TANK PROVIDED WITH A HATCH AND METHOD FOR PROVIDING ACCESS TO THE TANK

Abstract

A tank for water has a bottom and a surrounding wall with an inside and an outside. In a lower portion, the wall is provided with a hatch casing positioned in a hatch opening extending through the wall for access by personnel from the outside to the inside of the tank. The hatch casing is provided with a hatch with an inside and an outside. The hatch in a closed position closes the hatch opening in a liquid-tight manner. The inside of the hatch is flush with the inside of the wall when the hatch is in the closed position. A method for giving personnel access to the tank through the hatch opening is also described.

Claims

1. A tank for rearing fish, said tank having a bottom and a surrounding wall with an inside and an outside, when in a lower portion, the wall is provided with a hatch casing positioned in a hatch opening extending through the wall for access by personnel from the outside to the inside of the tank, and the hatch casing is provided with a hatch with an inside and an outside, the hatch in a closed position closing the hatch opening in a liquid-tight manner, and the inside of the hatch being flush with the inside of the wall when the hatch is in the closed position.

2. The tank according to claim 1, wherein the hatch casing is provided with a recess which is complementary to the edge portion of the hatch.

3. A method for providing access for personnel to a tank arranged to be filled with water for rearing fish, wherein the method comprises the steps of: a) providing a tank for rearing fish, said tank having a bottom and a surrounding wall with an inside and an outside, when in a lower portion, the wall is provided with a hatch casing positioned in a hatch opening extending through the wall for access by personnel from the outside to the inside of the tank, and the hatch casing is provided with a hatch with an inside and an outside, the hatch in a closed position closing the hatch opening in a liquid-tight manner, and the inside of the hatch being flush with the inside of the wall when the hatch is in the closed position; b) draining the tank of water until a water surface is at least below the lower edge of the hatch; c) opening the hatch; and d) entering the tank through the hatch opening.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0026] In what follows, an example of a preferred embodiment is described, which is visualized in the accompanying drawings, in which:

[0027] FIG. 1 shows a perspective view of a hatch casing provided with a hatch;

[0028] FIG. 2 shows on a smaller scale in accordance with the invention, a section through the hatch casing installed in a vessel wall, the hatch being in a closed position;

[0029] FIG. 3 shows the same as FIG. 2, but the hatch is in an open position;

[0030] FIG. 4 shows, on a different scale, a schematic side view of a tank according to the invention, the tank being provided with a hatch; and

[0031] FIG. 5 shows the same as FIG. 4 in another embodiment.

DETAILED DESCRIPTION OF THE DRAWINGS

[0032] In the figures, the reference numeral 1 indicates a hatch casing. The hatch casing 1 is provided with a hatch 2. In accordance with the invention, the hatch casing 1 is installed in a wall 3. The wall 3 is arranged to surround a bottom 60 as shown in FIGS. 4 and 5. Together, the wall 3 and bottom 60 form a tank 6 which can be filled with water (not shown). The water may be fresh water or sea water.

[0033] The wall 3 forms an inside 30, facing the water in the tank 6, and an outside 39. The wall 3 is provided with a through hatch opening 31. The hatch 2 forms an inside 20, facing the water in the tank 6, and an outside 29. The hatch casing 1 is provided with an inside flange 10 at the inside 30 of the wall 3 and an outside flange 19 at the outside 39 of the wall 3. The hatch casing 1 is positioned in the hatch opening 31.

[0034] The hatch casing 1 comprises a surrounding casing wall 11 which is provided with a first hinge 15 on an inside 13. On its outside 29, the hatch 2 is provided with a second hinge 25. An articulated arm 4 is attached, in a first end portion 40, to the first hinge 15 and attached, in an opposite second end portion 49, to the second hinge 25. In a middle portion 41, the arm 4 is provided with a joint 43.

[0035] The inside 13 of the hatch casing 1 is provided with a plurality of protruding locking faces 17. The outside 29 of the hatch 2 is provided with a plurality of locking handles 27.

