WO2002008091A2

WO2002008091A2 - Tanks for storage

Info

Publication number: WO2002008091A2
Application number: PCT/GB2001/003236
Authority: WO
Inventors: Christopher Bruce Giles; George Colin Robson
Original assignee: Bp Oil International Limited
Priority date: 2000-07-25
Filing date: 2001-07-18
Publication date: 2002-01-31
Also published as: WO2002008091A3; GB0018267D0; AU2001270869A1

Abstract

A combination comprising a manhole cover plate which is adapted to be able to be in releasably sealing relation to a manhole of an ISO tank, a liquid introduction means passing through said plate, and a liquid removal means also passing through said plate.

Description

TANKS FOR STORAGE

The present invention concerns tanks for aviation fuel storage and methods of using them.

During aviation fuel storage water may accumulate at the bottom of the fuel tank. Consequently when the fuel is being drawn from near the bottom of the tank the fuel may contain water. When the fuel is used in an aircraft engine the water may form ice particles at temperatures experienced at high altitude. These ice particles can then prevent fuel flow to the aircraft engine which is extremely hazardous. Furthermore the water can also encourage the formation of microbes which produce acids that lead to the corrosion of the aircraft fuel tanks. Consequently aviation fuel is stored at airports in tanks that are fitted with equipment that can minimise water transfer from the storage tanks to the aircraft. Standard ISO tanks are unsuitable for use as aviation fuel storage tanks, as they lack the facilities required to eliminate water from the fuel and their design does not permit the mandatory quality checks to be readily carried out. Consequently, although fuel transportation can be conducted using standard ISO tanks, the fuel must then be transferred from the ISO tanks into an aviation fuel storage tank before it can be used to fuel an aircraft.

The present invention, however, allows standard ISO tanks, which are freely available in the majority of locations throughout the world, to be reversibly converted into tanks which may be used to supply aviation fuel directly into aircraft.

The invention further provides equipment for fuelling which may be deployed and installed quickly at a location in urgent need of fuel and be capable of safely delivering aviation fuel to aircraft. Accordingly the present invention provides a combination comprising a manhole cover plate adapted to be able to be in releasably sealing relation to a manhole of an ISO tank, a liquid introduction means passing through said plate, and a liquid removal means also passing through said plate. In a modification of the combination of the invention the manhole cover plate has one liquid line passing through it, said line adapted to function as a liquid introduction means and a liquid removal means.

ISO tanks are defined by the International Standards Organisation No. 1496- 3:1995. ISO tanks are single skinned cylindrical containers having planar or usually outwardly hemispherical ends. They are usually metallic but may be made from rigid plastic material e.g. engineering plastic. They are standardised with respect to their dimensions. The containers have outer dimensions between 3-12m e.g. 6m in maximum length and are approximately 2.6m in maximum width. They usually have at least one e.g. 1-3 but especially a single manhole located at the top of the tank which usually has a diameter of 300-1000mm especially either 500mm or 800mm. The manhole usually has a raised lip, to which the cover plate is releaseably affixed. The tank also usually has an opening located at the bottom of the tank either in its end or in its bottom surface. The opening is reversibly closable with a valve positioned therein, the valve being usually a standard ISO tank foot valve. In addition said valve may also have a standard ISO tank butterfly valve connected to it but distant from the tank. The tank may contain at least, 5000 litres of liquid storage space e.g. at least 10000 litres storage space such as 20000 litres or 30000 litres. Thus a standard BVIO Type 1 or 2 20' stainless steel ISO tank provides approximately 25,000 litres of basic storage.

A single line may provide both an introduction and a removal means so that the liquid may pass in either direction in it. Alternatively the introduction means and the removal means may be separate lines. Preferably the introduction means comprises a first liquid line in fluid communication with the contents of the tank and the liquid removal means comprises a second liquid line, which is preferably a suction line, in fluid communication with the contents of the tank.

Preferably the liquid introduction means comprises a float which is adapted to move with the liquid level within the tank. Usually when the liquid introduction means comprises a first liquid line said first liquid line preferably comprises a closure means e.g. a valve therein. The float is positioned in use such that when the liquid level within the tank reaches a particular level the float activates the closure of the valve and the flow of further liquid into the tank via the first line is prevented. The float itself may activate closure of the valve or alternatively the float may activate a small valve which in turn controls a larger valve. Preferably the valve is located in the first liquid line. This arrangement prevents overfilling of the tank and thus the introduction means usually comprises the first line, a float, a valve and a valve actuating means such that movement of the float between two positions causes opening or closing of the valve and controls liquid introduction. Each of the valve and first line may itself move with movement of the float or may be in a fixed location relative to the tank. Preferably the liquid removal means comprises a second line, which is a suction line and a floating means and may also comprise a means to stop liquid suction through said suction line which is activated prior to complete tank drainage, usually a closure means.

