A plug for a drain, a kit of parts for a plug for a drain, a plug system, an over-bath showering system and a method of manufacturing a plug

Abstract

A plug 500 for a drain comprises a head portion 510 configured to block flow of water down the drain when the head portion is in a blocking position level with the drain and configured to permit flow

Description

A plug for a drain, a kit of parts for a plug for a drain, a plug system, an over-bath showering system and a method of manufacturing a plug Field The present invention relates to bath plugs. In particular, the present invention relates to bath plugs that are operable by mechanical means between draining and blocking positions. Background US 3010120 describes a bath plug construction, which facilitates the positioning of the plug in open position, allows manipulation to close the plug and prevents unauthorized removal of the valve member. WO 2013 / 112385 describes a stopper assembly for a drain system of a fluid basin. The stopper head assembly includes a stopper head having a seal to sealingly engage the drain system of the fluid basin when the stopper assembly is moved from a drain position to a plug position. The stopper head assembly further includes a stopper body operably coupleable to a control element to move the assembly between the drain position and the plug position. US9435109 describes a drain actuation system that includes a cable to actuate a drain head or stopper. One end of the cable is associated with the drain without additional moving parts and another end of the cable associated with an overflow cap of an overflow system wherein rotation of the overflow cap selectively moves the cable to move the head of the drain. EP 1338707 describes a device for opening and closing a plug for sanitary fittings, which comprises a movable portion coupled to a plug element and slidably engaged with a fixed portion mounted on a drain. The device further comprises means driven with a rotary-translating movement operating against a resilient means, thereby allowing the plug element to be switched from an open or raised position, to a closed or lowered position, by pushing on the plug element itself. Summary Existing bath plug mechanisms actuate a bath plug between a draining position (in which water may flow past the plug and down the drain) and a blocking position (in which the drain is blocked and water fills the bath, rather than draining away). However, if a user inadvertently applies a force to the plug when it is in the draining position (e.g. by standing on the plug while showering) then the mechanism may be forcibly actuated to the blocking position, causing the bath to fill. This may result in the user having to manually actuate the mechanism back to the draining position. The present invention aims to provide a bath plug that is operable in draining and blocking positions and that does not transition permanently from the draining position to the blocking position if the user steps on the plug. It is an aim of the present invention that the plug will transition permanently to the blocking position only if the mechanism is manually actuated by the user (e.g. by turning a dial). A plug for a drain is provided. The plug comprises a head portion configured to block flow of water down the drain when the head portion is in a blocking position level with the drain and configured to permit flow of water down the drain when the head portion is in a draining position above the level of the drain. The plug further comprises a stem portion configured to support the head portion in the draining position (e.g. when the stem is resting on a plug support in an upper position). The stem portion comprises a bias. The bias is configured to yield to an external force applied to the head portion, to move the head portion against the bias from the draining position to the blocking position. The bias is further configured to urge the head portion from the blocking position to the draining position when the external force is removed. The present invention provides a bath plug that is biased towards the draining position so that stepping on the plug only causes the plug to move temporarily to the blocking position. The bias urges the plug back to the draining position when the user steps off the plug. The only way to cause the plug to remain in the blocking position, without applying a continual force to the plug, is to manually actuate the mechanism to the blocking position (so that the plug support is moved from the upper position to the lower position). In other words, the drain closes temporarily if the user inadvertently applies pressure to the plug (e.g. by standing or sitting on it). Then, the drain re-opens when the cause of the pressure is removed. The proposed plug can reduce the frequency of incidents where the user inadvertently moves the plug to the blocking position and therefore needs to manually actuate the mechanism to the draining position. This can save time and therefore waste less water while showering. Some mechanisms are actuated by rotating a knob or dial positioned at the level of the bath overflow. If the user is showering in a standing position