GB2274856A - Drainage fitting - Google Patents

Abstract

A drainage fitting 10, for example a roof drain designed to be installed over an existing fitting 20a - d, includes a wall 16 in which there is provided a duct 32 through which filler material may be injected to occupy the space 24 behind the fitting 10, e.g. to provide insulation. The upper end of the duct 32 is closed by a self-tapping screw 38, bolt or plastics cap. Alternatively, the duct upper end 36 may be located so as to be covered by later installed roofing material. <IMAGE>

Description

DRAINS This invention relates to drainage fittings for incorporation into buildings, roads, paved areas or the like and particularly, although not exclusively, to fittings known as roof outlets for the drainage of flat roofs and roof gullies.

With the increased emphasis on energy conservation in recent times there is a need to insulate roof outlets and drainage fittings in similar situations to reduce heat loss from buildings. Particularly when the roof outlet or other fitting is a replacement item installed during refurbishment of a building, it is often difficult to gain access to the region below the fitting during installation to provide the necessary insulation.

The insulation must be a snug fit with the installed drain fitting but hitherto the fitting could often only be finally fixed in place after installation and any necessary trimming of the insulation. During the refurbishment of drain fittings there is also a need to leave existing insulation as undisturbed as possible, cutting out and replacing only sufficient insulation as allows access for installation of the refurbishment fitting.

Similar problems arise in other cases where it is necessary to bed a drain fitting closely into material filling a pre-existing cavity, for example to provide a water seal, or for mechanical support.

In accordance with a first aspect of the invention we have sought to mitigate these problems by providing a drain fitting having one or more ducts for the passage of filler material wherein, with the drain fitting in its installed position, a first end of the or each duct is accessible for supply of the filler material and a second end of the or each duct terminates at a location otherwise substantially obscured by the installed drain body.

The first end of the duct is preferably shaped to cooperate with an injection tool for the filler material, for example an injection nozzle for polyurethane foam insulation material.

The filler material may seal or assist in sealing the duct, but preferably a sealing plug is also provided. The plug may take the form of a screw or bolt threaded into the duct. Alternatively a press-fit plug may be provided, preferably captive with the drain body. The first end of the duct may terminate in a raised boss which is not submerged in normal use of the drain. Alternatively, the first end of the duct may terminate at a location coverable by an overlying flashing, membrane or other impermeable covering following installation of the drain fitting.

When installing refurbishment drain fittings it is highly desirable to be able to leave the existing fitting in place, as this reduces labour and material costs as well as disturbance to the building or other surrounding structure.

Refurbishment roof outlets are known, having a spigot designed to nest within and make a sealed connection with an existing outlet soil pipe; the spigot having a radial flange at its upper end for sealing against the new roof covering.

Such a refurbishment roof outlet can be installed without removing the existing outlet, but will restrict its flow capacity. Where there is little spare capacity in the original outlet this can lead to "ponding, water penetration and overloading of the roof structure.

It is known to increase the flow capacity of a roof outlet by providing a widened sump above the spigot, in which a head of water can accumulate. For optimum hydraulic efficiency, the sump should be deep, with relatively steep side walls. Such a design is incompatible with the space requirements of a refurbishment roof outlet, in which headroom is limited, particularly when the insulation layer on the refurbished roof is thin or absent. Additional difficulties are encountered where a single sump design is used with a range of spigot sizes, as is desirable to minimise production costs. Hitherto, therefore, sumps have not been employed in refurbishment roof outlets.

We have discovered that it is possible to design a refurbishment drainage fitting incorporating a sump to increase hydraulic efficiency which can be installed within an existing drainage fitting without compromising its flow capacity.

Accordingly, a second aspect of the invention provides a refurbishment drainage fitting having a spigot for connection to the soil pipe of an existing drainage fitting, a radial flange for sealing against a building or other surrounding structure, and a sump of dished form extending between the flange and the spigot. The design of most old roof drains (e.g. of the cast iron type for use with asphalt roof coverings) is hydraulically inefficient so that insertion of the roof drain of the invention will not reduce flow capacity. The dished sump of the present invention will tend to create a head of water and decrease the flow resistance of the fitting in use whereby a high flow rate can be achieved, but the sump need not be so deep as to make the refurbishment fitting exceed the space envelope dictated by an existing drain.

Conveniently, the included angle between the spigot centreline and a straight line between the junction of the flange and the sump and the junction of the sump and the spigot is between 45 and 80 , more preferably between 60 and 75". In a preferred embodiment the sump is frusto-conical in form.

The transition between the sump and spigot should preferably be smoothly curved conveniently of not less than lOmm radius at the internal surface, a radius of not less than 15mm being preferred.

