GB2537611A - A drain valve and drain valve insert - Google Patents

Abstract

A drain valve 10 comprises a body 11 having a first conduit 12 and a passage 15 extending therethrough. An additional conduit 16 also has a passage 19 extending therethrough. The first conduit 12 has a seat (36, Fig. 3) for an insert 22. The passage 15 of the first conduit 12 has an inner surface (27, Fig. 3) which is at least partially threaded. The insert 22 has an outer surface, a portion 25 of which is threaded such that the insert can be screwed into the first conduit 12. The outer surface of the insert 22 also has an unthreaded portion 26, which in use abuts against the threaded inner surface 27 of the first conduit 12 to create a fluid-tight connection.

Description

A Drain Valve and Drain Valve Insert

Field of the Invention

The invention relates to drain valves and drain valve inserts, and has particular application in the fields of drain valves and drain valve inserts for us in radiators and other residential and industrial fluid flow systems.

Background to the Invention

Drain valves are commonly used in both residential and industrial settings to control the flow of fluid in a pipe or tank and to drain a fluid system if required. One such common use is in radiators where a drain valve is typically positioned on either side of the radiator to control water flow across the radiator and to drain the radiator of water if needs be. For this and other similar uses, the closest prior art known to the Applicant is a drain valve comprising a valve body having an internal thread, and an insert having an external thread for connection with the valve body. The insert comprises multiple components, such as a stem, and a seal which is positioned between the stem and a seat of the valve body. In use, the multi-component insert is tightened to close off the flow of fluid from one conduit to another, and Loosened to allow the fluid to flow. An 0-ring, or washer, is typically placed around the circumference of the stem to prevent fluid from leaking beyond the 0-ring in operation.

The known drain valve, however, whilst providing the closest prior art known to the Applicant, has disadvantages in use. The major ones of these will be listed below.

First, being typically formed of metal, the drain valve of the closet prior art rusts over time and therefore becomes difficult or impossible to move from an open to a closed position or to even remove the insert. This increases the risk of leakage if the valve is not entirely dosed off, affects the flow of fluid if the valve gets stuck half way between open and dosed positions, and creates extra work for a workman as the whole valve will require replacement if the valve is no longer workable.

Second, it is not uncommon for fluid to leak out of the top of the valve as the insert is is unscrewed and the valve opened, because fluid travels up the threads of the valve body and insert and between an 0-ring or washer and the internal wall of the valve body. The risk of Leakage is increased because the insert comprises multiple components which must fit and work together.

An 0-ring or washer, which is placed around the circumference of a stem, provides little help as fluid can relatively easily work its way in between the 0-ring and an inner surface of a valve body as the insert is inserted or retracted. Moreover, an 0-ring or washer provides only temporary protection against leakage from the drain valve. This is because these components are typically formed of rubber which, over time, degrades, breaks apart and therefore Loses its sealing properties. Other sealing members between the insert and the valve body may also degrade and break apart for the same or similar reasons, corrupting the sealing properties of the whole valve. For most people, this will require the call-out of a plumber or similarly trained professional as the inner workings of the valve are either unknown or unclear to many people, especially when a radiator or similar fluid system is Located in a home.

Current drain valves must also be welded onto connecting pipes, which requires the work of a welder, plumber or similarly trained professional. The welding of existing drain valves to connecting pipes also minimises or removes the ability to adjust the drain valve during or after the fitting process, thereby running the marked risk of promoting leakage if the drain valve is not fitted properly.

Further disadvantages, such as the requirement for heavy tools such as spanners and wrenches, are also shared by the closest prior art as well as other forms of drain valve.

Further prior art which the Applicant is aware of is a ball valve which comprises a conduit having a sphere positioned internally, wherein the sphere incorporates a passage which extends through the entire sphere to allow fluid to flow when the sphere is in a particular orientation. Like the drain valve of the closest prior art, a ball valve has many of the disadvantages described above.

These and other disadvantages experienced in use make it essential for the design of the drain valve to be improved. The invention takes this particular apparatus and the need to improve it as its starting point.

