GB2388145A

GB2388145A - Drain cover unit

Info

Publication number: GB2388145A
Application number: GB0309809A
Authority: GB
Inventors: Michael George Mar Weatherhead; Simon Francis Godwin Bradbeer
Original assignee: Alumasc Ltd
Current assignee: Alumasc Ltd
Priority date: 2002-04-29
Filing date: 2003-04-29
Publication date: 2003-11-05
Also published as: GB0309809D0; GB0209754D0; AU2003222994A1; WO2003093591A1

Abstract

The drain cover unit 10, for use in roads, runways, garage forecourts etc., comprises an exposed first element 12 that has an upper surface which is downwardly inclined at an angle and a second element 14 that has a generally horizontal upper surface over which traffic can run. An elongate slot 16 is defined between a free edge of the second element and the lower edge of the top surface of the first element so that drainage liquid can flow down the inclined upper surface of the first element and through the slot. The upper edge of the first element is at generally the same level as the upper surface of the second element and the free edge of the second element extends at least as far as a position which is generally above the lower edge of the top surface of the first element so that the slot, when seen from above, has substantially no width. The first and second elements are preferably elongate and parallel to one another with the slot extending parallel to the long axis of the first and second members. The first and second elements may be connected by cross braces. The drain cover may have two first elements, one on either side of a second element that has two free edges so that two slots are formed, one on either side of the second element. A fin 28 may project from the underside of the second element that acts to deflect liquid passing through the slot(s) downwards.

Description

( 1 2388 1 45

DRArN COVER UNIT Background to the Invention

The present application relates to a surface drainage system. More particularly, the present invention relates to a high capacity surface drainage system suitable for use with aircraft standing areas, garage forecourts, roads, runways, airport taxiing ways, Quelling areas, fuel transfer depots, or any other area of hard standing where large amounts of liquid need to be drained on either a regular or emergency basis.

Figure 1 shows a conventional drain cover typically used in garage forecourts. The drain cover consists essentially of an elongate metal plate with transverse holes in it to allow drainage water through the cover into the drain. However, when high volumes of water flow on to the drain cover, especially when flowing from both sides at once, the water from one side interferes with the flow of water from the other side resulting in a pooling effect where the flow rate through the drain cover is reduced; if the water is flowing from just one side, most of it can flow right over the drain cover.

It is an object of the present invention to remove or ameliorate at least one of the disadvantages of the prior art.

The Invention According to the present invention there is provided a drain cover unit as set forth in Claim I or 23. The invention extends to a drain comprising the drain cover unit and

also to an area of hard standing comprising the drain cover unit. The dependent claims claim optional or preferred features of the invention.

The provision of the generally horizontal second member allows the passage of vehicles over the drain while retaining a wide drainage channel allowing the passage of large

( volumes of liquid through the drain. By having the upper edge of the top surface of the first member generally at the same level as the upper surface of the second member, the second member can be in the plane of the ground in which the drain cover is mounted and the drain cover can be installed without any bumps raised from the traffic bearing surface. As the slot into the drainage channel is elongate perpendicular to the direction of inflow of drainage liquid although the slot as seen directly from above, is not of substantial width, a large volume of liquid can flow into the drain per unit time whilst avoiding e.g. ladies' high heels going into the slot.

The first member has a surface inclined to the horizontal, whereby liquid flowing horizontally through the drain cover unit can flow down the inclined portion of the first member and through the slot. Such an incline has an advantage that the liquid flowing over the inclined portion is guided downwards prior to entering through the slot, so encouraging the flow of the liquid into the drain. Additionally, the downward incline allows to the slot to be slightly below the ground level, allowing use of slots with a vertical component so that a large volume of liquid can flow through the slot.

The feature of Claim 16 allows drainage liquid to pass through the drain when flowing towards the drain from either side, without the liquid flowing from one side interfering with the flow of the liquid from the other side outside the drain. The two flows do not interact until the liquid is inside the drain, i.e. when the liquid has passed through the respective slots.

