AU2008101132B4

AU2008101132B4 - Nozzle

Info

Publication number: AU2008101132B4
Application number: AU2008101132A
Authority: AU
Inventors: Ian Garden
Original assignee: Optima Solutions UK Ltd
Current assignee: Optima Solutions UK Ltd
Priority date: 2008-11-21
Filing date: 2008-11-21
Publication date: 2010-06-17
Anticipated expiration: 2016-11-21
Also published as: AU2008101132A4

Description

AUSTRALIA PATENTS ACT 1990 COMPLETE SPECIFICATION FOR AN INNOVATION PATENT Name and Rigcool Limited Address of Birchmoss Plant & Storage Depot Echt, Westhill Aberdeen AB32 6XL United Kingdom Actual Ian GARDEN Inventor(s): Address for McCarthy Port Patent and Trade Mark Attorneys Service: Suite 6 Level 1 447 Hay Street Perth WA 6000 Invention Title: Nozzle The following statement is a full description of this invention, including the best method of performing it known to me/us: AG1318-3-AUPA 1 Nozzle Field of the invention 5 The present invention relates in general to the field of nozzles for connection to pressurised water supplies, in particular for the purpose of forming curtains of water. Background to the invention 10 In oil and gas production, refining and storage, there is a periodic need to vent and burn off unwanted hydrocarbons as a flare. For example, in oil production operations, it is necessary to test the properties of the production stream, requiring that a portion of the stream be diverted to a test rig and the excess hydrocarbon from the diverted portion of the stream flared off whilst testing takes place. Flares generate a great deal 15 of heat and it is not always practicable for flares to be positioned a sufficient distance from other operations for those operations not to be prone to damage from the heat of the flare. Therefore, water curtains are routinely employed to protect operations from damage 20 cause by the heat from a flare. The provision of a water curtain permits operations behind the water curtains to continue and personnel may continue to utilise work areas which are separated from a flare by a water curtains. Water curtains are also used to protect building and equipment from other sources of 25 heat, in particular where it is not required or not practicable to extinguish the source of heat. For example, water may be most effectively used to protect buildings and equipment from bush fires, until said fires have passed. Alternatively, it may be required to disperse water over a wide area in order to soak that area and prevent the combustion of materials thereon. 30 Water curtains are typically formed by passing pressurised water through a deflecting nozzle. Nozzles commonly in use comprise a body with a through channel, opening onto a deflector positioned at or close to the outlet of the channel. For example, nozzles incorporating half-moon plates, such as those produced by Delta Fire Limited 35 (Norwich, UK), comprise a tubular body opening onto two large flat deflector plates oriented perpendicular to the through channel.

2 Nozzles of this type have a number of problems. The majority of water impinging on the deflector plates is directed along the surface of the plates, however a significant proportion is deflected out of the surface of the deflector plates, resulting in diffusion of the flow of water from the nozzle. This diffusion limits the extent of the curtain of 5 water formed from a nozzle at a given pressure and results in significant spray being deflected generally upstream of the nozzle, towards the operations which the nozzle is positioned to protect. Nozzles having generally conical deflectors have also been proposed, for example 10 the nozzles disclosed in GB 2,433,710 (Optima Solutions UK Limited) and nozzle type D42 produced by Spraying Systems Co. (Carol Stream, Illinois, USA). These nozzles of the prior art have conical deflectors with conical angles between 120 and 150 degrees, such that the flow of water impinges the conical deflectors at angles of approximately 120 degrees and 105 degrees, respectively. Since the angle of 15 incidence of the flow of water on the deflectors is reduced, the flow of water from the conical deflectors is more laminar and less energy is lost to deflection of water away from the surface of the conical deflector, and diffusion of the flow of water is reduced. However, although the amount of spray reaching operations behind the water curtain produced by nozzles of this type is reduced, since the water curtain is projected 20 forwards from the nozzle, such nozzles must be positioned further from a heat source in order for the operations behind the water curtain to be adequately protected from the heat source. Furthermore, as compared to nozzles having deflector plates perpendicular to the flow of water, a greater amount of "fall out" is created. "Fall out" is spray generated by a nozzle in front of the water curtain and is known to wash 25 unburned hydrocarbons from the region of the flare and to create polluted run-off from oil production operations. Water curtains also have applications in providing protection from other heat sources. For example, in the field of fire fighting, it may be more important that certain 30 scientific or industrial installations, for example where pressurised gas is stored, are protected from a fire than to attempt to put out a fire at that location. Indeed, it may not be practicable to put a fire out, for example if the fire is a bush fire or wild fire. In such cases, water curtains may be employed to protect an installation. As with the oil and gas applications discussed above, it is advantageous for water curtains having 35 the minimum of dispersion, and thus the greatest coverage, to be produced by nozzles employed for such applications.

