AU2006201660B2

AU2006201660B2 - Valve Control Mechanism

Info

Publication number: AU2006201660B2
Application number: AU2006201660A
Authority: AU
Inventors: Nicholas Grant Bodley; Terence Peter Clarke; Barry Raymond Rose
Original assignee: MTI Group Pty Ltd
Current assignee: MTI Group Pty Ltd
Priority date: 2005-02-01
Filing date: 2006-04-20
Publication date: 2008-08-14
Anticipated expiration: 2026-02-01
Also published as: AU2006201659A1; AU2006201660A1; AU2006201659B2

Description

2006 19:37 Wallington-Dummer Sydney N o, 50 55 P 4 P/001009 Regulation 3.2

AUSTRALIA

Patents Act 1990 COMPLETE SPECIFICATION VALVE CONTROL MECHANISM Invention Title: The invention is described in the following statement, including the best method of performing it known to us: Our Ref: 062002 COMS ID No: SBMI-03364487 Received by IP Australia: Time 18:47 Date 2006-04-20

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-2- 00 SVARIABLE DISCHARGE VALVE CONTROL MECHANISM The present invention relates to valves for aerosol cans and, more particularly, to release valves for aerosol cans provided with selectable flow rates for the c inflation of bore hole plugs.

5 BACKGROUND

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Typically explosive charges for mining and other excavation activities, are placed in boreholes. Frequently such charges are supported at some point below the

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surface, that is at some desired depth in the borehole. Inflatable plugs in the form of gas tight bags are used for this purpose. The plug is lowered to a desired depth and inflated such that it becomes firmly engaged with the sides of the borehole.

Typically, inflation is by means of an aerosol canister attached to, or located in the bag and arranged so as to discharge its pressurised contents during the descent of the bag down the borehole.

A common problem experienced with such arrangements is that in some situations the bag can inflate too quickly. For example, because aerosol gasses are temperature sensitive, on a hot day the gas passes from the canister at an accelerated rate, causing the plug to lodge at a point higher than intended.

Alternatively, inflation may be so slow that the bag needs to be retained at a desired level by means of an attached line for an undesirably long period.

It is an object of the present invention to address or at least ameliorate some of the above disadvantages.

DISCLOSURE OF THE INVENTION Throughout this specification and claims, unless the context requires otherwise, the word "comprise" or variations such as "comprises" or "comprising", will be understood to imply the inclusion of a stated integer or group of integers but not the exclusion of any other integer or group of integers.

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0 According to one aspect the invention resides in an aerosol canister control Nmechanism for inflation of a borehole plug; said aerosol canister having one end -nupon which, in use, the control mechanism is to be mounted, the one end having 0an outlet adapted to control the passage of the contents of canister from the canister though the outlet, said control mechanism comprising a body which is Oadapted to be mounted to the one end, the control mechanism further comprising I a first member supported for slidable movement relative to the outlet between a 0 closed position and an open position, the first member being formed with at least

(N

I one first orifice positioned to be capable of being in communication with the contents of the canister on said movement to the open position to permit said passage of the contents from the canister through the first orifice, a second member comprising a generally elongate element slidably retained in the body, to overlie the first member and supported by the body for slidable movement, wherein the slidable movement of the second member is generally transverse to the movement of the first member, the second member being movable between a retracted position and an engaged position, the second member being configured to cause said displacement of the first member to its open position, a retention means capable of retaining the second member in the engaged position, the retention means comprising a set of longitudinally spaced detents on the second member which are adapted to cooperate with the body to retain the second member in the engaged position.

According to a preferred feature of the invention the first member comprises a tubular member slidably supported in the outlet to be movable into the canister to permit said communication of the first orifice with the interior of the canister, the tubular member having a discharge outlet at its outer end and being closed at its inner end, said first orifice formed in the wall of the tubular member intermediate of discharge outlet and inner end.

According to a preferred feature of the invention the outlet is associated with a valve element which is positioned to in use close the first orifice when the first member is in the closed position.

According to a preferred feature of the invention said first orifice comprises an elongate slot extending axially along the wall, whereby the degree of said -4- 00

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communication is proportional to the displacement of the first member relative to the outlet.

