Technical Field of the Invention

The present invention relates to a drain valve. In particular, the present invention relates to a drain valve for preventing unpleasant odours and pests from entering an area in which the drain valve is located.

Background to the Invention

A drain can be considered as a conduit for unwanted or waste liquids to be flumed away. For example, in domestic establishments a drain is typically used to flume away waste water.

A drain system typically includes drain pipes arranged in fluid communication with a drain opening, e.g. a plughole, which provides a point of entry to an open space, e.g. a kitchen. Typically, a trap is provided between the drain opening and the drain pipes. It is known that unpleasant odours can emanate from drain valves, in one example when food is flushed down a plughole and decomposes in the trap. It is also known that drain systems can constitute an unwanted source of insects, spiders and other pests, which may crawl through the drain pipes and exit the opening into the open space. This can provide significant discomfort to nearby persons and can be unhygienic.

Various drain valves have been devised to prevent the emanation of unpleasant odours and/or entry of pests through drain openings. For example, AU2010202777 discloses an apparatus for preventing gases inside a drain from exiting the drain opening. The apparatus comprises a one-way valve element having two substantially opposed and abutting surfaces of elastomeric material.

A problem with known drain valves is that they can cause inconsistent fluid flow through the drain system, or even blockage of thereof. For example, this can occur because the drain valve requires a threshold pressure to open and/or the shape of the drain valve, even in a fully open position, provides a significant restriction to fluid flow. Thus, there is a need for a drain valve that can facilitate more consistent fluid flow. Another problem with known drain valves is that they can be ineffective and/or inefficient in preventing pests from exiting the drain opening. For example, this can occur because the drain valve does not return to a fully closed position, such that pests can simply crawl through the drain valve. Thus, there is a need for a drain valve that more effectively prevents pests from exiting the drain system through the drain opening.

Yet another problem with known drain valves is that its installation and/or removal can be difficult and/or inconvenient. For example, this can occur because the drain valve requires a significant amount of space and/or specific pipe fittings and/or securing means to secure the drain valve in place. Thus, there is a need for a drain valve that can be more easily and/or conveniently installed and removed.

It is an objection of the present invention to at least partially overcome or alleviate one or more of the abovementioned or other problems.

Summary of the Invention

According to a first aspect of the present invention, there is provided a drain valve adapted to be releasably retained in a pipe, the drain valve comprising: a valve seat; and a valve body, the valve seat and the valve body defining a non-return valve, wherein the valve body is at least partially deformable under fluid pressure in a forward flow direction from a closed position in which at least an end of the valve body is in contact with the valve seat to an open position spaced apart from the valve seat, and wherein the valve body is at least partially deformable under fluid pressure in a reverse flow direction from the open position to the closed position, wherein the valve seat and the valve body have correspondingly curved profiles and the valve body is provided with a bias patch.

The drain valve enables optimised fluid flow through the non-return valve in a forward direction and prevents fluid flow (e.g. unpleasant odours) and/or movement of pests in a reverse direction. The curved profiles enable the non-return valve to be arranged, in use, to correspond with the inner surface of a typical curved pipe (e.g. at the bottom of such a horizontally arranged pipe, where a liquid starts to build-up). In this way, the non-return valve can deform into the open position from exposure to only small volumes of liquid, which facilitates consistent fluid flow without fluid build-up. Furthermore, the curved profiles provide an inherent bias of the non-retum valve towards the closed position, which results in a reliable closed position, such that fluids and/or pests are reliably prevented from moving through the drain valve in the reverse direction. The curved profiles also enable the non-return valve to widely open in the open position, which facilitates consistent fluid flow such that the drain valve is compatible with a high rate of fluid flow. Moreover, in-use, hydrostatic pressure of any fluid flowing in a reverse direction acts as a closing force on the non-return valve. This effectively prevents fluids and/or pests from moving through the non-retum valve in the reverse direction.

Embodiments of the present invention also have the advantage of the bias patch acting to provide additional bias against excessive movement of the valve body to the open position. This helps prevent the excessive opening of the valve and avoid the valve body being moved so far as to become stuck in the open position. The bias patch additionally helps apply a biasing force to close the valve in the absence of fluid pressure in the forward direction.

The valve body may be thinner than the valve seat. The opening and closing of the valve is further facilitated by the valve body being thinner than the valve seat. This allows the valve body to respond more readily to flow pressure in either direction, as required.