then they would need to reach down to actuate the mechanism. Reaching down may cause difficulty if the user has issues with mobility. Moreover, health conditions can make users prone to fainting when bending down, especially in a warm steamy environment, such as a shower. Therefore, by reducing the frequency of incidents requiring the user to actuate the mechanism (or eliminating such incidents altogether), the present invention can improve user safety while showering. The plug can be moved to the blocking position by manual activation of the mechanism. Manual actuation of the mechanism may lower an internal plug support, thereby causing the plug to drop down under gravity. The full functionality of the plug arrangement is therefore retained. Some plugs are actuated between draining position and blocking position by a trip mechanism, commonly referred to as a “click-clack”, which operates the plug in a manner similar to the actuator usually used in a click-top ballpoint pen. The user must act impart a downwards axial force on the plug to trigger the click-clack mechanism and cause the plug to switch between the draining position and the blocking position. However, such mechanism may also be actuated inadvertently by the user and so this plug does not address the problem described above. In case of inadvertent actuation of such a device into the blocking position, the user must actuate the mechanism again to return the plug to the draining position. The stem portion may comprise a lower end configured to engage a plug support of the drain below the level of the drain. The stem portion may further comprise an upper end fixed to the head portion to support the head portion. The plug may be suitable for use in a drain having an actuation mechanism configured to move the plug support between an upper position and a lower position. The stem portion of the plug may be configured to support the head portion in the draining position when the plug support is in the upper position. The head portion of the plug may fall into the blocking position under gravity when the plug support is in the lower position (when the plug support is moved from the upper position to the lower position). The bias may comprise a helical spring. The helical spring may be located between the lower end of the stem portion and the upper end of the stem portion. The helical spring may be at the lower end of the stem portion. The head portion may further comprise a deformable elastic seal around a perimeter of the head portion. The seal may facilitate an interference fit between the head portion and the drain. Thereby, flow of water down the drain may be blocked more effectively. The seal may be formed from rubber or silicone, for example. An unbiased length of the stem portion may be adjustable. The unbiased length is the distance from the lower end of the stem portion to the upper end of the stem portion, when there is no external force applied. Advantageously, by making the unbiased length of the stem portion adjustable, the plug may be suitable for use in different drains. Each different drain may have a support that sits at a different level within the drain, compared to other drains. The stem may comprise a threaded portion (e.g. a threaded bolt) and a corresponding threaded socket, which are rotatable relative to each other to adjust the unbiased length of the stem portion. The threaded socket may comprise a nut. A threaded bolt and threaded nut provide a convenient means by which to adjust the length of the stem portion. The nut may be a first nut. The stem may further comprise a second nut adjacent to the first nut. The first and second nuts may be tightened against each other to fix the first nut and the second nut firmly in position. The stem portion may further comprise a cover over the bias. Advantageously, concealing the bias under a cover may help to prevent hair and other debris that washes down the drain from becoming trapped in the bias. The bias may be a concealed bias. In other words, the stem portion may appear externally as one or more solid cylinders, where the lower end of the stem is moveable against the bias to shorten the effective length of the stem. For example, where the bias is a spring, the stem portion may further comprise a cylindrical cover over the spring to conceal the spring. The cover may fit over a rigid shaft of the stem portion The plug may be a bath plug for a bath drain. A kit of parts for assembly to form a plug for a drain is also provided. The kit of parts comprises a head portion configured to block flow of water down the drain when the head portion is in a blocking position level with the drain and configured to permit flow of water down the drain when the head portion is in a draining position above the level of the drain. The kit of parts further comprises a stem portion fixed to the head portion or fixable to the head portion so that the stem supports the head portion in the draining position. The kit of parts further comprises a bias fixed to the stem or fixable to the stem so that the bias is configured to: yield to an external force applied to the head portion to move the head portion against the