WO2008017115A1

WO2008017115A1 - Improvements in safety shutoff apparatus

Info

Publication number: WO2008017115A1
Application number: PCT/AU2007/001114
Authority: WO
Inventors: John William Quee
Original assignee: Individual
Current assignee: Individual
Priority date: 2006-08-09
Filing date: 2007-08-09
Publication date: 2008-02-14
Anticipated expiration: 2009-02-09
Also published as: AU2007283452B2; AU2007283452A1

Abstract

A shut down mechanism which in one aspect is suitable for shutting down a fuel supply line of an apparatus, the mechanism comprising a releasable lock which is movable between a lock position in which position the fuel supply line is in an operating mode and a release position in which position the fuel supply line is in a shut down mode. The mechanism further includes a lock activating device activation of which is caused by manual activation or activation as a result of abnormal operating conditions of the apparatus. The shut down mechanism further includes a reservoir an interior which, in use, is at a lower pressure relative to a normal operating pressure of the fuel line. The reservoir includes an inlet which is in fluid communication with a downstream end of the fuel line when the lock is in the shut down mode enabling fuel in the downstream end of the fuel line to pass into the reservoir. Other aspects of the invention are concerned with shut down mechanisms for shutting down an electric circuit or other energy supply system.

Description

IMPROVEMENTS IN SAFETY SHUTOFF APPARATUS

Field of the invention

The present invention relates generally to shutdown mechanisms for shutting down an energy supply system. The present invention finds application in a wide range of operations, whether industrial or domestic such as for example dangerous workplaces including gas or fuel supplies, electricity supplies, hydraulic supplies, steam supplies, associated with the dangerous workplace or home. It will be convenient to describe the invention as it applies to vehicles, which is one application to which the invention is particularly suited, and in particular to vehicles such as cars and trucks which include internal combustion engines and on-board fuel storage. It is to be understood however that this is not to be taken as a limitation of the scope of the invention.

Background of the Invention

In any energy supply system, an off-design condition brought about by damage to the system, or a loss of control of the system, may result in further serious damage to nearby property and life, especially if the energy supply is maintained.

Vehicles, for example, have several energy supply systems, including fuel systems and electrical supply systems. In a crash situation, these systems may continue to supply energy to, for example, an engine bay, which may exacerbate the crash damage and lead to a potentially dangerous or destructive situation for persons and/or property.

Summary of the Invention

According to one aspect of the present invention there is provided a shut down mechanism for shutting down a fuel supply line of an apparatus, the mechanism comprising a releasable lock which is movable between a lock position in which position the fuel supply line is in an operating mode and a release position in which position the fuel supply line is in a shut down mode, a lock activating device activation of which is caused by manual activation or activation as a result of abnormal operating conditions of the apparatus, the shut down mechanism further including a reservoir an interior of which, in use is at a lower pressure relative to a normal operating pressure of the fuel line, the reservoir including an inlet which is in fluid communication with a downstream end of the fuel line when the lock is in the release position enabling fuel in the downstream end of the fuel line to pass into the reservoir.

The reservoir may include an outlet which is arranged so that the interior of the reservoir is at a lower pressure relative to the normal operating pressure of the fuel line.

The lock may comprise a valve associated with the fuel line which has an upstream end and a downstream end, the valve closing the fuel line when in the release position and opening the fuel line when in the lock position. The reservoir outlet may be in fluid communication with a low pressure zone so as to place the interior of the reservoir at a low pressure relative to the normal operating pressure of the fuel line. The outlet may for example be connected to a line which in turn is connected to an inlet manifold of an engine so as to create a venturi effect to hold the reservoir at a negative pressure during operation of the fuel supply line. The fuel supply line may be for a vehicle.

In one form the lock activating device may include a movable pressure-responsive member operatively associated with or in engagement with the lock, and which is responsive to detonation of an explosive charge which upon detonation causes the lock to move between the lock position and the release position, the activation device further including a detonator which may for example be a spark generator which when activated causes detonation of the explosive charge. Activation of the explosive charge may be caused by manual activation or activation as a result of selected operating conditions of the apparatus The lock activating device may include a casing having a chamber therein, the movable member being mounted for movement within the chamber. The chamber may be separated by the movable member into an explosive-containing compartment and a displacement compartment. The casing may be in the form of a cylinder and the movable pressure responsive member a piston movable within the piston said piston being operatively associated with or in engagement with the lock.