Summary of the Invention

In a first broad independent aspect, the invention provides a drain valve comprising a body; wherein the body comprises a first conduit having first and second ends and a passage extending therethrough; one or more additional conduits, the or each additional conduit having first and second ends and a passage extending therethrough; the first conduit comprising a seat for an insert; wherein said passage extending through the or each additional conduit is in fluid communication with the passage of said first conduit, the point of communication being located adjacent said seat; wherein the passage of said first conduit comprises an inner surface which is at least partially threaded; wherein the drain valve further comprises an insert having a diameter suitable to fit within the passage of the first conduit, and an outer surface, a portion of the outer surface being threaded such that the insert can be inserted into said first conduit with a screwing motion; the insert being movable from a first position whereby the insert is proximal to said seat, thus preventing the flow of fluid between the first end of the or each additional conduit and the second end of the first conduit, to a second position whereby fluid can flow between the first ends of the or each additional conduit and the second end of the first conduit, and vice versa; characterised by the feature(s) that a) the outer surface of said insert further comprises an unthreaded portion which, in use, abuts against the threaded inner surface of said first conduit to create a fluid-tight connection-and/or b) when feature a) immediately above is present, the unthreaded portion of said insert comprises a material which has pliancy such that the threaded inner surface of the first conduit cuts into the unthreaded portion of said insert as the insert is moved within the first conduit; and/or c) the insert is integrally formed of plastics material; and/or d) the seat of said first conduit comprises an internal flange with a squared edge which extends at least partially around the circumference of the first conduit perpendicular to the longitudinal direction; and said insert comprises a tapered front end such that, in use, the internal flange cuts into the tapered front end of the insert-and/or e) when features a) and d) above are present, the tapered front end, threaded and unthreaded portions of the insert are formed as a single piece-and/or f) a top surface of said insert comprises an opening which has a configuration suitable for the insertion of a Hex (Allen) key or screwdriver and/or g) said drain valve further comprises a locknut, wherein the locknut has an outer portion which is threaded such that the locknut can be inserted into said first conduit following the insertion of said insert, and removed prior to the removal of said insert-and/or h) where feature g) immediately above is present, the locknut comprises a ridge having a diameter which is wider than the diameter of the passage of the first conduit-and/or i) where features g) and h) above are present, said ridge has a toothed portion-and/or j) where feature g) above is present, a top surface of the locknut comprises a channel which has a configuration suitable for the insertion of a Hex (Allen) key or screwdriver; and/or k) where features f), g) and j) above are present, the channel extends through the entire locknut in the longitudinal direction and the opening of the insert and channel of the locknut are substantially in line with one another in use, such that the insert and locknut can be operated simultaneously-and/or l) where feature g) above is present, the drain valve comprises means for indicating when the locknut is fully engaged with the body-and/or m) where feature g) above is present, the body, insert and locknut are each formed of a single piece of plastics material; and/or n) the insert incorporates no washer or 0-ring; and/or o) at least one of the one or more additional conduits comprises a fitting with a seal for push fitting to a corresponding hose pipe connector.

Preferably, the outer surface of the insert further comprises an unthreaded portion which, in use, abuts against the threaded inner surface of the first conduit to create a fluid-tight connection. This configuration improves the sealing properties of the drain valve, without the use of an 0-ring, washer or similar, because the unthreaded portion of the insert abuts against the threaded inner surface of the first conduit to prevent fluid from flowing beyond the unthreaded portion of the insert. This configuration also prevents fluid from flowing beyond the unthreaded portion of the insert when the insert is moved from its first, closed position to its second, open position.

Preferably, the unthreaded portion of the insert comprises a material which has pliancy is such that the threaded inner surface of the first conduit cuts into the unthreaded portion of the insert as the insert is moved within the first conduit. The pliancy of the unthreaded portion of the insert allows the threaded inner surface of the first conduit to press or cut into the unthreaded portion to create an improved fluid-tight seal. The insert, in effect, is self-sealing. This prevents fluid from getting between the insert and the inner surface of the first conduit because a seal is continuously formed between the two components.

