IL137577A - Prefabricated external drop - Google Patents

Abstract

A prefabricated external drop operatively associated with a manhole and with a sewage pipe (6), the sewage pipe being located at a first level (H) and conveying an incoming flow of sewage, the external drop comprising: a collector comprising: an upper 90!-bend (13) with a first end forming a bend intake (15) configured for coupling to the sewage pipe and a second end forming a bend outlet (16) oriented vertically downward, and a control element (14) having a first lower end coupled between the bend intake and the bend outlet of the upper 90!-bend, the control element bifurcating radially outwards of the upper 90!-bend to terminate in a second higher end (H+) formed as a horizontal straight pipe coplanar with the upper 90!-bend and situated above the first level, the bend intake and the second higher end facing opposite directions, the latter being fixedly but releasably coupled to the manhole, and a discharge pipe (23) comprising: a vertical portion having a first higher end and a second lower end defining a length, the first higher end being coupled to the vertically downward-oriented bend outlet of the collector, and a horizontal portion having a first end and a second end, the second end being fixedly but releasably coupled to the manhole, and a lower 90!-bend coupling between the lower end of the vertical portion and the first end of the horizontal portion of the discharge pipe, whereby sewage from the sewage pipe flows through the collector and through the discharge pipe to the manhole. 1100 י" ב בסיון התשס" ד - June 1, 2004

Description

A PREFABFICATED EXTERNAL DROP A PREFABRICATED EXTERNAL DROP FIELD OF THE INVENTION The present invention relates generally to external drops for sewage, and more particularly, to prefabricated external drops.

BACKGROUND OF THE INVENTION Although water has always been scarce in arid countries, nowadays, water is recognized a precious commodity in ever growing parts of the world. It is therefore common practice to recycle used water in the attempt to reuse as much possible of the precious fluid. It is an extensive custom now to forbid the use of fresh water in specific sectors of industry and of agriculture and instead, to provide treated municipal water. As a result, extensive networks of municipal sewage are built to collect the outflow from dwellings to return spent water to waste water treatment facilities. Mostly in cities, an underground net of conduits and pipes is managed to gather wastewater in an efficient way.

Usually, spent water and sewage originating from various sources, such as from different buildings, are carried through ducts for concentration in manholes, from which they flow, in lager diameter pipes, to sanitizing and purification facilities.

Now however, as land is expensive, advantage is taken of plots previously regarded as unfit for construction purposes, such as steep inclines. Due to building-site layout and to the topography of the land, large differences of elevation occur between the various components of sewage networks. Because of differences of height, it often impractical to directly connect sewage pipes to a manhole. Therefore, to prevent large differences of level, instead of attaching a sewage-pipe to the top of a manhole, a external drop is built, adjacent to but outside of the manhole, to facilitate connection to the lower portion of the manhole.

Although beneficial, this solution has many drawbacks. First, the building of an vertical drop in situ is time consuming and thus, expensive. Second, that building activity requires skilled labor, which is not only scarce, but also expensive. TTiird, is almost impossible to assure that every external drop is of high quality, as manual work is hardly consistent and reproducible. Thus, even though building codes dictate the construction of external drops, these drops remain far from perfect underground man-built structures. Theoretically, external drops are watertight, but repeatedly, they are defective and leaky. Such leaks are the result of either some faulty workmanship or due to shifts of the ground or settling of the earth around the manhole. Hence, in due course, gasses, which are present in sewage, such as sulphide gas, gradually deteriorate and corrode the mortar and concrete of the external drops, to the point that in the end, a significant amount of ground water may infiltrate. However, the more serious implications that need earnest consideration relate to the 2 ! considerable amount of sewages seeps out of cracked manholes. ! ° c ^ p Fig. 1 illustrates a manhole and an external drop 5 attached thereto in a conventional manner. The manhole 1 is usually a cylindrical structure made of concrete, with a surrounding wall 2 and a cover 2C. A lid 3 at the top permits access to the inside 4 of the manhole. The inlet and the outlet at the bottom of the manhole are not shown in detail for the sake of simplicity. The external drop 5 is built in place adjacent to the manhole 1. A sewage pipe 6 penetrates to the inside 51 of the external drop 5 and discharges the inflowing sewage into a funnel-shaped drain 7 and from there through a drop pipe 8 and a 90°-bend 9 to an outlet not shown in Fig. 1. The square cross-section of the external drop top elevation is shown in Fig. 2. It is easy to discern the absence of a flow-smoothing device at the entrance inlet 10 of the external drop 5. Furthermore, it is practically impossible to inspect and maintain the inside of the external drop 5 even through the open lid 3.

