FI ELD OF THE I NVENTION AND PRIOR ART

The present invention relates to a leak preventing appliance accord ing to the preamble of claim 1 for preventing liqu id from leaking out of a damaged tank. The invention also relates to a method for preventing liqu id from leaking out of a damaged tank.

Liquid fuel and other types of liqu ids may be transported and stored in tanks of various types. If such a tank is damaged , for instance due to an accident or wear, the liquid in the tan k may leak to the surrounding environment, which may cause a lot of problem, for instance in the form of material damages, environmental pollution and health and safety hazards for people in the vicinity of the leaking tank. It is previously known , for instance from GB 1 020 581 A and DE 1 525 465 B, that liquid may be prevented from leaking out through a leak below the surface of the liquid in a tan k by producing a sufficient underpressure in a gas-filled space above the surface of the liquid in the tank by means of a vacuum pump.

A leak preventing appliance according to the preamble of claim 1 is previously known from WO 87/02650 A1 . This previously known appliance has the form of a leak sealing pad which is to be attached to an outer wall of a tank so as to cover a leak opening in the tank wall and thereby prevent gas or liquid from flowing out of the tank through the leak opening . The pad is pressed against the tank wall under the effect of an underpressure generated in a vacuum chamber of the pad by means of a vacuum pump. However, th is leak preventing appliance is on ly suitable for use when it comes to an easily accessible leak concentrated to a limited area.

OBJECT OF THE I NVENTION

The object of the present invention is to provide a new and favourable leak preventing appliance for preventing liquid from leaking out of a damaged tank.

SUMMARY OF THE I NVENTION According to the present invention , the above-mentioned object is ach ieved by a leak preventing appliance having the features defined in claim 1 .

The leak preventing appliance of the present invention comprises a vacuum pump and a suction head to be pressed against an outer wall of the tank under the effect of an underpressure generated by the vacuum pump, wherein the suction head comprises:

- a first suction chamber with an opening intended to face said tank wall when the suction head is pressed against it;

- at least one second suction chamber arranged around the first suction chamber and connected to a suction side of the vacuum pump, the second suction chamber having an opening intended to face said tan k wall so as to allow the suction head to be pressed against the tan k wall and thereby be attached to it when a reduced pressure is produced in the second suction chamber by the vacuum pump;

- a chamber wall which surrounds the first suction chamber, wherein this chamber wall is configured to keep the first suction chamber separated from the second suction chamber when the suction head has been attached to said tank wall ;

- a base structure, wherein said chamber wall is fixed to the base structure; and

- a penetration member which extends through the base structure and into the first suction chamber,

wherein the penetration member is moveably mounted to the base structure so as to allow a front end of the penetration member to penetrate said tank wall in order to make a hole therein when the suction head has been attached to the tan k wall, and wherein the first suction chamber is connectable to the suction side of the vacuum pump so as to allow a reduced pressure to be produced in the first suction chamber by the vacuum pump when the suction head has been attached to said tank wall.

With the leak preventing appliance of the present invention , a leak-preventing underpressure may be ach ieved inside a tan k in a simple manner. When in use, the first suction chamber of the suction head is intended to be in fluid communication with a gas- filled upper space of a damaged tank via a hole made by the penetration member in an outer wall of the tank above the surface of the liquid in the tan k, and an underpressure produced in said upper space of the tank by the vacuum pump is intended to prevent the liquid in the tank from leaking out of the tank through a leak opening at another part of the tank below the surface of the liquid in the tank. Thus, the suction head is not to be applied over the leak opening and the leak preventing appliance of the present invention may consequently be used even if the leak opening is inaccessible. Furthermore, the penetration member may remain in the above-mentioned hole in the tank wall during the leak preventing operation in order to prevent the suction head from moving along the tank wall and thereby ensure that the first suction chamber remains correctly positioned above the hole made by means of the penetration member.

Further advantageous features of the leak preventing appliance of the present invention will appear from the following description and the dependent claims.