bias from the draining position to the blocking position; and urge the head portion from the blocking position to the draining position when the external force is removed. The kit of parts may be assembled to provide a plug as described above. A plug system is also provided. The plug system comprises a plug as described above. The plug system further comprises a drain comprising a plug support and an actuation mechanism configured to move the plug support between an upper position and a lower position. An over-bath showering system is also provided. The over-bath showering system comprises a shower, a bath, and a plug system as described above. A method of manufacturing a plug is provided. The method comprises providing a head portion of the plug. The method further comprises fixing a stem portion to the head portion. The stem portion has a longitudinal axis defining an upward and a downward direction. The head portion is fixed to an upper end of the stem portion. The method further comprises providing a bias in the stem portion. The bias is configured to yield to an external force applied to the head portion in the downward direction to move the head portion against the bias in the downward direction. The bias is further configured to urge the head portion in the upward direction when the external force is removed. Brief description of the drawings Figure 1 illustrates a bath plug known from the prior art. Figures 2A and 2B illustrate a schematic cross-section of the bath plug of Figure 1 in operation in a drain comprising an actuation mechanism. The present invention will now be described with reference to the following non-limited examples. Figure 3 illustrates a bath plug comprising a bias. Figures 4A to 4C illustrate a schematic cross-section of the bath plug of Figure 3 in operation in a drain comprising an actuation mechanism. Figures 5A and 5B illustrates a bath plug comprising a rubber seal and an adjustable stem. Figure 6 illustrates a cross-section of a bath plug comprising a concealed bias. Detailed Description Figure 1 illustrates a bath plug 100 for use in a drain comprising a mechanism to raise and lower the plug. The plug comprises a head portion 110 for blocking the flow of water down the drain and a stem portion 120 for supporting the head portion. Figures 2A and 2B illustrates a schematic cross-section of the bath plug of Figure 1 in operation in a drain 230 comprising an actuation mechanism. The actuation mechanism comprises a moveable plug support 240 that is movable between a lower position 242A and an upper position 242B. The moveable plug support 240 is shown in the lower position 242A in Figure 2A and the moveable plug support 240 is shown in the upper position 242B in Figure 2B. As can be seen in Figures 2A and 2B, actuating the mechanism to move the plug support 240 between the lower position 242A and the upper position 242B moves the plug 100 between a blocking position and a draining position, respectively. In the blocking position, the head portion 110 is level with the drain 230 and flow of water down the drain 230 is prevented. The bath may therefore be filled with water with the plug 100 in the blocking position. In the draining position, the head portion 110 is raised vertically above the drain 230 and water may flow under the head portion 110 and down the drain 230. The drain may comprise a circular opening. The head portion 110 may be “level” with the drain 230 when the head portion 110 sits within the circular opening to block flow of water down the opening, as shown in Figure 2A. If the user steps on the plug 100 when the plug is in the draining position, the weight of the user may exert a force that is transferred through the stem portion of the plug to the plug support 240. The force may manually actuate the mechanism and force the plug support 240 from the upper position 242B to the lower position 242A. The drain may further comprise a structure within the circular opening that supports the plug in the blocking position when the head portion is level with the drain and the bottom of the head portion is in physical contact with the drain structure. The structure may comprise holes so that water flows through the structure when the plug is in the draining position. Figure 3 illustrates a plug 300 according to a specific non-limiting example. The plug 300 is for use in a drain comprising a mechanism to raise and lower the plug. The plug comprises a head portion 310 for blocking the flow of water down the drain, a stem portion 320 for supporting the head portion, and a bias 350. The bias is configured to yield to an external force applied to the plug and apply a resistive force to urge the plug back when the external force is removed. Figures 4A to 4C illustrate a schematic cross-section of the plug of Figure 3 in operation in a drain 430 comprising an actuation mechanism. The actuation mechanism comprises a moveable plug support 440 that is movable between a lower position 442A and an upper position 442B. The moveable plug support 440 is shown in the lower position 442A in Figure 4A and the moveable plug support 440 is shown in the upper position 442B in Figure 4B. As can be seen