A WATER-LEVEL CONTROL UNIT WITH A DOWNWARDLY HANGING HINGED LOWER FLAP PORTION OF A VALVE ELEMENT AND A FLOATING BODY CONNECTED THERETO

Abstract

A water-level control unit includes a housing with a flow channel. A valve element is positioned rotatable around a hinge axis inside the flow channel to close off a lower section of the flow channel while dividing it in a first upstream side and a second downstream side. The hinge axis is provided at a height above a bottom of the flow channel. The valve element includes a lower flap portion that in a closed position hangs down from the hinge axis. A floating body is provided at and connected to a side of the lower flap portion for moving the valve element from its closed towards an open position in dependence of a rising level of water at the first upstream side in the flow channel.

Claims

1. A water-level control unit configured for installation inside or onto a culvert, ditch or outlet of a drainage pipe and/or system of a water collecting surface area, the unit comprising: a housing that delimits a flow channel that has a lower section and an upper section; a valve element that is positioned rotatable around a hinge axis inside the flow channel between a closed and an open position, wherein the valve element is configured to in its closed position close off the lower section of the flow channel while dividing the flow channel in a first upstream side and a second downstream side, and to in its open position open the lower section; and a floating body for moving the valve element in dependence of a rising level of water, wherein the hinge axis of the valve element is provided at a height spaced above a bottom of the flow channel, wherein the valve element comprises a lower flap portion that in its closed position hangs down from the hinge axis, wherein the floating body is provided at and connected to a side of the lower flap portion at a height position in between the hinge axis and the bottom of the flow channel, wherein the lower flap portion, that in its closed position hangs down from the hinge axis, is rotatable around the hinge axis towards the first upstream side to rotate open from its closed position into its open position, and wherein the floating body is configured for moving the valve element from its closed position towards its open position in dependence of a rising level of water at the first upstream side in the flow channel.

2. The water-level control unit according to claim 1, wherein the floating body is configured for starting to pull the lower flap portion towards the first upstream side from its closed position into its open position due to buoyancy forces starting to act on the floating body when a level of water is reached at the first upstream side that corresponds to the height position at which the floating body is provided, while rotating the lower flap portion through the level of water at the first upstream side and opening up the lower section of the flow channel for the water to flow away towards the second downstream side.

3. The water-level control unit according to claim 1, wherein the floating body is provided at and connected to the first upstream side of the lower flap portion at the height position in between the hinge axis and the bottom of the flow channel.

4. The water-level control unit according to claim 1, wherein a primary height-adjustable connection system is provided between the floating body and the lower flap portion, which primary height-adjustable connection system is configured for varying the level of water to be reached at the first upstream side for the floating body to start pulling the lower flap portion towards the first upstream side from its closed position into its open position.

5. The water-level control unit according to claim 4, wherein the primary height-adjustable connection system comprises complementary mounting means that are fixedly mountable against the lower flap portion while extending perpendicular to the hinge axis, and that are configured to mount the floating body at different height positions against the lower flap portion in between the hinge axis and the bottom of the flow channel.

6. The water-level control unit according to claim 1, wherein the valve element is configured to leave open at least part of the upper section of the flow channel in its closed position.

7. The water-level control unit according to claim 1, wherein a partition wall is provided between the lower and upper section, which partition wall projects towards the first upstream side, and wherein the partition wall is configured for the floating body and/or lower flap portion to abut against in the open position.

8. The water-level control unit according to claim 1, wherein the hinge axis extends between the lower section and upper section.

9. The water-level control unit according to claim 8, wherein the valve element further comprises an upper flap portion that in its closed position projects upwardly from the hinge axis.

10. The water-level control unit according to claim 1, wherein a secondary height-adjustable connection system is provided between the valve element and the hinge axis.

11. The water-level control unit according to claim 1, wherein the housing comprises a holding/blocking arrangement, in particular an inwardly projecting abutment, more in particular forming a valve seat, at the lower section of the flow channel and configured for the lower flap portion to be held by and/or lie against in its closed position.

12. The water-level control unit according to claim 11, wherein the holding/blocking arrangement, in particular said inwardly projecting abutment, is positioned at such a distance from the hinge axis that the lower flap portion in its closed position hangs down obliquely angled towards the first upstream side.

13. The water-level control unit according to claim 1, wherein the housing comprises an outer blocking or sealing arrangement that is configured to fit blocking or sealing inside a culvert, ditch or outlet of a pipe.