Preferably the insert is integrally formed of plastics material. Being integrally formed of plastics material provides the insert with suitable pliancy to form a seal with the threaded inner surface of the first conduit. Being integrally formed of plastics material also reduces the risk of the insert becoming stuck within the passage of the first conduit because the plastic will not rust over time.

Preferably, the seat of said first conduit comprises an internal flange with a squared edge which extends at least partially around the circumference of the first conduit perpendicular to the longitudinal direction; and said insert comprises a tapered front end such that, in use, the internal flange cuts into the tapered front end of the insert. This configuration provides a fluid-tight seal between the tapered front end of the insert and the internal flange as the squared edge of the internal flange presses or cuts into the tapered front end of the insert. This improves the sealing property of the drain valve without the use of multiple components, such as a separate seal connected to the front of the insert.

Preferably, the tapered front end, threaded and unthreaded portions of the insert are formed as a single piece. Multiple insert components are therefore not provided, which minimises the risk of leakage beyond the insert. The risk of multiple components and moving parts becoming stuck or difficult to remove is also minimised or avoided altogether.

Preferably, a top surface of said insert comprises an opening which has a configuration suitable for the insertion of a Hex (Allen) key or screwdriver. The ability to operate the insert with a Hex key or screwdriver is preferable as the use of a spanner or wrench, which is typical with existing drain valves, is difficult. This is especially true when, as is almost always the case, a radiator is wall-mounted. A spanner or wrench has a large turning circle is which is usually obstructed by the wall a radiator is mounted to, requiring the spanner or wrench to be disconnected and reconnected many times whilst the insert of a drain valve is moved. The provision of an opening suitable for a Hex key or screwdriver provides a solution to this problem.

Preferably, said drain valve further comprises a locknut, wherein the locknut has an outer portion which is threaded such that the locknut can be inserted into said first conduit following the insertion of said insert, and removed prior to the removal of said insert. The locknut improves the safety of the drain valve as it minimises or avoids the risk of inadvertent removal of the insert. The locknut has to be consciously removed from the valve body prior to the adjustment or removal of the insert. Therefore the locknut also reduces the risk of tampering of the insert.

Preferably, the locknut comprises a ridge having a diameter which is wider than the diameter of the passage of the first conduit. The ridge therefore abuts against the first end of the first conduit when the locknut is fully engaged. This ridge prevents the locknut from being entirely located within the passage of the first conduit so that the locknut can be straightforwardly removed, if required, by hand of a user. The ridge also prevents any dirt from settling inside the passage of the first conduit, which in turn reduces the risk of leakage from or damage to the drain valve.

Preferably, said ridge has a toothed portion. The toothed portion improves the grip for a user to manually engage and disengage the locknut. This is particularly advantageous when the locknut is wet.

Preferably, a top surface of the locknut comprises a channel which has a configuration suitable for the insertion of a Hex (Allen) key or screwdriver. The ability to operate the locknut with a Hex key or screwdriver is preferable as the use of a spanner or wrench, which is typical with existing drain valves, is difficult. This is especially true when, as is almost always the case, a radiator is wall-mounted. A spanner or wrench has a large turning circle which is usually obstructed by the wall a radiator is mounted to, requiring the spanner or wrench to be disconnected and reconnected many times whilst the locknut is engaged with the valve body. A channel suitable for the insertion of a Hex key or screwdriver provides a solution to this problem.

is Preferably, the channel extends through the entire locknut in the longitudinal direction and the opening of the insert and channel of the locknut are substantially in line with one another in use, such that the insert and locknut can be operated simultaneously. Simultaneous operation of the insert and locknut simplifies the operation of the drain valve. Simultaneous operation also reduces the amount of time required to assemble and/or adjust the drain valve.

Preferably, the drain valve comprises means for indicating when the locknut is fully engaged with the body. This configuration improves the effectiveness and safety of the drain valve as a user can be aware of when the locknut is fully engaged with the body. The risk of damage to the drain valve is also reduced as the user will be discouraged from over-tightening the locknut, which could damage the threaded portion of the locknut and inner surface of the first conduit.

Preferably, the body, insert and locknut are each formed of a single piece of plastics material. This configuration is particularly advantageous because only a single component is required to be inserted into the first conduit of the valve body. This simplifies the use of the drain valve and improves the Life span of the drain valve as fewer components are provided, each of which might degrade over time, thus negatively affecting their interaction with one another.

