Field of the Invention

The present invention relates to a drainage fitting for sealing a drain.

Background to the Invention

Floor drains are used across the world to allow quick and easy removal of waste water and debris from tiled or hard surfaced flooring after washing. They are commonly used in showers and in factories where sanitation is extremely important. Floor drains are connected by a pipe to a soil stack or similar sewer.

A positive pressure differential normally exists between the sewer and the surrounding environment, that is the pressure is higher in the sewer than it is in the surrounding environment. Such a situation allows for a flow of air and associated odours from the sewer into the environment surrounding the floor drain and inlet.

It is preferable to provide some form of trap between the floor drain inlet and the soil stack or sewer to prevent the ingress of these odours and also to prevent the ingress of creatures from the sewer into the environment surrounding the floor drain and inlet.

Where a trap is provided, the style of trap typically used is a liquid trap.

However, liquid traps can get blocked quite easily if larger objects are brushed into the drain. Floor drains generally have no form of flushing system and are reliant on buckets of water to keep them clean and in the event of blockage, and often require rodding. Additionally, liquid traps, especially in hot countries, can evaporate allowing the ingress of rodents and odours from the sewers into the environment surrounding the drain opening.

Furthermore, in many countries, drainage systems are not vented, and a negative pressure differential can exist, that is the pressure within the sewer is lower than the environmental pressure which applies a downstream pulling force to the liquid trap, with the result that liquid traps can be sucked downstream, removing the trap and exposing the environment to downhole odours and rodents.

Floor drains without traps do not block as easily but have little resistance to odours and rodents from the sewer below, the only protection for the surrounding environment being the provision of a cover, such as a grating.

Summary of the Invention

According to a first aspect of the present invention there is provided a drainage fitting, the drainage fitting comprising:

a housing adapted to be inserted into a drainage outlet, the housing defining a housing inlet and a housing outlet;

a one way valve adapted to be received within the housing, the one way valve having a body defining a valve inlet, a valve outlet and a valve

passageway, the passageway providing fluid communication between the housing inlet and the housing outlet; and

a fitting insert adapted to be located in the housing inlet, the fitting insert defining an insert portion adapted to extend through the valve inlet and into the valve passageway; wherein in the presence of a negative pressure differential air can pass through the valve to relieve the pressure differential, but in the event of a positive pressure differential, the insert portion prevents the one way valve from inverting to relieve the pressure differential.

In the context of this application, a negative pressure differential exists when the pressure in the sewer is less than the environmental pressure and a positive pressure differential exists when the pressure in the sewer is greater than the environmental pressure. The environmental pressure, in the context of this application is the pressure of the atmosphere at the drainage outlet.

It has been found that the presence of the insert portion prevents the one way valve from inverting even under the influence of a significant force applied by a positive pressure differential. Surprisingly, it has been found by utilising an insert of this type, simple rubber duck bill valves can be used to provide the one way valve, the duck bill valve providing a cheap and effective barrier.

In at least one aspect of the present invention, a drainage fitting is provided which has the provision of a one way valve to allow the flow of liquids and objects from the environment surrounding the drainage fitting inlet into the sewer below. The one way valve additionally allows air to be sucked into the sewage system in the event of negative pressure in the sewage system. The presence of the one way valve prevents, or at least reduces, odours coming from the sewer through the inlet and provides a barrier for preventing the influx of creatures from the sewer.

The housing may have an upper surface, a side wall and an end surface. The upper surface may define the housing inlet, the lower surface may define the housing outlet and the side wall may define a housing throughbore. The housing may be cylindrical.

The drainage fitting may further comprise a seal for sealing the housing into a drainage outlet.

In one embodiment, the housing side wall defines an external surface adapted to receive the seal.

The seal may be adapted to be releaseably attachable to a housing external surface.

The seal may be received within the housing.

The housing upper surface may define a recess adapted to receive the seal. Such an arrangement permits the seal to be engaged with the housing such that if a pull force is applied to the housing, the seal and the housing remain together.

The seal may form an interference fit with the housing.

Particularly, an internal seal surface may form an interference fit with a housing side wall external surface.

The seal may be elastomeric.

The seal may define external ribs adapted to engage a drain internal surface.

The fitting insert may be locatable in the housing inlet.

The fitting insert may be releaseably locatable in the housing inlet.

The fitting insert may be releaseably locatable by means of a push fit, twist fit, screw fit or threadable connection.

Particularly, the fitting insert may be locatable in the housing inlet by means of a bayonet fitting.

The fitting insert may define an upper surface. Once located within the housing inlet, the fitting insert upper surface may be co-planar with the housing upper surface.

The draining fitting may further comprise a drain cover.

One or other or both of the fitting insert upper surface and/or the housing upper surface may define lugs adapted to support the drain cover.

The fitting insert may be adapted to sandwich the one way valve with the housing.

The fitting insert may define a filter.

The filter may be a coarse filter.

The filter may extend across the fitting insert inlet.

The filter may define a grill.

The insert portion may downwardly depend from the grill. Such an arrangement reduces the visual impact of the insert portion.

The fitting insert may define a valve engaging surface.

The fitting insert valve engaging surface may extend down into the valve.