14. The water-level control unit according to claim 1, wherein the housing comprises an inner blocking or sealing arrangement that is configured to fit sealing onto a culvert, ditch or outlet of a pipe.

15. The water-level control unit according to claim 1, wherein the flow channel at the first and/or second downstream side is covered by a filter and/or grating.

16. An assembly of a water-level control unit according to claim 1 and a culvert, ditch or outlet of a drainage pipe and/or system of a water collecting surface area.

17. A method for controlling a water-level by means of a water-level control unit according to claim 1, comprising the steps: installing the unit inside or onto a culvert, ditch or outlet of a drainage pipe and/or system of a water collecting surface area; positioning the floating body at a height position in between the hinge axis and the bottom of the flow channel that corresponds to an aimed level of water that needs to be reached at the first upstream side before starting to pull the lower flap portion through the level of water towards the first upstream side from its closed position into its open position due to buoyancy forces starting to act on the floating body; and passively and automatically controlling the water-level by means of: each time the level of water at the first upstream side of the lower flap portion reaches the height position of the floating body, have the floating body pull the lower flap portion through the level of water towards the first upstream side from its closed position into its open position due to buoyancy forces acting on the floating body, while opening up at least the lower section of the flow channel for the water to flow away towards the second downstream side; and each time the level of water at the first upstream side of the lower flap portion has dropped again to underneath the height position of the floating body, have the lower flap portion move back again from its open position into its closed position due to the buoyancy forces on the floating body dropping again, while closing off at least the lower section of the flow channel for the water to be blocked again at the first upstream side draining away towards the second downstream side.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0050] The invention shall now be explained in more detail below by means of describing some exemplary embodiments in a non-limiting way with reference to the accompanying drawings, in which:

[0051] FIG. 1a-d shows a water-level control unit according to the invention with different water levels at a first upstream side of a lower flap portion of its valve element leading to different closing and opening positions;

[0052] FIG. 2a-b shows different use of the units when installed into outer ends of drainage pipes ending out in a ditch that is pre-filled with water or is to run dry;

[0053] FIG. 3a shows a pipe-insertion-type embodiment of the water-level control unit that is configured to be inserted into a tubular pipe;

[0054] FIG. 3b shows an enlarged view of the valve element of FIG. 3a;

[0055] FIG. 3c shows a view of the unit of FIG. 3a shortly before placement inside a pipe;

[0056] FIG. 4 shows a pipe-insertion-type double-acting variant;

[0057] FIG. 5 shows a ditch-insertion-type double acting variant;

[0058] FIG. 6 shows an angled variant;

[0059] FIGS. 7a and 7b show variant embodiments of water-level control units for use along straight roof edges or at roof corners;

[0060] FIG. 8 shows a front side perspective view of another variant embodiment of a water-level control unit for mounting against an outer end of a duct; and

[0061] FIG. 9a-d shows the water-level control unit of FIG. 8 with different water levels at a first upstream side of a lower flap portion of its valve element leading to different closing and opening positions.

DETAILED DESCRIPTION OF THE INVENTION

[0062] In FIG. 1 a water-level control unit is shown that has been given the reference numeral 1. The unit 1 comprises a housing 2 that delimits a flow channel 3, that here extends around a horizontal central axis. At a central position inside the housing 2, spaced a height y1 above a bottom of the flow channel 3, a hinge axis 5 is provided. The hinge axis 5 here also extends in the horizontal direction but then perpendicular to the central axis. A plate-shaped valve element 7 is rotatable around the hinge axis 5 between a closed position (FIGS. 1a and b) and open positions (fig. c and d). The plate-shaped valve element 7 comprises a lower flap portion 7lo and an upper flap portion 7up that lie on opposing sides of the hinge axis 5.

[0063] An abutment 10 is provided at a bottom of the flow channel 3. The abutment 10 lies at a distance x1 in the horizontal direction underneath the hinge axis 5 such that the lower flap portion 7lo in its closed position gets to hang down under its own weight in an oblique angled orientation a from the hinge axis 5 while being blocked by the abutment 10.

[0064] The flow channel 3 is defined as having a lower section LS and an upper section US. The lower section LS is the part that is closable and openable by the valve element 7. The upper section US is the part that remains open, such that it can form an overflow.

[0065] The flow channel 3 furthermore is defined as having a first upstream side FS and a second downstream side SS. The first upstream side is here is formed by an upstream drainage side respectively downstream irrigation side of the unit 1 (at the right side of the valve element 7 in the FIG. 1), whereas the second downstream side here is formed by a downstream drainage side respectively upstream irrigation side of the unit 1 (at the left side of the valve element 7 in FIG. 1).

