AU1111301A - An inflatable bore hole plug having a delay means - Google Patents

Description

AUSTRALIA

Patents Act 1990 COMPLETE SPECIFICATION FOR A STANDARD PATENT Name of Applicant: M DE LUIS Actual Inventor(s): Address for Service: Invention Title: CULLEN CO., Patent Trade Mark Attorneys, 239 George Street, Brisbane, QIOld. 4000, Australia.

AN INFLATABLE BORE HOLE PLUG HAVING A DELAY MEANS Details of Associated Provisional Application: PQ5050 filed on 12 January 2000 The following statement is a full description of this invention, including the best method of performing it known to me: 2 AN INFLATABLE BORE HOLE PLUG HAVING A DELAY MEANS FIELD OF THE INVENTION This invention relates to an inflatable bore hole plug assembly having various types of delay means which can allow the plug assembly to be lowered down a bore hole before the plug inflates.

BACKGROUND ART Bore holes are drilled so that explosive charges may be placed in the bore hole at a particular position. Sometimes, the bore hole is entirely filled with explosive, but other times an explosive charge must be placed somewhere along the bore hole length. For this type of use, a plug is lowered down the bore hole to the desired area to form a support platform for the explosive.

Inflatable bore hole plug assemblies are well-known. The assemblies comprise an inflatable bag which can be inflated to form the bore 15 hole plug. Inside the bag is a pressurised can which contains the inflating substance. The can is provided with a valve which can be opened to expel the inflating substance into the bag to inflate the bag. The pressurised can has a one-way valve which can be locked into the open position to expel the inflating substance (typically hydrocarbons). The plug assembly is attached 20 to a measured length of rope and is lowered down the hole to be supported ~by the rope until the plug inflates to be jammed against the wall of the bore hole.

In the past, the valve was opened and the plug assembly was quickly lowered down or pushed down the bore hole and it was hoped that 25 the plug assembly could be positioned before the bag was inflated to the point where it formed the plug.

It is known to use reagents which, when mixed, create a gas which expands in the inflatable bag to create the plug. A major disadvantage with this arrangement is that the reaction rate varies depending on temperature and other climatic conditions which makes it difficult to ensure that the plug assembly is correctly positioned in the bore hole before substantial inflation takes place. Often, the inflation occurred too quickly which meant that the inflatable bag would plug the bore hole at an undesired position.

More recently, pressurised cans have been used to inflate the bag. As the bag can be lowered some considerable distance down the bore hole, it is necessary to actuate the can valve prior to lowering the bag down the bore hole. For this reason, various attempts have been made to provide some form of time delay between activating the can valve and substantial inflation of the bag.

One attempt involves a specially filled pressurised can which contains a quantity of water as well as the inflating substance (typically hydrocarbon). The water and the hydrocarbon do not mix and the water, being heavier than the hydrocarbon, settles at the bottom of the can. The can has an internal small diameter tube extending from the adjacent the bottom of the can and connected to the valve. When the valve is opened, the water will initially be expelled into the inflatable bag and, after the water has been expelled, the inflating substance will pass into the bag to cause inflation. The amount of water, the diameter of the internal tube, and other parameters can be varied to cause a time delay typically from between 10 to 40 seconds which is considered sufficient to lower the bag down the bore hole and to hold 20 it by the rope until inflation is complete.

While this arrangement was more reliable and provided a more reliable time delay, it suffers from a number of disadvantages. The main S. disadvantage is that the can can only be used in the upright position. Should the can be tilted, the water will not completely pass out of the can before the 25 inflating substance passes out of the can. This causes premature inflation. It should be appreciated that as the bag is lowered down the hole, the bag can catch on the sides of the bore hole and can be tilted or twisted. This can reduce the time delay provided by initial expulsion of the water from the can.

The bag also needs to be carefully held in the vertical position after opening the valve and before lower into the hole. A second disadvantage is that the pressurised can cannot be completely filled with the inflating substance which means that larger cans may be required. A third disadvantage is that specially designed and filled cans are required.

OBJECT OF THE INVENTION The present invention is directed to an inflatable bore hole plug assembly which contains a pressurised can which can contain only the inflating substance, and does not require any water or other special additives.

This may have an advantage that the can does not need to be held in the vertical position and can be tilted without detriment to expulsion of the inflating substance. A delay means is provided externally of the can to delay passage of the inflating substance into the inflatable bag. This means that standard pressurised cans can be used and, in some forms of the invention, the can can be tilted or even inverted with little or no detriment to the time delay.