It would therefore be advantageous to produce and install a prefabricated external drop, or PED, instead of building one in place, as an addition to a manhole. It would also be of advantage to provide a sealed prefabricated external drop, or PED, designed for smoothing the flow of the sewage.

Furthermore, it would be beneficial to supply a porthole for the inspection and maintenance of the inside of the PED. Moreover, a multiple-entry PED would be beneficial; to the industry.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a prefabricated external drop operatively associated with a manhole and with a sewage pipe. The sewage pipe is located at a first level and conveys an incoming flow of sewage.

The external drop comprises a collector with an upper 90°-bend with a first end forming a bend intake configured for coupling to the sewage pipe and a second end forming a bend outlet oriented vertically downward. The collector also comprises a control element having a first lower end coupled between the bend intake and the bend outlet of the upper 90°-bend. The control element bifurcates radially outwards of the upper 90°-bend to terminate in a second higher end formed as a horizontal straight pipe coplanar with the upper 90°-bend and situated above the first level, The bend intake and the second higher end face opposite directions, the latter being fixedly but releasably coupled to the manhole. The prefabricated external drop further comprises a discharge pipe comprising a vertical portion having a first higher end and a second lower end defining a length, the first higher end being coupled to the vertically downward-oriented bend outlet of the collector. The discharge pipe also comprises a horizontal portion having a first end and a second end, the second end being fixedly but releasably coupled to the manhole, and a lower 90°-bend coupling between the lower end of the vertical portion and the first end of the horizontal portion of the discharge pipe. This configuration allows the sewage from the sewage pipe to flow through the collector and through the discharge pipe to the manhole.

It is also an object of the present invention to provide a prefabricated external drop wherein the manhole to which the second higher end is releasably coupled comprises a circumferential wall defining an outside and an inside. The coupling to the manhole comprises a higher bore pierced in the wall for the second higher end to penetrate therethrough from the outside, till abutment to the wall, to the inside, and a necked flange configured to couple with the horizontal straight pipe from the inside adjacent the wall. Furthermore, screws engage the necked flange and the second higher end, whereby the collector is fixedly but releasably retained the to the wall.

It is another object of the present invention to provide a prefabricated external drop wherein the second higher end forms a control port for access to the upper 90°-bend and to the sewage pipe for inspection and maintenance thereof.

It is a further object of the present invention to provide a prefabricated external drop wherein the second end of the horizontal portion of the discharge pipe is releasably coupled to the manhole, the manhole comprising a circumferential wall defining an outside and an inside. The coupling to the manhole also comprises a lower bore pierced in the wall for the second higher end to penetrate from the outside to the inside, and a seal configured to tightly engage the horizontal portion of the discharge pipe on the outside of the manhole. The seal being mounted on the horizontal portion for introduction therewith into the lower bore is configured to achieve fixed but releasable retention of the discharge pipe with the manhole wall.

It is yet a further object of the present invention to provide a prefabricated external drop wherein the upper 90°-bend is configured for smooth flow of the sewage from the sewage pipe to the discharge pipe, from the discharge pipe to the manhole and from the sewage pipe to the manhole.

Another object of the present invention is to provide a prefabricated external drop wherein the material for production thereof is corrosion-resistant, such as plastic material.

