GB2465427A

GB2465427A - Nozzle having upstream and downstream conical deflectors

Info

Publication number: GB2465427A
Application number: GB0821313A
Authority: GB
Inventors: Ian Garden
Original assignee: RIGCOOL Ltd
Current assignee: RIGCOOL Ltd
Priority date: 2008-11-21
Filing date: 2008-11-21
Publication date: 2010-05-26
Anticipated expiration: 2028-11-21
Also published as: GB2465427B; GB0821313D0

Abstract

A nozzle 1 for connection to a pressurised water supply comprising a body 3 with a channel 7 therethrough, the channel having an inlet and an outlet, a downstream conical deflector 27 positioned at or near the outlet, wherein the downstream deflector has a width equal to or greater than the width/ diameter of the outlet, and an upstream conical deflector 17 attached to the body at the outlet, the upstream conical deflector having a width equal to or greater than the width of the downstream conical deflector, wherein the fluid is able to flow between the conical deflectors / guides 17, 27. The deflectors may have different angles / cone shapes. The downstream deflector may be spring-biased to allow for flushing of debris. Independent claims relates to nozzles with the downstream conical deflector having a conical angle greater than 160 degrees, and the body comprises an access port in the channel suitable for the introduction of a pressurised air.

Description

1 Nozzle

3 Field of the invention

The present invention relates in general to the field of nozzles for connection to 6 pressurised water supplies, in particular for the purpose of forming curtains of water.

8 Background to the invention

In oil and gas production, refining and storage, there is a periodic need to vent and 11 burn off unwanted hydrocarbons as a flare. For example, in oil production operations, 12 it is necessary to test the properties of the production stream, requiring that a portion 13 of the stream be diverted to a test rig and the excess hydrocarbon from the diverted 14 portion of the stream flared off whilst testing takes place. Flares generate a great deal of heat and it is not always practicable for flares to be positioned a sufficient distance 16 from other operations for those operations not to be prone to damage from the heat of 17 the flare.

19 Therefore, water curtains are routinely employed to protect operations from damage cause by the heat from a flare. The provision of a water curtain permits operations 21 behind the water curtains to continue and personnel may continue to utilise work 22 areas which are separated from a flare by a water curtains.

24 Water curtains are also used to protect building and equipment from other sources of heat, in particular where it is not required or not practicable to extinguish the source 26 of heat. For example, water may be most effectively used to protect buildings and 27 equipment from bush fires, until said fires have passed. Alternatively, it may be 1 required to disperse water over a wide area in order to soak that area and prevent the 2 combustion of materials thereon.

4 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 6 onto a deflector positioned at or close to the outlet of the channel. For example, 7 nozzles incorporating half-moon plates, such as those produced by Delta Fire Limited 8 (Norwich, UK), comprise a tubular body opening onto two large flat deflector plates 9 oriented perpendicular to the through channel.

11 Nozzles of this type have a number of problems. The majority of water impinging on 12 the deflector plates is directed along the surface of the plates, however a significant 13 proportion is deflected out of the surface of the deflector plates, resulting in diffusion 14 of the flow of water from the nozzle. This diffusion limits the extent of the curtain of water formed from a nozzle at a given pressure and results in significant spray being 16 deflected generally upstream of the nozzle, towards the operations which the nozzle 17 is positioned to protect.

19 Nozzles having generally conical deflectors have also been proposed, for example the nozzles disclosed in GB 2,433,710 (Optima Solutions UK Limited) and nozzle 21 type D42 produced by Spraying Systems Co. (Carol Stream, Illinois, USA). These 22 nozzles of the prior art have conical deflectors with conical angles between 120 and 23 150 degrees, such that the flow of water impinges the conical deflectors at angles of 24 approximately 120 degrees and 105 degrees, respectively. Since the angle of incidence of the flow of water on the deflectors is reduced, the flow of water from the 26 conical deflectors is more laminar and less energy is lost to deflection of water away 27 from the surface of the conical deflector, and diffusion of the flow of water is reduced.