The casing may include at least one vent in communication with the chamber, the vent being adapted to open in response to movement of the piston as a result of the detonation of the explosive charge.

In another form the lock activating device may include a linear actuator or transducer operatively connected to the lock and responsive to electrical signals such that upon receiving an electrical signal causes movement between the lock position and the release position. The linear actuator may be a solenoid which includes a core engaged with the lock so that when an electrical signal is received by the solenoid, the core is moved so that the lock moves from the lock position to the release position. A detent may be provided to hold the lock in the release position.

Preferably the linear actuator is mounted within the reservoir. The linear actuator may be adapted to allow fuel and air to pass therethrough.

The shut down mechanism may further include an isolating assembly which includes a movable contact element which is adapted for movement between an open position in which it breaks an electric circuit with which it is associated and a closed position in which it completes the electric circuit the contact element being operatively associated with said lock such that when said lock is in the lock position the contact element is held in the closed position and when the lock adopts the release position the contact element is arranged to move into the open position.

The isolation assembly may include a main body having the contact element operatively connected thereto and a biasing device urging said contact element into the open position. The main body may include an aperture therein through which the lock passes when in the lock position. The contact element may comprise a bridge which in the closed position connects to electrical contacts which form part of the electric circuit. A housing may be provided having a bore therein for receiving the main body of the isolating assembly the main body comprising a post slidably receivable within the bore and the biasing device comprising a spring which urges the contact element into the open position.

According to yet another aspect of the present invention there is provided a shut down mechanism for shutting down an apparatus energy supply system, the mechanism comprising a releasable lock which is movable between a lock position in which position the energy supply system is in an operating mode and a release position in which position the energy supply system is in a shut down mode, a lock activating device which includes a movable pressure-responsive member operatively connected to the lock responsive to detonation of an explosive charge which upon detonation causes movement of the lock between the lock position and the release position, the activation device further including a detonator which when activated causes detonation of the explosive charge, activation thereof being caused by manual activation or activation as a result of selected operating conditions of the apparatus.

According to still another aspect of the present invention there is provided a method of shutting down a fuel supply by manual operation or as a result of abnormal operating conditions, the method including the steps of: evacuating fuel in a downstream end of a fuel supply system through an outlet in an upstream region of the fuel supply system. The method may include the step of connecting the outlet in the upstream region of the fuel supply line to a reservoir which includes an interior having a negative pressure relative to the operating pressure inside the fuel supply line. The method may also include the step of connecting the interior of the reservoir to a negative pressure source. Preferably, the upstream region of the fuel supply system is disposed within a valve which is itself disposed upstream of the downstream end of the fuel supply system.

According to a yet further aspect of the present invention there is provided a shut down mechanism for shutting down a fuel supply line of an apparatus, the mechanism comprising a valve which is movable between an open position in which position the fuel supply line is in an operating mode and a closed position in which position the fuel supply line is in a shut down mode, a valve activating device activation of which is caused by manual activation or activation as a result of abnormal operating conditions of the apparatus, the shut down mechanism further including a reservoir an interior of which, in use is at a lower pressure relative to a normal operating pressure of the fuel line, the reservoir including an inlet which is in fluid communication with a downstream end of the fuel line when the lock is in the closed position enabling fuel in the downstream end of the fuel line to pass into the reservoir.

Brief Description of the Drawings

In order to enable a clearer understanding of the invention, drawings illustrating example embodiments are attached, and in those drawings:

Figure 1 is a section view of an electrical shutdown mechanism for a vehicle according to a preferred embodiment of the present invention in a lock position;

Figure 2 is a section view of the mechanism in Figure 1, in a release position;

Figure 3 is a section view of a fuel shutdown mechanism according to another preferred embodiment of the present invention in a lock position;

Figure 4 is a section view of the mechanism shown in Figure 3 shown in a release position; Figure 5 is a section view of another preferred embodiment of electrical shutdown mechanism shown in a lock position;

Figure 6 is a section view of the shutdown mechanism of Figure 5 shown in a release position;

Figure 7 is a section view of a second embodiment of fuel shutdown apparatus shown in a lock position;

Figure 8 is the fuel shutdown mechanism of Figure 7 shown in a release position;

Figure 9 is a section view of a fuel shutdown apparatus in accordance with a third preferred embodiment of the present invention;

Figure 10 is a section view of the fuel shutdown apparatus shown in Figure 9; and

Figure 1 1 is an exploded view of part of the fuel shutdown apparatus shown in Figures 9 and 10.