The fitting insert valve engaging surface may be vertically located in use. Such an arrangement may permit the valve to be lifted out of the housing by means of the fitting insert. Brief Description of the Drawings

An embodiment of the present invention will now be described with reference to the accompanying drawings in which:

Figure 1 is a perspective view of a drainage fitting according to an embodiment of the present invention;

Figure 2 is a section view through the drainage fitting of Figure 1 ; Figure 3 is a section view through the drainage fitting of Figure 1 shown in situ in a drainage outlet;

Figure 4 is a section view of the drainage fitting of Figure 1 shown in the drainage outlet of Figure 3 relieving pressure in a negative pressure differential situation; and

Figure 5 is a section view of the drainage fitting of Figure 1 shown in the drainage outlet of Figure 3 shown resisting a positive differential.

Detailed Description of the Drawings

Reference is first made to Figures 1 and 2, perspective and section views of a drainage fitting, generally indicated by reference numeral 10, according to an embodiment of the present invention.

The drainage fitting 10 comprises a housing 12 adapted to be inserted into a drainage outlet (shown and discussed in due course in connection with Figures 3 to 5). The housing 12 defines a housing inlet 14 and a housing outlet 16. The drainage fitting 10 further comprises a one way valve 18 adapted to be received within the housing 12, the one way valve 18 having a body 20 defining a valve inlet 22, a valve outlet 24 and a valve passageway 26.

The drainage fitting 10 further comprises a fitting insert 28 positioned within the housing inlet 14 and positively secured to the housing 12 by a bayonet connection 19. Once secured, a one way valve flange 21 is trapped between the fitting insert 28 and the housing 12, securing the one way valve 18 in the drainage fitting 10.

The housing 2 is cylindrical, having a wall 40 with an internal surface 42 and an external surface 46 for receiving and engaging with a drainage fitting seal 48. The housing wall 40 further defines an upper surface 50 and a lower surface 52, the upper surface 50 defining the housing inlet 14 and the lower surface 52 defining the housing outlet 16.

The housing 12 further defines a radially extending lip 54, the lip 54 defining a profile 59 which is complementary to a seal recess 56. When the drainage fitting 10 is assembled, the housing upper surface 50, the seal upper surface 58 and a fitting insert upper surface 29 are substantially coplanar.

The housing upper surface 50 further defines a plurality of castellations 62 adapted to support a portion of a drain cover (not shown). A drain cover can be provided to provide an aesthetic appearance to the floor drain.

Extending radially from a seal wall 90 are a seal lip 92 and four parallel seal fins 94. The purpose of the seal lip 92 and the fins 94 will be discussed in due course.

The one way valve 18 is a rubber duck bill valve. This is an effective device for allowing the flow of fluids through the drainage fitting 10 into a sewer (not shown). Valves 18 of this sort are robust and reliable but are prone to inversion in the presence of a pressure differential acting against the normal flow of fluid through the valve 18.

This deficiency is remedied by the fitting insert 28. The fitting insert 28 sits within the housing inlet 14 and defines a grill 60 to prevent large objects from entering into the one way valve 18. The fitting insert 28 defines a downwardly depending insert portion 30 adapted to extend from the grill 60, through the valve inlet 22 and into the centre of the valve passageway 26.

Reference is now made to Figures 3, 4 and 5. Figure 3 is a section view through the drainage fitting 10 of Figure 1 shown in situ in a drainage outlet 70, Figure 4 is a section view of the drainage fitting 10 shown relieving pressure in a negative pressure differential situation and Figure 5 is a section view of the drainage fitting 10 shown resisting a positive differential.

The drainage outlet 70 is an opening 72 defined by a floor 74. The drainage outlet 70 provides a route to remove waste water, for example, from a shower room 76 to a sewer 78. In many countries, these outlets 70 are covered by a simple grill which provides an ineffective barrier to odours and rodents wishing to enter the shower room 76 from the sewer 78. The problem can be particularly exacerbated if the drainage outlet 70 does not include water barrier, for example between the shower room 76 and the sewer 78.

Installation of the drainage fitting 0 is achieved by simply pressing the fitting 10 into the drainage outlet 70. The seal lip 92 is pressed into contact with the floor 74 and, as can be seen, the fins 94 deform to form a contact seal with an outlet wall 80. The combination of the seal lip 92 and the fins 94 provide an effective five point of contact seal between the outlet fitting 0 and the drainage outlet 70.

As the fitting insert 28 is attached to the fitting housing 14 by means of a bayonet connection 19, removal of the fitting insert 28 and consequently the oneway valve 18 can be achieved from above, without needing to remove the drainage fitting 10 from the drainage outlet 70. Such an arrangement facilitates cleaning of the fitting 10 and replacement of the one-way valve 18.

Referring to Figure 4, the drainage fitting 10 is constructed such that in the presence of a negative pressure differential, that is pressure below the drainage fitting 10 (that is in the sewer 78) is lower than pressure above the drainage fitting 10 (that is in the shower room 76), air can pass through the one way valve passageway 26 to relieve the pressure differential and equalise the pressure across the drainage fitting 10. In this situation, there is no contact between the downwardly depending portion 30 of the fitting insert and the one way valve 18.

However, referring to Figure 5, there is a positive pressure differential, that is the pressure below the drainage fitting 10 (that is in the sewer 78) is greater than pressure above the drainage fitting 10 (that is in the shower room 76), the insert portion 30 which extends into the valve passageway 26 prevents the one way valve 8 from inverting. This prevents the pressure being relieved and prevents odours being omitted from below the housing outlet into the

environment above the housing inlet.

Various modifications and improvements may be made to the above described embodiment without departing from the scope of the present invention. For example although the drainage fitting described is a floor drain, the principle of using the downwardly depending portion to prevent inversion of a one way valve may be used in other drainage fittings such as in sinks or tubs.