The drain valve may comprise opposing ends wherein the non-retum valve is located at one of the ends. In the closed position, one end of the valve seat may be in contact with the corresponding end of the valve body.

Each of the valve seat and the valve body may have an arcuate profile. Each of the valve seat and the valve body may have a substantially semi-circular profile.

The valve seat may curve in a plane perpendicular to a longitudinal axis between opposing ends of the drain valve.

The valve body may curve in a plane parallel and/or perpendicular to an axis between opposing ends of the drain valve. The valve body may curve in a plane parallel and/or perpendicular to the longitudinal axis of the drain valve. The valve body and valve seat may move between the open and closed positions in a direction transverse to the longitudinal axis. Such an opening direction may be substantially perpendicular to a tangent of the apex of the arcuate profile of the valve body and/or valve seat. The opening direction may define an opening axis perpendicular to the longitudinal axis. An apex edge and a distal edge may be defined at opposing ends of the transverse opening axis of the drain valve, the apex edge being located where the apex of the valve body and valve seat are provided. Side edges of the drain valve may be defined at opposing ends of a side axis mutually perpendicular to the opening axis and the longitudinal axis.

Advantageously, the curvature of the valve seat and the valve body can help to provide an inherent structural bias towards the closed position.

The valve body and the valve seat may be connected together by a living hinge at either edge. The living hinge may curve in a plane parallel and/or perpendicular to a longitudinal axis of the drain valve. Advantageously, the curvature of the living hinge connecting the valve seat and the valve body can help to provide an inherent structural bias towards the closed position.

The bias patch may be provided toward an end of the valve body away from the end that contacts the valve seat. The bias patch may be provided at a point closer to the distal edge of the drain valve than to the apex edge of the valve seat. This positioning of the bias patch thus ensures it has minimal effect on the fluid flow through the drain valve during normal operating conditions.

The bias patch may be provided at the midpoint between the longitudinal axis and the distal edge of the drain valve. The bias patch may span at least a third of the distance between the longitudinal axis and the distal edge of the drain valve. Thus, the bias patch is most effective as the section of the valve body containing the bias patch only flexes during very high flow conditions.

The bias patch may be located on opening axis. In a preferred embodiment, the bias patch is symmetrical about the opening axis. The bias patch may span at least half the distance between the opening axis and the respective side edges. Thus, providing a bias patch that spans at least half the valve body ensures excessive, or permanent, opening of the valve body is prevented.

The bias patch may be elliptically shaped. The major axis of the ellipse may be parallel to the side axis. The bias patch’s height and width may be defined by its size parallel to the first and second transverse axes respectively. Having the major axis parallel to the side axis allows the bias patch to permit a greater flow of fluid through the valve while still preventing excessive, or permanent, opening of the valve body.

The bias patch may comprise a relatively rigid area or structure formed on the valve body. In some embodiments, this may comprise a thicker area of the valve body. In other embodiments, the bias patch may comprise a relatively rigid material bonded to the valve body. The bias patch may be at least as thick as the valve body. The bias patch may be the same thickness as the valve body. The bias patch may be formed in, or bonded to, the inner or outer surface of the valve body. The bias patch may be formed centrally within the valve body. The region of the valve body containing the bias patch may be at least twice as thick as the rest of the valve body. When bonded on the outer surface of the valve body, bias patch is less likely to interfere with fluid flow through the drain valve.

The thickness of the bias patch may vary. The bias patch may comprise a decorative surface moulding.

As described above, the many different types of bias patch could be designed to suit the needs of the drain valve and provide additional resistance to excessive opening of the valve thereby preventing the valve becoming stuck in the open position.

In the open position and/or the closed position each of the valve seat and the valve body may have a curved profile. In the open position and/or the closed position each of the valve seat and the valve body may have an arcuate profile. In the open position and/or the closed position each of the valve seat and the valve body may have a substantially semi-circular profile.

In the open position the valve seat and the valve body may define an opening of the form of two opposing, back-to-back segments of an ellipse. In the open position the valve seat and the valve body may define a substantially elliptical opening. In the open position the valve seat and the valve body may define a substantially circular opening.

As a person skilled in the art will appreciate, the valve seat and the valve body are closed on each other in the closed position, and are spaced apart from each other in the open position.

In use, where the valve body is arranged to oppose the valve seat, fluid flow through the drain valve is consistent because the non-return valve can open widely (e.g. such that the valve seat and the valve body can correspond to a large fraction of the cross-sectional area of a pipe) and thus handle a high rate of fluid flow.

