AUSTRALIA Patents Act 1990 COMPLETE SPECIFICATION Innovation Patent Applicant (s) Weir Minerals Australia Ltd Invention Title: Valve Assembly The following statement is a full description of this invention, including the best method for performing it known to me/us: -2 "VALVE ASSEMBLY" FIELD OF THE INVENTION This application is a divisional application of Australian Application No. 5 2010200426, the contents of which are hereby incorporated by cross reference. This invention relates to a valve assembly. In particular, the invention relates to a valve assembly used to protect fuel tanks from being overfilled with fuel and therefore the invention will be described in this context. However, it is envisaged that the valve assembly may be used to protect the other types of containers from being 10 overfilled with other types of fluid. BACKGROUND OF THE INVENTION For many years large machinery fitted with fuel tanks have been equipped with fast fill systems to enable rapid filling of large capacity fuel tanks. The existing fast fill fuel systems rely on an air vent that prevents air from escaping the fuel tank when the is required level of fuel has been attained. This causes pressure in the fuel tank to increase to a level that automatic shuts-off a fuel supply nozzle. A major concern of this system is that when the fuel level activates the shut-off for the fuel supply nozzle, the shut-off can be overridden and fuel can continue to be forced into the fuel tank above the normal level. This can cause the fuel tank to rupture 20 from the high pressure attained when filling. US Patent No. 6,311,723, (by the applicant), has addressed this problem by devising a flow control valve assembly that prevents the build up of pressure within the fuel tank during and after filling. The flow control valve assembly also prevents the supply fuel nozzle from being overridden thus preventing the possibility of overfilling. 25 US Patent No. 6,311,723 is hereby incorporated by reference. The control valve assembly of US Patent No. 6,311,723 uses float valve to determine when the level of fuel in the fuel tank is at a desired level. When the desired level of fuel has been attained, the float valve is used to block the flow of fuel through a bleed pipe to stop the flow of fuel through a control valve. An open breather is provided 30 within the fuel tank to allow gas to escape from the fuel tank during filling to prevent the fuel tank rupturing. The flow control valve assembly operates very effectively on machinery that is predominately stationary. However, when the control valve assembly is mounted to 2695035_1 (GiMattes) P87219.AU.3 3/06/11 vehicles' fuel tanks, such as those located In trucks and excavators, some difficulties may be experienced during movement of the vehicle. One problem that may be experienced is that the float valve may become broken. The float valve comprises a float that is mounted on a pivotally movable 5 elongate arm. This arm can break due to the large forces that are exerted on the arm by the surging fuel caused by movement of the vehicle. In the event that the control valve assembly fails, in this or any other manner, the fuel supply nozzle will continue to fill the tank and pass fuel through the open breather until the nozzle is shut-off manually. This may lead to many hundreds or even 10 thousands of Iltres of fuel being wasted and the spilt fuel being disposed. Another problem that occurs is fuel is passed through the open breather during movement of the vehicle. Fuel surges cause fuel to flow through the open breather and escape the fuel tank, Again, this wastes fuel and is environmentally unfriendly. Further, the spilt fuel also creates a fire vehicle hazard. is SUMMARY OF THE INVENTION In a first aspect, there Is provided a valve assembly able to be mounted to a liquid container, the valve assembly comprising: a housing that Is hollow and substantially cylindrical In shape, said housing having at least two holes that allow liquid located within the container to pass In and out of the housing; a liquid inlet 20 located at a lower end of the housing, the liquid inlet allowing fluid to pass into the housing and being fluidly connected to a screw threaded aperture arranged to be connected to a bleed pipe to pass liquid through the liquid inlet; an inlet float valve that includes a float, a stem, and a valve seal located adjacent the end of the stem, the Inlet float valve mounted within the housing, the Inlet float valve movable between an open 25 posItion that permits the flow of liquid from the bleed pipe through the liquid Inlet into the housing and into the container and a closed position that does not permit the flow of liquid through the liquid inlet; a first hole in the housing lower end is configured to allow liquid from the liquid inlet to exit the housing lower end and a second hole in the housing lower end, located above the first hole, is configured to allow liquid to pass Into 30 the housing lower end to move the inlet float valve to the closed position; and a chamber that is located adjacent the liquid inlet in which liquid is passed and a shelter is provided within the chamber In which an end of the stem is located when the float valve is in the open position. 