Preferably, the insert incorporates no washer or 0-ring. Washers or 0-rings degrade and break up over time, negatively affecting or terminating the sealing properties of the drain valve. By providing no washer or 0-ring, the risk of this issue occurring is reduced or avoided altogether. There is no requirement for a washer or 0-ring because the unthreaded portion of the insert is self-sealing against the threaded inner surface of the first conduit.

Preferably, at least one of the one or more additional conduits comprises a fitting with a seal for push fitting to a corresponding hose pipe connector. This allows the drain valve to be connected to a hose pipe connector. Such a fitting is swift to engage and disengage and intuitive for a user to operate.

In a second broad independent aspect the invention provides a drain valve insert comprising front and rear ends, and at least one outer surface extending between said is front and rear ends; wherein said outer surface incorporates a threaded portion such that the insert can be inserted into the body of a drain valve with a corresponding threaded inner surface; characterised by the feature(s) that p) the outer surface of the insert comprises an unthreaded portion; whereby, in use, the portion of the outer surface which is unthreaded abuts against the threaded inner surface of a drain valve body to create a fluid-tight connection-and/or q) where feature p) immediately above is present, the unthreaded portion of said insert comprises a material which has pliancy such that the threaded inner surface of a drain valve body cuts into the unthreaded portion of said insert as the insert is moved within the drain valve body and/or r) the insert is integrally formed of plastics material-and/or s) the front end of the drain valve insert is tapered; whereby, in use, the tapered front end of the insert abuts against a seat of a drain valve body and/or t) where features p) and s) above are present, the tapered front end, threaded and unthreaded portions of the insert are formed as a single piece-and/or u) said insert incorporates no washer or 0-ring; and/or v) the insert comprises a top surface at its rear end which incorporates an opening which has a configuration suitable for the insertion of a Hex (Allen) key or screwdriver.

Preferably, the outer surface of the insert comprises an unthreaded portion; whereby, in use, the portion of the outer surface which is unthreaded abuts against the threaded inner surface of a drain valve body to create a fluid-tight connection. This configuration improves the sealing properties of the insert because the unthreaded portion of the insert abuts against the threaded inner surface of an existing valve body to prevent fluid from flowing beyond the unthreaded portion of the insert. This configuration also prevents fluid from flowing beyond the unthreaded portion of the insert when the insert is moved from its first, closed position to its second, open position within an existing valve body.

Preferably, the unthreaded portion of said insert comprises a material which has pliancy such that the threaded inner surface of a drain valve body cuts into the unthreaded portion of said insert as the insert is moved within the drain valve body. The pliancy of the unthreaded portion of the insert allows the threaded inner surface of an existing valve body to press or cut into the unthreaded portion to create an improved fluid-tight seal.

is This prevents fluid from getting between the insert and the inner surface of a valve body as a seal is continuously formed between the two.

Preferably, the insert is integrally formed of plastics material. Being integrally formed of plastics material provides the insert with suitable pliancy to form a seal with the threaded inner surface of a valve body. Being integrally formed of plastics material also reduces the risk of the insert becoming stuck within the passage of a valve body because the plastic will not rust over time.

Preferably, the front end of the drain valve insert is tapered; whereby, in use, the tapered front end of the insert abuts against a seat of a drain valve body. This configuration provides a fluid-tight seal between the tapered front end of the insert and the seat of an existing valve body, as the seat of the existing valve body presses or cuts into the tapered front end of the insert. This improves the sealing property of the insert Preferably, the tapered front end, threaded and unthreaded portions of the insert are formed as a single piece. Multiple insert components are therefore not provided which minimises the risk of leakage beyond the insert. This configuration also avoids the risk of multiple components and moving parts becoming stuck or difficult to remove.

Preferably, said insert incorporates no washer or 0-ring. Washers or 0-rings degrade over time, negatively affecting the sealing properties of the drain valve insert. By providing no washer or 0-ring, the risk of this is reduced. There is no requirement for a washer or 0-ring because the unthreaded portion of the insert is self-sealing against the threaded inner surface of a drain valve body.