Description of Preferred Embodiments

Referring to Figures I and 2 there is shown a shutdown mechanism generally indicated at 10, which includes a releasable lock 12, a lock activating device 14 and an isolating assembly 16. The lock 12 is in the form of a bolt 20 mounted for reciprocating movement.

The bolt 20 has a forward end 13 and a trailing end 15. The shutdown mechanism is for shutting down or breaking the electrical circuit of an apparatus which in a preferred application is a vehicle.

The lock activating device 14 includes a casing 65 disposed at one side of a housing 56.

The housing 56 protects the isolating assembly 16 and houses a pair of posts 34, one post for battery disconnect and one post for ignition circuit disconnect. A cylinder 26 is disposed on an interior of the casing 65. The lock activating device further includes an assembly 22 which includes a piston 24 disposed within the cylinder 26. On one side of the piston 24, within the cylinder 26 is disposed an explosive compartment containing an explosive charge 28. On the other side of the piston 24, within the cylinder 26 is a vacant or displacement compartment 27.

The piston 24 is operatively connected to the reciprocating bolt 20, so that bolt 20 may be moved from its lock position shown in Figure 1 to the release position shown in Figure 2. The bolt 20 reciprocates in bore 30.

The isolating assembly 16 includes a main body 32 in the form of an elongate post 34 which has apertures 36 through which the bolt 20 passes when in the lock position. The main body 32 includes friction reducing elements 38 in the form of roller bearings 40 having a bearing region extending slightly into a base portion of the apertures 36 to assist travel of bolt 20 when travelling to the release position.

An electrical connector assembly 42 is provided in the form of a pair of spaced-apart contact elements 44 and bridged in a closed position by a contact element in the form of a bridge plate or element 46 in electrical contact therewith. Nut 48 retains the bridge plate or element 46 onto post 34. Bridge plate or element 46 is a sliding fit on post 34 so that nut 48 may be tightened when the electrical connector assembly is in the contact position (Figure 1 ) so as to improve contact between bridge plate element 46 and contact elements 44. Biasing device 49 in the form of spring 50 is adapted to maintain the bridge plate or element 46 remote from the contact elements 44 when in the open position (Figure 2).

A cable (not shown) from a battery terminal is cut and its respective upstream and downstream ends attached with spades or other connectors to nuts 51 so that in the open position, current flow from the terminal is interrupted The same attachment arrangement may be provided for the ignition circuits, disposed adjacent the battery circuit in the Figures. Biasing devices 52 are provided for facilitating movement of the isolating assembly 16 to the open position. A first spring 53 is provided at a base of post 34 and a second spring 50 is disposed at a top of post 34, the second spring 50 acting on an underside face of bridge element or plate 46, which would otherwise remain connected to contact elements 44 even in the release position because of the sliding fit of the bridge element 46 on post 34.

An actuator 58 in the form of a spark generator or a system for shorting two wires 60 is provided in order to actuate the device 14.

In normal operation, the shutdown apparatus 10 is disposed in a lock position as shown in Figure 1. In the lock position, the bolt 20 is disposed in housing 56, within bore 30 and passing through holes 36 in posts 34, so as to lock the posts 34 in the closed position. The nut 48 is tightened so that bridge element 46 forms a good contact with contact elements 44. Springs 53 and 54 are retained in a coiled position, ready for release of energy.