According to a preferred feature of the invention said first orifice comprises a set Sof longitudinally spaced first orifices extending axially along the wall, whereby the degree of said communication is proportional to the displacement of the first member relative to the outlet.

According to a preferred feature of the invention said first orifice comprises a Ihelical array of spaced first orifices extending along the wall, whereby the degree Sof said communication is proportional to the displacement of the first member relative to the outlet.

According to a preferred feature of the invention the second member is provided with a second orifice which is positioned to be in alignment with the discharge outlet on the second member being moved to its engaged position.

According to a preferred feature of the invention the support provided by the body for the first and second members biases the opposed surfaces of the first and second members into sliding contact.

According to a preferred feature of the invention the detents are positioned such that when in the engaged position they are to each side of the outlet and cooperate with the body to either side of the outlet According to a preferred feature of the invention the detents are located on the face of the second member opposite to the face engaged with the first member.

According to a preferred feature of the invention engagement of the detents with the body will cause transverse movement of the second member relative to the body and cause displacement of the first member to its open position.

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SAccording to a preferred feature of the invention the detents comprise wedge shaped formations.

According to a preferred feature of the invention the one end has a rim N surrounding the discharge nozzle and the body is configured to be able to be attached to the rim to at least partially surround the discharge nozzle.

IND

IAccording to a preferred feature of the invention said body comprises a hollow 0 body formed as a cap-like element which is intended in use to be attached to I said rim of said canister.

N According to another aspect the invention resides in an aerosol canister control mechanism for inflation of a borehole plug; said aerosol canister having one end upon which the control mechanism is to be mounted in use, the one end having an outlet, said control mechanism comprising a body which is adapted to be mounted to the one end, the control mechanism further comprising first member in the form of a discharge nozzle in use supported by the outlet for slidable movement relative to the canister, between a discharging state and a closed state, the discharge nozzle having an opening at its outer end and at least one first orifice towards its inner end and a flow path between the opening and the at least one first orifice, the at least one first orifice being capable of communicating with the interior of the canister, the discharge nozzle associated with a valve element adapted in use to cooperate with the at least one orifice to close the at least one orifice when the discharge nozzle is in the closed state, whereby displacement of the discharge nozzle end to the discharging state will cause relative displacement between the at least one orifice and the valve element to permit the contents of the canister to escape through the opening, the degree of escape being proportional to the degree of displacement of the discharge nozzle, the control member further comprising a second member co-operable with the discharge nozzle and supported by the body for slidable movement generally transverse to the movement of the discharge nozzle, the second member being movable between a retracted position at which the discharge nozzle is in the closed state and a plurality of engaged positions at which the second member is in engagement with the discharge nozzle, the degree of displacement of the -6- 00

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Sdischarge nozzle differing for each engaged position, a second retention means capable of retaining the second member in at least one of its positions.

According to a preferred feature of the invention the discharge nozzle comprises N a tubular member slidably supported in the outlet to be movable into the canister to permit said communication of the at least one first orifice with the interior of the Ccanister, the tubular member having a discharge outlet at its outer end and being closed at its inner end, said at least one first orifice formed in the wall of the N tubular member intermediate of discharge outlet and inner end.

IND

OAccording to a preferred feature of the invention said at least one first orifice comprises an elongate slot extending axially along the wall, whereby the degree of said communication is proportional to the displacement of the discharge nozzle relative to the outlet.

According to a preferred feature of the invention said at least one first orifice comprises a set of longitudinally spaced first orifices extending axially along the wall, whereby the degree of said communication is proportional to the displacement of the discharge nozzle relative to the outlet.

According to a preferred feature of the invention said at least one first orifice comprises a helical array of spaced first orifices extending along the wall, whereby the degree of said communication is proportional to the displacement of the discharge nozzle relative to the outlet.

According to a preferred feature of the invention the second member generally comprises an elongate element slidably retained in the body, said second member overlying the discharge nozzle.

According to a preferred feature of the invention support between the body and the first and second members biases the opposed surfaces of the first and second members into sliding contact.

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NAccording to a preferred feature of the invention the second retention means comprises a set of longitudinally spaced detents which are adapted to cooperate with the body to retain the second member in the engaged position.