The suction line preferably comprises a non buoyant open end positioned below the liquid surface. The end is usually rigid and is advantageously positioned such that in use the open end is directed essentially vertically downwards. The end may be integral with the line or may be a separate member attached to the line.

The suction line may itself be buoyant in the liquid and thereby itself constitute a floating means or may be non buoyant with a separate float attached to said line or the float may be attached to a buoyant line. The separate float may be in direct contact with the suction line, or may be spaced therefrom by a spacer which in use holds the line rigidly below the float. Usually the separate float is attached near or at the end of the line situated in use inside the tank and positioned such that the float sits on the liquid surface and the end of the suction line is located below the surface. This ensures that the suction of the liquid occurs from below the surface level. The end of the suction line is preferably located 50-500mm, usually 100-300mm e.g. 150mm below the position of the float and is advantageously directed essentially vertically downwards.

The means to stop liquid suction in the suction line may be provided by a rigid end section of the line with a closed end and a lateral orifice distant from said end so the liquid suction occurs through said orifice. The orifice is located in use above the tank bottom by virtue of the floating means and/or by virtue of the rigid end section with a closed end contacting the tank bottom. The liquid suction is stopped when the liquid level drops below the orifice.

Preferably the means to stop liquid suction is a closure means and may comprise a valve actuatable by a float to control liquid removal. The float is positioned in use such that when the liquid level within the tank reaches a particular level, the float activates the closure of the valve and the removal of further liquid from the tank via the second line is prevented. h a preferred embodiment of the invention the closure means maybe provided by the rigid end of the suction line which in use will interact with the bottom of the tank which is inclined and wherein the rigid end is usually positioned towards the highest point of the inclined tank. Thus the closure means is activated as the rigid end contacts the bottom of the tank thereby closing the end so the liquid suction is stopped. The inclined slope of the tank ensures that the closure means is activated prior to complete tank drainage. The volume of liquid retained within the tank when the suction is prevented is dependant on the relative positioning of the end of the suction line below the float. This volume of liquid is usually more than the total volume of water likely to separate from the fuel in use.

Each of the first and second lines may be partly rigid e.g. with two or more rigid sections articulated via joints to allow free vertical movement of the end in use. Each line may alternatively be flexible and may or may not be of itself buoyant in the liquid. The first line and the second line may be introduced into the tank through the manhole and held in place therein by spacers, but are usually introduced via a manhole assembly comprising the cover plate. The cover plate may either comprise holes preferably fitted with bushes or sleeves to ensure sealing through which the lines pass, or may comprise the first and second lines as an integral part of the assembly. The cover plate for use in the invention is adapted to be able to be removably mounted on the manhole of the tank and usually replaces the normal manhole cover plate. The cover plate is preferably releasably attached to the tank using a quick release mechanism. The quick release mechanism may comprise swing bolts, preferably 2-8 e.g. 4 or 6 quick release swing bolts which are attached to hinges located on the tank around the manhole and the swing bolts adapted to engage the cover plate which is provided with a suitable number of notches for sealing engagement with corresponding swing bolts such that when the cover plate is positioned on top of the manhole the swing bolts may be moved about their hinges such that they interlock with the notches in the cover plate.

Alternatively the quick release mechanism may comprise an expandable plug attached to the underside of the cover plate such that when the cover plate is positioned on top of the manhole the plug fits inside the hole and can be expanded such that the body of the plug is forced against the wall of the manhole to provide a secure attachment. The plug is then moveable when in a collapsed position allowing the plate and plug to be removed from the manhole.

In a preferred embodiment of the invention the quick release mechanism comprises preferably 2-8 e.g. 4 or 6 brackets which may be hooked to the underside of the tank surrounding the manhole so they inwardly radially, extend therefrom. Each bracket comprises a bolt that protrudes essentially vertically upwards through the manhole which may be threaded through a corresponding hole in the assembly cover plate such that when the cover plate is positioned on top of the manhole the bolts pass through the holes in the cover plate which may then be releasably secured with the required number of nuts. The tightening of nuts also secures the bracket to the underside of the tank.