28 However, although the amount of spray reaching operations behind the water curtain 29 produced by nozzles of this type is reduced, since the water curtain is projected forwards from the nozzle, such nozzles must be positioned further from a heat source 31 in order for the operations behind the water curtain to be adequately protected from 32 the heat source. Furthermore, as compared to nozzles having deflector plates 33 perpendicular to the flow of water, a greater amount of "fall out" is created. "Fall out" 34 is spray generated by a nozzle in front of the water curtain and is known to wash unburned hydrocarbons from the region of the flare and to create polluted run-off from 36 oil production operations.

2 Water curtains also have applications in providing protection from other heat sources.

3 For example, in the field of fire fighting, it may be more important that certain 4 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 6 not be practicable to put a fire out, for example if the fire is a bush fire or wild fire. In 7 such cases, water curtains may be employed to protect an installation. As with the oil 8 and gas applications discussed above, it is advantageous for water curtains having 9 the minimum of dispersion, and thus the greatest coverage, to be produced by nozzles employed for such applications.

12 Therefore, there remains a need for a nozzle for connection to a pressurised water 13 supply operable to produce a water curtain with reduced fall out and with minimal 14 spray directed generally upstream of the nozzle so as to maximise the extent of the water curtain produced from a given pressure of water.

17 Summary of the invention

19 According to a first aspect of the present invention, there is provided a nozzle for connection to a pressurised water supply, the nozzle comprising; a body with a 21 channel therethrough, the channel having an inlet and an outlet; a downstream 22 conical deflector positioned at or near the outlet, having a width equal to or greater 23 than the width of the outlet; and an upstream conical deflector attached to the body at 24 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 26 pathway for water passing through the nozzle.

28 By the term "conical deflector" we exclude planar deflectors.

The two opposing deflectors defining a fluid pathway advantageously provide a more 31 laminar fluid flow, as compared to a nozzle comprising a single conical deflector.

32 Water passing through a nozzle having a single conical deflector will impinge on the 33 conical deflector and will be deflected generally along the surface of the deflector, but 34 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 36 pathway defined by two opposing conical surfaces and the angular distribution of the 1 water leaving the downstream conical deflector is limited by the upstream conical 2 deflector.

4 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 6 art.

8 Preferably, the width of the upstream conical deflector is greater than the width of the 9 downstream conical deflector. Most preferably, the upstream conical deflector, downstream conical deflector, and the channel are co-axial.

12 The provision of an upstream conical deflector with a width greater than the 13 downstream conical deflector ensures that residual diffusion of the curtain of water is 14 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 16 prior art having a single downstream conical deflector).

18 Preferably, the upstream conical deflector is wider than the body.

Preferably, the width of the downstream conical deflector is equal to or greater than 21 the width of the channel. In an embodiment, the downstream conical deflector does 22 not extend beyond the width of the body.

24 The body is preferably tubular and most preferably, the body has a generally circular cross section. In a preferred embodiment the downstream conical deflector is 26 secured to a mounting member, and the mounting member is positioned centrally 27 within the channel and connected to the body by one or more buttresses. Preferably, 28 the mounting member is generally circular, such that at least a portion of the channel 29 is annular. Most preferably, the mounting member is hollow (for example, tubular) to minimise the mass of the nozzle. In a preferred embodiment the mounting member is 31 provided with a conical upstream tip, to smooth fluid flow past the mounting member.

33 Preferably, the downstream conical deflector is threadably secured to the mounting 34 member. In one embodiment, the downstream conical deflector is provided with a threaded member adapted to be threadably secured to the mounting member. In an 36 alternative embodiment, the downstream conical deflector is secured to a spindle, 1 and the spindle is secured to the body. Most preferably, the spindle is adapted to be 2 secured, for example threadably secured, to a mounting member.

4 Preferably, the spindle is hollow. Most preferably, the spindle is generally tubular.

6 Preferably, the upstream conical deflector and the downstream conical deflector have 7 the same conical angle, such that the fluid pathway is conical. Alternatively, the 8 upstream and downstream conical deflectors have different conical angles or different 9 surface profiles.