3 Therefore, there remains a need for a nozzle for connection to a pressurised water supply operable to produce a water curtain with reduced fall out and with minimal spray directed generally upstream of the nozzle so as to maximise the extent of the water curtain produced from a given pressure of water. 5 Summary of the invention According to a first aspect of the present invention there is provided a nozzle for connection to a pressurised water supply comprising a body with a channel 10 therethrough, the channel having an inlet and an outlet, a downstream conical deflector positioned at or near the outlet, and, an upstream conical deflector positioned attached to the body at the outlet, having a width equal to or greater than the width of the downstream conical deflector, wherein the upstream and downstream conical deflectors define a fluid pathway for water passing through the nozzle. 15 By the term "conical deflector" we exclude planar deflectors. The two opposing deflectors defining a fluid pathway advantageously provide a more laminar fluid flow, as compared to a nozzle comprising a single conical deflector. 20 Water passing through a nozzle having a single conical deflector will impinge on the conical deflector and will be deflected generally along the surface of the deflector, but a component of the fluid flow will be deflected away from the conical surface of the deflector. Water passing through the nozzle of the present invention travels along a pathway defined by two opposing conical surfaces and the angular distribution of the 25 water leaving the downstream conical deflector is limited by the upstream conical deflector. The nozzle according to the present invention is therefore operable to produce a more extensive curtain of water for a given pressure of water than nozzles of the prior 30 art. In one form, the width of the upstream conical deflector may be greater than the width of the downstream conical deflector. In one form, the upstream conical deflector, downstream conical deflector, and the channel may be co-axial. 35 4 The provision of an upstream conical deflector with a width greater than the downstream conical deflector ensures that residual diffusion of the curtain of water is predominantly inside the cone of water produced by the nozzle in use, where it functions to reduce heat, and not in the direction of the operator (as for nozzles of the 5 prior art having a single downstream conical deflector). In one form, the upstream conical deflector may be wider than the body. In one form, the width of the downstream conical deflector may be equal to or greater 10 than the width of the channel. In an embodiment, the downstream conical deflector does not extend beyond the width of the body. The body may be tubular and, in one form, the body may have a generally circular cross section. In a preferred embodiment the downstream conical deflector may be 15 secured to a mounting member, and the mounting member may be positioned centrally within the channel and connected to the body by one or more buttresses. In one form, the mounting member may be generally circular, such that at least a portion of the channel is annular. In one form, the mounting member may be hollow (for example, tubular) to minimise the mass of the nozzle. In a preferred embodiment the 20 mounting member may be provided with a conical upstream tip, to smooth fluid flow past the mounting member. In one form, the downstream conical deflector may be threadably secured to the mounting member. In one embodiment, the downstream conical deflector may be 25 provided with a threaded member adapted to be threadably secured to the mounting member. In an alternative embodiment, the downstream conical deflector may be secured to a spindle, and the spindle may be secured to the body. In one form, the spindle may be adapted to be secured, for example threadably secured, to a mounting member. 30 In one form, the spindle may be hollow. In one form, the spindle may be generally tubular. In one form, the upstream conical deflector and the downstream conical deflector 35 may have the same conical angle, such that the fluid pathway is conical.