in Figures 4A and 4B, actuating the mechanism to move the plug support 440 between the lower position 442A and the upper position 442B moves the plug 300 between a blocking position and a draining position, respectively. In the blocking position, the head portion 310 is level with the drain 430 and flow of water down the drain 430 is prevented. The bath may therefore be filled with water with the plug 300 in the blocking position. In the draining position, the head portion 310 is raised vertically above the drain 430 and water may flow under the head portion 310 and down the drain 430. The drain may comprise a circular opening. The head portion 310 may be “level” with the drain 430 when the head portion 110 sits within the circular opening to block flow of water down the opening, as shown in Figure 4A. If the user steps on the plug 300 when the plug is in the draining position, the weight of the user may exert a force F that is transferred through the stem portion of the plug to the bias 350. The bias may deform under the force exerted by the user (e.g. a spring compressing) and the effective length of the stem may be reduced. In this way, the head portion of the plug may be pushed to the level of the drain. This is illustrated in Figure 4C. As a result, the user may step on the plug and force the plug to the blocking position, without manually actuating the mechanism and forcing the plug support 440 from the upper position 442B to the lower position 442A. When the force is removed from the plug, the bias may act to urge the plug back into the draining position. The drain may further comprise a structure within the circular opening that supports the plug in the blocking position when the head portion is level with the drain and the bottom of the head portion is in physical contact with the drain structure. The structure may comprise holes so that water flows through the structure when the plug is in the draining position. If the user steps on the plug when the plug is in the blocking position, the plug may be depressed until the upper portion of the plug contacts the structure of the drain, at which point the user's weight is supported by the inner structure of the drain and the plug does not go down any further. If the drain has no inner structure, the plug may be depressed until the upper portion of the plug sits within the circular opening of the drain, if the user steps on the plug. At this point, the user’s weight is supported by the bath tub surrounding the drain. The plug sits within the opening and does not go down any further. Figure 5A illustrates a plug 500 according to a specific non-limiting example. The plug 500 is for use in a drain comprising a mechanism to raise and lower the plug. The plug comprises a head portion 510 for blocking the flow of water down the drain and an adjustable stem portion 520 for supporting the head portion. The plug comprises a seal 560 to assist with blocking the flow of water down the drain when the plug is in the blocking position in the drain. The seal may be formed from a deformable elastic material, such as rubber or silicone. The adjustable stem 520 further comprises a threaded bolt 570 and a first threaded nut 572. The first threaded nut 572 may be rotated relative to the threaded bolt 570 to adjust the vertical position of the first threaded nut 572. The adjustable stem portion 520 further comprises a bias 550. The bias 550 is fixed to the first nut 572 so that adjusting the vertical position of the first nut 572 adjusts the position of the bias 550 relative to the threaded bolt 570 and thereby adjusts the length of the stem portion 520. The bias 550 is configured to yield to an external force applied to the plug 500 and apply a resistive force to urge the plug back when the external force is removed. The adjustable stem 520 further comprises a second threaded nut 574. The first and second threaded nuts may be tightened against each other to lock in place and prevent further relative rotation and adjustment of the length of the adjustable stem. This is illustrated in Figure 5B. The first and second nut are illustrated as square nuts but may be hexagonal or octagonal nuts, for example. Figure 6 illustrates a cross-section of a plug 600 according to a specific non-limiting example. The plug comprises a head portion 610 for blocking the flow of water down the drain and a stem portion 620 for supporting the head portion. The stem portion comprises a rigid portion 680 and a bias 650. The bias is configured to yield to an external force applied to the plug and apply a resistive force to urge the plug back when the external force is removed. The bias 650 is concealed within a casing 682, which is moveable relative to the rigid portion 680 of the stem. By concealing the bias 650 within the casing 682 the plug may be less prone to gathering hair and other debris that is washed down the drain that may otherwise become lodged in the bias (especially if the bias is a spring). A sheaf (not illustrated) may be fitted around the stem (over the join between the cover and the rigid portion), to prevent water ingress to the concealed portion in which the spring is positioned. Trapped