The valve may comprise a retention rib. The retention rib may be provided at an end of the drain valve opposite to the end of the drain valve comprising the non return valve. The retention rib may comprise a relatively rigid area or structure formed around the exterior of the valve. In some embodiments, the retention rib can be a relatively thick region or may comprise a relatively rigid material bonded to the valve. The retention rib helps the drain valve to retain the desired shape and helps retain the drain vale in position when fitted to a pipe or a check valve fitting.

As discussed herein, the valve is adapted to be releasably retained in a pipe. In this way, the valve be installed in a pipe without fastening means and without modifying the construction of the pipe. The valve be adapted to be resiliently and releasably retained in a pipe. The valve may be in the form of a pipe insert.

The valve may comprise a head. The head may be provided at an end of the drain valve opposite to the end of the drain valve comprising the non-return valve. The head may be adapted to be releasably retained in a pipe. The head may be adapted to be resiliently and releasably retained in a pipe. The head may be releasably connectable to, e.g. releasably mountable on, a fitting. The fitting may be an inline check valve fitting.

The drain valve may have a cross section of any particular shape. For example, the drain valve may have a substantially elliptical, e.g. circular, cross section.

The drain valve may be formed of a resiliently flexible material. Use of a resiliently flexible material facilitates quick and straightforward installation. In particular, in use, the drain valve can be installed in a pipe by compressing the head and inserting the drain valve into the desired location in a pipe and then releasing the head to releasably retain the drain valve in the pipe.

The resiliently flexible material may comprise any suitable materials as are known to a person skilled in the art. The resiliently flexible material may comprise polymeric material. The polymeric material may comprise elastomeric material. For example, the elastomeric material may comprise rubber, e.g. natural or synthetic rubber. Rubber is cheap, durable and readily available. The drain valve may be formed by injection moulding, e.g. of injection moulded rubber.

The valve body may comprise an inner surface and an outer surface. In the closed position the inner surface may be convex and the outer surface may be concave. In the open position the inner surface may be concave and the outer surface may be convex.

Herein,‘inner surface’ means the surface of the valve body proximal to fluid flow (in use).

Herein,‘outer surface’ means the surface of the valve body distal to fluid flow (in use).

The material forming the valve body may be thinner than the material forming the valve seat. In this way, the valve body is easily movable relative to the valve seat and is thus responsive to changes in fluid flow.

The drain valve may comprise sealing means.

The sealing means may comprise a sealing fin. The sealing means may be arranged, in use, to secure the drain valve in a predetermined position in a pipe. The sealing fin may be provided on the head, e.g. at an end of the drain valve opposite from an end of the drain valve comprising the non-retum valve. The sealing fin may be formed of an annular ring.

In use, e.g. when the drain valve is used as an in-line check-valve, the sealing fin functions as a pipe stop and can prevent the drain valve from becoming dislodged and moving further into the pipe under fluid flow. The sealing fin may be formed of a flexible material. Any suitable flexible materials may be used as are known by a person skilled in the art. The flexible material may be resiliently deformable. The flexible material may comprise polymeric material, e.g. elastomeric material. For example, the elastomeric material may comprise rubber (e.g. natural or synthetic rubber).

The sealing means may comprise at least one sealing protrusion. The sealing means may comprise a plurality of protrusions. The or each sealing protrusion may be arranged, in use, to provide a seal between the drain valve and a pipe. The or each sealing protrusion may be provided on the head, e.g. on an outer surface of the head. Where there is a plurality of sealing protrusions, the sealing protrusions may be spaced apart from each other. The or each sealing protrusion may be provided between the non-return valve and the sealing fin. The or each sealing protrusion may be in the form of a ridge or rib.

In use, the or each sealing protrusion flexes when in contact with an inner surface of a pipe, thereby creating the required seal. Thus, inadvertent fluid flow around the drain valve, rather than through the non-return valve as intended, can be avoided.

Where the drain valve comprises a plurality of sealing protrusions, the height of each sealing protrusion may increase as its distance from the non-return valve increases. In other words, the sealing protrusions closer to the non-return valve are smaller in height than the sealing protrusions further from the non-return valve. This arrangement facilitates ease of installation of the drain valve in a pipe and enables effective sealing engagement of each sealing protrusion with the pipe.