5 Alternatively, the upstream and downstream conical deflectors may have different conical angles or different surface profiles. In one embodiment, the downstream conical deflector may have a ramped surface 5 profile, such that the fluid pathway does not extend around the entire width of the nozzle, thereby providing a partial curtain of water, in use. In a preferred embodiment, the conical angle of the downstream deflector may be greater than 160 degrees. In one form, the conical angle of the downstream deflector 10 may be approximately 170 degrees. In one embodiment, the width of the fluid pathway may be adjusted. In one embodiment, the downstream conical deflector may be mounted on a spindle 15 and the spindle may be attached to the body. In one form, the spindle and/or the downstream conical deflector may be demountable and thereby replaceable. In an embodiment, the width of the fluid pathway may be adjustable by adjusting the position of the downstream conical deflector on the spindle. The position of the 20 downstream conical deflector on the spindle may be adjusted by placing one or more spacers on the spindle between the downstream conical deflector and the body. In an alternative embodiment, the downstream conical deflector may be threadably mounted on the spindle and the position of the downstream conical deflector can be adjusted by rotating the downstream conical deflector. 25 According to a second aspect of the present invention there is provided a nozzle for connection to a pressurised water supply comprising a body with a channel therethrough, the channel having an inlet and an outlet, and a downstream conical deflector positioned at or near the outlet, having a conical angle greater than 160 30 degrees. In one form, the conical angle may be between 165.0 and 175.0 degrees. In one form, the conical angle may be approximately 170 degrees. 35 A downstream conical deflector having a conical angle of at least 160 degrees and, in one embodiment, approximately 170 degrees is suitable for use in closer proximity to 6 a heat source, such as a flare, than nozzles of the prior art having conical deflectors with conical angles between 120 degrees and 150 degrees. The use of a larger conical angle, than conical deflectors of nozzles of the prior art, 5 reduces the amount of spray, or "fall out" reaching the flame from the nozzle. Fall out is known to wash unburned combustion products from a flame, for example unburned hydrocarbons from a flare, and may therefore cause pollution. In one embodiment the nozzle may comprise an upstream conical deflector attached 10 to the body at the outlet, having a width equal to or greater than the width of the downstream conical deflector, wherein the upstream and downstream conical deflectors define a fluid pathway for water passing through the nozzle. Whereas a nozzle with a deflector having a lower conical angle increases fall out, as 15 discussed above, it is known that increasing the conical angle of a conical deflector increases the amount of spray directed back from the nozzle, generally upstream, which is typically towards a work area. Therefore spray directed generally upstream is undesirable. An upstream conical deflector and a downstream conical deflector defining a fluid pathway is particularly advantageous, because, for a given conical 20 angle, fluid flow is more laminar than from a nozzle of the prior art comprising a single conical deflector. Therefore, spray directed generally upstream is reduced and use of a higher conical angle is possible, enabling use of such a nozzle in closer proximity to both a heat source and a work area than the nozzles of the prior art. 25 In one form, the upstream conical deflector may be wider than the body. In one embodiment, the downstream conical deflector may not extend beyond the width of the body. 30 In one form, the upstream conical deflector and the downstream conical deflector may have the same conical angle, such that the fluid pathway is conical. Alternatively, the upstream and downstream conical deflectors may have different conical angles or different surface profiles. 35 In one embodiment, the width of the fluid pathway may be adjusted.

7 In one form, the nozzle according to the first aspect, and the nozzle according to the second aspect may further comprise a flushing mechanism, operable to increase the width of the fluid pathway in order to flush trapped debris out of the nozzle if the fluid pressure in the nozzle is manually increased above a predetermined threshold 5 pressure. The flushing mechanism may be mounted on the spindle. In one embodiment, the downstream conical deflector is slideably mounted on the spindle and the flushing mechanism may comprise a spring mounted on the spindle between the downstream conical deflector and an abutting member positioned at the downstream end of the spindle, such that the spring is forced into compression if the 10 pressure in the nozzle is manually increased above a predetermined threshold pressure. In an alternative embodiment, a rigid collar may be provided in place of the spring. A rigid collar prevents the downstream conical deflector from sliding on the spindle. 15 The nozzle of the present invention may be used with abundant natural water sources, such as sea water or river water or water from an aquifer, and such natural water sources typically contain debris. Therefore, debris may become trapped in the nozzle, and the fluid pathway is particularly prone to capturing debris since the fluid 20 pathway typically defines the narrowest width for fluid flowing through the nozzle. A flushing mechanism operable to flush debris from the nozzle in the event the nozzle becomes blocked or partially blocked with debris, by temporarily increasing the width of the fluid pathway, advantageously releases trapped debris from the nozzle without 25 the requirement to discontinue the flow of water and disassemble the nozzle. In one form, the threshold pressure may be predetermined according to the operating conditions of the nozzle and is above the maximum pressure within the unblocked, partially blocked or fully blocked nozzle during normal operation. This ensures that 30 the flushing mechanism only operates if the pressure is manually increased above normal, such that the flushing mechanism cannot operate under normal circumstances. A threshold pressure so chosen ensures consistent operation of the nozzle and prevents debris sufficiently large to become trapped in the nozzle from being ejected from the nozzle when it is not safe, for example if personnel approach a 35 blocked or partially blocked nozzle for inspection.