In a different form, an inflatable bore hole plug assembly is provided, again having a pressurised can this time having an internal delay means which is insensitive to tilting or tipping of the can.

S"It is an object of the invention to provide an inflatable bore hold plug assembly which may overcome the abovementioned disadvantages or provide the public with a useful or commercial choice.

In one form, the invention resides in an inflatable bore hole plug assembly which has an inflatable bag which can be inflated to form the plug, a pressurised can which contains the inflating substance to inflate the bag, a valve which can be activated to cause the can to release the inflating substance, and a delay means which delays passage of the inflating substance into the bag for a period of time sufficient to allow the valve to be 25 opened, and the plug to be positioned in the bore hole before the bag inflates to plug the bore hole, characterised in that the delay means is external of the can and is in fluid communication with the valve such that the inflating substance passes through the valve and into the external delay means which delays passage of the inflating substance into the bag for the period of time.

In one form, the delay means is a housing which has an inlet and an outlet, the inlet being in fluid communication with the valve, and the outlet being in communication with the interior of the bag, the housing having an internal mass which moves along the housing in response to the pressure of the inflating substance entering into the housing and which delays passage of the inflating substance through the outlet of the housing and into the bag.

In another form, the delay means is a smaller burstable inflatable containment bag which is inside the outer bag, the valve of the can being in fluid communication with the containment bag, the containment bag, in use, initially being inflated and able to hold the pressure for the period of time before bursting to allow the outer bag to be subsequently inflated.

An advantage in having the external delay means is that a standard pressurised can can be used, possibly with some variation to the valve. This means that the can can be filled with the inflating substance and does not require any non-inflating material in the can. In one form, by having the delay means external of the can, the can does not need to be held in a 15 vertical position which gives greater versatility to the assembly according to the invention.

In another form, the invention resides in a time delay assembly operatively attachable to the outlet of a pressurised can and for use in an inflatable bore hole plug of the type having an inflatable bag, the assembly having attachment means to attach the assembly to the pressurised can, an unpressurised container which contains a time delay liquid, the container having an inlet which is adapted for fluid communication with the can outlet, an outlet which is adapted for fluid communication with the bore hole plug inflatable bag, whereby when the contents of the pressurised can pass into 25 the unpressurised container, the time delay liquid is initially expelled into the bag which does not appreciable inflate the bag, and thereafter the can contents pass through the outlet to cause inflation of the bag.

Inflatable bags are already known in the art and it is envisaged that the inflatable bag of the invention can be similar to bags already known.

Typically, the inflatable bag comprise multi-layer plastic bags which are gas tight. These bags can be formed from suitable material such as plastics. As mentioned above, such bags are known in the art. The size and volume of 6 the bag can also vary depending on the bore hole size, the weight of explosives to be supported by the plug and the like, and it is considered that this information is already public knowledge.

The pressurised can can be of a type already known in the art and already known to inflate bore hole plug bags. The valve is typically such that once opened, the valve stays open which means that the contents of the container will be totally released without interruption until the pressure in the container and the pressure in the bag equalises.

The inflating substance can vary to suit. The inflating substance is typically in the form of a volatile liquid which will expand and volatise once in the inflatable bag. Alternatively, the pressurised can can contain compressed gas, although a volatisable liquid is preferred as it will allow greater expansion of the bags.

Typical inflating substances may include, but need not be limited to hydrocarbons such as propane and butane, halohydrocarbons, low boiling point ethers; compressed gases such as nitrogen, carbon dioxide, mixtures thereof.

i The pressure in the can is typically between 150 to 1000kPa and is usually within the range of about 150 to 500kPa.

20 The delay means can be of various basic types. One type Soi.

comprises a mass which may be a viscous liquid, gel, grease, and the like; but can also include a plunger and the like which is within a housing. The

S

0 **0housing has an inlet and an outlet with the inlet being connected to or relative to the can valve and the outlet extending into the bag which means that the 25 inflating substance must pass through the housing before it can pass into the bag.

In an embodiment, the housing is a hollow tube one end of which comprises the inlet and the other end of which comprises the outlet and is filled with the thick viscous material such as a grease or gel. When the valve is opened, the inflating substance passes into the housing and first needs to push out the thick viscous material through the outlet before the inflating substance can pass through the outlet to inflate the bag. The size of the housing and the amount and type of mass in the housing will determine the time delay which will be enjoyed between opening the valve and inflation of the bag.