The or each sealing protrusion may be obliquely angled away from the non return valve with respect to an axis between opposing ends of the drain valve. The or each sealing protrusion may be obliquely angled away from the non-return valve with respect to a longitudinal axis of the drain valve. This arrangement further facilitates ease of installation of the drain valve in a pipe and effective sealing engagement of each sealing protrusion with the pipe.

The or each sealing protrusion may be formed of a flexible material. Any suitable flexible material may be used and those will be known by a person skilled in the art. The flexible material may be resiliently deformable. The flexible material may comprise polymeric material, e.g. elastomeric material. For example, the elastomeric material may comprise rubber (e.g. natural or synthetic rubber).

The drain valve may be monolithically formed. Herein,‘monolithically formed’ means formed as a single, integral, unit. This allows the drain valve to be quickly, simply and conveniently manufactured. Moreover, a monolithically formed drain valve can be more robust and reliable relative to drain valves having a plurality of distinct components.

According to another aspect of the present invention there is provided a kit of parts comprising the drain valve according to the first aspect of the present invention and a check valve fitting.

The check valve fitting may comprise a primary insert portion and a secondary insert portion. The check valve fitting may comprise an annular rim provided between the primary insert portion and the secondary insert portion. The annular rim may function to separate the insert portions from each other.

According to another aspect of the present invention there is provided a check valve comprising a drain valve according to the first aspect releasably connected to a check valve fitting.

The drain valve may be releasably connected to the primary insert portion and/or the secondary insert portion by way of a push-fit connection.

Detailed Description of the Invention

In order that the invention may be more clearly understood one or more embodiments thereof will now be described, by way of example only, with reference to the accompanying drawings, in which:

Figure 1 shows a side-on perspective view of a drain valve according to a first embodiment of the invention wherein the non-return valve is arranged in the closed position;

Figure 2 shows the drain valve according to Figure 1 wherein the non-retum valve is arranged in the open position; Figure 3 a shows a close-up view of a sealing fin and sealing ridges of the drain valve according to Figure 1 ;

Figure 3b shows a close-up view of the contact ends of the valve seat and valve body of the drain valve according to Figure 1

Figure 4 shows the drain valve according to Figure 1 installed in a pipe;

Figure 5 shows the drain valve according to Figure 2 installed in a pipe;

Figure 6 shows an end-on view of the drain valve according to Figure 1.

Figure 7 shows a side layered view of the drain valve according to Figure 1; Figure 8 shows the drain valve according to Figure 1 being releasably connected to a check valve fitting to thus form a check valve.

Figure 9 shows a perspective view of a check valve formed of the drain valve according to Figure 1 and a check valve fitting, wherein a portion of the check valve is being connected to a pipe; and

Figure 10 shows a side-on layered view of the check valve according to Figure 8 installed in a pipe.

With reference to Figs. 1 to 7, a drain valve 1 adapted to be releasably retained in a pipe 100, comprises a valve seat 2, a valve body 3 and a head 4. The valve seat 2 and the valve body 3 define a non-retum valve 5. The drain valve 1 comprises opposing edges 1A, IB and opposing ends 1C, ID. The head is located at end 1C and the non- return valve 4 is located at end ID. The valve seat 2 and the valve body 3 have correspondingly substantially semi-circular profiles. The head 4 is adapted to be releasably mountable on a check valve fitting.

The valve seat 2 curves in a plane perpendicular to an axis between the opposing ends 1C, ID. The valve body 3 curves in a plane perpendicular to the longitudinal axis of the drain valve 1 (i.e. perpendicular to an axis between the opposing ends 1C, ID) and in a plane parallel to the longitudinal axis of the drain valve 1 (i.e. parallel to an axis between the opposing ends 1C, ID). The valve body 3 and valve seat 2 are connected together at the edges 1A, IB by living hinges 9. As is shown in figure 1, the living hinges 9 are curved. This arrangement provides an inherent structural bias of the non-return valve 5 towards a closed position (as discussed below in more detail).

A sealing fin 6 is provided on the head 4 at the end 1C. The sealing fin 6 has a substantially annular form (see Fig. 3). The sealing fin 6 functions as a pipe stop when the drain valve 1 is used in a check valve fitting 20 as discussed in relation to figures 5 to 8 below.