2696035_ (OGHMalter) P87219.AU.2 27/10/11 -4 In one form of the valve assembly, the float is supported by a seat within the housing, the seat extending across the entirety of the float and being spaced from the liquid inlet. S in one form of the valve assembly, the first hole Is disposed between the liquid inlet and the seat and the second hole is disposed above the seat. In one form of the valve assembly, the float of the float valve is arranged to lift away from the seat in response to the liquid level within the housing so as to move i from its open position to Its closed position. In another aspect, there is provided a method of controlling the filling of a liquid container comprising: providing a control valve connectable to a pump and arranged in an open position to allow filling of the container by the pump; providing a valve is assembly mounted to the container, the valve assembly comprising: a housing; a liquid inlet; an inlet float valve that includes a float, a stem, and a valve seal located adjacent the end of the stem, the inlet float valve mounted within the housing, the inlet float valve movable between an open position that permits the flow of liquid from the bleed pipe through the liquid inlet Into the housing and into the container and a closed 2 D position that prevents the flow of liquid through the liquid Inlet; the housing including at least two holes through a wall of the housing, a first hole being configured to allow liquid from the liquid inlet to exit the housing and a second hole, located above the first hole, being configured to allow liquid to pass into the housing to move the inlet float valve to the closed position; and a chamber that Is located adjacent the liquid inlet and 25 a shelter is provided within the chamber in which an end of the stem is located when the float valve Is In the open position; providing a bleed pipe in fluid communication with the control valve and the chamber so that liquid Is able to be passed from the control valve to the chamber of the valve assembly along the bleed pipe and from the chamber into the container vla the liquid inlet and the first hole; and controlling the 30 control valve such that the control valve Is operative to become closed in response to liquid ceasing to flow through the bleed pipe as a result of the Inlet float valve being In the closed position. 295031 (GHMqcrs) P$7219,AU.3 27/10/11 -5 BRIEF DESCRIPTION OF THE DRAWINGS Embodiments of the invention will be described with reference to the accompanying drawings in which: FIG. 1 is a section side view of a valve assembly with a breather float valve and 5 an inlet float valve in an open position according to a first embodiment of the invention; FIG. 2 is a section side view of the valve assembly of FIG. 1 with the breather float valve and the inlet float valve in a closed position; and FIG. 3 is a section side view of the valve assembly of FIG. 1 with a relief valve in an open position. io FIG. 4 is a sectional side view of the valve assembly of with a breather float valve in an open position according to a second embodiment of the invention; FIG. 5 is a sectional side view if the valve assembly of FIG. 4 with a breather float valve in a closed position; and FIG. 6 is a schematic representation of the valve assembly connected to a is control valve. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT FIG. I shows a valve assembly 10 that is primarily used in a fuel tank 1. The valve assembly 10 is normally used in conjunction with a control valve 2, as described in US Patent No. 6,311,723, to prevent fuel from entering the fuel tank when the fuel 20 tank has reached a predetermined level. FIG. 6 shows the valve assembly 10 connected to the control valve 2 via a bleed pipe 3. The control valve 2 is connected to a fuel pump 4 and supply tank 5. The valve assembly 10 comprises a housing 20 that is hollow and substantially cylindrical in shape. The housing 20 has several fuel holes 21 located along its length 25 that allow fuel located within the fuel tank to pass in and out of the housing 20. An inlet 30 is provided at a lower end of the housing 20 through which passes fuel. The inlet 30 is fluidly connected to two separate screw threaded apertures 31 and 32. The bleed pipe 3 is connected to one of the apertures 31 or 32. The bleed pipe is fluidly connected to the control valve to activate the control valve as disclosed in US 30 patent No. 6,311,723. The screw-threaded apertures 31 and 32 allow the bleed pipe to be connected outside or inside the fuel tank. 2695035_1 (GIHMauters) P87219.AU.3 3/06/11 -6 An inlet float valve 40 is housed in a lower end of the housing 20. The inlet float valve 40 is formed from a inlet float 41 and stem 42. A valve seal 43 is located adjacent the end of the stem 42 for sealing the inlet 30. The inlet float valve 40 is mounted within the housing so that the stem 42 can s reciprocate between an open position, in which fuel is able to pass through the bleed pipe 3 and through the inlet 30 into the fuel tank 1, and a closed position that prevents the flow of fuel through the inlet. A fuel chamber 50 is located between the inlet 30 and the apertures 31 and 32. The fuel chamber 50 provides a shelter 51 in which an end of the stem 42 is located 10 when the inlet float valve 40 is in the open position. The top of the housing 20 is open so that a passageway 60 is provided between the inside and outside of the fuel tank. This allows gas to pass from within the fuel tank to the atmosphere so that the fuel tank does not rupture during filling of the fuel tank. A relief plate 71 is positioned within an upper end of the housing 20. Breather holes 72 15 are located within the relief plate 71. The breather holes 72 form part of the passageway 60. A breather float valve 80 is provided adjacent the breather holes. The breather float valve 80 is formed from a breather float 81 and a rod 82. A platform 83 and the relief plate 71 guide rod 82. The float 81 is able to reciprocate along the length of the 20 rod 82 between the relief plate 71 and the platform 83. The rod 82 is fixed to the float 81 with circlips. The breather float valve 80 is in an open position when the breather float 81 is located adjacent the platform 83 and gas is free to pass through the breather holes 72. The breather float valve 80 is in a closed position when the breather float 81 is located 25 over the breather holes 72 and fuel cannot pass through the breather holes 72. A relief valve 70 is formed adjacent a top end of the housing 20. The relief valve 70 is formed from the relief plate 71, a spring 73 and a cap 74. The relief plate is able to move within a skirt 22 formed at the top of the housing 20. The skirt 22 has a