The invention also relates to a method having the features defined in claim 13 for preventing liquid from leaking out of a damaged tan k. Further advantageous features of the method of the present invention will appear from the following description .

BRI EF DESCRI PTION OF THE DRAWI NGS With reference to the appended drawings, a specific description of embod iments of the invention cited as examples follows below. In the drawings:

Figs 1 -3 are schematic and partly cut lateral views of a leak preventing appliance according to a first embodiment of the present invention , as seen at different stages during a working operation , and

Fig 4 is a schematic and partly cut lateral view of a leak preventing appliance according to a second embod iment of the invention .

DETAI LED DESCRI PTION OF EMBODI MENTS OF THE I NVENTION

A leak preventing appliance 1 according to an embodiment of the present invention is schematically illustrated in Figs 1 -3. The leak preventing appliance 1 comprises a vacuum pump 3 and a suction head 4, wherein the suction head 4 is to be pressed against an outer wall 5 of a tan k 2 under the effect of an underpressure generated by the vacuum pump 3.

The suction head 4 comprises a first suction chamber 6 with an opening 7 which is to face said tank wall 5 when the suction head 4 is pressed against it. The suction head 4 further comprises a second suction chamber 9 which is arranged around the first suction chamber 6 and connected to the suction side of the vacuum pump 3. The second suction chamber 9 has an opening 10 which is intended to face said tank wall 5 so as to allow the suction head 4 to be pressed against the tank wall 5 and thereby be attached to it when a reduced pressure is produced in the second suction chamber 9 by the vacuum pump 3.

In the illustrated embod iment, the first suction chamber 6 is surrounded by one single second suction chamber 9, wherein the first suction chamber 6 is arranged inside the second suction chamber 9. As an alternative, the leak preventing appliance 1 could be provided with a plurality of mutually separated second suction chambers distributed around the first suction chamber 6. The suction head 4 is to be attached to the tank wall 5 under the effect of the reduced pressure produced in the second suction chamber 9 or the plurality of second suction chambers by the vacuum pump 3, wherein the suction head 4 is to be kept in place on the tan k wall 5 as long as the reduced pressure is maintained in the second suction chamber 9 or the plurality of second suction chambers by the vacuum pump 3.

The suction head 4 comprises a first chamber wall 1 1 which surrounds the first suction chamber 6, and a second chamber wall 12 which surrounds the second suction chamber 9 and separates the second suction chamber 9 from the ambient air. The first chamber wall 1 1 and the second chamber wall 12 are fixed to a base structure 13 of the suction head 4, wherein each chamber wall 1 1 , 12 has a first end facing the base structure 13 and an opposite second end facing away from the base structure 4. A rim 14 at said second end of the second chamber wall 12 is configured for engagement with the tank wall 5. A rim 15 at said second end of the first chamber wall 1 1 is configured to be pressed against the tank wall 5 when the suction head 4 has been attached to the tank wall 5, to thereby allow the first chamber wall 1 1 to separate the first suction chamber 6 from the second suction chamber 9 when the suction head 4 has been attached to the tank wall 5. The second chamber wall 12, or at least a part thereof, is of flexible material. Also the first chamber wall 1 1 may be of flexible material. The first and second chamber walls 1 1 , 12 are preferably of rubber, but may as an alternative be of any other suitable material.

The first suction chamber 6 is connectable to the suction side of the vacuum pump 3 so as to allow a reduced pressure to be produced in the first suction chamber 6 by the vacuum pump 3 when the suction head 4 has been attached to the tan k wall 5. In the illustrated embod iment, the first suction chamber 6 is connectable to the suction side of the vacuum pump 3 via a first suction line 16, whereas the second suction chamber 9 is connected to the suction side of the vacuum pump 3 via a second suction line 1 7, wh ich is connected to the first suction line 16 at a junction point 18. The second suction line 1 7 is connected to an outlet open ing 19 of the second suction chamber 9. A third suction line 20 extends between said junction point 18 and the suction side of the vacuum pump 3. The third suction line 20 or a part thereof may be formed by a flexible hose to thereby allow the vacuum pump 3 to be located at a distance from the suction head 4.

