositions or the like, water conditioning compositions such as pH control compositions and the like, in conventional manner. In addition to the exemplary aspects and embodiments described above, within which design there is provision for a multitude of intermediate engagements and as a consequence fluid flow attenuation outcomes, further aspects and embodiments will become apparent by reference to the figures and by study of the following detailed descriptions. Brief Description of the Figures

The invention will now be described by way of example only, with reference to figures 1 to 15 of the accompanying drawings, which are drawn to scale, in which: Figure 1 is a general perspective view of an assembled emitter (converted from an initial blind cap end) in a first embodiment, in accordance with the present invention;

Figure 2 is a sectioned side elevation view of the same;

Figure 3 is a side elevation of an emitter assembly as shown in figure 1;

Figures 4 and 5 show enlarged cross sectional views A-A and B-B respectively through the emitter in figure 3, in figure 5 a slidable ring component has been omitted for clarity;

Figure 6 is a side elevation as in figure 3 with a slidable adjustment ring shown in an engaged state;

Figure 7 is a sectional side elevation of an emitter assembly mounted on to one end of a ring barbed straight connector irrigation fitting (not sectioned);

Figure 8 is a perspective view of an emitter assembly and straight connector attached to the free ultimate end of a lateral irrigation hose in normal use - i.e., during watering;

Figure 9 shows the method for purging the invention in figure 8 during watering, and also using the invention as a spot watering device;

Figure 10 is a general perspective view of an assembled emitter of a second embodiment (converted from a blind cap end) in accordance with the present invention with the adjusting means, a double-tabbed ring, parked in a neutral position resulting in NO ATTENUATION of fluid flow;

Figure 11 is a perspective view in more detail of a second embodiment of a double- tabbed ring adjusting means;

Figure 12 is a perspective view of a second embodiment, of a double-tabbed adjusting ring reproducing the same engaged state as was the case for the first embodiment (referring to figure 6) when engaged to attenuate the flow of irrigation fluid, now referred to in this embodiment as resulting in I NTERMEDIATE ATTENUATION;

Figure 13 is a view of the assembly of a second embodiment, with a double-tabbed adjusting ring shown in a position of maximum engagement resulting in MAXI MUM ATTENUATION of flow;

Figure 14 is a view of the assembly of a second embodiment, where a double- tabbed adjusting ring has been turned round through 90° as compared with figure 13, to create a lesser PRIMARY ATTEN UATION of the flow. Like numerals are used where applicable;

Figure 15 shows a front perspective view of a n emitter being selectively pinched by hand to produce a gaping outflow aperture.

Detailed Description of the Figures

Referring to figures 1 to 5, describing a first embodiment, the assembled emitter (1) comprises two pa rts namely a short tubular body (2) [when completed essentially a modified Blind End Cap moulding] and a slidable ring (5) to provide adjustment. The short tubular body (2) is approximately 28 millimetres long and has a chamfered large open aperture (3) and integral collar (4) at the l n-flow end. I nboard of the collar there is a parallel portion of the body upon which is mounted a loose fitting slidable narrow ring (5) beyond which the body forms a domed end (6). I ntegral with the domed end are two diametrically opposed and low-angled ramped lugs (7) (protuberances) between which lugs, are displaced two horizontally- extended parallel cutting guides (8) which project a short distance beyond the end of the domed end. The cutting guides, projecting from the body (2) continue in a wrap around formation in the same plane, around the domed end of the body to terminate on each side of the body on a parallel portion of the body. Between the guides (8) the body material is thinned also in a wrap around manner (9) terminating on each side of the body and further along the parallel portion of the body than was the case for the guides. Within the thinned portion (9) of the body, the material is cut to form a relaxed and normally closed, slitted-aperture (10) approximately 15 millimetres in wrap around extent.

Figure 6 of a first embodiment shows the assembled emitter (1) with a slidable ring (5) slidably engaged with the lugs (7) which action forces the slitted-aperture (10) to become more positively closed than is shown in figure 3. This arrangement provides a mechanical form of adjustment to attenuate, if not to stop entirely, the out flowing of irrigation fluid from a source, for example, a water tank elevated to a height in the range of 1 to 3 metres above the ground to be irrigated.