As a result of abnormal operating conditions, or by manual activation, a detonation signal is received by a receiver (not shown) associated with the shutdown apparatus and sent to the actuator 58 which detonates the explosive charge 28. In some embodiments the detonation signal may be received wirelessly, for example, by a police or other radio, or by Bluetooth, or by SMS, or received by a wire from an accelerometer acting as a crash sensor. In response to the detonation signal the piston 24 and leading end 13 of bolt 20 travels along cylinder 26, towards the vacant or displacement compartment 27. Air is released through vent 59 as a result of the increase in pressure within the displacement compartment 27, and the lock bolt 20 is retracted from holes 36 in posts 34 which releases posts 34 which are urged upward and bridge element or plate 46 is displaced from contact elements 44. The apparatus 10 now adopts the open position shown in Figure 2, and the ignition and battery circuits are now open, reducing the risks of short or sparks, which reduces the risk of fires. A second embodiment of electrical shutdown apparatus is shown in Figures 5 and 6. Parts which are like those in Figures 1 and 2 are denoted by like numerals in Figures 5 and 6.

Thus, referring to Figures 5 and 6, there is shown a lock activating device 214 which is operatively connected to a lock 212. The lock 212 includes a keeper element 4 associated with each post 234 and a retaining element 2 operatively connected to the lock activating device so as to be. displaceabte in response to activation of the device. The keeper elements 4 are adapted to hold the post 234 in a closed position where the contacts are closed. The arrangement is such that displacement of the retaining element 2 enables release of the keeper element 4 from the post 234 with which it is associated whereupon the post can move into an open position where the contacts are open.

The keeper elements 4 are in the form of spherical bodies 7 which are at least partially receivable in a complementary recess 236 in the post 234 to inhibit movement thereof.

The retaining element 2 is in the form of a substantially spherical body 5 operatively connected to piston rod 8. In the lock position shown in Figure 5 the substantially spherical body 5 abuts keeper elements 4 to maintain their seating in the cooperating recess 236 to inhibit movement of post 234. A flat or slightly concave section is disposed on abutting faces of the retaining element 2 so as to hold the retaining element 2 in the lock position shown in Figure 5.

When the detonation signal is received, the piston 224 is moved from the lock position shown in Figure 5 to the release position shown in Figure 6, which draws the substantially spherical body 5 away, from the spherical bodies 7. The spherical bodies 7 are thus released, are unseated from the corresponding recesses 236 and caused to move into the space previously occupied by the substantially spherical body 5, because the posts 234 are displaced upwards under the influence of the springs 253, which in turn displaces the bridge 246 from the spaced connectors 244. Referring to Figures 3 and 4, there is shown a shutdown mechanism 70 suitable for use with vehicles having liquid fuel storage and supply systems on board. Parts which are like to those shown in Figures 1 and 2 are depicted with like numerals.

The shutdown mechanism 1 10 includes a releasable lock 1 12 and a lock activating device 1 14. The releasable lock 112 is movable between a lock position and a release position. The lock position is shown in Figure 3, in which position a fuel supply line 71 is in an operating mode, supplying fuel from a tank (not shown) to an engine (not shown). The release position is shown in Figure 4, in which position the fuel supply line 71 is in a shut down mode. The lock 1 12 is in the form of a valve 72 so that the fuel supply line 71 has an upstream end or region 61 and a downstream end or region 63. The valve is in the form of a spool valve 85 for controlling fuel flow from the upstream end 61 of the fuel delivery line 71 to the downstream end 63 of the fuel delivery line 71 , and to a fuel return pipe 74.

A reservoir 75 is provided, which, has a housing 81 and a chamber 79 within the housing, which in use is maintained at a lower pressure than that in the fuel supply line 71. The reservoir 75 has an inlet 67 which is adapted to be in fluid communication with the downstream end 63 of the fuel supply line 71 via the fuel return line 74 when the valve 72 is in the release position. Thus, in the release position, the arrangement is so as to draw fuel from the downstream end 63 of the fuel supply line 71. This is especially useful if the fuel supply line has been severed in an accident, because the fuel within the line 71 is not sprayed into the engine bay of the vehicle, but is substantially removed from a potentially hot area which may include electrical sparks.

In the embodiment shown the reservoir 75 has an outlet 77 which is connected to a fuel inlet manifold (not shown) which provides the lower or negative pressure to the chamber 79. A low Or bad vacuum pressure sensor 83 is connected to the chamber 79 to alert a user that a low vacuum pressure situation exists and maintenance may be required.

The valve 72 includes an aperture 87 to enable fuel to flow in delivery pipe 71 when in the lock position (Figure 3). In that lock position, the fuel return pipe 74 has end 69 closed off by valve 72, so that fuel is not sent straight from the fuel tank to the chamber 79 in normal operation.