CAccording to a preferred feature of the invention the detents are positioned such that when in the engaged position they are to each side of the outlet and cooperate with the body to either side of the outlet SAccording to a preferred feature of the invention the detents are located on the Nface of the second member opposite to the face engaged with the discharge 0 nozzle.

According to a preferred feature of the invention engagement of the detents with the body will cause transverse movement of the second member relative to the body and cause displacement of the discharge nozzle to its open position.

According to a preferred feature of the invention the detents comprise wedge shaped formations.

According to a preferred feature of the invention the one end has a rim surrounding the discharge nozzle and the body is configured to be able to be attached to the rim to at least partially surround the discharge nozzle.

According to a preferred feature of the invention said body comprises a hollow body formed as a cap-like element which is intended in use to be attached to said rim of said canister.

According to another aspect the invention resides in an aerosol canister for inflation of a borehole plug having a control mechanism of the form as described above applied thereto and positioned to cooperate with the discharge nozzle.

The invention will be more fully understood in the light of the following description of several specific embodiments BRIEF DESCRIPTION OF DRAWINGS The description is made with reference to the accompanying drawings wherein: -8- 00oo Figure 1 is a sectioned side view of a valve control mechanism according to a first preferred embodiment of the invention shown in a first deactivated state, Figure 2A is a sectioned view of a typical aerosol gas release valve, Figure 2 is a part sectioned end view of the valve control mechanism of Fig. 1, Figure 3 is a further view of the valve control mechanism of Fig 1 shown in a

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second activated state.

N Figure 4 is a part sectioned side view of a valve control mechanism according to a second preferred embodiment of the invention shown in a first non-activated state, Figure 5 is a further view of the valve control mechanism of Pig. 4 shown in a second activated state, Figures 6A to 6C show forms of a discharge valve component of the second preferred embodiment.

Figure 7 is a sectioned side view of a further example of a valve control mechanism according to the first preferred embodiment when in a nondischarging state, Figure 7A is a sectioned end view of the valve control mechanism of Fig. 7, Figure 8 is a sectioned side view of the valve control mechanism of Figs. 7 and 7A when in a discharging state, Figure 9 is a perspective view of the valve control mechanism of Figs. 7, 7A and 8, Figure 10 is a first side view of a further preferred embodiment of a valve control mechanism according to the invention, Figure 11 is a second side view of the valve control mechanism of Fig. Figure 12 is a part sectioned view of the valve control mechanism of Figs. 10 and 11 when in a non-discharging state with a first one of a plurality of discharge rates selected, -9- 00 Figure 13 is a part sectioned view of the valve control mechanism of Figs. 10 and 11 when in a non-discharging state with a second one of a plurality of discharge C rates selected, (N Figure 14 is a part sectioned view of the valve control mechanism of Figs. 10 and 1.1 when in a discharging state.

O DETAILED DESCRIPTION OF SPECIFIC EMBODIMENTS SFirst Preferred Embodiment SWith reference to Figs 1 and 2, in a first preferred embodiment of the invention a valve system 10 comprises a support structure 12 in the form of a hollow cap attached to the upper rim of an aerosol canister 14. Aerosol canister 14 in this embodiment is provided with a standard aerosol gas release valve 16, retained in the end wall 17 of canister 14.

Release valve 16, as shown in Fig. 1A, comprises a generally cylindrical, partially hollow nozzle 18, open at its upper end 20, and urged upwardly into a limiting position by a spring 22 when in a deactivated state. When nozzle 18 is depressed vertically downwards, an orifice 19 passes below the level of seal 23 thereby allowing pressurized gas 24 to pass through orifice 19 and eject from open end Referring again to Figs. 1 and 2, support structure 12 li3 adapted to retain a sliding control member 26 and an intermediate member 25 in pairs of opposing slots 11 and 13 respectively in the sides of support structure 12. Intermediate member 25 and sliding control member 26 are disposed at right angles one to the other and normal to the axis of canister 14. They are so arranged that sliding control member 26 slides over the upper surface 28 of the intermediate member 25, and conversely, so that intermediate member 25 may slide under sliding control member 26, as indicated by arrow A and B in Figs, 1 and 2 respectively.