The body (2) is made from a resilient material for example an injection moulded thermoplastic elastomer (TPE) or a rubber compound in the region of 60° Shore A hardness, providing sufficient elasticity and resilience to expand over and remain gripped onto a ring barbed end of an irrigation fitting when required for use in an irrigation system. In the embodiment shown the body (2) is injection moulded as a blind 'End Cap' component with the slitted-aperture (10) being made afterwards (as a part of the conversion process from an end cap to an emitter). If blind components are supplied to the end user, they can in a first instance be used as end caps to close off irrigation fittings, or preferably an operator can cut a slit - to create the slitted-aperture (10) - between the guides (8) with a sharp knife, Stanley® blade or similar. And with some basic knowledge, also decide how extensive to make the wrap around slit (cut) within the designated portion of the body (2) for example from 8 to 16 millimetres in wrap around extent, so that the newly created emitter will suit a particular irrigation need.

With the slidable narrow ring (5) parked in a neutral position as in figure 1, the inherent fluid out-flowing characteristics of the body (2) may also be modified by changes to the thickness of the thinned portion (9) and to the thickness of the surrounding domed material (6). Additionally by careful selection of the polymer i.e.; resilience, elasticity and hardness, the emitter body can be manufactured to flex the slitted-aperture (10) open - by the force of the water - to a greater or lesser degree for a given upstream water head. For example a stiffer grade of polymer used in the body would better resist the up-stream water head pressure from a tank supply, enabling a tank to be installed at a higher elevation to supply uniform outflows of irrigation water to a greater number of emitters or increase the emitter outflows to suit the watering needs of larger plants. By contrast a softer grade of polymer might be more suitable for a tank at a lower elevation and serving a smaller number of emitters, for example in the region of 20 emitters.

The narrow slidable ring (5), approximately 3 millimetres wide, is made from a stiffer (less flexible) polymer, than the body material, for example the narrow ring can be cut from an extruded tube having a hardness value in the region of 80° Shore A. Upon assembly and slidable engagement with the lugs (7), the ring (5) would distort locally to follow the external opposing ramped surfaces of the lugs. This feature would be beneficial in two respects namely, the imposed clamping forces on the slitted-aperture (10) would be accurately directed, and the low ramp angles of the lugs (7) would ensure that, by friction and with the intrinsic resilience (springiness) of the two components, they would be positively wedged together to maintain a preferred state of operation. Further, one or both of the component mating surfaces may be textured to increase the effectiveness of the wedging mechanism.

Alternatively the narrow ring could be made by moulding, machining, etc., (not shown) from a more rigid material to engage slidably with the lugs (7) on the body (2) preferably having at least one internal chamfer for smooth interaction with the ramped surfaces of the lugs (7), to provide a similar wedging action.

Assembly of the two parts of the emitter (1) is a simple matter of holding the body (2) by the integral collar (4) and pushing the ring (5) forcibly over the lugs (7) and the guides (8) - or by pushing the ring (5) forcibly over the collar (4). In either case the relevant body parts will collapse into the central region of the body with the ring distorting if need be, until the ring reaches a parallel portion of the body (2), at which point the lugs and guides or the collar will spring out to resume their normal positions, and the ring will be a captive fit on the central portion of the resilient body. Figure 7 of a first embodiment shows the assembled emitter (1) mounted on one end of a ring barbed straight connector irrigation fitting (20) - sometimes referred to as a straight coupler fitting. The purpose of the integral collar (4) is evident, acting as a reinforcing ring to ensure that one end of the straight connector is securely retained in the in-flow end of the emitter body (2). The straight connector shown is of the preferred type referred to earlier, where the bore size is no less than 5 mm, ensuring also that there are no restrictions in the fluid flow path as it enters the emitter body (2).

Figure 8 of a first embodiment shows a normally operating, assembled emitter (1) of the present invention mounted on to one end of a straight coupler (20) which is in turn connected to a resilient lateral hose (30) in similar fashion, having a preferred minimum bore of 5 mm. The other end of the hose lateral (not shown) is connected to a larger sub-main delivery hose along which length are connected a number of hose laterals similarly assembled with emitters. When forming part of a small scale, gravity-fed irrigation system in normal operating mode the lips forming the slitted-aperture (10) outflow, and surrounding resilient material (6) of the body (2) will only be incrementally sprung apart or displaced, by the force of the hose-fed water so that an attenuated fan shaped stream will issue forth for irrigation purposes.