The mass can comprise any type of flowable material which can be held in the housing. Greases, gels, thick viscous liquids, thick fluid oils, and the like can be used in the housing. Anti-freeze additives may be required depending on the type of mass which is in the housing to prevent freezing. The size and shape of the outlet can also be varied to vary the desired time delay. If desired, a valve and the like can be provided on the housing to allow adjustments to be made to the initial expulsion of the mass and therefore varying the time delay before the bag inflates. This can provide a degree of adjustability which is not found in conventional systems.

Alternatively, the mass can be in the form of a sliding piston or plunger or like member which slides along the housing to provide the time 15 delay. The degree of friction between the piston, plunger and the like, and the walls of the housing may affect the time delay. It is possible for the housing to contain both a thick viscous liquid and a plunger or piston in which case the fit of the plunger or piston can be quite loose with the thick viscous liquid providing the resistance to expulsion of the inflating substance for the 20 desired period of time. If a solid member such as a piston or plunger is used, the outlet may be positioned slightly away from one end of the housing which will allow the piston or plunger to be pushed past the outlet in order to not seal off the outlet against passage of the inflating substance into the bag.

The time delay can be varied to suit and is typically between 25 seconds to several minutes with a preferred time delay being between 20 to seconds.

In another embodiment, the delay means is in the form of a smaller inflatable containment bag which sits inside the outer bag. The valve of the can is attached to the containment bag such that when the valve is opened, the inflating substance passes into the containment bag first. The containment bag is much smaller than the main inflatable bag and will inflate to its full size and is then designed to burst open to allow the outer bag to be 8 subsequently inflated. Filling of the initial containment bag provides the required time delay to allow the plug to be lowered into a bore hole. The containment bag is designed to be of sufficient strength and size to contain the inflating substance for the desired time delay typically being between 7 to 10 seconds.

In the form of the invention which resides in a time delay assembly operatively attachable to the outlet of a pressurised can and for use in an inflatable bore hole plug of the type having an inflatable bag, the assembly has an attachment means to attach it to the pressurised can. In one form, the assembly comprises an outer unpressurised container which contains the time delay liquid and an inner open ended passageway in which the pressurised can can be held. Other forms of attachment such as simple straps and the like are also envisaged.

The unpressurised container may comprise an outer container 15 extending about the pressurised can. The outer container typically has a S* length approximately the same as the length of the pressurised can.

The container has an inlet which can be connected to the can outlet or can valve such that when the valve is open, the can contents pass into the outer container. This is typically in the form of a tube which can 20 attach to the can valve outlet.

~The time delay liquid may be aqueous or aqueous-based and may include water, water mixtures, but may also include non-aqueous liquids such as oils and the like. It is only necessary that the time delay liquid is sufficiently viscous to allow it to be pushed out of the container as the can 25 contents pass into the container and that the time delay liquid does not appreciably inflate the bag. In practice, it is found that water is a suitable time delay liquid. It is also envisaged that time delay agents other than liquid may be used, for instance flowable powders, gels and the like providing that they still provide an appropriate time delay function.

The container which contains the time delay liquid has an outlet which communicates with the inflatable bag. Typically, the outlet is spaced above the level of the time delay liquid in the outer container and a delivery tube extends from the outlet to below the level of the liquid and typically adjacent the bottom of the container such that the time delay liquid can be substantially expelled from the container before the inflating substance from the pressurised container passes through into the bag to cause inflation of the bag.

Another disadvantage with existing inflatable bag plug assemblies is that the bags need to be inflated fairly quickly in order to minimise the time taken to plug a bore hole. For this reason, the can contents are expelled as quickly as possible though the valve and into the bag. If the can contents contain butane or propane, volatisation of this material causes a large temperature drop in the bag. It is common for the bag temperature to drop below the boiling point of the propane or butane which causes a slow down in inflation.

It can be seen that the inflatable bore hole plug assembly 15 according to the invention has several advantages not hitherto realised. One OV. advantage is that the pressurised can can be used at any angle. Previously, the can contained a time delay liquid such as water which meant that the bag could only be used in the upright position and the bag and the can could not be shaken before use. For instance, if a number of plug assemblies were 20 transported over rough roads or rough terrain, each plug assembly was ***required to be rested for a period of time to ensure that the can contents were separated. With the present invention, no such restriction is required.