In abnormal operating conditions, the lock activation device 1 14 is moved upwards by detonation of the explosive charge 128, which draws post 134 upwards, allowing valve 72 to shuttle to one side under the biasing force of the spring 150. At the end of the valve stroke, head 91 abuts bore wall 93 and the device is in the release position shown in Figure

4. In that position, the valve 72 shuts off supply of fuel from the fuel tank and the end 69 of fuel transfer line 74 is caused to be in fluid communication with the reservoir chamber 79. A one-way valve is provided at 95 in case the connection between the inlet manifold and the chamber 79 is broken, so as to maintain vacuum in the chamber for as long as possible.

A similar embodiment of fuel shutdown apparatus is shown in Figures 7 and 8, wherein parts like to those shown in other Figures are indicated with like numerals. Therefore, there is shown a fuel shutdown apparatus generally indicated at 310. A valve 372 is in the form of a shuttle or spool valve 385 which incorporates port or aperture 398 to allow fuel to flow, in the lock position, from fuel tank to engine in the direction of arrows in Figure 7.

In this embodiment, the shuttle 385 is connected to the piston 324 so that they are adapted to move together.

In abnormal operation, explosive charge 328 is detonated and piston 324 moves to an outer end 359 of chamber 375 and the fuel flow through port 398 is blocked by the trailing end body 315 of the shuttle 385. Port 396 is opened by the movement of the shuttle 385 so that reservoir 375 is in fluid communication with fuel transfer line 374 and downstream end 363 of fuel supply line 371. Substantially all fuel remaining in the downstream end 363 of fuel supply line 371 is drawn back towards the reservoir 375, especially if the tube 373 is broken anywhere along its length between the reservoir 375 and the engine.

Another embodiment of fuel shutdown apparatus is shown in Figures 9 - 1 1 wherein parts like to those already described in other embodiments are indicated with like numerals. An activating device 414 is provided which is operatively connected to a valve 472. The activating device 414 is in the form of a linear actuator 453 in the form of a solenoid 455 which has a core 434 adapted to move in response to an electric or electromagnetic force.

In this embodiment, the reservoir 475 and cylinder 426 are the same void.

A biasing member 450 is disposed to bias the valve 472 towards a lock position, the lock position shown in Figure 9 in which position the fuel supply line 471 is in an operating mode. TTie valve 472, in the lock position, is held by the biasing member 450 against seals in the form of O-rings or quad rings 453 so that in the operating mode, fuel does not pass through end 469 of fuel return line 474.

A detent 447 is provided to hold the valve 472 in the release position against the biasing force of the spring.

In abnormal operation, an electromagnetic signal is sent to solenoid 455 which overcomes the biasing force from spring 450 and shuttles spool valve 485 so that fuel from the fuel tank is stopped at interface 499. The core 434 of the linear actuator has holes or other clearances to allow fuel and air through from inlet 467 to outlet 477.

The reference to any prior art in this specification is not, and should not be taken as, an acknowledgment or any form of suggestion that that prior art forms part of the common general knowledge in Australia or elsewhere.

Throughout this specification and the claims which follow, unless the context requires otherwise, the word "comprise", and variations such as "comprises" or "comprising", will be understood to imply the inclusion of a stated integer or step or group of integers or steps but not the exclusion of any other integer or step or group of integers or steps. Finally, it is to be understood that various alterations, modifications and/or additions may be incorporated into the various constructions and arrangements of parts without departing from the spirit or ambit of the invention.

Claims

CLAIMS:

1. A shut down mechanism for shutting down a fuel supply line of an apparatus, the mechanism comprising a releasable lock which is movable between a lock position in which position the fuel supply line is in an operating mode and a release position in which position the fuel supply line is in a shut down mode, a lock activating device activation of which is caused by manual activation or activation as a result of abnormal operating conditions of the apparatus, the shut down mechanism further including a reservoir an interior of which in use is at a lower pressure relative to a normal operating pressure in the fuel line, the reservoir including an inlet which is in fluid communication with a downstream end of the fuel line when the lock is in the release position enabling fuel in the downstream end of the fuel line to pass into the reservoir

2. A shut down mechanism according to claim 1 wherein the reservoir includes an outlet arranged so that the interior of the reservoir is at a lower pressure relative to the normal operating pressure of the fuel line.