The leak preventing appliance 1 comprises a pressure limiter 21 for limiting the underpressure in the first suction chamber 6. In the illustrated embodiment, the pressure limiter 21 is arranged in the first suction line 16 between the first suction chamber 9 and the above-mentioned junction point 18. The pressure limiter 21 is with advantage an adjustable pressure limiter so as to allow the minimum level of the pressure in the first suction chamber 6 to be set by an operator or by an electronic control system connected to the pressure limiter.

The suction head 4 comprises a penetration member 22 which extends through the base structure 13 and into the first suction chamber 6. The penetration member 22 is moveably mounted to the base structure 13 so as to allow a front end 23 of the penetration member 22 to penetrate the tan k wall 5, when the suction head 4 has been attached to the tan k wall 5, in order to make a hole 24 (see Fig 3) in the tank wall 5 into a gas-filled upper space 25 in the tank 2 above the surface 26 of the liquid in the tank and thereby establish fluid communication between the first suction chamber 6 and the gas-filled upper space 25 in the tank 2 via this hole 24.

In the embodiment illustrated in Figs 1 -3, the the penetration member 22 comprises an elongated shaft 27 and a punch tool 28 which is fixed to the elongated shaft 27 at a front end thereof and configured to cut a hole 24 in the tan k wall 5 when hit against it. The punch tool 28 preferably has a pointed tip 29 and is preferably provided with a cutting edge at the pointed tip 29. In the illustrated example, the penetration member 22 is configured to be actuated by a striking tool and comprises an impact head

30 which is fixed to the elongated shaft 27 at a rear end thereof, wherein the impact head 30 is provided with an impact surface

31 for receiving an impact from said striking tool.

The elongated shaft 27 is slidably mounted to the base structure 13 by being slidably received in a bore 32 which extends through the base structure 13. A first end 32a of the bore 32 opens into the surround ings and an opposite second end 32b of the bore opens into the first suction chamber 6. A ring-shaped sealing member 33, for instance in the form of an O-ring , is arranged at the interface between the elongated shaft 27 and the bore 32 in order to seal the first suction chamber 6 from the surroundings when the suction head 4 has been attached to the tan k wall 5. In the illustrated embodiment, the sealing member 33 is arranged in an annular recess 42 provided in an inner wall of the bore 32. In the illustrated embod iment, the first suction chamber 6 is connectable to the vacuum pump 3 via a flow port 34, which is provided in the base structure 13 and connected to the above- mentioned bore 32 , wherein the first suction chamber 6 is in flu id commun ication with the flow port 34 via a flow channel 35 provided at the interface between the elongated shaft 27 and the bore 32. In the illustrated example, the flow channel 35 has the form of an axial groove in an inner wall of the bore 32. The first suction chamber 6 cou ld of course be connectable to the vacuum pump 3 in any other suitable manner.

In the embod iment illustrated in Fig 4, the penetration member 22' comprises an elongated shaft 27' which extends through a bore 32 in the base structure 13. An external thread 37 is provided on the elongated shaft 27' , wherein th is external thread 37 is in engagement with a mating internal thread 38 provided in the axial bore 32 to thereby make the elongated shaft 27' move in its axial direction in relation to the base structure 13 when subjected to rotation in relation to the base structure. In this case, the penetration member 22' comprises a drilling tool 39 for making a hole in the tan k wall 5 by drilling , wherein the drilling tool 39 is fixed to the elongated shaft 27' at a front end thereof so as to be rotatable together with the elongated shaft. The elongated shaft 27' is to be rotated by means of a su itable torque tool, which is to be engaged with a tool fitting 40, for instance in the form of a socket head or hexagonal drive head , at the rear end of the elongated shaft 27' .

