DEVICE FOR COLLECTING, TEMPORARILY STORING AND DRAINING OFF RAINWATER

Abstract: A device for collecting, temporarily storing and draining off rainwater comprises an intermediate storage tank (2), which is provided with at least one infeed (4), a first outlet (8) arranged close to the bottom (6) of the tank and a second outlet (10) arranged at a distance above the bottom. The first outlet (8) is provided with a self-adjusting flow limiter (20), preferably in the form of a valve which is controlled by the flow rate into the first outlet (8) and has a ball-shaped valve body (24) which is able to close off the inflow opening (18) of the first outlet (8). The relative density of the ball (24) is slightly greater than that of water. In the event of light rainfall, contaminated rainwater is drained off via the first outlet (8), while in the event of heavy rainfall the first outlet is closed off by the ball (24) and relatively clean rainwater is drained off via the second outlet (10).

Description: Device for collecting, temporarily storing and draining off rainwater . The invention relates to a device for collecting, temporarily storing and draining off rainwater, comprising a temporary storage tank, which is provided with at least one infeed, a first outlet arranged close to the bottom of the tank and a second outlet arranged at a distance above the bottom of the tank. A device of this kind is known from German Patent No. 2506126. In this device, rainwater which comes from a feed line which is connected to the infeed, is collected in the tank. The first outlet, which compared to the infeed has a small diameter, under normal circumstances drains off rainwater to a sewer line and a sewage-water purification system situated downstream thereof. In the event of heavy rain showers, however, the amount of rainwater fed in is such that the outlet has insufficient capacity, so that the tank is filled up. The surplus water is then drained off via the second outlet to, for example, the surface water. In this way, the capacity of a sewer line and of a sewage- water purification system downstream thereof may be limited. Rainwater, in particular if it comes from roofs, roads or car parks, is not always sufficiently clean to be discharged directly into the surface water or to be reused. However, in the event of prolonged (heavy) rainfall, the dirt is drained off with the first flow of rainwater, and the following flow is in fact sufficiently clean. If the first quantity of rainwater is now guided via the first outlet to the sewage-water purification system, the following flow can be used for other purposes, such as reinfiltration into the ground in order to prevent an undesired fall in the groundwater table, reuse for various domestic applications, or, if necessary, discharge into the surface water. The known device is provided with a movable device which prevents floating dirt from passing into the second outlet together with the water. A device of this kind requires regular maintenance, since if it functions incorrectly floating dirt will be drained off as well. The first outlet is provided with an adjustable valve or slide in order to be able to adjust the quantity of water which is drained off through the first outlet. However, it is not easy to change a setting once it has been chosen. As a result, the setting has to seek a compromise between the amount of contaminated rainwater which has to be drained off to the sewage-water purification system in the event of light showers and the amount of cleaner rainwater which may still be drained off continuously via the same outlet in the event of heavy rainfall. In the latter situation, in actual fact, after the first flow of dirty rainwater, all the following clean rainwater should be drained off via the second outlet. The object of the invention is to provide an improved device which is less susceptible to failure and by means of which the amount of rainwater which can be employed usefully can be increased. According to the invention, this object is achieved in a device of the type mentioned at the outset in that the first outlet is provided with a self-adjusting flow limiter which leaves the first outlet open in the event of low flow rates in the first outlet and, in the event of increasing flow rates, closes the first outlet. In this way, in the event of light rainfall the rainwater is drained off via the first outlet, and in the event of heavy rainfall the first outlet is closed off and the rainwater is drained off mainly via the second outlet . Preferred embodiments of the device according to the invention are given in the dependent claims 2 to 12. The invention will be explained in more detail in the following exemplary embodiment with reference to the drawing, in which: Fig. 1 very diagrammatically shows a device according to the invention, Fig. 2 is a vertical section of a practical embodiment of a device according to the invention, in the form of a manhole, Fig. 3 is a vertical section of the manhole of. Fig. 2 along the line III-III, Fig. 4 is a top view of part of the manhole of Fig. 2, and Fig. 5 shows the first outlet of the manhole of Fig. 2 on an enlarged scale. Fig. 1 very