11 In one embodiment, the downstream conical deflector has a ramped surface profile, 12 such that the fluid pathway does not extend around the entire width of the nozzle, 13 thereby providing a partial curtain of water, in use.

In a preferred embodiment, the conical angle of the downstream deflector is greater 16 than 160 degrees. Most preferably, the conical angle of the downstream deflector is 17 approximately 170 degrees.

19 In one embodiment, the width of the fluid pathway may be adjusted.

21 In one embodiment, the downstream conical deflector is mounted on a spindle and 22 the spindle is attached to the body. Preferably, the spindle and/or the downstream 23 conical deflector are demountable and thereby replaceable.

In an embodiment, the width of the fluid pathway is adjustable by adjusting the 26 position of the downstream conical deflector on the spindle. The position of the 27 downstream conical deflector on the spindle may be adjusted by placing one or more 28 spacers on the spindle between the downstream conical deflector and the body. In an 29 alternative embodiment, the downstream conical deflector is threadably mounted on the spindle and the position of the downstream conical deflector can be adjusted by 31 rotating the downstream conical deflector.

33 According to a second aspect of the present invention there is provided a nozzle for 34 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 1 deflector positioned at or near the outlet, having a conical angle greater than 160 2 degrees.

4 Preferably, the conical angle is between 165.0 and 175.0 degrees. Most preferably, the conical angle is approximately 170 degrees.

7 A downstream conical deflector having a conical angle of at least 160 degrees and 8 preferably, approximately 170 degrees is suitable for use in closer proximity to a heat 9 source, such as a flare, than nozzles of the prior art having conical deflectors with conical angles between 120 degrees and 150 degrees.

12 The use of a larger conical angle, than conical deflectors of nozzles of the prior art, 13 reduces the amount of spray, or "fall out" reaching the flame from the nozzle. Fall out 14 is known to wash unburned combustion products from a flame, for example unburned hydrocarbons from a flare, and may therefore cause pollution.

17 In one embodiment the nozzle comprises an upstream conical deflector attached to 18 the body at the outlet, having a width equal to or greater than the width of the 19 downstream conical deflector, wherein the upstream and downstream conical deflectors define a fluid pathway for water passing through the nozzle.

22 Whereas a nozzle with a deflector having a lower conical angle increases fall out, as 23 discussed above, it is known that increasing the conical angle of a conical deflector 24 increases the amount of spray directed back from the nozzle, generally upstream, which is typically towards a work area. Therefore spray directed generally upstream 26 is undesirable. An upstream conical deflector and a downstream conical deflector 27 defining a fluid pathway is particularly advantageous, because, for a given conical 28 angle, fluid flow is more laminar than from a nozzle of the prior art comprising a single 29 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 31 both a heat source and a work area than the nozzles of the prior art.

33 Preferably, the upstream conical deflector is wider than the body.

In one embodiment, the downstream conical deflector does not extend beyond the 36 width of the body.

2 Preferably, the upstream conical deflector and the downstream conical deflector have 3 the same conical angle, such that the fluid pathway is conical. Alternatively, the 4 upstream and downstream conical deflectors have different conical angles or different surface profiles.

7 In one embodiment, the width of the fluid pathway may be adjusted.

9 Preferably, the nozzle according to the first aspect, and the nozzle according to the second aspect further comprise a flushing mechanism, operable to increase the width 11 of the fluid pathway in order to flush trapped debris out of the nozzle if the fluid 12 pressure in the nozzle is manually increased above a predetermined threshold 13 pressure. The flushing mechanism may be mounted on the spindle. In one 14 embodiment, the downstream conical deflector is slideably mounted on the spindle and the flushing mechanism comprises a spring mounted on the spindle between the 16 downstream conical deflector and an abutting member positioned at the downstream 17 end of the spindle, such that the spring is forced into compression if the pressure in 18 the nozzle is manually increased above a predetermined threshold pressure.

