AU618907B2

AU618907B2 - Floating boom

Info

Publication number: AU618907B2
Application number: AU60418/90A
Authority: AU
Inventors: Carsten Buch; Steen Jensen; Lars Boldt Rasmussen
Original assignee: Roulunds Fabriker AS
Current assignee: Roulunds Fabriker AS
Priority date: 1989-06-28
Filing date: 1990-06-19
Publication date: 1992-01-09
Anticipated expiration: 2010-06-19
Also published as: AU6041890A; DK165012C; DK320789D0; WO1991000393A1; DK165012B; DK320789A; JPH04501150A; EP0431140A1; CA2030808A1

Description

floating boom.

The invention relates to a floating boom of the type having a number of separate buoyancy chambers, a skirt, a ballast and an air supply conduit, the buoyancy chambers being disposed at one edge of the skirt and the ballast at the other edge of the skirt, said other edge being located beneath the first edge after the ±loating boom has been laid out, each buoy¬ ancy chamber having its own connection with the air supply conduit. The invention also relates to a method of using a floating boom of said type, in which the air supply conduit is disposed at the other edge of the skirt.

Floating booms of the above mentioned type are known, in which the buoyancy chambers are designed as closed chambers with an air supply, and possibly with a valve for discharging air from the buoyancy chamber in connection with recovery of the floating boom. The lay¬ ing out of such floating boom necessitates, in order to avoid the buoyancy chambers bursting, that the inlet pressure to the air supply conduit is kept lower than the bursting pressure of said chambers. If one of the buoyancy chambers is punctured, all buoyancy chambers empty through the common air supply conduit, following which the floating boom sinks. The floating boom according to the invention is characterized in that for each buoyancy chamber there is provided at least one duct extending from the interior of the buoyancy chamber to an outlet located between the buoyancy chamber and the other edge of the skirt.

The excess pressure in the buoyancy chambers will thereby be limited without requiring any limita¬ tion of the inlet pressure to the air supply conduit which may then feed the inlet air at a higher pressure, thereby resulting in a larger volume flow in the air supply conduit and/or a smaller dimension of said conduit.

The individual duct includes an outlet which in the position of use is located below the buoyancy chamber. The inflation of the buoyancy chamber causes the level of the water in the duct to drop with an increasing pressure in the buoyancy chamber until air starts bubbling out at the outlet of the duct. This occurs when the pressure in the buoyancy chamber has risen to the pressure prevailing in the surrounding sea water outside the duct outlet, thereby restricting the pressure in the buoyancy chamber to the pressure of the surrounding water. A further advantage of the floating boom according to the invention is that the ducts may be used for emptying the buoyancy chambers of air in con¬ nection with the recovery of the floating boom.

A preferred embodiment of the invention is characterized in that the connection of each buoyancy chamber with the air supply conduit opens into a duct associated with the chamber. This results in a barring of the air supply conduit connection between the buoyancy chambers at falling pressures so that the puncturing of a single buoyancy chamber does not cause all the buoyancy chambers to be emptied. At falling pressure in one buoyancy chamber the surrounding water will rise in the duct and upon reaching the air supply outlet, the pressure of the water will prevent further inflow of air from the remaining buoyancy chambers which are then capable of retaining a pressure corresponding to the pressure of the surrounding sea water at the level of the air supply outlet.

A further preferred embodiment according to the invention is characterized in that the air supply con¬ duit is disposed at the other edge of the skirt and that the connection of each buoyancy chamber with the air supply conduit includes a branch tube. This results in a particularly simple structure of the connection between the air supply conduit and the buoyancy chamber which is easy to produce and service. The completed air supply conduit with branch tube is now mounted at the other edge of the skirt and the branch tubes are inserted into the associated ducts, the outlet of the branch tube thereby forming the air supply outlet to the buoyancy chamber associated with the duct.

Still a preferred embodiment according to the invention is characterized in that the connection of each buoyancy chamber with the air supply conduit includes a non-return valve. Thereby, the air supply conduit connection between the buoyancy chambers is barred, whereby from the start any pressure drop in the remaining buoyancy chambers is completely avoided, if one chamber is punctured. A non-return valve that is particularly appropriate for this purpose is a so- called "gill valve" used in conjunction with air supply controllers for diving equipment and which is distin¬ guished by exhibiting an extremely low pressure drop in the flow direction. The method, as referenced in the preamble, is characterized in that the air supply conduit is filled with water after inflation of the floating boom, thus closing the buoyancy chambers from each other, and punc¬ turing of one buoyancy chamber does not cause all the buoyancy chambers to be deflated. As in the case with the non-return valve, a barring of the air supply con¬ duit, between the buoyancy chambers, is obtained from the beginning, thereby preventing a pressure drop in the remaining buoyancy chambers if one of them is punctured. The barring is obtained in that the water in the air supply conduit functions as a water seal for the air supply conduit connections of the individual buoyancy chambers.

The invention will now be explained in detail by means of some embodiments with reference to the drawings, in which

Fig. 1 is a side elevation of a floating boom according to the invention, shown in the position of use,

Fig. 2 on a larger scale illustrates a branch tube inserted into the duct outlet, one rubber sheet being removed for the sake of clearness,

Fig. 3 an embodiment as Fig. 2, in which the branch tube is fully inserted into the buoyancy chamber and provided with a non-return valve, and Fig. 4 a sectional view along line I-I in Fig. 2.