Preferably, the insert comprises a top surface at its rear end which incorporates an opening which has a configuration suitable for the insertion of a Hex (Allen) key or screwdriver. The ability to operate the insert with a Hex key or screwdriver is preferable as the use of a spanner or wrench, which is typical with existing drain valves, is difficult. This is especially true when, as is almost always the case, a radiator is wall-mounted. A spanner or wrench has a large turning circle which is usually obstructed by the wall a radiator is mounted to, requiring the spanner or wrench to be disconnected and reconnected many times whilst the insert is moved.

The invention includes within its scope a drain valve and drain valve insert substantially as described herein with reference to and as illustrated by the accompanying drawings.

zo Brief Description of the Drawings

The inventions are now described with reference to the accompanying drawings which show, by way of example, an embodiment of a drain valve and an embodiment of a drain valve insert.

In the drawings: Figure 1 shows an exploded perspective view of a drain valve of the invention; Figure 2A shows the insert of the drain valve in rear three-quarter view; Figure 2B shows the same insert viewed front three-quarter; Figure 3 shows a cross-sectional view of the assembled drain valve of the invention in a first, open configuration; and Figure 4 shows a cross-sectional view of the assembled drain valve of the invention in a second, closed configuration.

The illustrated embodiments of the inventions are currently the best way known to the Applicant of realising the inventions. But they are not the only ones: the skilled addressee of this specification may well be able to devise others without the need for inventive thought within the Summary of the Invention outlined above.

Detailed Description of the Embodiments

Referring in more detailed to the drawings, in which similar reference numerals identify corresponding parts, there is shown a drain valve, generally referenced 10, comprising a body 11, insert 22 and locknut 23. Shown in Figure 1, the body 11 comprises a first conduit 12 having first 13 and second 14 ends, an outer surface 20 and an inner surface 27. A passage 15 extends between the first 13 and second 14 ends of the first conduit 12.

In this preferred embodiment, the body 11 further comprises an additional conduit 16 which also has first 17 and second 18 ends and a passage 19 which extends between the first 17 and second 18 ends. The second end 18 of the additional conduit 16 is connected to the first conduit 12, at a position between the first 13 and second 14 ends of the first conduit 12. The passage 19 of the additional conduit 16 is fluidly connected to the passage of the first conduit 12 such that fluid can flow from the first end 17 of the additional conduit 16 to the second end 14 of the first conduit 12 and vice versa. In an alternative embodiment, more than one additional conduit is provided so that fluid can flow from multiple sources to the first conduit 12.

The second end 14 of the first conduit 12 and the first end 17 of the additional conduit 16 are configured to be connectable to the pipes or conduits of a fluid flow system. In the embodiment shown in Figure 1, the additional conduit 16 comprises a fitting 24 with a seal for push fitting to a corresponding connector. The seal 24 of the second conduit 16 may optionally incorporate an 0-ring (not shown). In another optional embodiment, the conduit 16 comprises a seal suitable for connecting the valve 10 to a hose pipe connector. In additional alternative embodiments the additional conduit 16, or indeed the first conduit 12, may comprise any sort of fitting or be suitable to be connected to any sort of connector. In a preferred embodiment, the valve body 11 is integrally formed of plastics material, such as polybutylene, such that the drain valve 10 can be glued to a pipe or conduit of a fluid flow system rather than welded. Gluing the drain valve 10 to a pipe or conduit allows the installer to adjust the position of the drain valve whilst the glue is setting, so that an accurate position can be obtained -reducing the risk of leakage from the drain valve. Gluing the drain valve 10 to a pipe or conduit also allows the drain valve be straightforwardly removed with an adhesive remover when the valve 10 is to be replaced.

In a preferred embodiment, the conduits 12, 16 are substantially circular in cross section so is that the number of corners in which dirt can accumulate is minimised.

The inner surface 27 of the first conduit 12 is at least partially threaded. In the drawings, the inner surface 27 of the first conduit 12 is threaded from the first end 13 to the point where the passage 15 narrows. At this point, as shown in Figures 3 and 4, a seat 36 comprising an internal flange, preferably having a squared edge is provided. The portion of the inner surface between the internal flange 36 and the second end 14 of the first conduit 12 is unthreaded.