It is turthermore an object of the present invention to provide a prefabricated external drop wherein sealed and watertight functioning is achieved when in operative association with a manhole and a sewage pipe.

Yet another object of the present invention is to provide a prefabricated external drop wherein the length of the vertical portion of the discharge pipe is adjustable in situ.

Still another object of the present invention is to provide a prefabricated external drop wherein installation and replacement in situ are achieved in operative association with a manhole and with a sewage pipe.

Furthermore, another object of the present invention is to provide a prefabricated external drop wherein the collector and the discharge pipe are made of at least two separate portions, or of more man two separate portions, adapted for assembly in situ.

It is an object of the present invention to provide a multiple-entry prefabricated external drop operatively associated with a manhole and with at least one sewage pipe located at a first level and conveying an incoming flow of sewage. The external drop comprises a multiple-entry collector comprising a body accommodating a plurality of entries for coupling to at least one sewage pipe and for receiving the incoming sewage. The body has a top and a bottom, a cover with a top and a back, and the cover is attached to the top of the body. A drain is attached to the bottom of the body for collection of the incoming sewage. A control member configured as a straight horizontal pipe is located above the first level and has a first end coupled to back of the cover and a second end fixedly but releasably coupled to the manhole. There is also a discharge pipe comprising a vertical portion having a first higher end and a second lower end defining a length, with the first higher end being coupled to the drain of the collector. A horizontal portion has a first end and a second end, the second end being releasably but fixedly coupled to the manhole. A lower 90°-bend couples between the lower end of the vertical portion and the first end of the horizontal portion of the discharge pipe, whereby sewage from the at least one sewage pipe flows through the collector and through the discharge pipe into the manhole.

In addition, it is an object of the present invention to provide a multiple-entry prefabricated external drop wherein the manhole to which the control member is releasably coupled comprises a circumferential wall defining an outside and an inside. The coupling to the manhole comprises a higher bore pierced in the wall for the control member to penetrate therethrough from the outside, till abutment to the wall, to the inside, a necked flange configured to couple with the control member inside adjacent the wall, and screws engaging the necked flange and the control member, for secure fixed but releasable retention of the external drop to the wall.

It is yet an object of the present invention to provide a multiple-entry prefabricated external drop wherein the second end of the control member defines a control port for access to the inside of the body of the collector and to the at least one sewage pipe for inspection and maintenance thereof.

It is furthermore an object of the present invention to provide a multiple-entry prefabricated external drop wherein the second end of the horizontal portion of the discharge pipe is releasably coupled to the manhole, the manhole comprising a circumferential wall defining an outside and an inside.The coupling to the manhole comprises a lower bore pierced in the wall for the second end of the control member to penetrate from the outside to the inside, and a seal configured to tightly engage the horizontal portion of the discharge pipe on the outside of the manhole, the seal being mounted on the horizontal portion for introduction therewith into the lower bore, and the seal being configured to achieve fixed but releasable retention of the discharge pipe with the manhole wall.

It is furthermore an object of the present invention to provide a multiple-entry prefabricated external drop wherein the collector body is configured for smooth flow of the sewage from the at least one sewage pipe to the discharge pipe, from the discharge pipe to the manhole and from the at least one sewage pipe to the manhole.

It is still further an object of the present invention to provide a multiple-entry prefabricated external drop wherein the material for production thereof is corrosion-resistant, such as plastic material.

It is even further an object of the present invention to provide a multiple-entry prefabricated external drop wherein sealed and water-tight functioning is achieved when in operative association with a manhole and with at least one sewage pipe.

It is still another object of the present invention to provide a multiple-entry prefabricated external drop wherein the length of the vertical portion of the discharge pipe is adjustable in situ. Also, installation and replacement in situ are achieved in operative association with a manhole and with a sewage pipe. Still a further object of the present invention to provide a multiple-entry prefabricated external drop wherein the collector and the discharge pipe are made of at least two separate portions, or of more than two separate portions, adapted for assembly in situ.