The punch tool 28 and the drilling tool 39 are with advantage provided with one or more axially extending flow channels 41 (see Fig 3) in order to make sure that flu id communication is established between the first suction chamber 6 and the space 25 on the inner side of the tan k wall 5 through the hole 24 in the tank wall when the tool 28, 39 remains in the hole 24. In the embodiment illustrated in Figs 1 -3, such a flow channel 41 is provided as an axial groove in the outer surface of the punch tool 28. The flow channel cou ld as an alternative be provided inside the tool 28 , 39.

The leak preventing appliance 1 is to be used for preventing liquid from leaking out through a hole or crack in a wall of a damaged liqu id containing tank 2 below the surface 26 of the liquid in the tank. The suction head 4 of the leak preventing appliance 1 is applied against an outer wall 5 of the tank 2 at a part of the wall located above the surface 26 of the liquid in the tank in such a manner that the rim 14 around the opening 10 of the second suction chamber 9 makes contact with the tank wall 5, as illustrated in Fig 1 . Thereafter, the vacuum pump 3 of the leak preventing appliance 1 is operated to reduce the pressure in the second suction chamber 9 to thereby cause the suction head 4 to be pressed against the tank wall 5 so as to be attached to it and at the same time cause the rim 15 around the opening 7 of the first suction chamber 6 to be tightly pressed against the tank wall 5, as illustrated in Fig 2. Thereafter, the penetration member 22, 22' is actuated so as to force the front end 23 of the penetration member into the tank wall 5 in order to make a hole 24 in the tan k wall into a gas-filled upper space 25 above the surface 26 of the liquid in the tank 2 and thereby bring the gas- filled upper space 25 of the tank into flu id commun ication with the suction side of the vacuum pump 3 via the hole 24 and the first suction chamber 6, as illustrated in Fig 3. The vacuum pump 3 is hereby allowed to reduce the pressure in the upper space 25 of the tank 2 and keep the pressure therein at such a low value that leakage of liquid from the tank 2 is prevented . The level of the underpressure produced by the vacuum pump 3 in the first suction chamber 6 and in the upper space 25 of the tank 2 is limited by the pressure limiter 21 , and a too low internal pressure in the tank 2 is thereby prevented .

In the illustrated embodiments, the first suction chamber 6 is connectable to the suction side of the vacuum pump 3 via a valve device 43 arranged in the first suction line 16 between the first suction chamber 6 and the junction point 18. When the rim 15 around the opening 7 of the first suction chamber 6 has been pressed against the tank wall 5, as illustrated in Fig 2, the valve device 43 is configured to keep the first suction chamber 6 connected to the suction side of the vacuum pump 3 when a reduced pressure produced in the second suction chamber 9 by the vacuum pump 3 is below a threshold value, and to otherwise keep the first suction chamber 6 disconnected from the suction side of the vacuum pump 3. Thus, the valve device 43 is configured to be in a closed position , and thereby keep the first suction chamber 6 disconnected from the vacuum pump 3, until the pressure in the second suction chamber 9 has been reduced to a given level under the effect of the vacuum pump 3, whereupon the valve device 43 assumes an open position and thereby allows a reduced pressure to be produced in the first suction chamber 6 under the effect of the vacuum pump 3. Said threshold value is so chosen that the reduced pressure already produced in the second suction chamber 9 when the valve device 43 is shifted from the closed position to the open position is sufficient for keeping the suction head 4 firmly attached to the tank wall 5. The valve device 43 is with advantage a spring- loaded check valve, such as for instance a spring-loaded ball check valve. The valve device 43 is preferably adjustable so as to allow the above-mentioned threshold value to be set by an operator or by an electronic control system connected to the valve device.

The invention is of course not in any way restricted to the embodiments described above. On the contrary, many possibilities to modifications thereof will be apparent to a person with ord inary skill in the art without departing from the basic idea of the invention such as defined in the appended claims.