Since the slitted-aperture is of a wrap around formation in the region of 15 mm in extent, the device will not be immediately compromised by a first or a number of larger debris particles which would normally block a conventional emitter - having an outflow orifice in the region of only 1.5 to 2.0 mm bore. This arrangement ensures that under normal operating conditions mobile debris which is capable of passing through an inline filter installed close to the tank outlet, and in the range of 20 to 150 mesh size, will either freely pass out through the partially sprung open - by the force of the supply water - slitted-aperture (10) with the stream of fluid, or in the case of larger debris these will lodge and accumulate immediately behind the slitted-aperture of the emitter - to be readily flushed or purged at a later time when the resulting disturbance to the regular fan shaped out flowing stream is observed by an operator.

It is important to restate here that the conventional emitters referred to tend to block up on their fluid inbound side i.e., at or immediately prior to the entry to their internal labyrinth or long narrow passage - making forward flushing or outflow- purging difficult if not impossible.

The operation has been described with the slidable adjustment ring (5) in the neutral position as in figure 1. If the outflow in figure 8 is deemed too great, the adjustment ring (5) may be slidably moved towards the domed end of the body (2) to engage with the lugs (7) to force the slitted-aperture (10) more tightly closed, attenuating the normal fluid outflow. This procedure might be employed on a number of emitters in a hose-fed distribution system, for example those closest to the fluid source (elevated tank supply), where the fluid force in the hose system would be greatest.

Figure 9 of a first embodiment shows the same lateral hose assembly as illustrated in figure 8 i.e., in a normal flowing state, but here the emitter assembly (1) is shown being squeezed (or pinched) about both sides of the domed region (6) at the guides (8) to force widely open, the normally narrow slitted-aperture (10) and rapidly purge out accumulations within the emitter, from the front of the emitter. Purging can be carried out most readily by selectively squeezing or pinching the domed nose of the emitter (6) about the guides (8) between a finger and thumb, to change the thin silted-aperture (10) into a gaping aperture when viewed from the front. Bearing in mind the small proportions of the emitter and the degree of manipulation the cutting guides (8) serve a further purpose. Projecting as they are illustrated from the side of the body (2), they act as stand-offs to prevent an operator's finger and thumb from obscuring the gaping aperture as it is being formed for front purging, their opposing relationship also ensures that they bow or flex away from each other and this action further assists the opening process.

The purging action may be employed at any time even when there are no accumulations to purge. For example - and with the thought that these emitters are designed to assist operators of smaller systems, working daily on their plots of land - if an operator wanted to provide a quick burst of water, i.e., spot watering, to a particular plant for say 10 seconds to rinse the leaves or to wash-in a new seedling, the emitter could be pinched to provide this extra flow of water. Referring to figures 10 to 15 a second embodiment of the present invention is shown, where the ring like adjusting means has two radially opposed tabs projecting perpendicularly from one of its end faces. In all other respects the details are the same as for the first embodiment, therefore like numbers are employed where these are appropriate.