The slots may be generally or substantially vertical. Thus the lower edge of the top surface of the first member can be precisely vertically below the free edge of the second member. However, for practical reasons (mould withdrawal of a cast drain cover unit), the slot may be slightly inclined to the vertical so that a thin slot can be seen looking directly from above, say not greater than about 10 men in width and preferably not greater than about 5 mm or about 3 or about 2 mm, the slot being at say about 5 to about 3 or even about 2 or about I to the vertical. In this context, "substantially" means that the slot should not be wide enough to allow ladies' high heels to enter the slot. In principle, the lower edge of the first member can project substantially below the free edge of the second member, in which case the slot could not be seen at all directly

from above, but this is not preferred for practical reasons as indicated above and because more material, say cast iron, may be required.

Preferably, the angle of inclination of each first member is in the range of about 10 to about 30 . More preferably, the angle of inclination is in the range of about 15 to about 25 , e.g. about 21 .

Preferably the height of the slots is between about 10 rnm and about 40 mm. More preferably, the height of the slots is between about 20 rorn and about 30 men.

Preferably, the ratio of the width of the or each first renumber to the second member is approximately 1: 1.2. This allows a suitable incline of the first member while allowing sufficiently large slots to allow liquid to flow freely into the drain.

Preferably, the drain cover unit further comprises cross braces connecting each the or each first member to the second member. This provides structural strength to the second member so that it may bear the load of vehicles passing over it. The cross braces can also provide support members or fillets which run from the (respective) edge of the second member laterally outwardly to the inclined surface of the or each first member. The support members will also provide support for vehicles passing over the drain cover unit.

Preferably, a fin runs along the underside of the second member, projecting downwardly therefrom. Such an arrangement may have two advantages. Firstly, this can prevent feet from being trapped in the slot as the toe will abut the fin before the whole foot can enter through the slot. Secondly, the fin provides structural rigidity to the drain cover unit and is preferably integral with the cross braces, and perpendicular thereto. Thirdly, the fin may help to channel drainage liquid flowing through the slots into the drain.

Preferably, the drain cover unit is arranged to be liftable out of the drain so that blockages in the drain can easily be cleared.

The drain cover unit may be cast or fabricated from steel. If cast, it may be cast from Iron. Prior Art and Preferred Embodiments

The present invention will now be described, purely by way of example, with reference to the accompanying drawings, in which: Figure 1 is a perspective view of a conventional drain cover; Figure 2 is a perspective view of a first drain cover unit according to the invention; Figure 3 is a section through plane III-III in Figure 2; Figure 4 is a detail of Figure 3; Figure 5 is a perspective view of a second drain cover unit according to the invention, when removed from the charnel; Figure 6 is a section through the plane VI-VI in Figure 5; Figure 7 is an underside view of the drain cover unit of Figures 5 and 6; and Figure 8 is a section of the drain cover unit of Figures 5, 6 and 7, in situ.

Figures 2 to 4 - a first drain cover unit Figure 2 shows a first drain cover unit 10. The drain cover unit 10 comprises two elongate first members 12 running parallel to each other and each downwardly inclined at a small angle of e.g. 21 . The fall line is at right angles to the long dimension of the respective inclined member 12. There is an elongate second member 14 running parallel to and between the first members 12. The fall line is at right angles to the long

dimension of the respective inclined member 12. The second member 14 is horizontal.

The first and second members 12, 14 are thus parallel to each other.

Slots 16 are formed between the respective edge of the second member 14 and inner edges ofthe respective first members 12. The slots 16 extend parallel to the long axis of the first and second members 12' 14. The length ofthe slot 16 is at least half the dimension ofthe unit as measured parallel to the slot 16. The slots 16 allow flow of liquid from outside the drain to the inside of the drain through the drain cover unit 10.

The slots 16 are approximately vertical. In one embodiment, the edges of the first members 12 and the second member 14 are at an angle of approximately 93 to the horizontal (the plane of the respective second member 14), i.e. the slots extend at 3 to the vertical. In this case, each slot 16, as seen directly from above, has a width of about 2 mm. The small angle of 3 facilitates mould withdrawal when casting.

