The present invention relates to an end wall for a vessel, which end wall may or may not be integral with the vessel wall and is provided with two openings diametrically opposite one another. An end wall of this type is generally known. The two openings in the end wall serve for filling and emptying the vessel. One of the holes serves as filling or emptying hole and the other as vent hole.

When emptying the vessel, the latter is turned over as soon as the bulk of its contents has been removed, in order to allow the final residues of fluid also to drain away. A problem which frequently arises is that a small layer of fluid still remains behind, which cannot be removed easily, especially if the end wall has interior cavities. However, even if the end wall is virtually flat, some fluid frequently still remains behind. Usually, the vessel is then tilted slightly so that the fluid can still drain away through the lower opening. Apart from the fact that this measure is not always sufficient, it can be desirable for other reasons to be able to empty the vessel completely even in the vertical position, without the vessel additionally having to be kept in a certain tilted position, or the vessel having to be inspected on the inside to determine whether any fluid residues are still present."

The aim of the invention is, therefore, to provide a vessel wall of the type mentioned in the preamble which does not have this disadvantage. This aim is achieved in that, from that section of end wall which extends between the two openings, the end wall slopes towards the peripheral edge thereof, the openings, on the one hand, and the peripheral edge, on the other hand, being in two planes which are a distance apart and essentially parallel, so that the inside of the end wall is concave.

The end wall according to the invention has the advantage that when the vessel equipped with the said wall is turned upside down in order to empty it completely, the openings are always at the lowest point of the end wall. Since the end wall is concave on the inside, there need be no fear of instability in the form of the base buckling towards the outside under the influence of the weight of the fluid still present in the vessel. In the case of known vessels, the consequence of the occurrence of this phenomenon was that, even if the vessel was tilted slightly, the buckled base sections were still below the openings and it was not possible properly completely to empty the vessel.

The section of end wall extending between the two openings can be

straight in the direction from one opening to the other. Together with the adjacent sloping end wall sections, this end wall section then forms a channel through which the fluid can flow to one or both holes.

According to one alternative, provision can be made that the section of end wall extending between the two openings slopes from each opening towards the midpoint of the end wall.

An additional advantage of the end wall according to the invention lies in the fact that during transport and storage, if the vessel is upright and the end wall according to the invention is at the top of the vessel, the end wall drains towards the edge of the vessel. If any fluids, such as rainwater or leakage fluids originating from a vessel stacked on top, are then also able to drain away via holes in the raised edge at the periphery of the end wall, it can always be ensured that no fluids are present on the top of the vessel. This has advantages when handling the vessels. Thus, it is precluded that an amount of fluid sloshes from the vessel lid over the edge when the vessel is tilted. In particular with regard to leakage fluids, the risk to staff is reduced by this means.

The end wall according to the invention is in particular suitable for use with plastic vessels.

The invention will be explained in more detail below with reference to an illustrative embodiment shown in the figures.

Figure 1 shows a perspective view of a vessel containing the end wall according to the invention. Figure 2 shows a cross-section along II-II in figure 1, without vessel wall.

Figure 3 shows a cross-section along III-III in figure 1, without vessel wall.

As shown in Figure 1, the end wall has two openings 1, 2 which are made in the vicinity of the raised edge 3 of the end wall. This edge 3 merges into a flange •*., with which the end wall can be fixed on the body

17 of a vessel. As an alternative, however, the end wall can be integral with the vessel wall (blowing technique) .

As is indicated by means of shaded lines in Figure 1, the end wall is not flat. The various features can be seen more clearly in Figures 2 and 3.

Figure 2 shows that the section of the end wall between the emptying opening 1 or 2 and the edge 3 s of sloping design. These sloping areas are indicated by 5 -a d 6 respectively. The end wall section

7 between the openings 1 and 2 is straight. This section 7 can be of a certain width so that a flat end wall section is formed between openings 1 and 2. As shown in Figure 1, however, this end wall section is of cam- shaped design, although it must be taken into account that the height of the cam is very small. What is involved here is more a barely discernible curvature than a sharply delimited bend. A section slightly curved in this way does not have an adverse effect on the strength of this end wall section.

The various features can be clearly seen in Figure 3. where two regions 8, 9 adjoin the end wall section 7 between the openings 1 and 2. These regions extend to the edge 3» Depending on the size of the regions 5 and 6 between, respectively, the opening 1 and 2 on the one hand and the ridge 3 on the other hand, the regions 8 and 9 extend over a more or less large section of the circumference of the edge 3- As is shown in Figure 1, one of the regions 10, 11, 12 and 13 is formed every time. These regions adjoin the regions , 6, 8 and 9 without a break.

It is also pointed out that the regions 8 and are not flat, because their connection to the edge 3 is purely circular and that to the edge 3 is straight-line. In this way an end wall is formed which is slightly concave seen from the inside. This end wall can be provided at its circumference, in a known manner, with an end face 15, in which a groove 14 is provided for fixing the vessel wall. As already mentioned, the end wall can, however, also be integral with the vessel wall (blowing technique) . The openings 1 and 2, and the end wall section 7 located between these openings 1 and 2, are now in an imaginary plane parallel to the end face 15, at a distance therefrom. As a result of the shape of the wall sections described above, the openings 1 and 2 and the end wall section 7 are the greatest distance away from said end face 15- All other sections of the end wall slope towards this section when the end wall is in the upside down position, compared with the position shown in Figures 1 to 3- Consequently, all fluid will flow towards the end wall section 7 and the adjacent openings 1 and 2, through which all fluid will flow away.

Furthermore, Figure 2 also shows a drain hole 16, which passes through the edge 3- Any fluid which is present on top of the end wall on the outside thereof can always drain through this hole. Since, in the position shown in Figures 1 to 3. which corresponds to the position when the vessel provided with this end wall is upright, the end wall section 7 is at the highest level, all fluid will immediately flow away in the

direction of the edge 3 and finally drain through the opening 16.