8 In one form, a nozzle comprising a flushing mechanism operable to temporarily increase the width of the fluid pathway, may comprise an upstream conical deflector which has a width greater than the width of the downstream conical deflector and, in one embodiment, a width greater than the width of the body. The upstream conical 5 deflector thus provides some physical protection to the flushing mechanism. According to a third aspect of the present invention, there is provided a kit of parts for a nozzle for connection to a pressurised water supply, comprising; a body with a channel therethrough, the channel having an inlet and an outlet; a first upstream 10 conical deflector attached or adapted for attachment to the body at the outlet; and a first downstream conical deflector adapted to be attached to the body at or near the outlet. In one form, the kit of parts may comprise one or more further upstream or 15 downstream conical deflectors adapted to be attached to the body instead of the first and/or second conical deflectors, each said further conical deflector having a different surface profile to each said first conical deflector. The kit of parts is thus suitable to assemble nozzles having a variety of fluid 20 pathways. In one form, the kit of parts may comprise a spindle adapted to support the downstream conical deflector and adapted to be attached to the body. In one form, the kit may further comprise one or more spacers adapted to be mounted on the 25 spindle and thereby adjust the position of the downstream conical deflector when mounted on the spindle. In one embodiment, the kit of parts may comprise an abutting member adapted to be mounted on the spindle and a first spring and adapted to be mounted on the spindle 30 between the downstream conical deflector and the abutting member and thereby provide a flushing mechanism. In one form, the kit may comprise one or more further springs adapted to be mounted on the spindle in place of the first spring, having a different spring rate to the first spring, such that the kit is suitable to assemble nozzles having flushing mechanisms operable above different threshold pressures. 35 9 Typically, the nozzle of the present invention is suitable to be employed in a number of locations. Installation of a nozzle may require adjustments to, or optimisation of, one or more of the threshold pressure, the width of the fluid pathway or the conical angle, the degree of dispersion, and direction of the water curtain. Provision of a kit 5 of parts suitable to assemble nozzles having a range of properties therefore advantageously enables the rapid installation of a nozzle optimised for given set of operating conditions. Further optional and preferred features of the nozzle assembled from the kit of parts 10 according to the third aspect of the present invention correspond to those disclosed in relation to the first and second aspects. According to a fourth aspect of the present invention there is provided a nozzle for connection to a pressurised water supply comprising a body with a channel 15 therethrough, the channel having an inlet and an outlet, and a downstream conical deflector positioned at or near the outlet, wherein the body further comprises an access port in communication with the channel suitable for the introduction of a pressurised fluid. 20 In one form the access port may be adapted to be suitable for connection to a compressed air supply. The provision of an access port in communication with the channel facilitates the dispersion or mixing of a second pressurised fluid within the pressurised water 25 supply, prior to exiting the nozzle. For certain applications, for example in extinguishing fire, or suppressing heat (as compared to providing protection therefrom) it is advantageous to mix, or disperse a secondary fluid within the pressurised water supply passing through the nozzle, in use. For example, introduction of compressed air enables the nozzle, in use, to eject a curtain of fine 30 water droplets resulting from the dispersion of the compressed air with the pressurised water supply. Alternatively, fire retardant fluid, or oil dispersing fluid might be introduced into the access port and dispersed or mixed with the pressurised water supply.