In another invention or form of the invention, there is provided an inflatable bore hole plug assembly which has an inflatable bag which can 25 be inflated to form the plug, a pressurised can which contains the inflating substance to inflate the bag, a valve which can be activated to cause the can to release the inflating substance, the valve being connected to an internal tube which extends to adjacent the bottom of the can, and a delay means which delays passage of the inflating substance into the bag for a period of time sufficient to allow the valve to be opened, and the plug to be positioned in the bore hole before the bag inflates to plug the bore hole, characterised in that the delay means comprises a viscous flowable mass which is inside the tube and which needs to be initially expelled when the can valve in opened, the mass delaying passage of the inflating substance through the valve for the period of time.

This form of the invention has the same benefits as described above in that the can can be tilted or even inverted and can be shaken without appreciably affecting the time delay. In this version of the invention, the internal tube which is present in the can is plugged with the viscous mass.

The viscous mass stays in the internal tube until the valve is opened after which the inflating substance will slowly push the viscous mass through the tube and out of the valve. This causes the time delay, and once the viscous mass has been pushed out of the valve, the inflating substance can pass out of the can to inflate the bag. Again, the can can be completely filled with the inflating substance (apart from the very small volume of the internal tube), and there is no need for the can to contain water or other undesirable time 15 delay liquid.

BRIEF DESCRIPTION OF THE DRAWINGS Embodiments of the invention will be described with reference to the following drawings in which Figure 1 illustrates a deflated inflatable bore hole plug assembly 20 containing an inflatable bag, a pressurised can, and an external delay means.

Figure 2 is an enlarged view of the external delay means according to one embodiment.

Figure 3 is an enlarged view of an external delay means according to a second embodiment.

25 Figure 4 is an enlarged view of an external delay means according to a third embodiment.

Figure 5 illustrates a delay means which consists of a deflated but inflatable containment bag attached to the outside of the can.

Figure 6 shows the containment bag of Figure 5 fully inflated.

Figure 7 shows the containment bag of Figure 6 bursting open to release the inflating substance.

Figure 8 illustrates another embodiment of the invention where the internal tube of the can is filled with a thick viscous material to provide a time delay.

Figure 9 shows a deflated bore hole plug assembly lowered to a desired distance in a bore hole.

Figure 10 shows the bore hole plug assembly fully inflated and able to support an explosive charge.

Figure 11 shows a time delay assembly attached to a pressurised can which can be of conventional manufacture.

Figure 12 is a view of an external delay means according to a fourth embodiment.

DETAILED DESCRIPTION Referring to the drawings and initially to Figure 1, there is illustrated an inflatable bore hole plug assembly 10 which consists of an inflatable bag 11 which can be inflated to form the plug (see Figure 10), a 15 pressurised can 12 which has a valve 13 and a delay means 14 which is external of the can.

Inflatable bag 11 can be of conventional design and a person skilled in the art would be able to manufacture the inflatable bag. Typically, the inflatable bag consists of two bags connected together to provide 20 strength. It is typical that the pressurised can 12 is initially inserted into the inner bag through an open end, the open end then being sealed. The inner bag is then inserted into the outer bag and the open end of the outer bag is also sealed to form the bag 11.

Can 12 can be of conventional design and manufacture and is :25 sized and holds enough inflating liquid to allow bag 11 to be properly inflated in the bore hole. Of course, the size and the contents of the can will depend on the size of the bag 11. Typically, can 12 has a top valve 13 which is connected to an internal tube 15 through which the inflating substance can pass. Valve 13 is usually provided with some form of lock down mechanism which can be easily manipulated via the outside of bag 11 to lock valve 13 in the open position when required.

Can 12 is filled with a suitable inflation substance which in the embodiment comprises a mixture of propane and butane. In the embodiment, can 12 does not need any additional internal ingredients such as water and the like.

Attached to valve 13 is a delivery tube 16 which connects to delay means 14.

Figure 2 illustrates a particular type of delay means. In Figure 2, the delay means consists of a hollow tubular housing 17 which contains an upper inlet 18 and a lower open tapered outlet 19. The housing can be formed of plastics, metal or other suitable material. Inside the housing is a thick viscous grease 20 which is thick enough to stay in housing 17 notwithstanding the open outlet 19.