The drain valve 10 further comprises a single piece insert 22 which is substantially circular and of a diameter suitable to fit within the passage 15 at the first end 13 of the first conduit 12. Where the passage 15 of the first conduit 12 is a different shape in cross section, the shape of the insert 22 will differ, i.e. the insert 22 will not be substantially circular. The insert 22 comprises front 29 and rear 30 ends, and an outer surface 28 with a threaded portion 25 and an unthreaded portion 26. The threaded portion 25 is connectable to the thread of the inner surface 27 of the first conduit 12. In this preferred embodiment, the threaded portion 25 is located in front of the unthreaded portion 26 so that the insert 22 can be straightforwardly inserted into the valve body 11. The single piece insert 22 provides a more compact means for controlling the flow in a drain valve compared to 1.3 existing inserts, which typically comprise multiple components, including a stem, seal and 0-ring.

In a preferred embodiment, the unthreaded portion 26 comprises a material which has pliancy such that the threaded inner surface 27 of the first conduit 12 presses or cuts into the unthreaded portion 26 of the insert 22 as the insert 22 is moved within the first conduit 12. Even more preferably, the unthreaded portion 26 is integrally formed of plastics material, and more preferably the whole insert 22 comprises plastics material such as polybutylene. Even more preferably, the insert 22 comprises a plastic which has improved non-stick properties so that the insert 22 does not become stuck within the first conduit 12 over time. The valve body 11 also comprises plastics material. Optionally, the valve body 11 and insert 22 both comprise plastics material, and the insert 22 comprises plastics material which is more ductile than the plastics material of the body 11.

is The front end 29 of the insert 22 is tapered away from the threaded portion 25 of the insert 22. In a preferred embodiment, the front end 29 is frustoconical in shape. However, in an alternative embodiment, the front end 29 may be conical, squared or rounded in shape. As will be explained in more detail below, the front end 29 is tapered in order for the insert 22 to interact with the internal flange 36 of the first conduit 12 when the insert 22 is inserted into the valve body 11. In a preferred embodiment, the front end 29 is integrally formed of plastics material.

The tapered front end 29, threaded portion 25 and unthreaded portion 26 of the insert are formed as a single piece.

In use, the insert 22 is screwed into the first end 13 of the first conduit 12, facilitated by the thread of the inner surface 27 of the first conduit 12. Once the insert 22 is at least partially screwed connected to the thread of the inner surface 27 of the first conduit 12 the insert 22 can be moved from a first position where the insert 22 prevents the flow of fluid between the first 12 and second 16 conduits, to second position where flow between the first 12 and second 16 conduits is permitted, and vice versa.

Referring now to Figures 3 and 4, as the insert 22 is further screwed into the first conduit 12, the unthreaded portion 26 of the insert 22 abuts against the threaded inner surface 27 of the first conduit 12 to create a fluid-tight seal between the insert 22 and the body 11. In a preferred embodiment the unthreaded portion 26 of the insert 22 comprises a material, such as a plastics material, which has pliancy such that the threaded inner surface 27 of the first conduit 12 presses or cuts into the unthreaded portion 26 of the insert 22 to create a fluid-tight seal (see Figures 3 and 4). Abutment of the unthreaded portion 26 against the threaded inner surface 27 of the first conduit 12 improves the sealing property of the valve, particularly when the insert 22 is moved from the first, closed position to the second, open position. The fluid-tight seal which is continuously formed between the inner surface 27 and the insert 22 as the insert 22 is inserted or retracted prevents fluid from getting in between the insert 22 and the valve body 11 and working its way out of the first end 13 of the first conduit 12.