In an alternative embodiment, a rigid collar is provided in place of the spring. A rigid 21 collar prevents the downstream conical deflector from sliding on the spindle.

23 The nozzle of the present invention is typically used with abundant natural water 24 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 26 nozzle, and the fluid pathway is particularly prone to capturing debris since the fluid 27 pathway typically defines the narrowest width for fluid flowing through the nozzle.

29 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 31 of the fluid pathway, advantageously releases trapped debris from the nozzle without 32 the requirement to discontinue the flow of water and disassemble the nozzle.

34 Most preferably the threshold pressure is predetermined according to the operating conditions of the nozzle and is above the maximum pressure within the unblocked, 36 partially blocked or fully blocked nozzle during normal operation. This ensures that 1 the flushing mechanism only operates if the pressure is manually increased above 2 normal, such that the flushing mechanism cannot operate under normal 3 circumstances. A threshold pressure so chosen ensures consistent operation of the 4 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 6 blocked or partially blocked nozzle for inspection.

8 Most preferably, a nozzle comprising a flushing mechanism operable to temporarily 9 increase the width of the fluid pathway, comprises an upstream conical deflector which has a width greater than the width of the downstream conical deflector and 11 preferably, a width greater than the width of the body. The upstream conical deflector 12 thus provides some physical protection to the flushing mechanism.

14 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 16 channel therethrough, the channel having an inlet and an outlet; a first upstream 17 conical deflector attached or adapted for attachment to the body at the outlet; and a 18 first downstream conical deflector adapted to be attached to the body at or near the 19 outlet.

21 Preferably, the kit of parts comprises one or more further upstream or downstream 22 conical deflectors adapted to be attached to the body instead of the first and/or 23 second conical deflectors, each said further conical deflector having a different 24 surface profile to each said first conical deflector.

26 The kit of parts is thus suitable to assemble nozzles having a variety of fluid 27 pathways.

29 Preferably, the kit of parts comprises a spindle adapted to support the downstream conical deflector and adapted to be attached to the body. Preferably, the kit further 31 comprises one or more spacers adapted to be mounted on the spindle and thereby 32 adjust the position of the downstream conical deflector when mounted on the spindle.

34 In one embodiment, the kit of parts comprises an abutting member adapted to be mounted on the spindle and a first spring and adapted to be mounted on the spindle 36 between the downstream conical deflector and the abutting member and thereby 1 provide a flushing mechanism. Preferably, the kit comprises one or more further 2 springs adapted to be mounted on the spindle in place of the first spring, having a 3 different spring rate to the first spring, such that the kit is suitable to assemble nozzles 4 having flushing mechanisms operable above different threshold pressures.

6 Typically, the nozzle of the present invention is suitable to be employed in a number 7 of locations. Installation of a nozzle may require adjustments to, or optimisation of, 8 one or more of the threshold pressure, the width of the fluid pathway or the conical 9 angle, the degree of dispersion, and direction of the water curtain. Provision of a kit of parts suitable to assemble nozzles having a range of properties therefore 11 advantageously enables the rapid installation of a nozzle optimised for given set of 12 operating conditions.

14 Further optional and preferred features of the nozzle assembled from the kit of parts according to the third aspect of the present invention correspond to those disclosed in 16 relation to the first and second aspects.

18 According to a fourth aspect of the present invention there is provided a nozzle for 19 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 21 deflector positioned at or near the outlet, wherein the body further comprises an 22 access port in communication with the channel suitable for the introduction of a 23 pressurised fluid.

Preferably the access port is adapted to be suitable for connection to a compressed 26 air supply.

28 The provision of an access port in communication with the channel facilitates the 29 dispersion or mixing of a second pressurised fluid within the pressurised water supply, prior to exiting the nozzle. For certain applications, for example in 31 extinguishing fire, or suppressing heat (as compared to providing protection 32 therefrom) it is advantageous to mix, or disperse a secondary fluid within the 33 pressurised water supply passing through the nozzle, in use. For example, 34 introduction of compressed air enables the nozzle, in use, to eject a curtain of fine water droplets resulting from the dispersion of the compressed air with the 36 pressurised water supply. Alternatively, fire retardant fluid, or oil dispersing fluid might 1 be introduced into the access port and dispersed or mixed with the pressurised water 2 supply.