10 Further optional and preferred features of the nozzle according to the fourth aspect of the present invention correspond to those disclosed in relation to the first and second aspects. 5 Brief Description of the Drawings An example embodiment of the present invention will now be illustrated with reference to the following Figures in which: 10 Figure 1 shows a perspective view of a nozzle, viewed from the upstream end, with the body of the nozzle shown in cross section. Figure 2 shows a cross sectional view of a nozzle. 15 Figure 3 shows an exploded view of a nozzle, viewed from the downstream end. Figure 4 shows a kit of parts for a nozzle. Detailed Description of Example Embodiments 20 Figure 1 shows a perspective view of a nozzle 1 according to an embodiment of the present invention, with the body 3 of the nozzle shown in cross section through the axis A of the nozzle. 25 The body is generally tubular, with a cylindrical inner surface 5 defining a channel 7. The body comprises an externally threaded portion 11 at the upstream end 13 of the body adapted to be screwed into a corresponding internally threaded portion of pipe work connected to a pressurised water supply (not shown). The outer surface of the 30 body comprises flattened sections 9 to enable the body to be gripped by a tool such as a spanner. At the downstream end 15 of the channel is an upstream conical deflector 17. In the embodiment shown, the upstream conical deflector is integral to the body but in 35 alternative embodiments a separate upstream conical deflector is fixedly attached to 11 the body. The upstream conical deflector will be discussed in further detail with reference to Figure 2, below. Positioned centrally within the channel, along A, supported within the channel by 5 buttresses 19 is a supporting brace 21 (functioning as a mounting member). The portion of the channel comprising the supporting brace is therefore annular. The supporting brace is tubular, to minimize the weight of the nozzle, and is provided with an internally threaded section at its downstream end, into which spindle 25 is threadably secured. 10 The upstream end of the supporting brace is provided with a conical tip 22, having a conical angle of 90 degrees. The upstream edges 20 of the buttresses are similarly provided with a tapered profile. The upstream edges and conical tip are adapted to break up debris entering the nozzle into fragments sufficiently small to pass along the 15 annular section of the channel. Mounted on the spindle are downstream conical deflector 27, spring 29 and end cap 31. The spring abuts the end cap at the its downstream end and abuts the downstream conical deflector at its upstream end. The downstream conical deflector 20 is slideably mounted on the spindle, and in normal operating conditions is held firmly against the upstream end of the spindle, in the position shown, by the force of the spring. However, as discussed in further detail below, the downstream conical deflector is operable to slide in a downstream direction along the spindle in response to manually increasing the pressure of water in the nozzle above a threshold 25 pressure sufficient to overcome the force of the spring. Therefore, above the threshold pressure, the spindle, the downstream conical deflector, the spring and the end cap function as a flushing mechanism. In an alternative embodiment (not shown) a rigid collar is provided in place of the 30 spring. A rigid collar prevents the downstream conical deflector from sliding on the spindle. Figure 2 shows a cross section of the nozzle 1 through axis A. Upstream conical deflector 17 has an upstream conical surface 18 extending from the inner cylindrical 35 surface 5 at the downstream end 15 of the channel 7 beyond the external width of the body 3.