[0036] The inside flange 10 of the hatch casing 11 is provided with a recess 18 which is complementary to the edge portion 28 of the hatch 2. The recess 18 is provided with a sealing element 5. The inside 20 of the hatch 2 is flush with the inside 30 of the wall 3 when the hatch 2 is positioned in the recess 18 and the locking handles 27 are in contact with the locking faces 17. The sealing element 5 seals in a liquid-tight manner between the outside 29 of the hatch 2 and the recess 18.

[0037] FIG. 2 shows the hatch 2 in a closed position. The outside 29 of the hatch 2 is pressed against the sealing element 5 when the locking handles 27 are in contact with the locking faces 17. The locking handles 27 are provided with a slanted contact surface which cooperates with the locking faces 17 in a known manner. In the closed position, the inside 20 of the hatch 2 will be flush with the inside 30 of the wall 3. The tank 6 is filled with water and fish are released into the tank 6. The fish cannot possibly bump into any elements on the hatch 2 and therefore cannot become injured by the hatch 2. The water in the tank 6 exerts a hydrodynamic pressure against the hatch 2 so that the outside 29 of the hatch 2 is pressed further against the sealing element 5.

[0038] FIG. 3 shows the hatch 2 in an open position. The hatch 2 cannot be opened until the water in the tank 6 has been drained away so that the water surface is at least below the lower edge 22 of the hatch 2 and the water no longer exerts a hydrodynamic pressure against the inside 20 of the hatch 2. The water will then not flow out the hatch opening 31, and the hatch 22 will swing freely inwards in the tank 6 above the water surface. All the water in the tank 6 may be drained away. The locking handles 27 are released from the locking faces 17 and the hatch can be swung inwards in the tank 6 as shown in FIG. 3. The arm 4 is articulated in such a way that the hatch 2 can be swung all the way to the side of the hatch casing 1. This simplifies the access for personnel to the inside of the tank 6 through the hatch casing 1 as the hatch 2 will not be in the way. The personnel may easily enter the tank 6 through the hatch casing 1 as the hatch casing 1 is positioned in the lower portion of the tank 6. In this way, maintenance work in the drained tank 6 may be performed without the tank 6 being entered from the top by means of a ladder (not shown) or other means, such as a flight of stairs within a scaffold (not shown).

[0039] After maintenance work has been carried out, the hatch 2 is brought into its closed position, and the tank 6 may be filled with water. Fish may be put into the water-filled tank 6.

[0040] In accordance with the invention, the work of completing the tank 6 in the construction period is simplified. Access to the inside of the tank 6 is through the hatch 2. Thereby, building a scaffold for a flight of stairs on the inside of the tank 6 is avoided. This also increases the safety for the personnel in that fall injuries and injuries by falling objects are avoidable. It is also easier and quicker to evacuate the staff from the tank 6 through the hatch 2. In its open position, the hatch 2 will ventilate the tank 6, so that harmful gases cannot accumulate on the inside of the tank 6 during the construction period.

[0041] FIG. 4 shows a tank with an octagonal wall 3. The hatch casing 1 and the hatch 2 are shown in a rectangular shape and with rounded corners. FIG. 5 shows an alternative design. The hatch casing 1 and the hatch 2 are of a circular shape. This has the advantage of allowing the wall 3 to be cast without an opening, and of allowing the hatch opening 31 to be formed by core drilling after casting. This also has the advantage of the hatch 2 being retrofittable to existing tanks 6.

[0042] The tank 6 may consist of cast concrete. In an alternative embodiment, the tank 6 may consist of another solid material, such as fibreglass, or a laminate.

[0043] It should be noted that all the above-mentioned embodiments illustrate the invention, but do not limit it, and persons skilled in the art may construct many alternative embodiments without departing from the scope of the attached claims. In the claims, reference numbers in brackets are not to be regarded as restrictive.

[0044] The use of the verb “to comprise” and its different forms does not exclude the presence of elements or steps that are not mentioned in the claims. The indefinite article “a” or “an” before an element does not exclude the presence of several such elements.

[0045] The fact that some features are indicated in mutually different dependent claims does not indicate that a combination of these features cannot be used with advantage.