[0066] The lower flap portion 7lo and upper flap portion 7up together have width and length dimensions that are complementary with a cross-sectional profile of the lower section LS of the flow channel 3, seen over a line extending through the hinge axis 5 and the abutment 10.

[0067] A floating body 14 is connected to the lower flap portion 7lo at its first upstream side FS. The floating body 14 can be formed by an air- or gas-inflatable or filled hollow body, but may also be filled with or formed by any kind of material having floating capacity on water. The floating body 14 is connected to the lower flap portion 7lo at a position in between the hinge axis 5 and the abutment 10, and in the closed position of the valve element 7 lies at a height y2 above the bottom of the flow channel 3, and at a distance x2 in the horizontal direction from the hinge axis 5.

[0068] A partition wall 17 is provided just above a level of the hinge axis 5. The partition wall 17 extends in the horizontal direction from the hinge axis 5 towards the first upstream side FS.

[0069] A internal filter 18 extends obliquely angled towards the first upstream side FS between a free outer end of the partition wall 17 and the bottom of the flow channel 3.

[0070] An advantageous method of operation shall now be described for the FIG. 1 embodiment.

[0071] In FIG. 1a the situation is shown in which the unit 1 is fully dry. Due to the own weight of the lower flap portion 7lo minus the own weight of the upper flap portion 7up, a clockwise directed momentum acts on the valve element 7 to maintain lying against the abutment 10 in its closed position.

[0072] In FIG. 1b the situation is shown in which water has entered the unit 1 from its first upstream side FS (in that situation forming an upstream drainage side), which water at that moment has built up in front of the closed valve element 7 to a water level Lw1 that lies beneath the initial height position y2 of the floating body 14 in the closed position of the valve element 7. Due to the own weight of the lower flap portion 7lo minus the own weight of the upper flap portion 7up, added with the water pressure acting on the valve element 7 at its first upstream side, an increased clockwise directed momentum acts on the valve element 7 to maintain lying even stronger sealed against the abutment 10 in its closed position.

[0073] In FIG. 1c the situation is shown in which water has kept on entering the unit 1 from its first upstream side FS, which water at that moment has built up in front of the closed valve element 7 to an increased water level Lw2 that lies above said initial height position y2 of the floating body 14. Due to the floating body 14 having started to float on top of the increased water level Lw2, a corresponding upwardly directed pulling force F is exerted on the lower flap portion 7lo of the valve element 7 to have it rotate counter-clockwise to a semi-open position against the weight forces and against the water pressure also still acting on the valve element 7 at its first upstream side. In this semi-open position, water is able to start draining away towards the second downstream side SS (in that situation forming a downstream drainage side) via the partly opened up lower section LS of the flow channel 3.

[0074] In FIG. 1d the situation is shown in which a further increased water level Lw3 is offered to the unit 1 at its first upstream side FS. This further increased water level Lw3 even lies above the height y1 of the hinge axis 5. In that situation the valve element 7 has fully opened up with the floating body 14 having come to lie against the partition wall 17, and with both the lower flap portion 7lo and the upper flap portion 7up having come to lie in a horizontal position. With this the water draining away to the second downstream side SS, advantageously exerts an additional opening force upon the upper flap portion 7up. Together with the clockwise directed momentum due to the buoyancy force F also acting on the valve element 7, this shall lead to the valve element 7 to maintain lying even stronger against the partition wall 17 in its closed position. In this fully-open position, water is able to drain away at even higher capacities towards the second downstream side SS via the now fully opened up lower section LS of the flow channel 3.

[0075] Should more water get offered to the first upstream side FS, then also the already open upper section US shall automatically get used for water to drain away towards the second downstream side SS. This may be important in situations of heavy rainfall, monsoon, flooding or the like.

[0076] As soon as the level of offered drainage water at the first upstream side FS drops again to below the initial height position y2 of the floating body 14 in the closed position of the valve element 7, the valve element 7, due to the own weight of the lower flap portion 7lo minus the own weight of the upper flap portion 7up, added with the water pressure still acting on the valve element 7 at its first upstream side, shall exert a counter-clockwise directed momentum on the valve element 7 to return to its sealing closed position against the abutment 10.