An outer circumferential surface of the head 4 is provided with a plurality of sealing ridges 7 which are arranged spaced apart from each other (see Fig. 3a). In use, the ridges 7 form a seal between the drain valve 1 (i.e. the outer circumferential surface of the head 9) and the pipe 100 (i.e. the inner surface of the pipe 100), so that fluid cannot flow between the drain valve 1 and the pipe 100 (see Fig. 4). The ridges 7 increase in height as the distance from the non-return valve 5 increases, so that the ridges 7 closer to the non-return valve 5 are of a greater height than the ridges 7 further from the non-return valve 5 (not illustrated). This facilitates ease of installation of the drain valve 1 in a pipe and provides for an effective sealing arrangement. Each ridge 7 is obliquely angled away from the non-return valve 5 with respect to the longitudinal axis of the drain valve 1. This further facilitates ease of installation of the drain valve 1 and further enhances the sealing arrangement. Each ridge 5 is smaller in height than the sealing fin 6.

The head 4 is further provided with a retention rib 10. The retention rib 10 is a relatively rigid structure that extends around the circumference of the head 4. The retention rib helps both retain the shape of the valve 1 and can help seal the valve when installed in a pipe 100.

To install the drain valve 1 in a pipe 100, the drain valve 1 can be compressed, e.g. by hand or using a tool, and then inserted into a desired position within the pipe 100, and then released so that the drain valve returns to its normal form. In this way, the outer surface of the drain valve 1 radially, outwardly, grips an inner surface of the pipe 100 so as to releasably retain the drain valve 1 in the pipe 100 (see Fig. 4). The drain valve 1 can be removed from the pipe 100 by following the reverse process. That is, the drain valve 1 can be compressed, e.g. by hand or using a tool, so that an outer surface of the drain valve 1 is spaced from an inner surface of the pipe, and then withdrawn from the pipe 100.

In use, the non-return valve 5 is deformable from a closed position in which fluid is not permitted to flow through the non-return valve 5 to an open position in which fluid is permitted to flow through the non-return valve 5. Specifically, in the closed position an end 3D of the valve body 3 is in contact with an end 2D of the valve seat 2. In the closed position, an inner surface 3A of the valve body 3 defines a concave surface and an outer surface 3B of the valve body 3 defines a convex surface. In the closed position, each of the valve seat 2 and the valve body 3 has a substantially semi circular profile.

When fluid flows through the non-retum valve 5 in a forward direction the valve body 3 deforms away from the valve seat 2 into the open position. On deforming from the closed position to the open position where the valve body 3 is at its maximum extension, the valve body 3 undergoes inversion and resultantly opposes the valve seat 2. In the open position where the valve body 3 is at its maximum extension, each of the valve seat 2 and the valve body 3 has a substantially semi-circular profile. Thus, in the open position where the valve body 3 is at maximum extension, the valve seat 2 and the valve body 3 form opposing semi-circles and thus a substantially circular opening, which traces the inner circumferential surface of the pipe 100. In other words, in the open position where the valve body 3 is at maximum extension, the inverted valve body 3 corresponds with a secondary, semi-circular, inner surface of the pipe 100 (see Fig. 2).

In the open position where the valve body 3 is at maximum extension, the inner surface 3A of the valve body 3 defines a concave surface and the outer surface 3B of the valve body 3 defines a convex surface. As a person skilled in the art will appreciate, the inner surface 3A and the outer surface 3B of the valve body 3 can transition through various different configurations on deforming from the closed position to the open position at maximum extension.

When fluid flow is eliminated, the shape of the non-return valve 5 (in particular, of the curved profile of the valve body 3) is such that the valve body 3 tends to move towards the closed position. Thus, the shape of the non-retum valve 5 is such that the valve body 3 is inherently biased towards the closed position. As such, when fluid flow is eliminated, any foul odours and/or pests are prevented from traversing through the non-return valve 5 in the reverse direction.

When fluid flow is reversed (i.e. in the reverse direction), the hydrostatic pressure of the fluid acting on the valve body 3, in particular on the valve body 3, causes the valve body 3 to return towards the closed position, such that the valve body 3 closes on the valve seat 2, to thereby prevent fluid flow in the reverse direction.

As is shown in figure 3b, the valve body 3 is thinner than the valve seat 2. This makes the valve body relatively flexible and thus facilitates movement of the valve body 3 to the open position under forward fluid flow. Additionally, the relatively thin valve body permits ready movement of the valve body 3 to the closed position under reverse fluid flow so as to form a seal against the valve seat 2.