3. A shut down mechanism according to claim 1 or 2 wherein said lock comprises a valve associated with the fuel line, the valve closing said fuel line when in the release position and opening the fuel line when in the lock position.

4. A shut down mechanism according to claim 2 or 3 wherein the reservoir outlet is in fluid communication with a low pressure zone so as to place the interior of the reservoir at a low pressure relative to the normal operating pressure of the fuel line.

5. A shut down mechanism according to claim 4 wherein the low pressure zone is associated with an inlet manifold of an engine, the arrangement being such that the reservoir outlet is connected to a line which in turn is connected to the inlet manifold so as to create a venturi effect to maintain the reservoir at a negative pressυre during normal operation when in the operating mode.

6. A shut down mechanism according to any previous claim wherein the lock activating device includes a movable pressure-responsive member operatively associated or engaged with the lock, and which is responsive to detonation of an explosive charge which upon detonation causes the lock to move between the lock position and the release position, the activation device further including a detonator which when activated causes detonation of the explosive charge, activation thereof being caused by manual activation or activation as a result of abnormal operating conditions of the apparatus.

7. A shut down mechanism according to claim 6 wherein said lock activating device includes a casing having a chamber therein, said movable pressure- responsive member being mounted for movement within said chamber, said chamber being separated by the movable pressure-responsive member into an explosive-containing compartment and a vacant or displacement compartment.

8. A shut down mechanism according to claim 7 wherein said casing is a cylinder and said movable pressure responsive member is a piston movable within the piston said piston being operatively associated with or engaged with said lock.

9. A shut down mechanism according to claim 8 wherein said casing includes at least one vent in communication with the chamber, the vent being adapted to open in response to movement of the piston as a result of the detonation of the explosive charge.

10. A shut down mechanism according to any one of claims 6 - 9 wherein the detonator comprises a spark generator.

I I . A shut down mechanism according to any one of claims 1 - 7 wherein the lock activating device includes a linear actuator or transducer operatively connected to the lock responsive to electrical signals which upon receiving an electrical signal causes the lock to move between the lock position and the release position.

12. A shut down mechanism according to claim 1 1 wherein the linear actuator is a solenoid which includes a core engaged with the lock so that when an electrical signal is received by the solenoid, the core is moved so that the lock moves from the lock position to the release position.

13. A shut down mechanism according to any previous claim wherein the lock includes a detent so as to hold the lock in the release position.

14. A shut down mechanism according to any one of claims 1 1 - 13 wherein the linear actuator is mounted within the reservoir.

15. A shut down mechanism according to claim 14 wherein the lock activation device is adapted to allow fuel and air to pass therethrough.

16. A shut down mechanism according to any previous claim wherein the fuel supply line is a vehicle fuel supply line.

17. A shut down mechanism according to any previous claim further including an isolating assembly which includes a movable contact element which is adapted for movement between an open position in which it breaks an electric circuit with which it is associated and a closed position in which it completes the electric circuit said contact element being operatively associated with said lock such that when said lock is in the lock position the contact element is held in the closed position and when the lock adopts the release position the contact element is moved into the open position.

18. A shut down mechanism according to claim 17 wherein the isolation assembly includes a main body having said contact element operatively connected thereto and a biasing device urging said contact element into the open position.

19. A shut down mechanism according to claim 18 wherein said main body includes an aperture therein through which the lock passes when in the locking position.

20. A shut down mechanism according to any one of claims 17 - 19 wherein said contact element comprises a bridge which in the closed position connects to electrical contacts which form part of the electric circuit

21. A shut down mechanism according to any one of claims 17 - 20 including a housing having a bore therein for receiving the main body of the isolating assembly said main body comprising a post slidably receivable within the bore and the biasing device comprising a spring which urges the contact element into the open position.