In use, valve 13 is locked in the open position and the inflating liquid will pass through tube 15 and through delivery tube 16 and into inlet 18.

The inflating liquid will then start to push grease 20 out through outlet 19 an 15 when all the grease has been pushed out, the inflating fluid can now pass into bag 11 to inflate the bag. The time it takes to push out grease 20 determines fooooo: the time delay to allow the bag to be lowered in the hole after the valve has been locked open and before the bag fully inflates. This time delay will of course depend upon the size and length of the housing and the type of 20 grease or other mass in the housing but is typically somewhere between 7 to 30 seconds. Once the correct size and shape of the housing and the correct type of grease has been chosen, the time delay will be fairly exact, will be S* repeatable, and is mostly insensitive to ambient temperature variations.

Figure 3 shows a second type of delay means. In Figure 3, 25 there is again provided a housing 17 but this time the outlet 21 is to one side of the housing and spaced from the bottom. The delay is caused by a slidable plunger 22 which is initially adjacent inlet 18 but which will be pushed under the force of the inflating fluid to below outlet 21 after which the inflating fluid can inflate the bag. The rate of sliding of plunger 22 will determine the time delay. The plunger can be made of plastics or other suitable material.

Figure 4 illustrates another type of time delay which is basically a combination of the grease 20 and the plunger 22. In this embodiment, 13 plunger 22 can be a fairly loose fit as the expulsion of grease 20 through outlet 21 will determine the time delay with plunger 22 functioning to ensure a steady and uniform expulsion of the grease 20. In Figure 4, a second outlet 23 is provided to allow plunger 22 to pass past outlet 21.

It can be seen that with the external delay means, the pressurised can 12 can be of conventional manufacture and can be shaken, inverted, and tilted as the can itself does not contain any time delay liquid such as water which requires to be handled carefully.

Figure 5 illustrates another embodiment of the invention. In this embodiment, a standard pressurised can 12 and valve 13 are provided again having an internal tube 15. Valve 13 is connected to a delivery tube 24 which passes into a smaller burstable inflatable containment bag 25. Bag 25 has an open end which is sealed against the outer wall of can 12 with the end of .delivery tube 24 passing into the bag. When valve 13 is locked open, the 15 inflating fluid passes through delivery tube 24 and inflates bag 25 to the fully inflated position illustrated in Figure 6. As the expansion causes a temperature reduction, it is envisaged that some of the inflating liquid 27 will not vaporise and instead will pool in the bottom of the bag.

After a predetermined period, the pressure within bag 25 will 20 cause it to burst as illustrated in Figure 7 which will now allow the inflating fluid to inflate bag 11. The bag size and strength can be created such that the bag will burst after approximately 7 to 10 seconds after valve 13 has been opened.

Figure 8 shows an invention in which can 12 has an internal 25 tube 30 which is of larger diameter than normal and where tube 30 is plugged or filled with grease or other viscous liquid. When valve 13 is locked open, the inflating liquid will first need to push out the grease within tube 30 before the inflating liquid can pass out of the can to inflate the bag.

Figure 9 illustrates the bore hole plug assembly in a bore hole.

In Figure 9, the pressurised can 12 has been activated and the as yet deflated bag 11 has been lowered into a bore hole 32 to a desired distance limited by lowering rope 33. The as yet deflated bag is lowered to the desired 14 distance during the time delay period after which the bag will inflate and plug the bore hole as illustrated in Figure 10. At this time, an explosive charge 34 can be poured or placed on top of the inflated bag 11.

Referring to Figure 11, there is illustrated a time delay assembly which is attached to a pressurised can of the type which inflates a bore hold plug assembly. The bore hole plug assembly consists of an inflatable bag which can be inflated to form the plug. The inflatable bag is not illustrated and is of conventional design and a person skilled in the art would be able to manufacture the inflatable bag. Typically, the inflatable bag consists of two bags connected together to provide strength. It is typical that the pressurised can and the time delay assembly is inserted into the inner bag through an open end, the open end then being sealed. The inner bag is then inserted into the outer bag and the open end of the outer bag is also sealed.

The time delay assembly is illustrated in Figure 11 and 15 comprises an outer cylindrical container 50 having a hollow centre 51 for location of the aerosol can 52.