The first members 12 are connected to the second member 14 by fillets 18 which run perpendicular to the long axis of the first and second members 12, 14. The fillets 18 are equally spaced along the drain cover unit 10, and define the ends of the slots 16.

The upper surface 20 of the second member 14 is level with the ground in which the drain cover unit 10 is mounted and traffic can pass over the drain cover unit 10 and over the upper surface 20 ofthe second member 14.

In one embodiment, each fillet 18 is about 8 mm wide; each slot 16 is about 24 mrn high and about 165 mm wide; the first members 12 are 95 mm wide and 8 mm thick and are inclined at an angle of 21 to the horizontal; the second member 14 is 1 15 mm wide and 8 Tnm thick and the drain cover unit is 304 men wide. The drain cover unit I O may be formed in a single piece from cast iron, e.g. example ductile grade 600/3, although other suitable grades of iron or materials can be used. However, the drain cover unit 10 could be produced in multiple pieces and then joined together. The drain cover units 10 can be supplied in 500 mm lengths in order to meet requirements for handling of materials, e.g. having a weight of less then 25 kg. The upper surface 20 of the second member can be formed as a non-slip surface. Preferably, the drain cover unit is arranged to allow a flow rate of at least 44 litres per second in a drain cover unit of 2 m in length. This is in

order to comply with the specification found in "Guidance for the Design, Construction,

Modification and Maintenance of Petrol Filling Stations" without overflowing or contamination of areas outside the boundary of the drain cover unit.

The drain cover unit 10 is mounted in a channel 2, e.g. using 12 mrn mounting bolts (not shown) with a cap head suitable for use with an Alen Key, or similar. The mounting bolts pass through holes 24 in the drain cover unit 10. Once the bolts have been removed, the cover unit 10 can be easily lifted out for cleaning and maintaining the channel 2.

The holes 24 are defined by cylindrical portions extending downwardly from the lower inclined surface ofthe first members 12.

The channel 2 has two outer L-shaped lips 4 which run parallel to the long axis of the channel 2. The drain cover unit 10 sits on the horizontal parts of these lips 4. As shown in Figure 3, the first members 12 have a substantially vertical outer part 30, the top of which is connected to an inclined portion 22. The bottom of the outer part 30, together with the bottom of the cylindrical portions; act as a foot, which rests upon the lip 4 of the channel 2. The drain cover unit 10 is supported along its sides and not at its ends.

The drain cover unit 10 may be designed to withstand a load as stated in British Standard PREN 1433 and have dimensions commensurate with BS EN124.

The channel 2 may be approximately 305 mm wide and 300 mm high, and the lips 40 mm wide and have walls 40 mm high. However, the dimensions of the channel 2, as such, are not critical; a 2 m length of drain should be able to carry away 44 litres/second of drainage liquid to a suitable outlet without overflowing, over a period of 3 minutes.

This ensures that all the liquid flowing through the drain cover unit 10 is carried away in the channel 2. The channel 2 may be made in one piece from galvanised mild steel or plastic extrusion or GRP or polymer concrete. The channel 2 may be supplied in 3 m lengths to facilitate easy and quick assembly and installation.

All joints between the channels 2 are sealed. This is achieved by using either a suitable mastic, a suitable tape, for example "Denso" (RTM), or a suitable rubber seal.

Figure 3 shows a fin 28 running longitudinally below the second member 14. A cross brace 26 is also showr. The cross brace 26 extends across the whole width of the drain cover unit 10, extending between the substantially vertical outer parts 30. There can be a cross brace 26 at each end of the unit 10 and beneath each fillet 18. The cross braces 26 provide support and strength to the drain cover unit 10. In the region of the substantially vertical outer parts 30, the cross brace 26 may also rest on the horizontal surface of the lips 4 when the drain cover unit 10 is in the channel 2. A central part of the cross brace 26 extends downwardly below the bottom of the outer parts 30, to form a central portion which extends below the second member 14 by the same amount as the fin 28. The fin 28 and the cross brace 26 are substantially perpendicular. In one embodiment the fin 28, cross brace 26 and outer parts 30 are tapered slightly, narrowing away from the second member, at an angle of approximately 93 from the plane of the second member 14. This slight angle to the perpendicular is introduced to ease in removal of the drain cover unit l O from the cast in which it is formed.