22. A shut down mechanism for shutting down an electric circuit for an apparatus, the mechanism comprising a releasable lock which is movable between a lock position in which position the electric circuit is in an operating mode and a release position in which position the electric circuit is in a shut down mode, a lock activating device responsive to activation caused by manual activation or activation as a result abnormal operating conditions of the apparatus, the shut down mechanism further including an isolating assembly which includes a movable contact element which is adapted for movement between an open position in which it breaks the electric circuit with which it is associated and a closed position in which it completes the electric circuit said contact element being operatively associated with said lock such that when said lock is in the lock position the contact element is held in the closed position and when the lock adopts the release position the contact element is moved into the open position.

23. A shut down mechanism according to claim 22 wherein the isolation assembly includes a main body having said contact element operatively connected thereto and a biasing device urging said contact element into the open position.

5

24. A shut down mechanism according to claim 23 wherein said main body includes an aperture therein through which the lock passes when in the locking position.

I O 25. A shut down mechanism according to any one of claims 22 - 24 wherein said contact element comprises a bridge which in the closed position connects to electrical contacts which form part of the electric circuit.

26. A shut down mechanism according to any one of claims 22 - 25 including a

15 housing having a bore therein for receiving the main body of the isolating assembly said main body comprising a post slidably receivable within the bore and the biasing device comprising a spring which urges the contact element into the open position. 0 27. A shut down mechanism for shutting down an apparatus energy supply system, the mechanism comprising a releasable lock which is movable between a lock position in which position the energy supply system is in an operating mode and a release position in which position the energy supply system is in a shut down mode, a lock activating device which includes a movable pressure- 5 responsive member operatively connected to the lock responsive to detonation of an explosive charge which upon detonation causes movement of the lock between the lock position and the release position, the activation device further including a detonator which when activated causes detonation of the explosive charge, activation thereof being caused by manual activation or activation as a 0 result of selected operating conditions of the apparatus .

28. A shut down mechanism according to claim 27 wherein said lock activating device includes a casing having a chamber therein, said movable pressure responsive member being mounted for movement within said chamber, said chamber being separated by the movable pressure responsive member into an explosive containing compartment and a vacant compartment.

29. A shut down mechanism according to claim 28 wherein said casing is a cylinder and said movable pressure responsive member is a piston movable within the piston said piston being operatively connectible to said lock.

30. A shut down mechanism according to any one of claims 27 - 29 wherein the detonator comprises a spark generator.

31. A shut down mechanism according to any one of claims 28 - 30 wherein said casing includes at least one vent in communication with the chamber.

32. A shut down mechanism according to any one of claims 27 - 31 further including an isolating assembly which includes a movable contact element which is adapted for movement between an open position in which it breaks an electric circuit with which it is associated and a closed position in which it completes the electric circuit said contact element being operatively associated with said lock such that when said lock is in the lock position the contact element is held in the closed position and when the lock adopts the release position the contact element is moved into the open position.

33. A shut down mechanism according to claim 32 wherein the isolation assembly includes a main body having said contact element operatively connected thereto and a biasing device urging said contact element into the open position.

34. A shut down mechanism according to claim 33 wherein said main body includes an aperture therein through which the lock passes when in the locking position.

35. A shut down mechanism according to claim 34 wherein said contact element comprises a bridge which in the closed position connects to electrical contacts which form part of the electric circuit.

36. A shut down mechanism according to claim 35 including a housing having a bore therein for receiving the main body of the isolating assembly said main body comprising a post slidably receivable within the bore and the biasing device comprising a spring which urges the contact element into the open position.

37. A method of shutting down a fuel supply by manual operation or as a result of abnormal operating conditions, the method including the steps of: evacuating fuel in a downstream end of a fuel supply system through an outlet in an upstream region of the fuel supply system.

38. A method of shutting down a fuel supply according to claim 37 wherein the method includes the step of connecting the outlet in the upstream region of the fuel supply line to a reservoir which includes an interior having a negative pressure relative to the operating pressure inside the fuel supply line.

39. A method of shutting down a fuel supply according to claim 38 wherein the method includes the step of connecting the interior of the reservoir to a negative pressure source.

40. A method of shutting down a fuel supply according to claim 37 wherein the upstream region of the fuel supply system is disposed within a valve which is itself disposed upstream of the downstream end of the fuel supply system.

41. A shut down mechanism substantially as hereinbefore described with reference to the attached drawings.

42. A method of shutting down a fuel supply substantially as hereinbefore described with reference to the attached drawings.