BRIEF DESCRIPTION OF THE DRAWINGS In order to better understand and more fully appreciate the invention and to see how the same may be carried out in practice, some preferred embodiments will now be described, by way of non-limiting example only, with reference to the accompanying drawing in which Fig. 1 is a cross-section of a conventional manhole and an external drop built adjacent thereto, Fig. 2 is a top elevation of Fig. 1, Fig. 3 is a cross-section of a first embodiment of a prefabricated external drop, Fig. 4 is an exploded view of Fig. 3, showing parts of the prefabricated external drop, 137577/2 Fig. 5 is an isometric view of Fig. 3, with the prefabricated external drop and a portion of the manhole, Fig. 6 illustrates a cross-section of a second embodiment, as a multi-entry prefabricated external drop, Fig. 7 depicts an exploded view of Fig. 6, showing parts of the second embodiment of prefabricated external drop, and Fig. 8 presents an isometric view of Fig. 7, illustrating the multi-entry prefabricated external drop and a portion of the manhole.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS Referring now to Fig. 3, there is shown a first embodiment 100 of a prefabricated external drop PED and only ¾ portion of a manhole 1 with a wall 2. The peripheral wall 2 of the manhole 1 defines a manhole inside 41 and a manhole outside, or manhole exterior 4E. A portion of a sewage pipe 6 is coupled to a collector 12 comprising an upper 90°-bend 13 and a control element 14. At a first end, the upper 90°-bend 13 has a bend intake 15 and at the second end, a lower bend outlet 16. It should be noted that the upper 90°-bend 13 is configured to assure smooth flow there through. The sewage pipe 6 with inflowing sewage is connected to the bend intake 15 and the upper 90°-bend 13 thus ensures a smooth flow of the sewage to the bend outlet 16.

In between the bend intake 15 and the bend outlet 16, protruding radially outwards, but coplanar with the upper 90°-bend 13, there is connected a first lower end 17 of the control element 14. The control element 14 bifurcates out of the upper 90°-bend 13 and returns to the horizontal to terminate in a second higher end 18. It should be noted that while the inflowing sewage pipe 6 resides at a first level H, the second higher end 18 is located at a higher level H+. It should also be noted that although the bend intake 15 and the second higher end 18 have their openings oriented in opposite direction, they are offset by the distance between the level H and H+. There is access from the second higher end 18 to the bend intake 15; however, sewage will not flow from the level H to the higher level H+. This offset is preferably of the order of magnitude of one diameter.

To attach the collector 12 to the manhole 1, the second higher end 18 penetrates from the outside 4E of the manhole 1 to the inside 41 thereof, through a higher bore 20 pierced at the level H+ in the vertical wall 2. The higher bore 20 is configured to snugly fit the periphery of the higher end 18. The attachment is achieved by inserting a necked flange 21 to straddle the circumference of the second higher end 18 from the inside 41 of the manhole 1. The second higher end 18 is first inserted into the higher bore 20 until arrested by an annular protrusion 22 or circular rim 22. That rim 22 is appropriately located to surround the second higher end 18 and to remain at the outside 4E of the manhole. Then, the necked collar 21 is firmly pressed form the inside 41 against the wall 2. The next step consists of tightening radial screws, not shown in Fig. 3 for the sake of clarity, retained by the neck of the necked collar 21, into the second higher end 18. The control element 14 is thus fixedly retained to the wall 2 to support the collector 12: on the outside 4E by the circumferential rim 22 and on the inside 4I^by the screwed-down necked flange 21. The control element 14 may be released and removed when required, by releasing those screws, not seen in Fig. 3. Evidently, the collector may be refastened to the wall 2.