Intermediate member 25 and sliding control member 26 are biased upwardly, for example by a spring (not shown), so that the lower surface of intermediate member 25 is just clear of nozzle 18; the upward movement of sliding control member 26 being limited by the upper limits of slots 11.

00 As best seen in Fig. 2, intermediate member 25 comprises an elongate bar provided with a plurality of orifices, three in the example of Fig. 2) 27A, 27D and S27C, each of which is adapted to engage with the outer end 20 of nozzle 16 but which have a gradation of outlet openings in the upper surface 28 of intermediate member 25. Each gradated opening of orifices 27A to 27C may be calibrated for 0a desired rate of flow and length of time of exhaustion of gas from canister is.

N intermediate member 25 may be slid laterally to select any one of the three orifices 27A to 17C to align with nozzle 18. Positive locations may be provided, for example by detent grooves (not shown) in upper surface 28 of sliding control member 25, adapted to engage with a suitable projection downwardly (not shown) from sliding control member 26.

As best seen in Fig. 1, sliding control member 26 is provided with wedge formations 30A and 30B, rising from a first lower level to an upper' level, at which detent areas are provided with detent notches 31A and 31B along the upper edges. Detent notches 31A and 31B are arranged to retain said sliding control member 26 in the position shown in Fig. 3.

Comparing now Figs. 1 and 3, it will be understood that when sliding control member 25 is driven from the position shown in Fig. 1 in the direction of arrow A to that shown in Fig. 3, its underside is progressively driven downwardly and consequently, intermediate member 25 will be driven downwardly to firstly engage and then depress nozzle 18 thus releasing gas 24 from canister 14.

Sliding control member 26 is provided with orifice 34 arranged, such that when detent formations 31A and 31)3 engage the upper edges of slots 11 of support structure 12, as shown in Pig. 3, orifice 34 is aligned with the selected orifice 27A, BorC.

A further example of a valve control mechanism according to this first preferred embodiment is shown in Figs. 7, 8 and 9 in which like features are numbered alike, and in which the support structure 12 comprises a base ring 40 with opposing pairs of vertical posts, each pair bridged by a cross member 42 and 44 respectively, to provide opposing slots 11 analogous to the slots 11 depicted in Figs. 1 and 3.

-11 00 oo SSecond Preferred Embodiment CWith reference to Figs. 4 and 5, a support structure 112 is similarly attached to the upper rim of an aerosol canister 114. A control member 126 is slidably C~ retained in support structure 112, passing through slots 111A and 1115.

The underside of control member 126 is provided with a wedge structure 128 IDarranged so that when control member 126 is driven from the position shown in Fig. 4 to that shown in Fig. 5, wedge structure 128 causes discharge nozzle 118 IDto be depressed vertically downward.

N The upper side of control member 126 is provided with a. plurality of detent grooves 131 for engagement with the upper inside edge of slot 111. By this means, control member 126 and wedge structure 128, may be retained against the spring biasing of nozzle 118, at any degree of depression of nozzle 118 within the range provided by the form of wedge structure 128.

Control member 126 is further provided with elongate slot 130 arranged so that when wedge structure 128 depresses nozzle 118 sufficient for gas to flow from canister 114, the gas will pass through slot 130 and. thence through aperture 132 in support structure 112.

Aerosol canister 11.4 is in this embodiment provided with a modified nozzle 118 according to one of the preferred forms shown in Figs. 6A to 6C. In contrast to the typical valve nozzle described in the first preferred embodiment above, nozzle 1.18 is provided with at least one orifice which allows a rate of gas to pass from the canister depending on the degree of depression of the nozzle 118 relative to seal 123.

In a first preferred form of the orifice shown in Fig. 8A, an array of small holes 119 is arranged in a vertical line in the wall of nozzle 118. The further nozzle 118 is then depressed relative to seal 123, the more. holes will be available to pass gas 124 from the canister 114. It will be clear that the holes need not be all the same size, for example increasing in size from the smaller at the bottom of the array to the larger at the top, so that the flow of gas increases exponentially with depression of the nozzle.

-12o00 In a further preferred form, the orifice in the wall of nozzle 118 may be in the form of a slot 1.20 as shown in Fig. 6B. The flow of gas thus increases with the length C of slot exposed to gas 124 below seal 123.