Can 52 can be of conventional design and manufacture and is ooooo: sized and holds enough inflating liquid to allow the bag to be properly inflated :in the bore hole. The size and contents of the can will depend upon the size .0 20 of the bag. It is typical for the can to have a top valve 53 which is connected to an internal tube (not illustrated) extending to the bottom of the can and through which the inflating substance can pass. The time delay assembly has a lock down activator cap 54 which can be pressed to open valve 53 to discharge the contents of can 52. Cap 54 can be manipulated by a person 25 through the outside of the bag in which the can and the time delay assembly is sealed.

The can is filled with a suitable inflation substance which, in the embodiment, comprises a mixture of propane and butane. The can does not contain any additional internal ingredients such as water and the like.

Valve 53 is attached to a delivery tube 55 which delivers the can contents to the inside of outer container Outer container 50 has an outlet 56 which is adjacent the can valve 53. Attached to outlet 56 is a discharge tube 57 which extends through outer container 50 to adjacent the bottom wall 58 of the container.

Outer container 50 holds a volume of water which comprises the time delay liquid. The amount of water can vary depending on the time delay required but is typically such that a time delay of between 7 to 30 seconds is experienced before the water 59 is expelled through discharge tube 57 and through outlet 56 and into the bag.

Referring to figure 12 there is illustrated a fourth embodiment of the invention. In this embodiment, a conventional aerosol can 60 is connected to a lock down cap 61 which can be depressed by a person's fingers to activate can 60. A tube 62 is connected to the can outlet 63 such that the contents of the can pass through tube 62. A delay means is provided which is in the form of a smaller outer container 64 which can be strapped or 1 otherwise attached relative to can 60. Container 64 has an upper end 15 adjacent the top of can 60 and a lower end 66 adjacent the bottom of can *:***Container 64 is filled with a delay fluid 67. The fluid can be as described.

above and may include water, oil, grease, and the like. Tube 62 communicates with the upper end 65 of container 64. The lower end 66 of container 64 has a screw on cap 68 having a small lower opening 69 which S 20 can be temporarily sealed with a plug of grease. When can 60 is activated, the can contents pass through tube 62 and into the top of container 64. The pressure will build up to the point that the plug of grease is pushed out of opening 69 thereby allowing the delay fluid 67 to pass through small opening 69. The small opening 69 acts as a "throttle" to delay the passage of fluid S 25 through the opening. Once the fluid has been pushed out of container 64 and through opening 69, the can contents can pass through opening 69 and into the bag to inflate the bag.

In use, a bore hole plug assembly containing the time delay assembly and a pressurised can, as illustrated in Figure 11, is taken to the top of a bore hole. The activator cap 54 is pressed down to cause the pressurised can contents to flow through tube 55 into the outer unpressurised container 50. The bore hole plug assembly can then be lowered into the bore hole during which time the pressure in can 52 pushes water 59 through discharge tube 57 and into the inflatable bag with the water being expelled for approximately between 7 to 30 seconds. Once the water has been discharged, the propane/butane mixture then passes through discharge tube 57 and into the bag to cause the bag to inflate.

It should be appreciated that various other changes or modifications can be made to the embodiments described without departing from the spirit and scope of the invention. For instance, anti-freeze additives may be required to regulate the time delay.

Claims (16)

1. An inflatable bore hole plug assembly which has an inflatable bag which can be inflated to form the plug, a pressurised can which contains the inflating substance to inflate the bag, a valve which can be activated to cause the can to release the inflating substance, and a delay means which delays passage of the inflating substance into the bag for a period of time sufficient to allow the valve to be opened, and the plug to be positioned in the bore hole before the bag inflates to plug the bore hole, characterised in that the delay means is external of the can and is in fluid communication with the valve such that the inflating substance passes through the valve and into the external delay means which delays passage of the inflating substance into the bag for the period of time.

2. The assembly of claim 1, wherein the delay means is a housing which has an inlet and an outlet, the inlet being in fluid communication with 15 the valve, and the outlet being in communication with the interior of the bag.

3. The assembly of claim 2, wherein the housing contains an internal mass which moves along the housing in response to the pressure of the inflating substance entering into the housing and which delays passage of the inflating substance through the outlet of the housing and into the bag.

4. The assembly of claim 2, wherein the delay means comprises water. The assembly of claim 1 or claim 2, wherein, the delay means is a smaller burstable inflatable containment bag which is inside the bag, the valve of the can being in fluid communication with the containment bag, the 25 containment bag, in use, initially being inflated and able to hold the pressure for the period of time before bursting to allow the bag to be subsequently inflated.