The cross brace 26, fin 28 and outer parts 30 each have a width of 8 mm at their lower edges and the outer parts 30 are 40 mm high in one embodiment.

In one embodiment the lower edge of the cross brace 26 adjacent the outer parts 30 extends horizontally to a distance of 52 mm from the outer edges of the outer parts 30 before extending downwardly at an angle of 45 towards the fin 28 until the central portion of the cross brace 26 is reached, where the central portion of the cross brace 26 and the fin 28 extends 65 mm from the top of the second member 14.

The intersection of each cross brace 26 with the fin 28 is radiussed in order to remove sharp corners from the drain cover unit l O and reduce stress points. The same strengthening method is used wherever two perpendicular parts intersect, for example, between the inclined portion 22 ofthe first member 12 and the cross brace 26; between the outer part 30 and the cross brace 26; and between the second member 14 and the cross brace 26.

As shown in Figure 3, the channel 2 is placed in a trench. The trench is approximately 1 m wide in one embodiment. A mounting bracket (not shown) comprising two vertical members connected at their lower ends by a transverse member dimensioned complimentary to the width of the channel 2 is attached to the channel 2. The vertical sides of the mounting brackets extend below the lowest point of the channel 2. A plurality of such mounting brackets may be used in this manner.

The transverse member of the mounting brackets is set in a blinding layer of concrete (not shown), which is filled into the bottom of the trench. This blinding layer does not extend up to the level of the bottom of the channel 2.

When the blinding layer of concrete has at least partially set, the remaining concrete is poured, and the blinding layer prevents the channel rising due to natural buoyancy.

Depending on the type of surface into which the drain cover unit will be set, the lips 4 of the channel may be set either on polymer modified mortar, if the surface is to be brick paving, or simply set to the top of the lip of the channel in concrete if tarrnacadam or other hard standing surfaces (i.e. concrete) are to be used. The blinding layer is approximately 75 mm high in the trench.

Figures 5 to 8 - a second drain cover unit Figure 5 shows a second drain cover unit 110. The drain cover unit 110 comprises an elongate first member 112, and an elongate second member 114 running parallel to and to one side of the first member 112. The first member 112 is downwardly inclined at a small angle of e.g. 21 towards the second member 114, which is horizontal.

Slots 1 16 are formed between the respective edge of the second member 1 14 and the inner edge of the first member 1 12, as in the first drain cover unit 10. The first member 1 12 is connected to the second member 1 14 by fillets 1 18. The arrangement of the first and second member 1 12, 1 14, slots 1 16 and fillets 1 18 is the same as the arrangement on one side of the first drain cover unit 10 (comprising one first member and one second member).

The second drain cover unit 110 has a substantially vertical outer part 130 extending downwardly from the outer edge of the first member 1 12, as in the first drain cover unit 10. A second outer part 131 extends vertically downwards from the outer edge of the second member 114. In one embodiment, the position of the second outer part 131 corresponds to the position of the fin 28 on the second member 14 in the first drain cover unit 10, the features to one side of the fin 28 as shown in the first drain cover unit 10, having been removed from the second drain cover unit I 10.

Figure 6 shows a cross brace 126 extending across the whole of the drain cover unit 110, extending between the substantially vertical outer parts 130, 131. There may be a plurality of cross braces 126 arranged at each end and under each fillet 1 18, as in the first drain unit 10.

Mounting holes 124 defined in the same way as in the first drain cover unit 10 are only provided on the side of the drain cover unit 1 10 of the first member 1 12. As the cylinders forming the holes are not formed on the side of the unit 110 adjacent the second member, the cross brace 126 extends downwardly in the region of the outer part 131 so as to be level with the bottom of the outer part 131, in order to support the unit 1 10 when placed in the channel 102.