In an alternative embodiment of the invention the tank may comprise bolts that are permanently attached to the tank which also protrude essentially vertically upwards through the manhole and which may be threaded through a corresponding hole in the assembly cover plate, hi this embodiment the manhole cover plate may comprise more holes than the number of bolts e.g. 2-6 such that when the cover-plate is mounted on the lid of the tank there remains a number of holes unthreaded by bolts. These holes are preferably sealed using a sealing means e.g. a cap, a screw or a bolt. In a further embodiment of the invention the cover plate may comprise both holes and notches such that said cover plate may be removably mounted to a manhole of a tank wherein the tank comprises vertically protruding bolts or swing bolts as herein described above. The cover plate may then be removably mounted to the manhole of a tank comprising swing bolts and the holes sealed using a sealing means as herein described above. Alternatively the cover plate may be removably mounted to a manhole comprising brackets such that the notches of said cover plate are usually positioned around the rim of the manhole such that the cover plate maintains a sealing relation to the manhole.

The manhole assembly cover plate preferably comprises flexible sealing means e.g. a rubber seal adapted to seal between the cover plate and the top of the tank. The cover plate is usually provided with at least one orifice capable of acting as both a free or pressure/vacuum vent and a reversibly closable dip hatch and may also have a second orifice capable of acting as an emergency vent.

The liquid within the tank usually comprises a liquid hydrocarbon and is preferably a fuel, particularly a fuel suitable for use in aircraft e.g. jet fuel. The liquid may comprise hydrocarbon and water. Due to the relative densities of the water and the hydrocarbon the water settles at the bottom of the tank. The relative positioning of the float and the end of the suction line ensures that the end remains above the level of the water in the tank so the hydrocarbon essentially without water is removed from the tank and that suction is prevented prior to the transfer of water with the fuel.

However if the water level inside the tank were to increase to a level such that, when the float sits on the hydrocarbon surface, and the end of the suction line is below the water surface, then water may then be sucked from the tank.

To overcome this problem in a preferred embodiment of the invention the combination may also comprise a separate draining means to drain liquid from the bottom of the tank. The draining means may comprise a reversibly removable plug or a standard ISO foot valve adapted to close the opening at the bottom of the ISO tank. The tank could then be drained by the removal of the plug or opening of the valve. Preferably the draining means comprises a drain line for external attachment to the bottom tank opening and capable of being in fluid communication with the liquid therein, especially at its lowest point. The drain line preferably comprises a sump which may be attached to the standard foot valve on the ISO tank, usually via a butterfly valve and threaded fitting. The sump is preferably attached to the side of the foot valve distant from the tank to enable removal.

The sump is usually located in a position relative to the ISO tank so that the bottom of the sump may be positioned below the level of the bottom of the tank and especially above ground level. The sump has a drain at its bottom, and especially in use the tanks and sump are disposed so that there is a space for a container below the drain.

The liquid introduction means and the liquid removal means (and the draining means if present) are usually fitted to the tank in the location where the tank is to be used for the storage of fuel which allows the tank to remain within its ISO dimensions whilst being transported. The tank is usually empty of liquid at the time of their fitting. The draining means assembly may be fitted when the tank contains liquid but the tank is preferably empty of liquid.

Another embodiment of the invention provides fuelling equipment comprising an ISO tank and a combination according to the invention. Preferably the equipment also comprises at least one pump capable of introducing and removing liquid from the ISO tank comprising a combination according to the invention. Usually the liquid introduction means of the combination is capable of fluid communication with a fuel supply e.g. a tanker via said pump and advantageously the liquid removal means of the combination is also capable of fluid communication with a vessel receiving the fuel e.g. an aircraft or helicopter via said pump.

The fuelling equipment may also be provided with additional liquid storage by using at least one additional tank e.g. a pillow tank but preferably an ISO tank which is capable of internal connection via liquid communication to at least one ISO tank comprising a combination according to the invention. The additional tanks usually have a larger capacity than the ISO tank comprising a combination according to the invention; e.g. 1-3 times the capacity, i a preferred embodiment of the invention the additional tank is a 8-12m ISO tank e.g. 9 or 10m and 6m tanks are preferred for the ISO tank comprising a combination according to the invention.

The additional tank usually comprises a liquid removal means and a liquid supply means and advantageously comprises a draining means facility as herein described above. Preferably the liquid removal means and the liquid supply means are in liquid communication with the tank via the draining means facility e.g. a sump.