1 In yet a further preferred form, the orifices may again take the form of small holes 119 but in this example arranged in a spiral formation as shown in Fig. 6C. This Sformation allows for an increasing flow of gas for. relatively small depressions of

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nozzle 118.

O Third Preferred Embodiment c with reference to Figs. 10 to 14 in a further embodiment of the invention, a valve control mechanism 200 is adapted for assembly to an opening 21.0 of a borehole plug 212 (shown partially in Figs. 10 and 11) so that discharge of a pressurised gas from a canister 214 is discharged within the plug 212 from one of a plurality of discharge orifices 216 but a discharge flow rate selection Control member 218 and activation of the discharge are external to the outer surface of the plug 212.

As shown in Figs. 10 and 11 the opening 210 at one end of the plug 212 is ultrasonically welded or attached by other suitable means to a peripheral flange 220 extending outwardly from the body 222 of valve control mechanism 200. As best seen in the sectioned side view of Fig. 11A, integrally attached to the upper surface of flange 220 is a cylindrical housing 224. Two support posts 226 and 228 extend from the underside of flange 220 and integrally connect the flange 220 to a ring base 230 which in turn is adapted for snap-on attachment to the upper rim of an aerosol canister 214.

Ring base 230 is flexibly connected, for example by a radial array of flexible elements (not shown) to a central discharge member 232 which is seated on the discharge nozzle 234 of the Canister 214. Discharge selection control member 218 is rotatably mounted in housing 224, with its axis of rotation coaxial with discharge nozzle 234, and rotates about central discharge member 232 (which is prevented from rotation by its connections to ring base 230). Control member 218 is further adapted for axial sliding movement within housing 224.

-13- 00 SThe internal structure of central discharge member 232 includes a central bore 235 which is seated over the canister 214 discharge nozzle 234, and a horizontal C passage 235 between bore 236 and an exit recess 240 at the outer surface of central discharge member 232.

The lower skirt 242 of control member 218 is provided with at least two, but C preferably three graded sized orifices 216A, 216$ and 2160 arranged at each

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degree interval around skirt 214 and at a level so as to coincide with exit recess C 240. It is the size of a particularly selected orifice 21.6A to 21.6C which 0 ultimately determines the discharge flow rate from canister 214 into the borehole c 10 plug 212 once discharge nozzle 234 has been activated. It will be understood that selection of a discharge rate and activation of discharge Nozzle 234 can both be effected by manipulation of the control member 218. Control member 218 can be rotated to bring a particular orifice into alignment with recess 240 (as shown in the views of Figs. 12 and 13), and depressed to force discharge nozzle 234 into a discharging state.

Discharge selection control member 218 is further provided with locking means to retain it in the depressed and discharging state, for example by a bayonet arrangement so that a combination of completing a final degree of rotation with downward pressure both brings a desired orifice into alignment and locks control member 218 into the discharge state.

In Use In use, the control mechanism of any one of the above described embodiments is attached to the canister which is contained within or fixed to the borehole plug (not shown). Prior to lowering a plug into s. borehole, the mechanism of the present invention can be manipulated through the flexible sides of the still deflated bag of the plug, or in the case of the Third Embodiment activated from the outside of the plug.

In the first embodiment described above, a user selects an appropriate orifice of intermediate member 25 for alignment with the discharge nozzle 18, and drives sliding control member 26 to the detent position.

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NFor the second embodiment, a user drives the control member to a desired detent position within the range of detent positions provided.

For the third embodiment the control member is rotated towards the selected N discharge orifice position and depressed to lock the mechanism into a discharge state.

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CIn each case the plug is then lowered into the borehole. The retention of the Scontrol member in the discharging state ensures that the discharge nozzle Iremains depressed so that discharge from the canister continues until it is 0 exhausted. Selection of a discharge rate may be made with reference to a guide chart, for example where input arguments may for example include characteristics of the borehole and borehole plug, the estimated lowering time and ambient temperature.

The above describes only some embodiments of the present invention and modifications, obvious to those skilled in the art, can be made thereto without departing from the scope and spirit of the present invention.