diagrammatically shows a device for collecting, temporarily storing and draining off rainwater. The device comprises a temporary storage tank 2, which is provided with an infeed 4, a first outlet 8 arranged close to the bottom 6 of the tank and a second outlet 10 arranged at a distance above the bottom 6. The first outlet 8 is provided with a self- adjusting flow limiter 20 which leaves the first outlet 8 open in the event of low flow rates and, in the event of increasing flow rates, closes the first outlet 8. In the embodiment depicted in Fig. 1, the first outlet 8 is formed by a pipe bend 14, which is arranged in the side wall 12 of the tank 2 and the end part 16 of which, situated inside the tank 2, faces towards the bottom 6 of the tank, so that the outlet 8 has an inflow opening 18 which faces towards the bottom 6 of the tank 2. The flow limiter 20 is arranged on the underside of the end part 16 facing towards the bottom 6 and is formed by a valve which is controlled by the flow rate into the first outlet 8. This valve comprises a valve body in the form of a ball 24 which can move freely in a housing 22 arranged around the inflow opening 18. An inflow opening 26 is arranged on the underside of the housing 22. The relative density of the ball is slightly greater than the relative density of water and is, for example, equal to 1.2. A higher relative density is also possible, but in that case the space between the ball 24 and the housing 22 has to become smaller, increasing the risk of blockage. A permanent passage 28 with a low through-flow capacity is present between the interior of the tank 2 and the first outlet 8. The second outlet 10 is formed by a pipe bend 30 which is arranged in the side wall 12 of the tank 2 and the end part 32 of which, situated inside the tank, faces towards the bottom 6 of the tank 2, so that the outlet 10 has an inflow opening 34 which faces towards the bottom 6 of the tank 2. The infeed 4 is arranged opposite and at substantially the same height as the second outlet 10, in the side wall 12 of the tank 2. The operation of the device according to the inven- tion depicted in Fig. 1 is as follows. In the event of light rainfall, when the flow rate through the housing 22 and the first outlet 8 is low, the ball 24 floats, as it were, in the rainwater flowing from the inflow opening 26 and towards the inflow opening 18 and the inflow opening 18 is not closed off. In the event of heavier rainfall, when greater flow rates occur in the housing 22, the ball 24 is carried along by the water flowing from the inflow opening 26 towards the inflow opening 18 and is pressed onto the opening 18, so that this opening is closed off by the ball 24. From that moment, the tank 2 fills up further and the ball 24 is pressed ever more against the inflow opening 18 by the static pressure. When the water level in the tank has reached the level of the second outlet 10, the rainwater, which is then relatively clean, is drained off via the second outlet 10. This rainwater can be reused or can be discharged into the surface water. If rainwater is no longer coming into the tank via the infeed 4, the tank empties due to the fact that a leakage flow passes through the passage 28 towards the first outlet 8. At a given moment, the disappearance of the static pressure results in the ball 24 sinking downwards and releasing the opening 18, so that the full capacity of the first outlet 8 is again available. Owing to the design of the device according to the invention, simple means enable relatively clean rainwater to be drained off separately, while dirty rainwater can always be drained off to a sewer line and a sewage-water purification system which is downstream of the latter. - o - Due to the regular movement of the ball 24; the risk of the first outlet 8 becoming blocked is low. However, if it should become blocked, it will be a very long time before heavy, sinking dirt is drained off via the second outlet 10. If a first outlet 8 which has a low capacity and no self-adjusting flow limiter is selected, the risk of the first outlet becoming blocked is much higher. Light, floating dirt is effectively retained by the design of the second outlet 10 with the inflow opening 34 facing towards the bottom 6 of the tank. If, owing to dirt, the ball 24 does not function correctly and does not close off the first outlet 8 correctly, the only effect is that the quantity of water which is incorrectly guided via the first outlet 8 to a sewage line is greater than intended, but dirty rainwater is not drained off via the second outlet 10. A further advantage of the design according to the invention is that the maintenance required is minimal, owing to a small number of components and the simple and operationally reliable design. The design of the various components of the device according to the invention may differ from the design depicted in Fig. 1, as long as the intended function is maintained. Thus, for example, the valve body of the valve serving as the self-adjusting flow limiter may have a different form. The second outlet may also be designed differently. The infeed may be arranged at a different location in the side wall or on the top of the