The unit 110 is mounted in a chaMel ofthe same type as used with the first unit 10.

In one embodiment, the dimensions of the first member 1 12, are the same as in the first drain cover unit 10 and the second member 1 14 is approximately half the width of the second member 14 of the first drain cover unit 10. The overall width of the drain cover unit I 10, and therefore the channel 102, is smaller. The depth of the channel 102 is the same. As in the first drain cover unit 10, the dimensions of the channel 102 are important in terms of the flow capacity of liquid through it.

Figure 7 shows a plurality of cross braces 126 on the underside of the first and second members 112, 114. The joints between the cross braces 126, first and second members

112, 114 and outer parts 130, 131 are radiussed, in the same way as the first unit. The joints of the fillets 1 18 with the first member 1 12 are also radiussed.

Figure 8 shows the second drain cover unit 110 placed in the channel 102 with the outer parts 130, 131 and the region of the cross brace 126 adjacent outer part 131 abutting the lip 104 of the channel 102.

As can be seen from Figures 5 to 8, the second drain cover unit does not have a fin running longitudinally along the underside of the second member 214.

x x x x Any discussion of the prior art through the specification should in no way be considered

as an admission that such prior art is widely known or forms part of common general

knowledge in the field.

Unless the context clearly requires otherwise, throughout the description and the claims,

the words 'comprise', 'comprising', and the like, are to be construed in an inclusive as opposed to an exclusive or exhaustive sense; that is to say, in the sense of"including, but not limited to".

The present invention has been described above purely by way of example, and modifications can be made within the spirit of the invention. The invention also consists in any individual features described or implicit herein or shown or implicit in the drawings or any combination of any such features or any generalization of any such features or combination. In particular, the dimensions and ratios given in the description above are not intended to be limiting, but merely examples of possible

construction dimensions. Other dimensions giving a drain cover unit as claimed may also be used. For convenience, the drain cover unit is described and claimed in the orientation it would assume in use. However, during for instance manufacture, transport and storage, it could be in another orientation, for example upside down, and the invention extends to the drain cover unit in these other orientations.

Claims

CLAIMS:

1. A drain cover unit over which traffic can pass, comprising: an exposed first member which has an upper surface which is downwardly inclined at a small angle and has an upper edge and a lower edge; and a second member having a generally horizontal upper surface over which traffic can pass; an elongate slot being defined between a free edge of the second member and the lower edge of the top surface of the first member so that drainage liquid flowing horizontally across the ground can flow down the inclined upper surface of the first member and through the slot, the upper edge of the top surface of the first member being generally at the same level as the upper surface of the second member so that the free edge of the second member is above the level of the lower edge of the top surface of the first member, the free edge of the second member extending at least as far as a position which is generally above the lower edge of the top surface of the first member so that the slot, as seen directly from above, is not of substantial width.

2. A drain cover unit according to Claim 1, the first and second members being elongate and parallel to each other with the slot extending parallel to the long axis of the first and second members.

3. A drain cover unit according to Claim I or 2, wherein the lower edge of the first member is substantially vertically below the free edge of the second member.

4. A drain cover unit according to any of the preceding claims, wherein the angle of inclination of the first member is not less than about 10 .

5. A drain cover unit according to any of Claims 1 to 3, wherein the angle of inclination of the first member is not less than about 15 .

6. A drain cover unit according to any of the preceding claims, wherein the angle of inclination of the first member is not greater than about 30 .

7. A drain cover unit according to any of Claims 1 to 5, wherein the angle of inclination of the first member is not greater than about 25 .

8. A drain cover unit according to any of the preceding claims, wherein the length of the slot is at least half the dimension of the unit as measured parallel to the slot.

9. A drain cover unit according to any of the preceding claims, wherein the distance between the free edge of the second member and the top surface of the first member is not greater than about 40 mm.

1 O. A drain cover unit according to any of Claims 1 to 8, wherein the distance between the free edge of the second member and the top surface of the first member is not greater than about 30 mm.