[0077] In dry situations it is also possible to use the unit 1 according to the invention in a reverse direction for irrigation purposes. This is possible by, in the dry situation as is shown in FIG. 1a, actively offer irrigation water to the second downstream side SS (in that situation forming an upstream irrigation side). As soon as this irrigation water then reaches the closed valve element 7, water pressure shall start acting on the lower flap portion 7lo of the valve element 7. As soon as this water pressure is high enough to be able to overcome the weight forces of the valve element 7 itself, this shall cause the valve element 7 to rotate counter-clockwise to a semi-open position. In this semi-open position, irrigation water is able to start flowing from the second downstream side SS towards the first upstream side FS (in that situation forming a downstream irrigation side) via the opened up lower section LS of the flow channel 3. In this reversed irrigation situation, buoyancy of the floating body 14 does not play a role in the opening behaviour of the valve element 7.

[0078] In FIGS. 2a and b it is schematically shown as an example that units with hinged downwardly hanging lower flap portions of valve elements 7a-c are provided inside free outlet ends of regularly spaced apart drainage pipes 20a-c. For that a housing of each unit comprises a sealing arrangement that is configured to fit sealing inside its drainage pipe 20a-c. The outlet ends of the drainage pipes 20a-c end out above a ditch 21. Halfway the ditch 21 a culvert 22 is provided of which a throughflow opening 23 can be controlled. In FIG. 2a the opening 23 is substantially closed, whereas in FIG. 2b the opening 23 is partly opened.

[0079] In the upper half of FIGS. 2a and b a situation is shown in which an upstream portion 21us of the ditch 21, that is to say upstream of the culvert 22, is filled with a relative large amount of water at a level above the outlet end of the drainage pipe 20a, whereas in the lower halves of FIGS. 2a and b situations are shown in which a downstream portion 21ds of the ditch 21, that is to say downstream of the culvert 22, is only filled with a relative small amount of water at a level far underneath the outlet ends of the drainage pipes 20b and c.

[0080] Due to high water level in the upstream portion 21us of the ditch 21, water shall start to flow from out of the ditch 21 into the drainage pipe 20a while pushing open the respective valve element 7a. This water then shall distribute itself over the length of the drainage pipe 20a and from there be able to irrigate the surrounding land. This same situation is also shown in FIG. 2b.

[0081] Due to low water level in the downstream portion 21ds of the ditch 21, water falling on the land above the drainage pipes 20b and c may drain into those drainage pipes 20b and c and start to accumulate in front of the respective closed valve elements 7b and c. This is shown in FIG. 2a. As soon as the water level inside the drainage pipes 20b and c then reaches the level of floating bodies on lower flap portions of their valve elements 7b and c, the floating bodies shall pull the valve elements 7 to their open positions, such that water may drain away into the downstream portion 21ds of the ditch 21. This is shown in FIG. 2b.

[0082] In FIG. 3a-c an embodiment is shown in which the housing 2 and flow channel 3 have a substantially rectangular cross-sectional profile with round edges. This brings the advantage that the valve element 7 also can be made with a substantially rectangular plate-shape with rounded edges with a width dimension complementary to the one of the flow channel 3.

[0083] In FIG. 3a-c an obliquely angled closed position is shown for the valve element 7 in which its lower flap portion 7lo fully closes off the lower section LS of the flow channel 3, and in which its upper flap portion 7up partly closes off the upper section US of the flow channel 3.

[0084] The floating body 14 is mounted at the first upstream side FS to the lower flap portion 7lo by means of a primary height-adjustable connection system 30. This primary height-adjustable connection system 30 here comprises a left and right mounting screw with thickened heads that are threaded into the lower flap portion 7lo while extending through longitudinal slits 31 that extend perpendicular to the hinge axis 5. Thus the floating body 14 is mountable at different height positions onto the lower flap portion 710.

[0085] The valve element 7 is further provided with a secondary height-adjustable connection system 32 that here comprises mounting rails that extend along opposing side edges of the valve element, here at its second downstream side SS. The mounting rails are equipped with a plurality of holes 33 into which pins of the hinge axis 5 can be placed. Thickened head ends of the pins then come to lie outside the housing 2 against the side walls thereof while projecting through complementary openings in those side walls. Thus the position of the valve element 7 relative to the hinge axis hinge axis 5 is adjustable, due to which the valve element 7 in its closed position may come to lie at a steeper or less steep angle, and due to which the surface areas of the lower flap portion 7lo and upper flap portion 7up can quickly and easily be increased respectively decreased relative to each other.