The embodiment of the floating boom illustrated in Fig. 1 includes buoyancy chambers 1 formed along one edge 5 of the floating boom and ducts 8 extend- ing downwards from the buoyancy chambers in the posi¬ tion of use. A skirt 2 is positioned below buoyancy chambers 1. Said skirt is provided with reinforcements 10 along the lower edge for securing a ballast chain 3 by means of fixing members 11. Said ballast chain 3 serves in a known manner to maintain the floating boom in a substantially vertical position in the sea. An air supply conduit 4 with a branch tube 7 is secured to ballast chain 3. The branch tube 7 is inserted into duct 8 of buoyancy chamber 1. The function of the embodiment according to the invention illustrated in Fig. 1 will be explained in the following with reference to Fig. 2, from which cer¬ tain parts have been omitted in respect of clearness. Buoyancy chamber 1 is inflated by pressurized air being supplied through air supply conduit 4 and branch tube 7. The level of the water in the duct will from the outset be the same as the level c of the surrounding sea water. In step with rising pressure in the buoyancy chamber, the water level drops and finally reaches level a at the outlet of the duct, following which a further pressure rise causes air to escape through the duct. After inflation, the water level in the duct will be equal to level a. If a chamber is punctured the pressure above the water in the duct drops, thereby causing the water level to rise in the duct. When the water has attained level b, the water flows down into the air supply conduit and so bars the connection between the buoyancy chambers, following which the water in the duct of the punctured buoyancy chamber may rise to water level c, causing the pressure at the outlet to become equal to that of the sea surrounding the floating boom on this level. Briefly spoken, upon the puncturing of one chamber the pressure in the other chambers drops from the water pressure at a to the water pressure at b. Said pressure drop is eliminated by making use of the method according to the invention, because the water-filled air supply conduit obstructs air transfer from the intact chambers to the punctured chamber. It will be recognized from the above description that it is important that branch tube 7 is inserted from below, when the method according to the invention is used. The barring is solely determined by level b of the outlet of the air supply conduit.

In the embodiment illustrated in Fig. 3 the barring between chambers 1 is ensured from start by means of a non-return valve 9 mounted on air supply connection 7 of each chamber 1. In Fig. 3 the air supply conduit is disposed at the lower edge 6 of skirt 2, however, in this embodiment the position is unimportant.

The described floating booms offer a quicker inflation of the booms by making use of a higher inlet pressure. In this respect the ducts ensure that the positive pressure in buoyancy chamber 1 does not exceed the pressure difference between buoyancy chamber 1 and the outlet of duct 8. In the method according to the invention the filling of the air supply conduit with water may either be effected by pumping water into the air supply con¬ duit or by thrusting one end of the air supply conduit down into the water and let the water flow in by itself, while the air in the air supply conduit escapes through the outlets of the buoyancy chambers and bubbles out from the duct outlets.

There are many possibilities of varying a floating boom according to the invention, e.g. the air supply conduit may pass along the upper edge, provided the outlet to the individual buoyancy chamber be located in the duct associated with the chamber. The outlet of the ducts associated with the chamber may also be positioned on an arbitrary level of the floating boom, which merely has to be positioned below the buoyancy chamber, e.g. one of the rubber sheets 13 or 14 may end above lower edge 6 of the floating boom or there may be an opening in one of the rubber sheets 13 or 14 on an appropriate level. A substantial advantage of the floating boom according to the invention over and above other imagi¬ nable solutions to the problems with respect to excess pressure security of and barring between the buoyancy chambers consists in that said problems are solved without introducing other components such as valves or the like, which would increase the risk of failure and requirement for service, overhaul, spare parts and edu¬ cation of staff.

Claims

P A T E N T C L A I M S 1. A floating boom of the type having a number of separate buoyancy chambers, a skirt, a ballast and an air supply conduit, the buoyancy chambers being disposed at one edge of the skirt and the ballast at the other edge of the skirt, said other edge being located beneath the first edge after the floating boom has been laid out, each buoyancy chamber having an individual connection with the air supply conduit, characterized in that for each buoyancy chamber there is provided at least one duct extending from the interior of the buoyancy chamber to an outlet located between the buoyancy chamber and the other edge of the skirt.
2. A floating boom as claimed in claim 1, characterized in that the connection of each buoyancy chamber with the air supply conduit opens into a duct associated with the chamber.
3. A floating boom as claimed in claims 1 to 2, characterized in that the air supply conduit is disposed at the other edge of the skirt and that the connection of of each buoyancy chamber with the air supply conduit includes a branch tube.
4. A floating boom as claimed in claims 1 to 3, characterized in that the connection of each buoyancy chamber with the air supply conduit includes a non¬ return valve.
5. A floating boom as claimed in claim 4, char¬ acterized in that the non-return valve is a so-called "gill valve".
6. A method of using a floating boom as claimed in claim 1, in which the air supply conduit is arranged below the duct outlet, characterized in that the air supply conduit is filled with water after inflation of the floating boom, thus closing the buoyancy chambers from each other, and puncturing of one buoyancy chamber does not cause all the buoyancy chambers to be deflated.