These and other preferred features of the invention will be apparent from the following description made by way of example and with reference to the drawing, wherein: Figure 1 is a cross-sectional view of an embodiment of a drain fitting according to the invention; Figure 2 is a cross-sectional view of a second embodiment; Figure 3 is a cross-sectional view of a third embodiment; Figure 4 is a broken away cross-sectional view of the duct and plug of a fourth embodiment of a drain fitting according to the invention; and Figure 5 is a perspective view of a sealing cap in the embodiment of Figure 4.

Figure 1 shows a refurbishment roof outlet body 10 having a flange 12 for securing by screws 15 to a flat roof structure 14, a shallow frusto-conical sump or water collecting portion 16, and a depending spigot 18 for conveying collected water through the end 20a of an existing soil pipe 22. The included angle a between the sump surface and the spigot centreline is 700 as shown. The body 10 may be of die cast aluminium alloy LM6.

The frusto-conical portion 16 and spigot 18 depend within a cavity 24 formed in the building structure for passage of the soil pipe 22. Any previously existing roof outlet and surrounding insulation or other material 26 can be removed to permit installation of the outlet body 10.

However, where possible it is preferable to install the refurbishment roof outlet without removing the existing outlet, thereby minimising disturbance to the building structure. The spigot 18 may be cut to length with a hacksaw.

A seal (not shown, which may be as disclosed in our copending patent application entitled "Pipe Seal") is installed between the spigot 18 and the pipe 22 to prevent penetration of water into the building structure should water back up beyond the existing roof drain rim 20a. The seal will also prevent the ingress of insulation or other filler material into the pipe 22, during the subsequent installation procedure described below.

As shown, the existing roof drain is of the cast-iron type having a luting flange 20b for installation in an asphalt roof covering. The drain rim 20a originally accommodates a grating (not shown) and leads to a short cylindrical section 20c and a steep frusto-conical section 20d. This arrangement in the absence of the refurbishment outlet is hydraulically inefficient.

Once the flange 12 is secured to the roof structure 14, roofing felt, asphalt or the like (not shown) may be applied to the roof and dressed into the frusto-conical portion 16 so as to cover circumferential bitumen grooves 17. When the body 10 is used with single ply membranes, an 0-ring (not shown) may be placed in groove 28. The edge of the membrane is then secured to portion 16 in known manner by a clamping ring (not shown) bolted to bosses 30 and studs 45. To complete the installation a grating may be provided, spanning portion 16, as is conventional.

The installed outlet body 12 obscures access to the cavity 24. To permit the space between the old and new outlets to be filled with for example polyurethane foam insulating material, sealant or grout (hereafter "foam"), a duct 32 is provided, extending between an inner, water collecting surface 34 of the outlet body 10 and the cavity 24. The end of the duct 32 remote from the cavity 24 is counterbored at 36 for snug reception of a nozzle for injection of the foam. The foam may be supplied from an aerosol, for example "Soudafoam IK", manufactured by NV Soudal SA, Everdongenlaan 18-20, B-2300 Turnhout, Belgium.

The foam will tend to seal the duct 32 when set but additional sealing is provided by a self-tapping screw 38 (e.g. a GKN "TAPTITE" (RTM) screw) threaded into the duct 32 beyond the base of the counterbore 36, following injection of the foam. A self-tapping screw will clear the foam material from the duct 32 as it is screwed home. Being a standard component, it is readily replaced if lost. A sealing washer 40 is provided between the screw head and the base of the counterbore 36.

To allow penetration of the foam fully into cavity 24, a sufficient clearance must be left between the existing outlet rim 20a and the refurbishment outlet body 10. The foam will also penetrate between the spigot 18 and the surrounding pipe 22, providing a further seal between these components.

In the alternative embodiment of Figure 2, the duct 32 terminates in a boss 42 raised above the water collecting surface 34 so that it is not submerged under normal conditions. The counterbore 36 is sealed by a self-tapping bolt 44, e.g. a "SPEDEC" (RTM) stainless steel bolt, type TZ-BS, threaded into duct 32, with a seal washer assembly 46, e.g. a WRS aluminium bonded washer type T16, placed between the bolt head and the top of the boss 42. Preferably the bolt 44 is held captive by an elastomer retaining strap 43 attached for example to the clamping ring securing stud 45.

Figure 3 shows a further alternative embodiment in which the counterbore 36 opens into the flange 12 where it will be covered and sealed by the impermeable membrane, roofing felt, asphalt or the like. The duct 32 runs through a radial rib 48 formed on the undersurface of the frusto-conical portion 16. The end of the duct 32 opposite to the counterbore 36 terminates close to the spigot 18 for injection of foam between the spigot 18 and the pipe end or existing outlet (not shown).