Claims

1. An aerosol canister control mechanism for inflation of a borehole plug; said aerosol canister having one end upon which, in use, the control mechanism is to be mounted, the one end having an outlet adapted to control the Ipassage of the contents of canister from the canister though the outlet, said control mechanism comprising a body which is adapted to be mounted to I the one end, the control mechanism further comprising a first member 0 supported for slidable movement relative to the outlet between a closed position and an open position, the first member being formed with at least one first orifice positioned to be capable of being in communication with the contents of the canister on said movement to the open position to permit said passage of the contents from the canister through the first orifice, a second member comprising a generally elongate element slidably retained in the body, to overlie the first member and supported by the body for slidable movement, wherein the slidable movement of the second member is generally transverse to the movement of the first member, the second member being movable between a retracted position and an engaged position, the second member being configured to cause said displacement of the first member to its open position, a retention means capable of retaining the second member in the engaged position, the retention means comprising a set of longitudinally spaced detents on the second member which are adapted to cooperate with the body to retain the second member in the engaged position.

2. An aerosol canister control mechanism as claimed at claim 1 wherein the first member comprises a tubular member slidably supported in the outlet to be movable into the canister to permit said communication of the first orifice with the interior of the canister, the tubular member having a discharge outlet at its outer end and being closed at its inner end, said first orifice formed in the wall of the tubular member intermediate of discharge outlet and inner end. -16- 00

3. An aerosol canister control mechanism as claimed at claim 2 wherein the outlet is associated with a valve element which is positioned to in use close the first orifice when the first member is in the closed position.

4. An aerosol canister control mechanism as claimed at claim 2 or 3 wherein said first orifice comprises an elongate slot extending axially along the wall, 0whereby the degree of said communication is proportional to the displacement of the first member relative to the outlet. An aerosol canister control mechanism as claimed at claim 2 or 3 wherein 0 0 said first orifice comprises a set of longitudinally spaced first orifices extending axially along the wall, whereby the degree of said communication is proportional to the displacement of the first member relative to the outlet.

6. An aerosol canister control mechanism as claimed at claim 2 or 3 wherein said first orifice comprises a helical array of spaced first orifices extending along the wall, whereby the degree of said communication is proportional to the displacement of the first member relative to the outlet.

7. An aerosol canister control mechanism as claimed at any one of claims 1 to 6 wherein the second member is provided with a second orifice which is positioned to be in alignment with the discharge outlet on the second member being moved to its engaged position.

8. An aerosol canister control mechanism as claimed at claim 1 to 7 wherein the support provided by the body for the first and second members biases the opposed surfaces of the first and second members into sliding contact.

9. An aerosol canister control mechanism as claimed at any one of claims 1 to 8 wherein the detents are positioned such that when in the engaged position they are to each side of the outlet and co-operate with the body to either side of the outlet An aerosol canister control mechanism as claimed at claim 8 or 9 wherein the detents are located on the face of the second member opposite to the face engaged with the first member. -17- 00 O

11. An aerosol canister control mechanism as claimed at claim 8 or 9 or wherein engagement of the detents with the body will cause transverse movement of the second member relative to the body and cause Odisplacement of the first member to its open position.

12. An aerosol canister control mechanism as claimed at claim 11 wherein the detents comprise wedge shaped formations.

13. An aerosol canister control mechanism as claimed at any one of claims 1 to I12 wherein the one end has a rim surrounding the discharge nozzle and the Sbody is configured to be able to be attached to the rim to at least partially surround the discharge nozzle.

14. An aerosol canister control mechanism as claimed at any one claims 1 to 12 wherein said body comprises a hollow body formed as a cap-like element which is intended in use to be attached to said rim of said canister. An aerosol canister control mechanism for inflation of a borehole plug; said aerosol canister having one end upon which the control mechanism is to be mounted in use, the one end having an outlet, said control mechanism comprising a body which is adapted to be mounted to the one end, the control mechanism further comprising first member in the form of a discharge nozzle in use supported by the outlet for slidable movement relative to the canister, between a discharging state and a closed state, the discharge nozzle having an opening at its outer end and at least one first orifice towards its inner end and a flow path between the opening and the at least one first orifice, the at least one first orifice being capable of communicating with the interior of the canister, the discharge nozzle associated with a valve element adapted in use to cooperate with the at least one orifice to close the at least one orifice when the discharge nozzle is in the closed state, whereby displacement of the discharge nozzle end to the discharging state will cause relative displacement between the at least one orifice and the valve element to permit the contents of the canister to escape through the opening, the degree of escape being proportional to the degree of displacement of the discharge nozzle, the control member further comprising a second member co-operable with the discharge nozzle and -18- 00 O supported by the body for slidable movement generally transverse to the movement of the discharge nozzle, the second member being movable ;between a retracted position at which the discharge nozzle is in the closed 0 state and a plurality of engaged positions at which the second member is in engagement with the discharge nozzle, the degree of displacement of the 0 discharge nozzle differing for each engaged position, a second retention IND Imeans capable of retaining the second member in at least one of its Opositions. IND