The collector 12 is fastened to a discharge pipe 23 in the shape of an elbow. The discharge pipe 23 comprises a vertical pipe portion 24, a horizontal pipe portion 25 and a lower 90°-bend 26 connecting between the vertical and the horizontal pipe portions. The vertical pipe portion 24 presents a higher end 27 that is joined to the bend outlet 16 and a lower end 28. The whole length of the vertical pipe portion 24, from the higher end 27 to the lower end 28 runs outside the manhole 1, closely and in parallel to the wall 2.

A first pipe end 29 of the horizontal pipe portion 25 is fixed to one side of the lower 90°-bend, while the other side of that same bend is connected to the lower end 28 of the vertical pipe portion 24. The second pipe end 30 is inserted from the outside 4E of the wall 2 to the inside 41 of the manhole 1, through a lower bore 31 drilled into the wall 2. The lower bore 31 resides at a level H-lower than the level H of the sewage pipe 6. Prior to the insertion of the second pipe end 30 into the lower bore 31, an annular neck-seal 32 is engaged on the second pipe end 30, so that when pushed through the lower bore 31, the neck-seal provides both sealing and retention of the horizontal pipe portion 25 to the wall 2.

The prefabricated external drop 100 is preferably implemented from corrosion-resistant material such as plastic material of an appropriate kind. As an inert standard material, plastic offers advantageous properties such as ease of shaping, low-cost manufacturing and inherent resilience. When mounted in place, often-occurring settlements of the earth will not affect the integrity of the external drop, as those small movements will be taken up by the prefabricated product thanks to its flexibility.

Fig. 4 is an exploded view of the PED showing the product broken down in parts. The PED is implemented either as one single-piece structure or, as a plurality of parts for assembly in situ, or even as a plurality of parts cut to size and assembled in place. Since the PED is a structure comprising a combination of pipe elements and pipe connections, different techniques, all well known to the art, are applicable. For example, referring to Fig. 7, the sewage pipe 6S is coupled to the bend intake 15 of the collector 12 by help of a seal 6S. Other methods of coupling are evidently also appropriate.

Fig. 5 shows an isometric view of the PED coupled to a manhole 1 represented as a portion of the wall 2. The PED features a simple structure of simple installation, adjacent to the exterior 4E of the wall 2.

The ease of installation, in the field, of the embodiment 100 of the prefabricated external drop PED will now be explained. First, a higher bore 20 and a lower bore 31 are drilled in the wall 2 of the manhole 1. Then, the control element 14 and the horizontal pipe portion 25, with the neck-seal 32, are pushed through their respective bores 20 and 31. Next, the necked collar 21 is mounted on the horizontal pipe portion 25 and pressed against the wall 2, while the bolts, not shown in Fig. 3, are tightened to fasten the necked collar 21 to the horizontal pipe portion 25 in retention. All that remains to be done to complete the installation of the prefabricated external drop is to couple the sewage pipe 6 to the bend intake 15 of the upper 90°-bend 13.

The operation of the prefabricated external drop PED is straightforward. Inflowing sewage from the sewage pipe 6 flows smoothly into the collector 12 through the upper 90°-bend 13. From there the flow continues down the discharge pipe 23, smoothly again through the lower 90°-bend 26, to finally reach the inside 41 of the manhole 1.

A second embodiment 200 of the prefabricated external drop PED will now be described with reference to Figs. 6, 7 and 8. The main difference between the second embodiment 200 and the first embodiment 100 resides in the configuration of the collector, which is configured to join up with more than one single sewage pipe. The discharge pipe described in the previous embodiment 100 is similar if not identical to the drop pipe of embodiment 200.

Referring to Fig. 6, there is shown a PED comprising a multiple-entry collector 40, and a discharge pipe 23 that was explained above will not be described again. The multiple-entry collector 40 features a box 41 with a cover 42, a funnel drain 43 and a control member 44. The box 41 comprises a circumferential vertical curved wall 45 of predetermined height bent in the shape of a horseshoe, a box roof 46, a box bottom 47 and a box back 48. The curved wall 45 comprises a front portion 49, oriented towards the at least one sewage pipe 6, and a couple of wall sides 50. The front portion 49 carries multiple circular entries 51, side by side, each entry 51 being accommodated to fit a sewage pipe 6 with inflowing sewage.