To aid the return of the valve body 3 to the closed position an optional bias patch 8 is provided. The bias patch 8 is typically a thicker area of the valve body 3. In the embodiment shown in Fig. 7, the bias patch 8 is the same thickness as the valve body 3. As such, the region containing the bias patch 8 is twice as thick as the rest of the valve body 3. This resists excessive movement of the valve body 3 to the open position and urges the valve body 3 to move towards the closed position. In particular, it can help prevent the valve body moving so far as to become stuck in an inverted open position.

With reference to the embodiment shown in Figs. 6 and 7, perpendicular to the longitudinal axis of the drain valve are defined mutually perpendicular an opening axis T1 and side T2 axis. The opening axis T1 is parallel to a line connecting the apex 2a of the valve seat 2 and the longitudinal axis of the drain valve 1 and is in the same direction as the valve body 3 moves from open to closed positions. Whereas, the side axis T2 is parallel to a line connecting each respective side of the valve body 3 and/or valve seat 2 and the tangent of the valve seat 2 at its apex 2a. The height and width of the bias patch is defined in terms of its extent in a direction parallel to the opening and side axes respectively. The distal edge 35 of the drain valve 1 is defined as the edge furthest from the apex 2a of the valve seat 2 along the opening axis Tl. The bias patch is positioned on the valve body 3 closer to the distal edge 35 than the apex 2a along the opening axis Tl. The bias patch is on the outer surface of the valve body 3 and is positioned centrally, as defined relative to the side axis T2, between the two side edges of the valve body 3. The centre of the bias patch 8 on the valve body 2 is at the midpoint between the longitudinal axis 34 and upper edge 35 of the drain valve 1.

The extent of the bias patch parallel to the side axis T2 31 is half the extent of the valve body width 32, measured at a position parallel to 33 of the centre of the bias patch 8 on the valve body 3. The shape of the bias patch 8 is not particularly limited, in this embodiment, the bias patch 8 is elliptically shaped, typically with the major axis parallel to the side axis T2. The extent of the bias patch parallel to the opening axis Tl is approximately one third the distance between the longitudinal axis 34 and upper edge 35 of the drain valve 1.

In this embodiment, the profile of the bias patch 8 is also shaped to coincide with a surface decoration.

The drain valve 1 is made of injection moulded rubber such that the valve seat 2, the valve body 3, the head 4, the sealing fin 6, the sealing ridges 7, and bias patch 8 are monolithically formed with each other (i.e. the entire drain valve 1 is monolithically formed).

With reference to Figs. 8 to 10, the drain valve 1 can be connected to a check valve fitting 20 to form an inline check valve, which is used herein to connect respective pipes together.

The check valve fitting 20 has a substantially circular cross section and comprises a primary insert portion 21, a secondary insert portion 22 and an annular rim 23 provided between the primary insert portion 21 and the secondary insert portion 22, the annular rim 23 being arranged on an outer circumferential surface of the check valve fitting 20. Each of the primary insert portion 21 and the secondary insert portion 22 is provided with engagement means, e.g. resiliently flexible ribs 24, which function to provide a secure, sealing connection to respective pipes. Check valve fittings are known to a person skilled in the art. A person skilled in the art will appreciate that the check valve fitting 20 may further comprise various additional components, e.g. sealing means and/or sealings fins, as desired.

To assemble the check valve, the drain valve 1 can be mounted on the check valve fitting 20 by inserting (e.g. push-fitting) the primary insert portion 21 into the head 4 to form a releasable connection (e.g. a push-fit connection) therebetween (see Fig. 8). Where the drain valve 1 is suitably mounted on the check-valve fitting 20, the outer surface of the primary insert 21 outwardly, radially, grips an inner circumferential surface of the valve seat 2, and the sealing fin 6 abuts the annular rim 23 (see Figs. 6 to 8).

The resiliently flexible ribs 24 on the primary insert portion form a secure, sealing connection between the primary insert portion 21 and a pipe to which it is inserted when in use as an in-line check valve, as depicted in Figs. 8 to 10. A person skilled in the art will be familiar with check valve systems, such as in-line check valve systems. A person skilled in the art will also appreciate that the check-valve can be disassembled by removing the drain valve 1 from the check valve fitting 20, e.g. by hand or using a tool.

The one or more embodiments are described above by way of example only. Many variations are possible without departing from the scope of protection as defined by the appended claims.