In figure 10 the assembly (1) of the two parts, the resilient body (2) and the alternative and more versatile adjusting ring (15) are shown with the adjusting ring 'parked' in a neutral position on a plain cylindrical portion of the body. The short tubular body (2) is approximately 28 millimetres long and has a chamfered large open aperture (3) and integral collar (4) at the ln-flow end. Inboard of the collar there is a parallel portion of the body upon which is mounted a slidable narrow ring (15) having a pair of radially opposed tabs projecting from one of its end faces, beyond which the body forms a domed end (6). Integral with the domed end are two diametrically opposed and low-angled ramped lugs (7) (protuberances) between which lugs, are displaced two horizontally-extended parallel cutting guides (8) which project a short distance beyond the end of the domed end. The cutting guides, projecting from the body (2) continue in a wrap around formation in the same plane, around the domed end of the body to terminate on each side of the body on a parallel portion of the body. Between the guides (8) the body material is thinned also in a wrap around manner (9) terminating on each side of the body and further along the parallel portion of the body than was the case for the guides. Within the thinned portion (9) of the body, the material is cut to form a relaxed and normally closed, slitted-aperture (10) approximately 15 millimetres in wrap around extent. Assembly of the two parts of the emitter (1) is a simple matter of holding the body (2) by the integral collar (4) and pushing the ring (15) forcibly over the lugs (7) and the guides (8) - or holding the domed end of the body, by pushing the ring (15) forcibly over the collar (4). In either case the relevant body parts will collapse into the central region of the body with the ring distorting if need be, until the ring reaches a parallel portion of the body (2), at which point the lugs and guides or the collar will spring out to resume their normally relaxed shapes, and the ring will be a captive fit on the central portion of the resilient body. The ring (15) may be assembled on the body (2) facing either towards the inflow or the outflow depending on the setting required by the End User.

For clarity Figure 11 shows an adjusting ring (15) with its pair of opposing tabs projecting from one of the end faces. The dimensions of the slots (16) between the tabs are important as they must be capable of accommodating, in one mode of operation, the two cutting guides (8), and in another mode of operation, the ramped protuberances (7).

Figure 12 shows the assembled emitter (1) with a slidable ring (15), presenting a plain end face in the direction of fluid flow, slidably engaged with the lugs (7) which action forces the slitted-aperture (10) to become more positively closed than is shown in figure 3. This reproduces the same level of engagement as shown in figure 6 which demonstrates the first embodiment. This arrangement provides a mechanical form of adjustment to attenuate, if not to stop entirely, the out flowing of irrigation fluid from a source, for example, a water tank elevated to a height in the range of 1 to 3 metres above the ground to be irrigated. Figure 13 shows the assembled emitter (1) with a slidable ring (15) slid to its maximum position towards the outflow end, with the double-tabs facing the direction of fluid flow and slidably engaged over the lugs (7) which action forces the slitted-aperture (10) to become more positively closed than is shown previously, achieving MAXIMUM ATTENUATION. This produces a level of engagement in excess of that achievable in figure 6 which demonstrates the maximum attenuation to flow obtainable in the first embodiment. This arrangement provides a mechanical form of adjustment to attenuate, if not to stop entirely, the out flowing of irrigation fluid from a source, for example, a water tank elevated to a height in the range of 1 to 3 metres above the ground to be irrigated.

Figure 14 shows the assembled emitter (1) with a slidable ring (15) rotated round the body by 90° from its position as shown in figure 13 and slid to its maximum extent towards the outflow end so that the ramped protuberances (7) are not engaged and nestle in the gaps between the tabs on the ring (15). In this condition the trailing edges of the cutting guides acting as a limit to the sliding movement of the ring engage with the outermost faces of the tabs. A position which ensures that the ring has overlapped both ends of the wrap around slitted-aperture by a predetermined amount and constricted the expansive movement of the resilient slitted-aperture, giving rise to a PRIMARY ATTENUATION of the fluid outflow.

Figure 15 shows a front perspective view of an emitter being selectively pinched by hand - thumb (17) and forefinger (18) - to produce a gaping outflow aperture (19). The pinching force is applied to the sides of the cutting guides (8) causing them to bow away from each other. The wrap around lips (thinned region) of the slitted- aperture (9) are clearly visible as is the gaping aperture (19) formed by them in the middle of the assembled emitter (1). The resilient body including the slitted- aperture returns to its normal shape once the pinching force is removed, for example immediately after the emitter has been purged of trapped debris.

The body (2) is made from a resilient material for example an injection moulded thermoplastic elastomer (TPE) or a rubber compound in the region of 60° Shore A hardness, providing sufficient elasticity and resilience to expand over and remain gripped onto a ring barbed end of an irrigation fitting when required for use in an irrigation system. As stated previously and also in the second embodiment shown, the body (2) is injection moulded as a blind component with the slitted-aperture (10) being made afterwards. If blind components are supplied to the end user, they can in a first instance be used as end caps to close off irrigation fittings, afterwhich an operator can cut a slit - to create the slitted-aperture (10) - between the guides (8) with a sharp knife, Stanley® blade or similar. And with some basic knowledge, also decide how extensive to make the wrap around slit (cut) within the designated portion of the body (2) for example from 8 to 16 millimetres in wrap around extent, to suit a particular irrigation need.