The entries 51 in the multiple-entry collector 40 are provided for operative coupling to the sewage pipes 6, at the level H. The number of circular entries 51 defines the maximum possible number of sewage pipes 6 able to be coupled to the multiple-entry collector 40. However, it is evidently possible to couple less sewage pipes 6 than the available entries 51 open in the front portion 49, provided that those entries 51 not fitted to sewage pipes 6, are duly sealed by lids, not shown in the Figures.

The funnel drain 43 that collects the outflow from the one or many sewage pipes 6, is attached to the box bottom 47, in direct communication with the inside 411 of the box 41. The funnel drain 43 conveys the sewage to the exit 52 of the funnel drain for the sewage to flow into the discharge pipe 23, in the same manner as was explained above with reference to the first embodiment 100.

The cover 42 is attached to the box roof 46 and is in direct communication with the inside 411 of the box 41. The cover 42 has a cover back 53 coextensive with the box back 48. Since the box 41 is generally at the level H of the sewage pipes 6, the cover 42 resides at a level H+, higher than the level H.

The control member 44, which is a hollow pipe, fulfills the same role as the control element 14 in embodiment 100. The control member 44 comprises a collector end 54 integral with the cover back 53 and a free end 55 for insertion through the wall 2 to the inside of the manhole 1. There is free passage for communication from the box 41 to the manhole 1 so that again, the free end 55 provides access to the inside 411 of the box 41 and to the at least one sewage pipe.

Installation in the field is easy and similar to the description relating to the embodiment 100 of the prefabricated external drop PED. As above, a higher bore 20 and a lower bore 31 are first drilled in the wall 2 of the manhole 1. Then, the control member 44 and the horizontal pipe portion 25, with the neck-seal 32, are pushed through their respective bores 20 and 31. The multiple-entry PED is pushed against the wall 2 until the box-back 48 rests against the wall 2 and the rest of the connection proceeds as explained above for the embodiment 100. Thus, the necked collar 21, is mounted on the control member 44 from the inside 41 of the manhole 1 and pressed against the wall 2, while the screws, not shown in Figs. 6, 7 and 8, are tightened to fasten the necked collar 21 to the control member 44. All that remains to be done to complete the installation of the multiple-entry PED is to couple the single or more sewage pipes 6 to the entries 51 of the box 14. Each sewage pipe 6 is either connected by help of an annular seal 6S mounted on the pipe 6 before insertion into the box 14, or by any other of the many methods well known to the art.

The operation of the embodiment 200 of the multiple-entry PED remains the same as described above. Inflowing sewage from one or more sewage pipe 6 enters the box 41 and flows, through the funnel drain 43, to the discharge pipe 23. From there the flow continues down the discharge pipe 23, smoothly through the lower 90°-bend 26, to finally reach the inside 41 of the manhole 1.

While preferred embodiments of the invention have been shown and described in detail, it should be apparent that many modifications and variations thereto are possible, all of which fall within the true spirit and scope of the invention. For example, in the embodiment 100, the PED is not restricted to the vertical but may be mounted in a slanted position to the manhole 1. Furthermore, the elements of the PED may be manufactured with a cross-section other than a circular cross-section and more than one kind of material may be used for the same PED. Moreover, more than one PED may be attached to the same manhole.

It is therefore intended by the appended claims to cover any and all such applications, modifications and embodiments within the scope of the present invention.