6. The assembly of claim 1, operatively attachable to the outlet of a pressurised can and for use in an inflatable bore hole plug of the type having an inflatable bag, the assembly having attachment means to attach the assembly to the pressurised can, an unpressurised container which contains a time delay liquid, the container having an inlet which is adapted for 18 fluid communication with the can outlet, an outlet which is adapted for fluid communication with the bore hole plug inflatable bag, whereby when the contents of the pressurised can pass into the unpressurised container, the time delay liquid is initially expelled into the bag which does not appreciable inflate the bag, and thereafter the can contents pass through the outlet to cause inflation of the bag.

7. The assembly of any one of the previous claims, wherein the inflatable bag comprises a multi-layer plastic bag which is gas tight.

8. The assembly of any one of the previous claims, wherein, the valve, once opened, stays open to totally release the can contents without interruption until the pressure in the container and the pressure in the bag equalises.

9. The assembly of any one of the previous claims, wherein the inflating substance comprises a volatile liquid which will expand and volatise 15 once in the inflatable bag. The assembly of any one of the previous claims, wherein the pressurised can comprises compressed gas. S11. The assembly of any one of the previous claims, wherein the inflating substance may includes hydrocarbons such as propane and butane, 20 halohydrocarbons, low boiling point ethers; compressed gases such as nitrogen, carbon dioxide, and mixtures thereof.

12. The assembly of any one of the previous claims, wherein the pressure in the can is between 150 to 1000kPa and is preferably within the range of about 150 to 500kPa. 25 13. The assembly of any one of the previous claims, wherein the delay means comprises a viscous liquid, gel, paste, oil and/or grease.

14. The assembly of any one of the previous claims, wherein the delay means comprises a plunger which is within a housing. The assembly of any one of the previous claims, wherein the housing is a hollow tube one end of which comprises the inlet and the other end of which comprises the outlet and is filled with a thick viscous material such as a grease or gel. 19

16. The assembly of any one of the previous claims, wherein the time delay is between 20 to 60 seconds.

17. The assembly of claim 1, which is operatively attachable to the outlet of a pressurised can and for use in an inflatable bore hole plug of the type having an inflatable bag, the assembly having an attachment means to attach it to the pressurised can, the assembly comprising an outer unpressurised container which contains the time delay liquid and an inner open ended passageway in which the pressurised can can be held.

18. The assembly of claim 17, wherein the unpressurised container comprises an outer container extending about the pressurised can.

19. The assembly of claim 17 or 18, wherein the outer container has a length approximately the same as the length of the pressurised can. The assembly of any one of claims 17-19, wherein the inlet is a tube which can attach to the can valve outlet. S 15 21. The assembly of any one of claims 17-20, wherein the time delay liquid is aqueous or aqueous-based.

22. The assembly of claim 21, wherein the liquid comprises water, water mixtures, non-aqueous liquids such as oils, flowable powders, and/or gels. 20 23. The assembly of any one of claims 17-22, wherein the container which contains the time delay liquid has an outlet which communicates with the inflatable bag, the outlet being spaced above the level of the time delay liquid in the outer container and a delivery tube extends from the outlet to below the level of the liquid and adjacent the bottom of the container such 25 that the time delay liquid can be substantially expelled from the container before the inflating substance from the pressurised container passes through into the bag to cause inflation of the bag.

24. The assembly of claim 1, comprising an inflatable bore hole plug assembly which has an inflatable bag which can be inflated to form the plug, a pressurised can which contains the inflating substance to inflate the bag, a valve which can be activated to cause the can to release the inflating substance, the valve being connected to an internal tube which extends to adjacent the bottom of the can, and a delay means which delays passage of the inflating substance into the bag for a period of time sufficient to allow the valve to be opened, and the plug to be positioned in the bore hole before the bag inflates to plug the bore hole, characterised in that the delay means comprises a viscous flowable mass which is inside the tube and which needs to be initially expelled when the can valve in opened, the mass delaying passage of the inflating substance through the valve for the period of time. An assembly substantially as hereinbefore described with reference to the drawings. DATED this 9 th day of January 2001 M DE LUIS By his Patent Attorneys CULLEN CO. e S t* OtiD ooof fo eft ft ft t t f-t' egotf f *f ft•