tank. Figs. 2 to 4 show a more practical embodiment of the device according to the invention, in the form of a manhole. In these figures, components which correspond to components from the device depicted in Fig. 1 are indicated with the same reference numerals. In Figs. 2 to 4 , the second outlet 10 is at right angles to the infeed 4 and the first outlet 8. As can be seen in particular in Fig. 3, the bottom 6 of the manhole is V-shaped and is formed by a separate manhole bottom part 40. On this manhole bottom part 40 is situated a manhole - - shaft 42 which forms the side wall of the manhole. -A sealing ring 44 is arranged on the top of the manhole shaft 42, for the purpose of sealing with respect to a manhole cover part which is not shown here. The device according to the invention may also be designed as a street or pavement gully hole (not shown) . In that case, the infeed will usually not be arranged in the side wall of the tank, as in the embodiment depicted in Figs. 1-4, but rather on the top of the tank. Possible advantages of a design as a gully hole are that no, or fewer, manholes are required in the sewage system, the system is less susceptible to faults, and, unlike in the case of a manhole, regular inspections take place. As indicated in Fig. 5, the housing 22 may be provided with one or more tubes 46 which are easy to install and remove. In this way, the cut-out flow rate can easily be altered. Preferably, the housing 22 is equipped as standard with one tube 46. This design is then suitable for a manhole to which 1 to 5 inlets are connected. If it is necessary to connect more inlets, for example 6 to 10, to the manhole, then the tube 46 can be removed after unscrewing a screw cover 48. The removable cover 48 is also advantageous in the event of any maintenance . Both in the device depicted in Fig. 1 and in the manhole depicted in Figs. 2 to 4, there is space available below the housing 22 which can serve as a "sand trap" for collecting sinking dirt. From time to time, this dirt will have to be removed by suction, as is usual for street and pavement gully holes. The height and the diameter of the manhole may be selected depending on the conditions, as may the positioning (height) and the diameters of the infeed and the outlets .

Claims: _ CLAIMS 1. Device for collecting, temporarily storing and draining off rainwater, comprising a temporary storage tank, which is provided with at least one infeed, a first outlet arranged close to the bottom of the tank and a second outlet arranged at a distance above the bottom of the tank, characterized in that the first outlet (8) is provided with a self-adjusting flow limiter (20) which leaves the first outlet open in the event of low flow rates in the first outlet and, in the event of increasing flow rates, closes the first outlet. 2. Device according to claim 1, characterized in that the first outlet (8) is formed by a pipe bend (14) , which is arranged in the side wall (12) of the tank and the end part (16) of which, situated inside the tank (2) , faces towards the bottom (6) of the tank (2) and is provided on the underside with a valve which is controlled by the flow rate into the first outlet and is able to close off the inflow opening (18) of the pipe bend (14) , which opening faces towards the bottom of the tank. 3. Device according to claim 2, characterized in that the valve comprises a valve body in the form of a ball (24) which can move freely in a housing (22) arranged around the inflow opening (18) and has a relative density which is slightly greater than the relative density of water. 4. Device according to claim 3, characterized in that the housing (22) is provided with one or more insert tubes (46) having a diameter which is smaller than the internal dimension of the housing. 5. Device according to one of claims 1 to 4, charac- terized in that there is a permanent passage with a low through-flow capacity present between the interior of the tank (2) and the first outlet (8) . 6. Device according to one of claims 1 to 5 , characterized in that the second outlet (10) has an inflow opening (34) which faces towards the bottom of the tank. 7. Device according to claim 6, characterized in that the second outlet (10) is formed by a pipe bend (30) , which _ _ is arranged in the side wall (12) of the tank (2) and the end part (32) of which, situated inside the tank, faces towards the bottom (6) of the tank (2) . 8. Device according to one of claims 1 to 7, charac- terized in that it is designed as a manhole. 9. Device according to claim 8, characterized in that the infeed(s) (4) is (are) arranged in the side wall (12) of the tank (2) . 10. Device according to one of claims 1 to 7, charac- terized in that it is designed as a street or pavement. 11. Device according to claim 10, characterized in that the infeed is arranged on the top of the tank (2) . 12. Device according to one of claims 1 to 11, characterized in that the tank (2) is provided at the bottom with a sand trap.

Inventors: OFFRINGA OEGE RENE, OFFRINGA, OEGE, RENE
Applicants: OFFRINGA OEGE RENE, WAVIN BV, OFFRINGA, OEGE, RENE, WAVIN B.V.
Application year: 1997
Main classification: E03F1
IPC codes: E03F1, E03F5