[0086] Along the outer edge of the valve element 7 a sealing rubber 34 is provided that is configured to lie sealing against the inner bottom and side walls of the housing 2 in the closed position.

[0087] At the outer ends of the housing 2 blocking/sealing arrangements 35 are provided that are complementary to the pipe 20 into which the unit 1 is to be inserted. Those arrangements 35 here are formed by outwardly projecting flange portions that are provided alongside the bottom and side walls of the housing 2 and that together delimit three-quarter of a circle, such that when the unit 1 is inserted into the pipe 20 no water can leak away underneath or sideways of the unit 1.

[0088] Furthermore, at the outer end of the housing 2 that lies at the first upstream side FS, a dismountable anti-intrusion cap 37 is provided. This ant-intrusion cap 37 comprises an external grating 38 with a relative coarse mesh and an internal filter 39 with a relative fine mesh. The grating 38 covers the entire cross-section of the pipe 20 respectively flow channel 3 and is destined to block relative large strange objects from entering the unit 1. The filter 39 merely covers the lower section LS of the flow channel 3 and is destined to filter out any debris that otherwise might hinder or block the proper functioning of the valve element 7. The cap 37 can easily and quickly be removed for periodic cleaning purposes.

[0089] In FIG. 4 a double-acting variant is shown in which the unit 1 comprises two mirrored height-adjustable valve elements 7 at opposing sides of the unit 1, one valve element 7 being orientated with its height-adjustable floating body 14 towards the first upstream side FS, whereas the other valve element 7 is orientated with its height-adjustable floating body 14 towards the second downstream side SS. This makes it possible to in both directions be able to actively control the level of water that first needs to be reached before having the respective valve element 7, 7 be pulled towards its open position.

[0090] In FIG. 5 a double-acting variant is shown that is configured to be placed inside a ditch. For that the at the outer ends of the housing 2 blocking/sealing arrangements 40 are provided that are complementary to the ditch into which the unit 1 is to be inserted. Those arrangements 40 here are formed by outwardly projecting flange portions that are provided alongside the bottom and side walls of the housing 2 and that together delimit a somewhat triangular-shape. When the unit 1 is lowered into the ditch the plate-shaped flange portions can penetrate to some extent into the ground walls that delimit the ditch such that no water can leak away underneath or sideways of the unit 1. For the picking up and lowering of the unit a hoisting ring 42 is provided on top of the housing 2.

[0091] In FIG. 6 a variant is shown in which the valve element 7 besides comprising the lower flap portion 7lo with the floating body 14 mounted against it at its first upstream side FS, also comprises a perpendicular angled upper flap portion 7up that is configured to automatically close off the upper section US of the flow channel 3 when the lower flap portion 7lo of the valve element 7 is rotated towards the open position of the lower section LS of the flow channel 3.

[0092] In FIGS. 7a and b variants are shown in which the valve elements 7 merely comprise lower flap portions 7lo that hang down from hinge axes 5. The hinge axes are positioned at heights y1. At first upstream sides FS of the valve elements 7, floating bodies 14 are fixedly mounted onto the lower flap portions with centres of buoyancy positioned at heights y2 that are lower than the heights of the hinge axes 5. The lower flap portions 7lo here are dimensioned such that in the shown closed positions they entirely cover corresponding outlet openings of a drainage system of a water collecting surface area, for example a roof. The housings 2 here are shaped such that they can easily be integrated into upstanding side walls, like roof edges, that circumvent the water collecting surface area. The housings 2 comprise blocking walls 70 that extend upwardly up till the level y1 of the hinge axes 5. The outlet openings are provided at upper center positions of those blocking walls 70, and are delimited by U-shaped frames 71 against which circumferential side and lower edges of the lower flap portion 7lo lie sealing against in the closed position.

[0093] In FIGS. 8 and 9 a variant is shown in which a housing 2 comprises a blocking wall 70 that is mounted in front of a flow channel 3. An outlet opening is provided inside the blocking wall 70. This outlet opening is bordered by a sealing frame 71. A hinge axis 5 is positioned at an intermediate height position y1 of the outlet opening. A valve element 7 is mounted rotatable around the hinge axis 5 between a closed position (FIG. 9a) and open positions (FIG. 9b-d).

[0094] The valve element 7 comprises a lower flap portion 7lo that in the closed position hangs down from the hinge axis 5 while covering a lower section LS of the outlet opening, and an upper flap portion 7up that in the closed position projects upwardly from the hinge axis 5 while covering an upper section US of the outlet opening.