Usually the liquid introduction means of the combination according to the invention is capable of liquid communication with the liquid removal means of the additional tank preferably via a pump.

Preferably the fuelling equipment comprises 2-10 e.g. 4-8 additional tanks in liquid communication with the ISO tank comprising a combination according to the invention, in series/or parallel therewith.

In a preferred embodiment of the invention the fuelling equipment may comprise an ISO tank comprising a combination according to the invention, at least one first pump and at least one second pump and at least one additional tank comprising a liquid removal means and a liquid supply means wherein the liquid removal means of the combination being capable of fluid communication with a vessel receiving the fuel via said first pump and the liquid introduction means of the combination being capable of in liquid communication with the liquid removal means of the additional tank via said second pump. Advantageously the liquid supply means of the additional tank is capable of liquid communication with a fuel supply via said second pump.

In further embodiment of the invention the fuelling equipment may comprise at least one first ISO tank comprising a first combination according to the invention and at least one second ISO tank comprising a second combination according to the invention, at least one first pump, at least one second pump and at least one first additional tank comprising a first liquid removal means and a first liquid supply means wherein the liquid removal means of the first combination is capable of fluid communication with a vessel receiving the fuel via said first pump and the liquid introduction means of the second combination is capable of liquid communication with the first liquid removal means of the additional tank via said second pump.

Advantageously the equipment may also comprise at least one second additional tank comprising a second liquid removal means and a second liquid supply means and at least one third pump wherein the second removal means of the second additional tank is capable of fluid communication with a fuel supply via said third pump.

In a further aspect of the invention fuelling equipment comprises at least two ISO tanks each comprising a combination according to the invention one of said ISO tanks may be used to fuel a vessel whilst at least one other of said ISO tanks may be filled with fuel.

In use the ISO tank comprising the combination according to the invention is usually at an angle to the horizontal e.g. with a fall of 1:10 to 1:100 e.g. 1:30 towards the bottom opening.

The ISO tank may also be provided with at least one external ladder, especially with at least one handrail for said ladder to permit safe access to the top of the tank and the manhole.

The ISO tanks may be fitted with an external frame e.g. a rectangular frame or \ located in a rectangular container. This helps to protect them from damage, enable the containers to be stacked and allows easier transport. The fuelling equipment may be transported to the location by rail, air, road or sea. Preferably the equipment is located on a pallet and transported to allow rapid deployment and installation to a location in urgent need of the fuel. The apparatus according to the invention may be deployed to a location and be suitable for use within 2-24hours e.g. 12hours.

The tanks may rest on or in the ground or may be supported above ground. As the ISO tanks are single skin tanks the ISO tanks of the fuelling equipment are usually housed within a bund; e.g. an earth bund, the bunded area is usually covered with a membrane.

The present invention also comprises a method of assembling fuelling equipment of the invention, which comprises transporting to a fuelling location, at least one combination according to the invention from a first location and at least one ISO tank from a second location which may be the same as or distant from the first location, and fitting said cover plate comprising the introduction means and suction means to said tank, and if required fitting said draining means to said tanks.

In another embodiment of the present invention provides a method of fuelling an aircraft wherein fuel is transferred from an ISO tank comprising a combination according to the invention or from fuelling equipment according to the invention on land to a fuel chamber in an aircraft.

The invention is illustrated in and described with reference to the drawings, in which Fig. 1 is a cross section of the ISO tank comprising a combination according to the invention, Fig. 2 is an end elevation of the ISO tank and Fig. 3 is a plan view of the ISO tank showing connections and the manhole piping. Fig. 4 is a plan view of the manhole assembly cover plate and Fig. 5 shows a manhole lid fixing bracket. Fig. 6 and 7 show the end elevation of an ISO tank comprising a combination according to the invention and a draining means. Fig. 8 shows an additional tank with fill and suction connections to enable connection to the ISO tank comprising a combination according to the invention and Figs. 9-12 show another embodiment of the invention wherein an ISO tank comprising a combination according to the invention is in internal liquid communication with an additional ISO tank(s) and pumps. Referring now to Fig 1-3. The ISO tank (1) has a manhole (2) covered by a cover plate (9) through which passes a internal suction line (3) and a internal fill line (5). Suction line (3) has a flexible line (3A) to which is attached on its upper side a ball float (4). Fill line (5) has a float valve (6) therein. The suction line (3) is connected to external suction line (10) and connector (7) to suction means (not shown) such as a suction pump. The fill line (5) is connected to external fill line (11) and a connector (8) and a liquid source.