An additional sear is formed between the tapered front end 29 of the insert 22 and the internal flange 36 of the first conduit 12. The internal flange 36 of the first conduit 12 is positioned between the fluid connection between the passages 15, 19 of the first 12 and additional 16 conduits and the second end 14 of the first conduit 12. In use, the internal flange 36 acts as a seat for the insert 22 when the insert 22 is in the first, closed position. When the insert 22 is in this first, closed position the tapered front end 29 of the insert 22 abuts against the squared edge of the internal flange 36 to create a fluid-tight seal (see Figure 4). The combination of the seal between the tapered front end 29 and the internal flange 36, and the seal between the unthreaded portion 26 and the inner surface 27 reduces the risk of leakage from the drain valve 10 whilst providing an intuitive and effective means for controlling the flow of fluid from the passage 19 of the additional conduit 16 to the passage 15 of the first conduit 12, and vice versa.

The insert 22 incorporates no washer or 0-ring, as the insert 22 is self-sealing with the inner surface 27 of the first conduit 12. As washers or 0-rings degrade over time, this disadvantage is avoided, prolonging the life span of the insert 22 and in turn the whole drain valve 10.

The drain valve 10 preferably further comprises a locknut 23 which, in use, is inserted into the first conduit 12 of the body 11 once the insert 22 has been inserted. The locknut 23 allows the insert 22 to be hidden in use, thus preventing or minimising the risk of tampering or inadvertent removal of the insert 22. It also reduces the risk of Leakage from the drain valve 10 because the locknut provides an additional barrier to fluid and because, in use, the locknut 23 must be removed from the first conduit 12 prior to or in conjunction with the removal of the insert 22. In an alternative embodiment, the drain valve 10 is provided without a Locknut 23.

The locknut 23 comprises a first end 31 and a second end 32. The first end 31 of the locknut 23 comprises a threaded outer surface 33; the second end 32 of the locknut 23 comprises a ridge which abuts the first end 13 of the first conduit 12 when the locknut 23 is fully engaged. The ridge has an outer surface 34 which is, in a preferred embodiment, toothed. The toothed outer surface 34 of the locknut 23 improves the ability of a user to tighten and loosen the locknut 23, because grip is improved, without the use of a tool. This is particularly important when the locknut is wet. In an alternative embodiment, the outer surface 34 may comprise a number of dimples or protrusions to improve grip.

is In a preferred embodiment, the locknut 23 further comprises means for indicating when the locknut 23 is fully engaged with the valve body 11. In one embodiment, the means may include a protrusion (not shown) located on the first end 31 of the Locknut 23 adjacent the ridge, and a corresponding recess (also not shown) located on the inner surface 27 of the first conduit 12 adjacent the first end 13 of the first conduit 12. When the locknut 23 is fully engaged with the body 11, the protrusion of the locknut 23 connects with the corresponding recess of the body 11 to indicate to a user that the locknut 23 is fully engaged. Connection and disconnection of the indicating means will be straightforwardly completed by a user applying slightly more twisting force on the locknut 23. In an alternative embodiment, the protrusion is located on the inner surface 27 of the first conduit 12 and the corresponding recess is Located on the locknut 23. Alternative means for indicating to a user that the locknut 23 is fully engaged with the valve body 11 may instead be provided.

As shown in Figure 2A, the insert 22 preferably further comprises an opening 35 at the second end 30 which is suitable for receiving the functional end of a Hex (Allen) key (not shown). In an alternative embodiment, the opening 35 is suitable to receive the functional end of a screwdriver. The provision of the opening 35 allows the insert 22 to be intuitively inserted into and removed from the valve body 11, and moved from the first, closed to the second, open positions and vice versa. The ability to operate the insert 22 with a Hex key or screwdriver is preferable as the use of a spanner or wrench, which is typical with existing drain valves, is difficult. This is especially true when, as is almost always the case, a radiator is wall-mounted. A spanner or wrench has a large turning circle which is usually obstructed by the wall a radiator is mounted to, requiring the spanner or wrench to be disconnected and reconnected many times whilst the insert of a drain valve is moved.