16. An aerosol canister control mechanism as claimed at claim 15 wherein the N 10 discharge nozzle comprises a tubular member slidably supported in the outlet to be movable into the canister to permit said communication of the at least one first orifice with the interior of the canister, the tubular member having a discharge outlet at its outer end and being closed at its inner end, said at least one first orifice formed in the wall of the tubular member intermediate of discharge outlet and inner end.

17. An aerosol canister control mechanism as claimed at claim 16 wherein said at least one first orifice comprises an elongate slot extending axially along the wall, whereby the degree of said communication is proportional to the displacement of the discharge nozzle relative to the outlet.

18. An aerosol canister control mechanism as claimed at claim 16 wherein said at least one first orifice comprises a set of longitudinally spaced first orifices extending axially along the wall, whereby the degree of said communication is proportional to the displacement of the discharge nozzle relative to the outlet.

19. An aerosol canister control mechanism as claimed at claim 16 wherein said at least one first orifice comprises a helical array of spaced first orifices extending along the wall, whereby the degree of said communication is proportional to the displacement of the discharge nozzle relative to the outlet.

20. An aerosol canister control mechanism as claimed at any one of claims 16 to 19 wherein the second member is provided with a second orifice which is -19- 00 O positioned to be in alignment with the discharge outlet on the second member being moved to its engaged position.

21. An aerosol canister control mechanism as claimed at any one of claims 16 to 20 wherein the second member generally comprises an elongate element slidably retained in the body, said second member overlying the discharge nozzle.

22. An aerosol canister control mechanism as claimed at claim 16 to 21 I wherein support between the body and the first and second members Obiases the opposed surfaces of the first and second members into sliding contact.

23. An aerosol canister control mechanism as claimed at claim 22 wherein the second retention means comprises a set of longitudinally spaced detents which are adapted to cooperate with the body to retain the second member in the engaged position.

24. An aerosol canister control mechanism as claimed at claim 23 wherein the detents are positioned such that when in the engaged position they are to each side of the outlet and co-operate with the body to either side of the outlet An aerosol canister control mechanism as claimed at claim 23 or24 wherein the detents are located on the face of the second member opposite to the face engaged with the discharge nozzle.

26. An aerosol canister control mechanism as claimed at claim 23 or 24 or wherein engagement of the detents with the body will cause transverse movement of the second member relative to the body and cause displacement of the discharge nozzle to its open position.

27. An aerosol canister control mechanism as claimed at claim 26 wherein the detents comprise wedge shaped formations.

28. An aerosol canister control mechanism as claimed at any one of claims 16 to 27 wherein the one end has a rim surrounding the discharge nozzle and the body is configured to be able to be attached to the rim to at least 24 Jul 2000 11:47 Wrayj Bunburyj Faxt 97914133 p. 2 00 0 0- 3 partially surround the discharge nozzle.

29. An aerosol canister control mechanism as claimed at any one claims 16 to 29 wherein said body comprises a hollow body formed as a cap-like element which is Intended in use to be attached to said rim of said canister. \O 5 30. An aerosol canister control mechanism substantially as herein described Swith reference to Figures 4. 5 and 6 of the accompanying drawings. N 31. An aerosol canister for inflation of a borehole plug having a control 0 mechanism of the form as claimed at any one of the preceding claims applied thereto and positioned to cooperate with the discharge nozzle. COMS ID No: ARCS-199536 Received by IP Australia: Time 12:52 Date 2008-07-24