12 Downstream conical deflector 27 is slideably mounted on spindle 25 and is held against flange 33 by the force of spring 29. Flange 33 has the same external diameter as the supporting brace. Spring 29 is held in position about the spindle by opposing radial channels 35,36 set into the faces of end cap 31 and the downstream 5 conical deflector to which the spring abuts. The downstream conical deflector has a downstream conical deflecting surface 28 extending radially from the external surface of the flange to the external width of the body. Conical surfaces 18,28 have a conical angle of 170 degrees and are therefore 10 at an angle of 5 degrees to plane B, which is perpendicular to axis A. The opposing conical surfaces 18,28 overlap and thereby define a conical fluid pathway 37. The width of the conical fluid pathway is adjustable by positioning one or more spacers around the spindle between the downstream conical deflector and the flange. 15 In use, the nozzle is connected to a pressurised water supply. Water passes into the channel 7 and exits the downstream end of the channel and impinges the downstream conical deflector. The portion of the downstream conical surface directly in line with the channel 7 is shown by shaded region 39 in figure 1. 20 The water is directed generally radially, away from axis A along the downstream conical surface. Any water reflected in an upstream direction away from the downstream conical surface impinges the upstream conical surface and is directed generally radially away from axis A along the upstream conical surface. The flow of water out of the channel along the fluid pathway is thus substantially laminar. 25 The spindle, the spring, the cap and the downstream conical deflector slideably mounted on the spindle function as a flushing mechanism. Nozzles of the present invention are typically used in the field and are thus connected to natural water sources such as sea water, river water, aquifers and the like. Debris such as soil or 30 rocks may be introduced into the nozzle when used with such water sources. If debris enters the nozzle, there exists the risk that the nozzle will become blocked and the extent and effectiveness of the water curtain will become compromised. The risk of such a blockage occurring is reduced by the provision of the conical tip and the 35 upstream edges of the supporting braces, as discussed above. However, residual debris may become trapped upstream of the conical fluid pathway. If the water 13 pressure in the nozzle is manually increased above a threshold pressure, as determined by the spring force of the spring, the downstream conical deflector slides downstream along the spindle such that the width of the conical fluid pathway is increased and debris is flushed from the nozzle. 5 In an alternative the conical angles of the downstream conical deflector and the upstream conical deflector are not equal. In certain applications, for example where a plurality of nozzles are connected to a pressurised water supply and wherein a curtain of water having a different size is required, the provision of conical surfaces 10 having different conical angles allows the extent and divergence of the curtain of water to be adjusted. In another embodiment, one or other of the upstream and downstream conical deflectors, and preferably the downstream conical deflector is provided with a ramped 15 surface profile. In certain applications, for example due to space constraints, it may be required to produce a directional curtain of water. The provision of a ramped surface enables the downstream conical surface and the upstream conical surface to come into contact around a portion of the circumference of the nozzle such that a fluid pathway is provided around a portion of the circumference of the nozzle. 20 In a still further embodiment (not shown) an injection port is provided in the body, in fluid communication with the annular region of the channel. In certain applications, for example in fighting bushfires, it is required to generate a wide dispersion of water droplets in order to wet a large area and impede progression of a fire. Thus, 25 compressed air injected into the injection port becomes dispersed in the flow of pressurised water and the nozzle produces an "atomised" spray of water suitable for wetting a broad area. Figure 3 shows an exploded view of a nozzle according to the present invention, 30 showing the relationship between the component parts. Figure 4 shows a kit of parts for a nozzle according to the present invention. Nozzles are typically shipped to remote locations, for example to offshore installations, and must be adapted to suit the requirements at that location. The nozzle of the present 35 invention is advantageously suited to be disassembled into a number of compatible components. In the example shown in figure 4, the kit comprises body 3 and 14 alternative body 4, having upstream conical deflector 17 and alternative upstream conical deflector 17a, respectively, wherein upstream conical deflectors 17 and 17a have different conical angles. 5 The kit further comprises a plurality of spacers 34 adapted to fit over a spindle 25 and thereby adjust the width of the conical fluid pathway of an assembled nozzle. The kit also comprises downstream conical deflector 17 and alternate conical deflector 17a, having different conical angles and/or surface profiles. Each 10 downstream conical deflector 17,17a is adapted to be installed on either of body 3 or alternative body 4. The kit also comprises a spring 29 and may comprise alternative springs having different strengths. Adjustment of the strength of a spring and/or introduction or 15 removal of one or more washers (to adjust the length of the spring in an assembled nozzle) facilitates adjustment of the threshold pressure at which the flushing mechanism actuates, when the assembled nozzle is in use. In an alternative embodiment, spring 29 may be replaced by cylinder 30 such that the downstream conical deflector is held rigidly in place. This arrangement may be advantageous, for 20 example, for applications wherein the pressure of the pressurised water supply is highly variable. Further variations and modifications can be made within the scope of the invention herein disclosed. 25 It will be clearly understood that, although a number of prior art publications or systems are referred to herein, this reference does not constitute an admission that any of these documents or systems forms part of the common general knowledge in the art, in Australia or in any other country. In the statement of invention and 30 description of the invention which follow, except where the context requires otherwise due to express language or necessary implication, the word "comprise" or variations such as "comprises" or "comprising" is used in an inclusive sense, i.e. to specify the presence of the stated features but not to preclude the presence or addition of further features in various embodiments of the invention. 35

Claims

1. A nozzle for connection to a pressurised water supply comprising a body with a channel therethrough, the channel having an inlet and an outlet, a downstream 5 conical deflector positioned at or near the outlet, and, an upstream conical deflector positioned attached to the body at the outlet, having a width equal to or greater than the width of the downstream conical deflector, wherein the upstream and downstream conical deflectors define a fluid pathway for water passing through the nozzle. 10

2. The nozzle according to claim 1 wherein the downstream conical deflector has a conical angle greater than 160 degrees,

3. The nozzle according to claim 1, wherein the downstream conical deflector has a conical angle of approximately 175 degrees. 15

4. The nozzle according to any one of claims 1 to 3 further comprising a flushing mechanism operable by manually increasing fluid pressure in the nozzle above a predetermined threshold pressure, in use. 20

5. A kit of parts for a nozzle for connection to a pressurised water supply, the kit comprising a body with a channel therethrough, the channel having an inlet and an outlet, at least one downstream conical deflector adapted to be attached to the body at or near the outlet, and, an upstream conical deflector positioned attached to the body at the outlet, having a width equal to or greater than the width of the 25 downstream conical deflector, wherein the upstream and downstream conical deflectors define a fluid pathway for water passing through the nozzle.