[0095] At a first upstream side FS of the valve element 7, a floating body 14 is fixedly mounted onto the lower flap portion 7lo. In the closed position of the valve element 7, a centre of buoyancy of the floating body 14 is positioned at a height y2. As can be seen y2<y1, that is to say that the floating body 14 in the closed position finds itself below the hinge axis 5.

[0096] In the closed position, edges of the lower flap portion 7lo are blocked by and lie sealing against the sealing frame 71 at the first upstream side FS of the blocking wall 70, whereas edges of the upper flap portion 7up are blocked by and lie sealing against the sealing frame 71 at the second downstream side SS of the blocking wall 70. In the closed position the lower and upper flap portions 710, 7up together entirely cover the outlet opening. See FIG. 9a.

[0097] When a water level Lw1 at the first upstream side FS starts to rise to above the initial height level y2 of the floating body 14, this floating body 14 starts to exert an upwards directed pulling force F on the lower flap portion 7lo. This causes the valve element 7 to rotate open around the hinge axis 5 (clockwise in FIG. 9). The edges of the lower flap portion 7lo then are rotated away from the sealing frame 71 towards the first upstream side FS of the blocking wall 70, whereas edges of the upper flap portion 7up are rotated away from the sealing frame 71 towards the second downstream side SS of the blocking wall 70. See FIG. 9b. Water then starts to flow from the first upstream side FS towards the second downstream side SS via the partially opened outlet opening.

[0098] When the water level Lw2 at the first upstream side FS rises further to above the height level y1 of the hinge axis 5, the floating body 14 increases its upwards directed pulling force F on the lower flap portion 710. Furthermore, the water pressure of the water above the height level y1 of the hinge axis 5 then starts to exert a pushing force P on the upper flap portion 7up as well. Together this causes the valve element 7 to rotate further open around the hinge axis 5 (clockwise in FIG. 9). See FIG. 9c. More water then starts to flow from the first upstream side FS towards the second downstream side SS via the half opened outlet opening.

[0099] When the water level Lw3 at the first upstream side FS then even rises further, the floating body 14 further increases its upwards directed pulling force F on the lower flap portion 7lo, and the pushing force P by the water above the height level y1 of the hinge axis 5 then also increases. The valve element 7 then may take in its fully open position, that is to say here a horizontal position, as shown in FIG. 9d. Water then even starts to flow over the valve element 7, that is to say through the upper section US, from the first upstream side FS towards the second downstream side SS.

[0100] Besides the shown and described embodiments, numerous variants are possible. For example the dimensions and shapes of the various parts can be altered. Also it is possible to make combinations between advantageous aspects of the shown embodiments. Instead of using substantially rectangular-shaped flow channels and valve elements, they may have any other desired shape, like circular, triangular, oval, etc. The valve element, floating body, abutment, valve seat, sealing rubber, and the like also may have all kinds of desired shapes, thicknesses, etc. All kinds of materials can be used for the various components of the unit. Preferably however they are made of aluminium, stainless steel, plastic, etc. Instead of using the unit inside a pipe or inside a ditch, it can also be placed inside a throughflow opening of a culvert, or be mounted onto an outer end of a pipe or the like. Instead of making the floating body height adjustable relative to the lower flap portion of the valve element, it is also possible to fixedly connect it thereto. Instead of only providing a floating body one-sided at the first upstream side of the valve element, it is also possible to provide an additional floating body at the second downstream side of the valve element. Thus a two-sided floating body, that is to say at both opposing sides of the valve element, is obtained. If desired the lower flap portion of the valve element may also be weighted, biased, or the like, in a direction away from the first upstream side, in order to deteriorate the valve element's opening moment/movement during drainage when the water level starts to rise at its first upstream side, for example when it has started to rain. This weighting, biasing, or the like, might help to prevent flapping of the valve element at too high frequencies between its closed and open positions. It may also help to speed up the valve element's closing moment/movement against a sealing seat when the water level drops again at its first upstream side, for example when it has stopped raining again. Furthermore, the weighting also may help to deteriorate the valve element's opening moment/movement when the water level rises at its second downstream side, for example when irrigation of water in the opposing direction from the second downstream side towards the first upstream side is desired. If desired also an operable lock can provided that is configured to temporarily lock the valve element in its closed position whenever desired.

[0101] It should be understood that various changes and modifications to the presently preferred embodiments can be made without departing from the scope of the invention, and therefore will be apparent to those skilled in the art. It is therefore intended that such changes and modifications be covered by the appended claims.