Claims (30)

C L A I M S

1. A prefabricated external drop operatively associated with a manhole and with a sewage pipe, the sewage pipe being located at a first level and conveying an incoming flow of sewage, the external drop comprising: a collector comprising: an upper 90°-bend with a first end forming a bend intake configured for coupling to the sewage pipe and a second end forming a bend outlet oriented vertically downward, and a control element having a first lower end coupled between the bend intake and the bend outlet of the upper 90°-bend, the control element bifurcating radially outwards of the upper 90°-bend to terminate in a second higher end formed as a horizontal straight pipe coplanar with the upper 90°-bend and situated above the first level, the bend intake and the second higher end facing opposite directions, the latter being fixedly but releasably coupled to the manhole, and a discharge pipe comprising: a vertical portion having a first higher end and a second lower end defining a length, the first higher end being coupled to the vertically downward-oriented bend outlet of the collector, and a horizontal portion having a first end and a second end, the second end being fixedly but releasably coupled to the manhole, and a lower 90°-bend coupling between the lower end of the vertical portion and the first end of the horizontal portion of the discharge pipe, whereby sewage from the sewage pipe flows through the collector and through the discharge pipe to the manhole. 137577/2

2. The prefabricated external drop according to Claim 1, wherein the manhole to which the second higher end is releasably coupled comprises a circumferential wall defining an outside and an inside, and the coupling to the manhole comprising: a higher bore pierced in the wall for the second higher end to penetrate therethrough from the outside, till abutment to the wall, to the inside, a necked flange configured to couple with the horizontal straight pipe from the inside adjacent the wall, and screws engaging the necked flange and the second higher end, whereby the collector is fixedly but releasably retained the to the wall.

3. The prefabricated external drop according to the Claims 1 or 2, wherein the second higher end forms a control port for access to the upper 90°-bend and to the sewage pipe for inspection and maintenance thereof.

4. The prefabricated external drop according to Claim 1, wherein the second end of the horizontal portion of the discharge pipe is releasably coupled to the manhole, the manhole comprising a circumferential wall defining an outside and an inside, and the coupling to the manhole comprising: a lower bore pierced in the wall for the second end of the horizontal portion to penetrate from the outside to the inside, a seal configured to tightly engage the horizontal portion of the discharge pipe on the outside of the manhole, the seal being mounted on the horizontal portion for introduction therewith into the lower bore, and the seal also being configured to achieve fixed but releasable retention of the discharge pipe with the manhole wall.

5. The prefabricated external drop according to the Claims 1 or 2, wherein the upper 90°-bend is configured for smooth flow of the sewage from the sewage pipe to the discharge pipe.

6. The prefabricated external drop according to the Claims 1 or 4, wherein the lower 90°-bend is configured for smooth flow of the sewage from the discharge pipe to the manhole. 137577/2

7. The prefabricated external drop according to the Claims 1, 5 or 6, wherein smooth flow of the sewage is provided from the sewage pipe to the manhole.

8. The prefabricated external drop according to any of the preceding Claims, wherein the material for production thereof is corrosion-resistant.

9. The prefabricated external drop according to Claim 8, wherein the material for production thereof is plastic material.

10. The prefabricated external drop according to any of the preceding Claims, wherein sealed and water-tight functioning is achieved when in operative association with a manhole and a sewage pipe.

11. 1 1. The prefabricated external drop according to Claim 1 , wherein the length of the vertical portion of the discharge pipe is adjustable in situ.

12. The prefabricated external drop according to any of the preceding Claims, wherein installation in situ is achieved in operative association with a manhole and with a sewage pipe.

13. The prefabricated external drop according to any of the preceding Claims, wherein replacement in situ is achieved in operative association with a manhole and with a sewage pipe.

14. The prefabricated external drop according to any of the preceding Claims, wherein the collector and the discharge pipe are made of at least two separate portions adapted for assembly in situ.

15. The prefabricated external drop according to any of the preceding Claims, wherein the collector and the discharge pipe are made of more than two separate portions adapted for assembly in situ.