In a preferred embodiment, the locknut 23 comprises a channel 37 which is also suitable for receiving a functional end of a Hex (Allen) key or, in an alternative embodiment, a screwdriver, so that the locknut 23 can be tightened and loosened within the first conduit 12. In an alternative embodiment, shown in Figures 3 and 4, the locknut 23 has a channel 37 which is of a greater diameter than that of the insert 22. In this embodiment, the locknut 23 may be loosened and tightened by hand or by a larger sized Hex (Allen) key than is required to Loosen and tighten the insert 22.In a preferred embodiment, the channel 37 of the locknut 23 extends through the entirety of the locknut 23 between the is first 31 and second 32 ends. In this preferred embodiment, the channel 37 of the locknut 23 and opening 35 of the insert 22 are aligned when inserted into the valve body 11 and are of an equal or near equal size such that the insert 22 and locknut 23 can be operated simultaneously. However, the parts will need to be operated separately where the insert 22 is to be moved to its first, closed position, as the locknut 23, once fully engaged with the body 11, will prevent the inserted Hex key from turning further. It will therefore be preferable to operate the two parts separately when inserting them or when moving the insert 22 into its closed position, but conjointly when removing both parts.

In the embodiment described, the insert 22 and locknut 23 are separate pieces. This is because the safety of the drain valve 10 is improved because an operator will have to consciously loosen and remove both parts separately, at least where the insert 22 and locknut 23 have channels of differing size. However, in an alternative embodiment, the insert comprises the features of the locknut 23, e.g. the ridge and toothed outer surface. In this alternative embodiment, the insert 22 is of a length suitable to block the flow of fluid between the passage 19 of the additional conduit 16 and the passage 15 of the first conduit 12 when fully engaged.

In a preferred embodiment, the whole drain valve 10, including the body 11, insert 22 and locknut 23 is comprised of plastics material. However, in alternative embodiments, any or all of the components may comprise another material, such as a metal. Being formed of plastics material means that the drain valve 10 degrades more slowly over time compared to existing drain valves which are formed of metal and rust.

In a preferred embodiment, the first conduit 12 has a stepped portion 21 along its outer surface 20. The passage 15 of the first conduit 12 is also reduced in diameter from the stepped portion 21 to the second end 14 (see Figures 3 and 4).

The narrowing of the passage 15 at the stepped portion 21 of the first conduit 12 is shown more clearly in Figures 3 and 4. The internal flange 36 of the first conduit 12 is also shown being positioned around the circumference of the first conduit 12.

Figure 3 shows a cross-sectional view of the drain valve when assembled and in the second position, whereby fluid can flow between the first conduit 12 and the additional conduit 16. In the preferred embodiment, as the insert 22 is inserted into the passage 15 at the is first end 13 of the first conduit 12, the threaded portion 25 of the insert 22 connects with the threaded inner surface 27 of the first conduit 12. In the embodiment of the drawings the inner surface 27 of the first conduit 12 between the first end 13 and the stepped portion 21 is entirely threaded. However, in an alternative embodiment, only a portion of the inner surface 27 may be threaded.

In a preferred embodiment, the internal flange 36 has a squared edge such that, when the front end 29 of the insert 22 contacts the internal flange 36, a water tight seal is created between the flange 36 and the front end 29. The insert 22 is thereby prevented from moving further into the first conduit 12 than the internal flange 36 comprising the seat The seal between the internal flange 36 and the tapered front end 29 of the insert 22 is shown in Figure 4. In an alternative embodiment, the edge of the internal flange 36 may be rounded.

In both the first, closed position (Figure 4) and second, open position (Figure 3) a seal is formed between the threaded inner surface 27 of the first conduit 12 and the unthreaded portion 26 of the insert 22. The threaded inner surface 27 presses or cuts into the pliant unthreaded portion 26 of the insert continuously as the insert 22 is moved to and from the first and second positions.

When removing the insert 22, fluid is prevented from leaking beyond the insert 22 and out of the valve 10 as the unthreaded portion 26 of the insert 22 is constantly formed around the threaded inner surface 27 of the first conduit 12 to maintain the fluid-tight seal.

In another embodiment, an insert 22, having the same essential features as the insert 22 of the preferred embodiment, is provided for retrofitting to an existing drain valve body (not shown). The insert 22 is preferably integrally formed of plastics material such that the internal thread of an existing valve body cuts into the pliant plastics material when the insert 22 is inserted. The insert 22 also has a tapered front end 29 for forming a seal with the seat of the existing valve body.