4 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 6 aspects.

8 Brief Description of the Drawings

An example embodiment of the present invention will now be illustrated with 11 reference to the following Figures in which: 13 Figure 1 shows a perspective view of a nozzle, viewed from the upstream end, with 14 the body of the nozzle shown in cross section.

16 Figure 2 shows a cross sectional view of a nozzle.

18 Figure 3 shows an exploded view of a nozzle, viewed from the downstream end.

Figure 4 shows a kit of parts for a nozzle.

22 Detailed Description of Example Embodiments

24 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 26 axis A of the nozzle.

28 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 31 body adapted to be screwed into a corresponding internally threaded portion of pipe 32 work connected to a pressurised water supply (not shown). The outer surface of the 33 body comprises flattened sections 9 to enable the body to be gripped by a tool such 34 as a spanner.

1 At the downstream end 15 of the channel is an upstream conical deflector 17. In the 2 embodiment shown, the upstream conical deflector is integral to the body but in 3 alternative embodiments a separate upstream conical deflector is fixedly attached to 4 the body. The upstream conical deflector will be discussed in further detail with reference to Figure 2, below.

7 Positioned centrally within the channel, along A, supported within the channel by 8 buttresses 19 is a supporting brace 21 (functioning as a mounting member). The 9 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 11 an internally threaded section at its downstream end, into which spindle 25 is 12 threadably secured.

14 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 16 provided with a tapered profile. The upstream edges and conical tip are adapted to 17 break up debris entering the nozzle into fragments sufficiently small to pass along the 18 annular section of the channel.

Mounted on the spindle are downstream conical deflector 27, spring 29 and end cap 21 31. The spring abuts the end cap at the its downstream end and abuts the 22 downstream conical deflector at its upstream end. The downstream conical deflector 23 is slideably mounted on the spindle, and in normal operating conditions is held firmly 24 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 26 deflector is operable to slide in a downstream direction along the spindle in response 27 to manually increasing the pressure of water in the nozzle above a threshold 28 pressure sufficient to overcome the force of the spring. Therefore, above the 29 threshold pressure, the spindle, the downstream conical deflector, the spring and the end cap function as a flushing mechanism.

32 In an alternative embodiment (not shown) a rigid collar is provided in place of the 33 spring. A rigid collar prevents the downstream conical deflector from sliding on the 34 spindle.

1 Figure 2 shows a cross section of the nozzle 1 through axis A. Upstream conical 2 deflector 17 has an upstream conical surface 18 extending from the inner cylindrical 3 surface 5 at the downstream end 15 of the channel 7 beyond the external width of the 4 body 3.

6 Downstream conical deflector 27 is slideably mounted on spindle 25 and is held 7 against flange 33 by the force of spring 29. Flange 33 has the same external 8 diameter as the supporting brace. Spring 29 is held in position about the spindle by 9 opposing radial channels 35,36 set into the faces of end cap 31 and the downstream conical deflector to which the spring abuts.

12 The downstream conical deflector has a downstream conical deflecting surface 28 13 extending radially from the external surface of the flange to the external width of the 14 body. Conical surfaces 18,28 have a conical angle of 170 degrees and are therefore at an angle of 5 degrees to plane B, which is perpendicular to axis A. The opposing 16 conical surfaces 18,28 overlap and thereby define a conical fluid pathway 37. The 17 width of the conical fluid pathway is adjustable by positioning one or more spacers 18 around the spindle between the downstream conical deflector and the flange.

In use, the nozzle is connected to a pressurised water supply. Water passes into the 21 channel 7 and exits the downstream end of the channel and impinges the 22 downstream conical deflector. The portion of the downstream conical surface directly 23 in line with the channel 7 is shown by shaded region 39 in figure 1.