With the slidable ring (15) parked in a neutral position as in figure 10, the inherent fluid out-flowing characteristics of the body (2) may also be modified by changes to the thickness of the thinned portion (9) and to the thickness of the surrounding domed material (6). Additionally by careful selection of the polymer i.e.; resilience, elasticity and hardness, the emitter body can be manufactured to flex the slitted- aperture (10) open - by the force of the water - to a greater or lesser degree for a given upstream water head. For example a stiffer grade of polymer used in the body would better resist the up-stream water head pressure from a tank supply, enabling a tank to be installed at a higher elevation to supply uniform outflows of irrigation water to a greater number of emitters or increase the emitter outflows to suit the watering needs of larger plants. By contrast a softer grade of polymer might be more suitable for a tank at a lower elevation and serving a smaller number of emitters, for example in the region of 20 emitters. The slidable double-tabbed ring (15) is preferably made from a stiffer (less flexible) polymer than the body material, for example the ring can be cut and notched from an extruded tube having a hardness value in the region of 80° Shore A. Upon assembly and slidable engagement with the lugs (7), the ring (15) would distort locally to follow the external opposing ramped surfaces of the lugs. This feature would be beneficial in two respects namely, the imposed clamping forces on the slitted-aperture (10) would be accurately directed, and the low ramp angles of the lugs (7) would ensure that, by friction and with the intrinsic resilience (springiness) of the two components, they would be positively wedged together to maintain a preferred state of operation. Further, one or both of the component mating surfaces may be textured to increase the effectiveness of the wedging mechanism.

Alternatively the ring (15) could be made by moulding, machining, etc., (not shown) from materials with properties already stated or from a more rigid material to engage slidably with the lugs (7) on the body (2) preferably having at least one internal chamfer for smooth interaction with the ramped surfaces of the lugs (7), to provide a similar wedging action.

When it comes to using the device as an emitter in a tank fed hose system for anything from 1 to 50 emitters on a mixed planting scheme, i.e. a dryland subsistence farmer plot of land, the following is a rough guide of adjustments that might be needed:

With reference to the second embodiment the operation is described with the slidable adjustment ring (15) in the neutral position as in figure 10 - NO ATTENUATION. This would favour the furthest away emitters in a system of distribution hoses - or large plants.

With reference to the second embodiment the operation is described with the slidable adjustment ring (15) in the engaged position on the start of the ramps (7) as in figure 12 with the double tabs facing upstream, providing only INTERMEDIATE ATTENUATION - identical with figure 6 of the first embodiment. This would favour mid-positioned emitters in a system of distribution hoses.

With reference to the second embodiment the operation is described with the slidable adjustment ring (15) in the engaged position fully atop of the ramps (7) as in figure 13 with the double tabs facing towards the direction of flow and providing MAXIMUM ATTENUATION. This would favour those emitters closest to the fluid supply tank in a system of distribution hoses or very large plants. With reference to the second embodiment the operation is described with the slidable adjustment ring (15) in the engaged position, where the ring has been rotated 90° from the position shown in figure 13 to that of figure 14 so that there is no engagement with the ramps (7) but there is an overlap of the ring over the ends of the wrap around slitted-aperture (10) constricting the expansion of this feature and providing PRIMARY ATTENUATION to the flow. This would favour those emitters further away from the fluid supply tank than was the case for figure 13 in a system of distribution hoses or very large plants.

The above examples serve to illustrate the design, the scope for material and performance variations, the assembly and method of use of the present invention and it will be understood that, referring here to an assembled emitter body and adjusting ring, it will be evident to those skilled in the art that further modifications and variations are possible without departing from the underlying principles of the invention, and that all such modifications and variations should be considered within the scope of the present invention.

Claims

1. An emitter having: a hollow body defining a flow channel having a fluid inlet, which channel continues towards a fluid outflow in the form of a resilient slitted-aperture, which aperture provides a resistance to the flow of fluid from the body, the said body having one or more radially displaced projections from the outer surface of the body and adjusting means in mechanical association with the body and assembled to move relative to the body to selectively engage with the projection(s), and with said resilient slitted-aperture also being selectively deformable.