number of circumferentially spaced relief holes 23. The spring 73 holds the relief plate 30 at the base of the skirt 22. The spring 73 is held in position by a cap 74 that is located over the housing 20. In use, the valve assembly 10 has a number of functions. In a fuelling normal operation, the inlet float valve 40 is in the open position such that the stem 42 sits 2695035_1 (GIMaters) P87219.AU.3 3/06111 -7 within the shelter 51 as shown in FIG. 1. The bleed pipe 3 passes fuel in to the fuel chamber 50. The fuel then passes through the inlet 30, into the housing 20 and out the fuel holes 21 into the fuel tank. Any turbulence that is created by the fuel passing through the fuel chamber 50 does not effect the valve seal 43 as it is located within the 5 shelter 51. As the fuel tank fills with fuel, the passageway 60 of the housing 20 also fills with fuel to the same level. The inlet float 41 rises within the housing until the valve seal 43 blocks the inlet 30 as shown in FIG. 2. The pressure of the fuel within the bleed pipe, as well as the fuel within the tank acting on float, maintains the valve seal 43 in position 10 within the inlet 30. Once the inlet 30 is blocked, the bleed pipe 3 fills with fuel causing the control valve 2 to become closed and prevents further filling of the fuel tank. When the vehicle is moving, the housing 20 prevents damage of the inlet float valve 40. The impact forces created by surging fuel within the fuel tank impact the housing 20 not the inlet float valve 40. is However, the surging fuel can still extend up passageway 60 and up to the breather holes 72. The breather float valve 80 prevents this surging fuel from escaping through the breather holes 72 as the breather float 81 moves with the surging fuel blocking the breather holes 72 as shown in FIG. 2. The breather float valve 80 also provides a fail safe during fuelling of the fuel tank. 20 If the bleed pipe 3 is severed or the control valve fails or the inlet float valve fails, then a fuel supply nozzle (not shown) will continue to pump fuel into the fuel tank. The fuel tank will fill with fuel until the breather float 81 moves to the closed position to block the breather holes 72. The continued fuelling of the fuel tank creates pressure within the fuel tank. When the fuel tank reaches a fuel nozzle shut off pressure, then the fuel 25 supply nozzle will shut-off stopping the fuel tank from rupturing. If the fuel supply nozzle does not shut off automatically due to a mechanical fault, then the fuel supply nozzle will continue to supply fuel to the fuel tank. This causes the pressure within the fuel tank to increase. At a pressure less than the rupture pressure of the tank, the pressure relief valve is opened as shown in FIG. 3. 30 This occurs when the fuel tank pressure becomes greater than the spring pressure causing the relief plate 71 to move upwardly until it passes over the relief holes 23 in skirt 22. Fuel then passes from the tank, through the relief holes 23, into the cap 74 and through a cap hole 75. The fuel flowing from the cap 74 will indicate to an operator to shut the fuel supply nozzle off manually. 2695035_ 1 (GIManers) P87219.AU.3 3/06/11 -8 FIG. 4 and FIG. 5 show a second embodiment of a valve assembly 10. In this embodiment, a breather float valve spring 84 is mounted around the rod 82 on the modified platform 83 below the breather float 81. The breather float valve spring 84 engages the breather float 81. s The breather float valve spring 84 assists in moving the breather float 81 to the closed position in the event of a vehicle roll over. The breather float 81 is of sufficient weight to compress the breather float valve spring 84 when the valve assembly is in a substantially vertical position. However, during a roll over, less force is applied by the breather float 81 on the io breather float valve spring 84 when the valve assembly 10 moves from a substantially vertical position to a substantially horizontal position. Therefore, the breather float valve spring 84 causes the breather float 81 to move to the closed position so that fuel cannot escape from the tank through the breather holes 72 in the event of a vehicle roll over. is The valve assembly provides a number of advantages. Firstly, the valve assembly is not damaged by surging fuel making the valve assembly suitable for use in vehicles. Secondly, the breather float valve prevents fuel from escaping the valve assembly when the fuel surges within the fuel tank during movement of the vehicle. Thirdly, in the event of failure of the inlet float valve, control valve or bleed pipe, the 20 breather float valve prevents the loss of fuel by blocking the breather holes causing pressure build up within the fuel tank and thus causing the fuel supply nozzle to shut off. Lastly, the pressure relief valve prevents the fuel tank from rupturing from over pressurising of the fuel tank. The valve assembly can be easily retro fitted or fitted into existing tanks. It is 25 sized to fit into holes that are located in tanks for existing systems. It should be appreciated that various other changes and modifications may be made to the embodiment described without departing from the spirit or scope of the invention. 30 It is to be understood that, if any prior art publication is referred to herein, such reference does not constitute an admission that the publication forms a part of the common general knowledge in the art, in Australia or any other country. In the claims which follow and in the preceding description of the invention, except where the context requires otherwise due to express language 2695035_1 (GIIMaters) PS7219.AU.3 3/06/11 -9 or necessary implication, the word "comprise" or variations such as "comprises" or "comprising" is used in an inclusive sense, i.e. to specify the presence of the stated features but not to preclude the presence or addition of further features in various embodiments of the invention. 5 2695035_1 (GH Matters) P87219.AU.3 3/06/11