16. A multiple-entry prefabricated external drop operatively associated with a manhole and with at least one sewage pipe located at a first level and conveying an incoming flow of sewage, the external drop comprising: a multiple-entry collector comprising: a body accommodating a plurality of entries for coupling to at least one sewage pipe and for receiving the incoming sewage, the body having a top and a bottom, a cover having a top and a back, the cover being attached to the top of the body, a drain attached to the bottom of the body for collection of the incoming sewage, a control member configured as a straight horizontal pipe located above the first level and having a first end coupled to back of the cover and a second end fixedly but releasably coupled to the manhole, a discharge pipe comprising: a vertical portion having a first higher end and a second lower end defining a length, the first higher end being coupled to the drain of the collector, and a horizontal portion having a first end and a second end, the second end being releasably but fixedly coupled to the manhole, and a lower 90°-bend coupling between the lower end of the vertical portion and the first end of the horizontal portion of the discharge pipe, whereby sewage from the at least one sewage pipe flows through the collector and through the discharge pipe into the manhole.

17. The multiple-entry prefabricated external drop according to Claim 16, wherein the manhole to which the control member is releasably coupled comprises a circumferential wall defining an outside and an inside, and the coupling to the manhole comprises: 137577/2 a higher bore pierced in the wall for the control member to penetrate therethrough from the outside, till abutment to the wall, to the inside, a necked flange configured to couple with the control member inside adjacent the wall, and screws engaging the necked flange and the control member, for secure fixed but releasable retention of the external drop to the wall.

18. The multiple-entry prefabricated external drop according to the Claims 16 or 17, wherein the second end of the control member defines a control port for access to the inside of the body of the collector and to the at least one sewage pipe for inspection and maintenance thereof.

19. The multiple-entry prefabricated external drop according to Claim 16, wherein the second end of the horizontal portion of the discharge pipe is releasably coupled to the manhole, the manhole comprising a circumferential wall defining an outside and an inside, and the coupling to the manhole comprising: a lower bore pierced in the wall for the second end of the control member to penetrate from the outside to the inside, a seal configured to tightly engage the horizontal portion of the discharge pipe on the outside of the manhole, the seal being mounted on the horizontal portion for introduction therewith into the lower bore, and the seal being configured to achieve fixed but releasable retention of the discharge pipe with the manhole wall.

20. The multiple-entry prefabricated external drop according to the Claim 16 or 17, wherein the collector body is configured for smooth flow of the sewage from the at least one sewage pipe to the discharge pipe. 137577/2

21. The multiple-entry prefabricated external drop according to Claim 16 or 19, wherein the lower 90°-bend is configured for smooth flow of the sewage from the discharge pipe to the manhole.

22. The multiple-entry prefabricated external drop according to the Claims 16, 20 or 21, wherein smooth flow of the sewage is provided from the at least one sewage pipe to the manhole.

23. The multiple-entry prefabricated external drop according to any of the Claims 16 to 22, wherein the material for production thereof is corrosion-resistant.

24. The multiple-entry prefabricated external drop according to Claim 23, wherein the material for production thereof is plastic material.

25. The multiple-entry prefabricated external drop according to any of the Claims 16 to 24, wherein sealed and water-tight functioning is achieved when in operative association with a manhole and with at least one sewage pipe.

26. The multiple-entry prefabricated external drop according to Claim 16, wherein the length of the vertical portion of the discharge pipe is adjustable in situ.

27. The multiple-entry prefabricated external drop according to any of the Claims 16 to 26, wherein installation in situ is achieved in operative association with a manhole and with a sewage pipe.

28. The multiple-entry prefabricated external drop according to any of the Claims 16 to 27, wherein replacement in situ is achieved in operative association with a manhole and with a sewage pipe.

29. The multiple-entry prefabricated external drop according to any of the Claims 16 to 28, wherein the collector and the discharge pipe are made of at least two separate portions adapted for assembly in situ.

30. The multiple-entry prefabricated external drop according to any of the Claims 16 to 29, wherein the collector and the discharge pipe are made more than two separate portions adapted for assembly in situ. For the Applicants, Patent Attorney