An emitter in accordance with claim 1 wherein the device adjusting means is slidably assembled to slide along the body to selectively engage with the projection(s).

3. An emitter in accordance with claim 1 or 2 wherein the device adjusting means is rotatably assembled to rotate about the body to selectively engage with the projection(s).

4. An emitter in accordance with any preceding claim wherein the device adjusting means comprises a resilient material.

5. An emitter in accordance with any preceding claim wherein the device adjusting means comprises an annular formation surroundingly disposed about the body.

6. An emitter in accordance with any preceding claim wherein the adjusting means comprises a flexibly resilient ring-like formation slidable on the body.

7. An emitter in accordance with any one of claims 1 to 6 wherein the adjusting means comprises a rigid ring-like formation slidable on the body.

8. An emitter in accordance with any preceding claim wherein the adjusting means comprises ring-like formation having one or more tabs projecting perpendicularly from one of its end faces, complementarily arranged with respect to the one or more ramped protuberances or other projections on the body.

9. An emitter in accordance with any preceding claim wherein the resilient slitted-aperture takes the form of an elongate slit in a flexibly resilient formation comprising at least an end portion the body.

10. An emitter in accordance with any preceding claim wherein the body is a resilient body manufactured from a flexibly resilient material.

11. An emitter in accordance with claim 10 comprising a body having an opening at one end to receive fluid under pressure and a slitted-aperture at the other end to provide a means for fluid egress, with said slitted-aperture providing a resilient resistance to the passage of fluid, and the body so engaged in mechanical association with an adjusting means as to attenuate the norma l fluid outflow, said resilient body being selectively deformable such that the slitted-aperture may be changed from a narrow slitted state to a gaping state to significantly increase the egress of fluid and purge entrapped debris.

12. An emitter in accordance with claim 10 or claim 11 wherein the resilient body is manufactured from a thermoplastic elastomer or rubber compound by a process of moulding.

13. An outflow-purgable and adjustable emitter in accordance with any preceding claim comprising a body upon which is slid a slidable ring like formation slidable on the body from a position of neutrality towards the resilient slitted-aperture end of the body for engagement with one or more ramped protuberances from the body surface and where said engagement forces the slitted-aperture towards a more closed position attenuating the outflow of fluid.

An emitter in accordance with any preceding claim wherein the body is manufactured without the slitted-aperture so that the body can be installed onto the end of an irrigation hose fitting, to provide a blind cap end.

An emitter in accordance with claim 14 wherein the body has one or more integral cutting guides projecting in a wrap around formation around an intended fluid outflow end of the body to assist in cutting a slitted-aperture to convert a blind cap end device into an emitter device for the purposes of irrigation.

An emitter in accordance with claim 15 wherein the cutting guides in the form of two closely spaced parallel wings projecting from the body are made of resilient material, which resilience enables the guides to act as stand-offs when the device is selectively squeezed to reduce the incidence of an operator's finger and thumb from obscuring the gaping aperture as it is being formed for front purging, with said resilience also enabling the guides to bow away from each other during the squeezing action so further assisting the formation of the gaping aperture.

A preform for an emitter device in accordance with any one of claims 1 to 13 provided as a blind end cap component for sealing off a fluid passage, with said component adapted to be convertible to an emitter device in accordance with any one of claims 1 to 13.

A preform for an emitter device in accordance with any one of claims 1 to 13 provided as a blind end cap component and comprising a hollow body defining a flow channel having a fluid inlet, which channel continues towards a second end having a closed end cap convertible to a resilient slitted- aperture to provided an emitter in accordance with any one of claims 1 to 13, the said body having one or more radially displaced projections from the outer surface of the body and adjusting means in mechanical association with the body and assembled to move relative to the body to selectively engage with the projection(s).

19. A preform in accordance with claim 18 wherein the body has one or more integral cutting guides projecting in a wrap around formation around an intended fluid outflow end of the body to assist in cutting a slitted-aperture to convert the preform into the emitter device.