The water is directed generally radially, away from axis A along the downstream 26 conical surface. Any water reflected in an upstream direction away from the 27 downstream conical surface impinges the upstream conical surface and is directed 28 generally radially away from axis A along the upstream conical surface. The flow of 29 water out of the channel along the fluid pathway is thus substantially laminar.

31 The spindle, the spring, the cap and the downstream conical deflector slideably 32 mounted on the spindle function as a flushing mechanism. Nozzles of the present 33 invention are typically used in the field and are thus connected to natural water 34 sources such as sea water, river water, aquifers and the like. Debris such as soil or rocks may be introduced into the nozzle when used with such water sources.

1 If debris enters the nozzle, there exists the risk that the nozzle will become blocked 2 and the extent and effectiveness of the water curtain will become compromised. The 3 risk of such a blockage occurring is reduced by the provision of the conical tip and the 4 upstream edges of the supporting braces, as discussed above. However, residual debris may become trapped upstream of the conical fluid pathway. If the water 6 pressure in the nozzle is manually increased above a threshold pressure, as 7 determined by the spring force of the spring, the downstream conical deflector slides 8 downstream along the spindle such that the width of the conical fluid pathway is 9 increased and debris is flushed from the nozzle.

11 In an alternative the conical angles of the downstream conical deflector and the 12 upstream conical deflector are not equal. In certain applications, for example where 13 a plurality of nozzles are connected to a pressurised water supply and wherein a 14 curtain of water having a different size is required, the provision of conical surfaces having different conical angles allows the extent and divergence of the curtain of 16 water to be adjusted.

18 In another embodiment, one or other of the upstream and downstream conical 19 deflectors, and preferably the downstream conical deflector is provided with a ramped surface profile. In certain applications, for example due to space constraints, it may 21 be required to produce a directional curtain of water. The provision of a ramped 22 surface enables the downstream conical surface and the upstream conical surface to 23 come into contact around a portion of the circumference of the nozzle such that a 24 fluid pathway is provided around a portion of the circumference of the nozzle.

26 In a still further embodiment (not shown) an injection port is provided in the body, in 27 fluid communication with the annular region of the channel. In certain applications, for 28 example in fighting bushfires, it is required to generate a wide dispersion of water 29 droplets in order to wet a large area and impede progression of a fire. Thus, compressed air injected into the injection port becomes dispersed in the flow of 31 pressurised water and the nozzle produces an "atomised" spray of water suitable for 32 wetting a broad area.

34 Figure 3 shows an exploded view of a nozzle according to the present invention, showing the relationship between the component parts.

1 Figure 4 shows a kit of parts for a nozzle according to the present invention. Nozzles 2 are typically shipped to remote locations, for example to offshore installations, and 3 must be adapted to suit the requirements at that location. The nozzle of the present 4 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 6 alternative body 4, having upstream conical deflector 17 and alternative upstream 7 conical deflector 17a, respectively, wherein upstream conical deflectors 17 and 17a 8 have different conical angles.

The kit further comprises a plurality of spacers 34 adapted to fit over a spindle 25 and 11 thereby adjust the width of the conical fluid pathway of an assembled nozzle.

13 The kit also comprises downstream conical deflector 17 and alternate conical 14 deflector 17a, having different conical angles and/or surface profiles. Each downstream conical deflector 17,17a is adapted to be installed on either of body 3 or 16 alternative body 4.

18 The kit also comprises a spring 29 and may comprise alternative springs having 19 different strengths. Adjustment of the strength of a spring and/or introduction or removal of one or more washers (to adjust the length of the spring in an assembled 21 nozzle) facilitates adjustment of the threshold pressure at which the flushing 22 mechanism actuates, when the assembled nozzle is in use. In an alternative 23 embodiment, spring 29 may be replaced by cylinder 30 such that the downstream 24 conical deflector is held rigidly in place. This arrangement may be advantageous, for example, for applications wherein the pressure of the pressurised water supply is 26 highly variable.

28 Further variations and modifications can be made within the scope of the invention 29 herein disclosed.