Fig. 4 shows the manhole assembly cover plate in detail. The cover plate (9) is welded to the suction line (3) and the fill line (5) and also has a combined free vent and dip hatch (12) welded thereto but passing through it and an emergency vent (25). The cover plate (9) is fixed to the ISO tank (1) by four fixing brackets (13). Fig. 5 shows the manhole lid fixing bracket (13) connecting the ISO tank shell (1) to the cover plate (9).

Fig. 6 and 7 show the end elevation of an ISO tank comprising a combination according to the invention and illustrate a preferred embodiment of the invention wherein the ISO tank is also fitted with a draining means. ISO tank (1) has an opening (14) at the bottom of the tank closed by a standard ISO tank foot valve (15). From the foot valve (15) extends a drain line (16) leading to a sump (17). From the sump (17) extends an exit line (18) to drain point (19) positioned so that a space for a bucket (20) under the drain point (19) is available. The sump also comprises a pressure gauge (21) to measure the tank head pressure.

Fig. 8 shows the additional tank containing fill and suction connections (23) that are connected to the additional tank via the sump (17).

Fig. 9 is a schematic representation of the fuelling equipment with an ISO tank comprising a combination according to the invention and a pump. An ISO tank (1) having a fill line (5) is connected to a fuel supply (26) via a pump (27). A vessel receiving fuel (28) is also connected to the ISO tank (1) via a suction line (3) and the pump (27).

Fig. 10 is also a schematic representation of the fuelling equipment with an ISO tank comprising a combination according to the invention, two pumps and an additional tank. An ISO tank (1) is connected to an additional ISO tank (22) via a fill line (5), a liquid removal line (23) and second pump (27'). The additional tank (22) is also connected to a fuel supply (26) via a liquid introduction line (29) and the second pump (27'). The vessel receiving fuel (28) is again connected to the ISO tank (1) via a suction line (3) and the pump (27).

Fig. 11 shows fuelling equipment with 2 ISO tanks each comprising a combination according to the invention, two pumps and an additional tank. A first ISO tank (1) is connected to vessel receiving fuel (28) via the suction line (3) and the pump (27). A second ISO tank (1 ') is connected an additional tank (22) via the second pump (27'), a fill line (5') and a liquid removal line (23). The additional tank (22) is also connected to the fuel supply (26) via a liquid introduction line (29) and the second pump (27'). Fig. 12 shows fuelling equipment with 2 ISO tanks each comprising a combination according to the invention, three pumps and two additional tanks. The first ISO tank (1) is connected to vessel receiving fuel (28) via the suction line (3) and via the pump (27). A second ISO tank (1 ') is connected an additional ISO tank (22) via a second pump (27'), a fill line (5') and a liquid removal line (23). A second additional tank (22') is connected to the fuel supply (26) via a liquid introduction line (29') and a third pump (27").

Claims

1. A combination comprising a manhole cover plate which is adapted to be able to be in releasably sealing relation to a manhole of an ISO tank, a liquid introduction means passing through said plate, and a liquid removal means also passing through said plate.

2. A combination according to claim 1 wherein the liquid introduction means comprises a first liquid line.

3. A combination according to claim 1 or 2 wherein the liquid introduction means comprises a float adapted to move with at least part of said introduction means.

4. A combination according to claim 2 or 3 wherein the first liquid line has a valve therein.

5. A combination according to claim 4 wherein the liquid introduction means comprises a valve actuating means.

6. A combination according to anyone of the preceding claims wherein the liquid removal means comprises a second liquid line.

7. A combination according anyone of the preceding claims wherein the liquid removal means comprises a floating means.

8. A combination according to claim 7 wherein the floating means comprises a buoyant suction line.

9. A combination according to claim 7 wherein the floating means comprises a non buoyant suction line and a separate float.

10. A combination according to anyone of claims 8 and 9 wherein the suction line comprises a non buoyant open rigid end.

11. A combination according to claim 9 and 10 wherein a separate float is attached to said line such that it may be positioned 50-500mm distant from the non buoyant open rigid end.

12. A combination according to anyone of the preceding claims 1-9 wherein the liquid removal means comprises a valve.

13. A combination according to claim 12 wherein the liquid removal means comprises a valve actuating means.

14. A combination according to anyone of claims 1-9 wherein the liquid removal means comprises a rigid end section with a closed end and a lateral orifice distant from said end.