Figure 4 shows in fragmentary section an embodiment similar to Figure 2, but in which the bolt 44 and washer assembly 46 are replaced by a plug in the form of a soft plastics or rubber sealing cap 50. The mouth of the counterbore 36 is lipped at 52 to retain a grooved body portion 54 of the cap 50. Alternatively the cap may be bonded, screwed, press-fitted or otherwise retained in the counterbore 36.

The cap also comprises a stopper 56 attached to the body portion 54 by a flexible web 58 and pressed into a bore 60 within the body portion 54 to close the duct 32, a stopper lip 62 snap-fitting into a groove 64 within the bore 60.

This also serves to retain the cap 50 more securely within the counterbore 36. Advantageously, the cap when open acts as a seal for the foam injection nozzle, which is a tight fit within the bore 60. The stopper 56 is held captive by the web 58 and so cannot be lost. Other forms of sealing cap will be apparent.

The transition between the sump 16 and the spigot 18 is smoothly curved. For a spigot of 60mm bore a radius of 15mm at the internal surface gives good performance, whereas with a spigot of 85mm a radius of 22mm is preferred.

The flow performance of the refurbishment outlets installed in an existing cast iron outlet as shown in the drawings is superior to many prior designs, including that of the illustrated cast iron outlet as originally installed.

Comparative figures are tabulated below.

Flow Rates (l/s) Pipe Size Standard Outlet Refurbishment Outlet [as available from the Applicants] 75 mm 3.9 4.2 100 mm 6.1 8.2 Although in the drawings only a single duct is shown, more than one (for example three, or preferably two) ducts may be distributed about the outlet body inner surface.

Although only a frusto-conical sump is shown, other forms will be apparent which in use can produce the required head of water, thereby enhancing hydraulic efficiency.

Claims (8)

CLAIMS:

1. A drain fitting having one or more ducts for the passage of filler material wherein, with the drain fitting in its installed position, a first end of the or each duct is accessible for supply of the filler material and a second end of the or each duct terminates at a location otherwise substantially obscured by the installed drain body.

2. A drain fitting as claimed in claim 1 wherein the first end of the duct is shaped to co-operate with an injection tool for the filler material.

3. A drain fitting as claimed in claim 1 or claim 2 wherein the duct is sealed by a sealing plug after passage of the filler material.

4. A drain fitting as claimed in claim 3 wherein the plug comprises a screw or bolt threaded into the duct.

5. A drain fitting as claimed in claim 3 wherein the plug is a press-fit.

6. A drain fitting as claimed in any of claims 3-5 wherein the plug is captive with the drain fitting.

7. A drain fitting as claimed in any preceding claim wherein the first end of the duct terminates in a raised boss which is not submerged in normal use of the drain.

8. A drain fitting as claimed in claim 1 or 2 wherein the end of the duct adjoining the surface directed face terminates at a location covered by a flashing, membrane or other impermeable covering following installation of the drain fitting.

8. A drain fitting as claimed in claim 1 or 2 wherein the first end of the duct terminates at a location coverable by an overlying flashing, membrane or other impermeable covering following installation of the drain fitting.

9. A refurbishment drainage fitting having a spigot for connection to the soil pipe of an existing drainage fitting, a radial flange for sealing against a building or other surrounding structure, and a sump of dished form extending between the flange and the spigot.

10. A drainage fitting as claimed in claim 9 wherein the included angle between the spigot centreline and a line passing through the junction of the flange and the sump and the junction of the sump and the spigot is between 45 and 80".

11. A drainage fitting as claimed in claim 10 wherein the included angle is between 60 and 750 12. A drainage fitting as claimed in any of claims 9-11 wherein the transition between the sump and the spigot is smoothly curved with a radius of not less than l0mm at the internal surface.

13. A drainage fitting as claimed in claim 12 wherein the radius of the transition at the internal surface is not less than 15mm.

14. A drainage fitting as claimed in claim 10 or 11 wherein the sump is of frusto-conical form.

15. A drain fitting substantially as described or as shown with reference to the drawings.

Amendments to the claims have been filed as follows 1. A drain fitting for installation in a surface to be drained, comprising a wall which, when the fitting is so installed, has a face directed towards the surface and an opposite face directed away from the surface, wherein there is provided a duct interconnecting the surface directed face and the opposite face for the passage of filler material through the wall.

2. A drain fitting as claimed in claim 1 wherein the end of the duct adjoining the surface directed face is shaped to cooperate with an injection tool for the filler material.

7. A drain fitting as claimed in any preceding claim wherein an end of the duct terminates in a boss raised above the surface directed face so that said end is not submerged in normal use of the drain.