1 1. A drain cover unit according to any of the preceding claims, wherein the distance between the free edge of the second member and the top surface of the first member is not less than about 10 mm.

12. A drain cover unit according to any of Claim I to 10, wherein the distance between the free edge of the second member and the top surface of the first member is not less than about 20 mm.

13. A drain cover unit according to any of the preceding claims, wherein the ratio of the width of the first member as measured at right angles to the lower edge of the top surface, to the width of the second member as measured at right angles to the free edge of the second member, is about 1:1.2.

14. A drain cover unit according to any of the preceding claims, further comprising cross braces connecting the first member to the second member.

15. A drain cover unit as claimed in any of the preceding claims whose length parallel to the or each slot is 2 m and arranged to allow a flow rate of at least about 44 litres per second, or the equivalent for a longer or shorter drain cover unit.

16. A drain cover unit according to any of the preceding claims, and comprising two said first members, on either side of a said second member, said second member having two said free edges and two said slots being formed, on either side of the second member.

17. A drain cover unit according to Claim 16, further comprising a fin projecting from the underside of the second member and spaced from the respective free edge of the second member and from the lower edge of the respective first member, for defecting fluid flow downwards.

18. A drain cover unit according to Claim 17, wherein the fin projects substantially downwardly.

19. A drain cover unit according to Claim 14 and also Claims 17 or 18, wherein the fin is formed integrally with the cross braces.

20. A drain cover unit according to any of the preceding claims, arranged to be mounted in a channel.

21. A drain cover unit according to Claim 20 and arranged so that it can be lifted from the channel.

22. A drain cover unit according to any preceding claim, made from a single casting.

23. A drain cover unit, substantially as herein before described with reference to Figures 2 to 4 or Figures 5 to 8 of the accompanying drawings.

24. A drain comprising a drain cover unit according to any of the preceding claims.

25. An area of hard standing, comprising a drain cover unit according to any of Claims I to 23.

Amendments to the claims have been filed as follows 1. A drain cover unit over which traffic can pass, comprising: a first member having an exposed, extended top surface which is downwardly inclined at a small angle and has an upper edge and a lower edge; and a second member having an exposed, generally horizontal, extended top surface over which traffic can pass and which has a free edge generally parallel to the lower edge of the top surface of the first member; an elongate slot being defined between said free edge of the second member and the lower edge of the top surface of the first member so that drainage liquid flowing horizontally across the ground can flow down the inclined top surface of the first member and through the slot, the upper edge of the top surface of the first member being generally at the same level as the top surface of the second member so that the free edge of the second member is above the level of the lower edge of the top surface of the first member, the free edge of the second member extending at least as far as a position which is generally above the lower edge of the top surface of the first member so that when the drain cover unit is viewed directly from above, the slot is not of substantial width.

3. A drain cover unit according to Claim 1 or 2, wherein the lower edge of the first member is substantially vertically below the free edge of the second member.

10. A drain cover unit according to any of Claims I to 8, wherein the distance between the free edge of the second member and the top surface of the first member is not greater than about 30 rnrn.

I 1. A drain cover unit according to any of the preceding claims, wherein the distance between the free edge of the second member and the top surface of the first member is not less than about 10 mm.

12. A drain cover unit according to any of Claim 1 to 10, wherein the distance between the free edge of the second member and the top surface of the first member is not less than about 20 mm.

[L 16. A drain cover unit according to any of the preceding claims, and comprising two said first members, on either side of a said second member, said second member having two said free edges and two said slots being Donned, on either side of the second member. 17. A drain cover unit according to Claim 16, further comprising a fin projecting from the underside of the second member and spaced from the respective free edge of the second member and from the lower edge of the respective first member, for defecting fluid flow downwards.

18. A drain cover unit according to Claim 17, wherein the fin projects substantially downwardly. 19. A drain cover unit according to Claim 14 and also Claims 17 or 18, wherein the fin is formed integrally with the cross braces.

21. A drain cover unit according to Claim 20 and arranged so that it can be lined from the channel.