15. A combination according to anyone of the preceding claims wherein the cover plate is provided with 2-8 notches suitable for sealing engagement with corresponding swing bolts attached to an ISO tank.

16. A combination according to anyone of the preceding claims wherein the cover plate is provided with 2-8 holes suitable for interaction with 2-8 corresponding bolts protruding essentially vertically upwards through the manhole of an ISO tank.

17. A combination according to anyone of the preceding claims wherein the cover plate is provided with at least one orifice capable of acting as an emergency vent and a dip hatch.

18. A combination according to anyone of the preceding claims also comprising a separate draining means.

19. A combination according to claim 18 wherein the draining means comprises a reversibly removable plug or a standard ISO foot valve adapted to close an opening at the bottom of an ISO tank.

20. A combination according to claim 19 wherein the draining means comprises a drain line suitable for external attachment to an opening at the bottom of an ISO tank.

21. A combination according to claim 20 wherein the drain line comprises a sump.

22. A combination substantially as described with reference to or as shown in the drawings.

23. Fuelling equipment comprising at least one first ISO tank and at least one first combination according to anyone of the preceding claims.

24. Fuelling equipment according to claim 23 comprising at least one additional tank wherein the tanks are internally connected by internal communication.

25. Fuelling equipment according to claim 24 connected via liquid communication to at least 1-8 additional ISO tanks.

26. Fuelling equipment according to anyone of claims 23-25 comprising at least one first pump capable of fluid communication with a vessel receiving fuel and the liquid removal means of the first combination.

27. Fuelling equipment according to claim 26 wherein the first pump is capable of fluid communication with a fuel supply and the liquid introduction means of the first combination.

28. Fuelling equipment according to claim 26 comprising at least one additional tank comprising a liquid removal means and a liquid supply means and at least one second pump wherein the liquid introduction means of the first combination is capable of liquid communication with the liquid removal means of the additional tank via said second pump and the liquid supply means of the additional tank is capable of liquid communication with a fuel supply via said second pump.

29. Fuelling equipment according to claim 26 comprising at least one second ISO tank comprising a second combination according to the invention, at least one second pump and at least one additional tank comprising a liquid removal means and a liquid supply means wherein the liquid introduction means of the second combination is capable of liquid communication with the liquid removal means of the additional tank via said second pump and the liquid supply means of the additional tank is capable of liquid communication with a fuel supply via said second pump.

30. Fuelling equipment according to anyone of the preceding claims 23-29 wherein in use at least one ISO tank is positioned at an angle to the horizontal of between 1:10- 1:100 e.g. 1:30.

31. Fuelling equipment according to anyone of the preceding claims 23-30 wherein at least one ISO tank is provided with at least one external ladder and at least one handrail for said ladder.

32. Fuelling equipment according to anyone of claims 23-31 located on a pallet.

33. Fuelling equipment substantially as described with reference to or as shown in the accompanying drawings.

34. A method of assembling fuelling equipment according to anyone of claims 23- 33, which comprises transporting to a fuelling location at least one combination according to anyone of claims 1-22 from a first location and at least one ISO tank from a second location which is the same as or distant from the first location and fitting said combination to said tank.

35. A method of fuelling an aircraft wherein fuel is transferred from an ISO tank comprising a combination according to anyone of claims 1-22 or from fuelling equipment according to anyone of claims 23-33 or assembled by method claim 34 to a fuel chamber in an aircraft.

36. A method of fuelling an aircraft according to claim 34 wherein the fuel is removed from the ISO tank from a position below the fuel surface.

37. A method of fuelling an aircraft according to anyone of claims 35 and 36 wherein liquid removal is stopped prior to the complete removal of the liquid from the tank.

38. A method of fuelling an aircraft according to claim 37 wherein the liquid removal means comprises a rigid end section with a closed end and an orifice distant from said end and wherein the orifice is positioned above the tank bottom such that in use as the rigid end section contacts the tank bottom, liquid removal is stopped when the liquid level inside the tank drops below the level of the orifice.

39. A method of fuelling an aircraft according to claim 38 wherein the liquid removal means comprises a float, a valve and a valve actuating means and wherein the float is positioned in use such that when the liquid level within the tank reaches a particular level the float actuates the closure of the valve.

40. A method of fuelling an aircraft according to claim 39 wherein the liquid removal means comprises a non buoyant open rigid end and wherein the liquid removal is stopped when the rigid end contacts the bottom of an inclined tank.

41. A method substantially as described with reference to or as shown in the accompanying drawings.