water in this concealed portion may hinder relative movement between the cover and the rigid portion because the spring is intended to be compressible but water is not compressible. Moreover, water may cause rusting of the spring. Additionally or alternatively, a drainage hole may be provided at the bottom of the cover, to allow water to drain from the concealed portion. The features of the plugs described in this application (such as a rubber seal, an adjustable stem, and a concealed bias) may be included separately or in combination. Due to mechanical constraints, there is a maximum distance that the bias may displace under the influence of an external force. Once this distance is reached, the bias will not displace further under normal conditions and forces applied to the plug head will therefore be transferred directly via the stem to the plug support. This distance may be referred to as the action length of the bias. This distance should be greater than the distance between the blocking and draining positions of the plug. When in the draining position, the plug can therefore be urged by the user (e.g. if the user steps on the plug) to the level of the drain (i.e. the same level as when the plug is in the blocking position), without actuating the plug raising / lowering mechanism (as a result of excess force being applied to the plug support). Experimentally, it is found that an action length of around 7mm is sufficient. To ensure the plug is suitable for different mechanisms having different distances between blocking and draining positions, it is suggested that a maximum action length of 20mm is provided. The force exerted by the bias should be sufficient to push the plug against water pressure that occurs when the bath starts to fill (so that the bias can break the seal and move the plug to the draining position). The force exerted also needs to be sufficient to support the weight of the plug and prevent the plug from being forced down by pressure exerted by water falling onto the plug (e.g. from a shower or faucet). Otherwise, the force of the water may urge the plug to the blocking position. Experimentally, the force exerted on the plug in an over-bath shower system was found to be no more than 3 Newtons. However, these forces were only recorded over short periods of time. It was found experimentally that a bias that is able to exert 1 Newton of force on the plug is sufficient to operate without being urged into the blocking position by forces from water. The force exerted by the bias when the plug is urged so that the upper portion is level with the drain needs to be less than a force required to manually actuate the mechanism. Otherwise, the bias may transfer too much force to the plug support and the mechanism may be inadvertently actuated when the user steps on the plug. Experimentally, forces in excess of 12 Newtons were found to actuate the plug mechanism. Therefore, a suitable bias may be one that does not exert forces greater than 12 Newtons when displaced by the maximum action length. If a rubber seal is used to facilitate an interference fit between the head portion of the plug and the drain, the force exerted by the bias (when the plug support is in the upper position and the upper portion of the head portion of the plug is in the blocking position) must be sufficient to overcome the interference fit and release the head portion from the drain. Experimentally, a force of 0.5 Newton was found to be sufficient to break the seal formed by the interference fit between the plug head and the drain. The bias may also need to support the weight of the plug itself and this weight may need to be taken into consideration. For heavier plugs, a stiffer bias may be needed. A standard plug was found to weigh around 50g and therefore can be supported by 0.5 Newtons of force from the bias. Experimentally, it is found that a suitable bias exerts a force of 2 Newtons when displaced by 7mm. A bias that exerts forces between 1 and 12 Newtons during operation may be suitable (when the bias is displaced between the unbiased length and the action length). Where the bias is a spring, the relationship between the force applied to the spring and the displacement of the spring may be given by Hooke’s law: F=kx Where F is the force in Newtons, k is the spring constant and x is the displacement of the spring in metres. A suitable spring constant may be 286N / m. Suitable springs may have a spring constant in the range of 100 to 1000 N / m (more preferably in the range 200 to 400) and the particular value may be selected depending on the specific parameters of the system. Where this application refers to an element as “a” or “an”, it will be understood that the disclosure is not limited to precisely one of the element but that one or more of each of the elements described may be provided, where appropriate.

Claims

CLAIMS: LL A plug for a drain, the plug comprising: a head portion configured to block flow of water down the drain when the head portion is in a blocking position level with the drain and configured to permit flow of water down the drain when the head portion is in a draining position above the level of the drain; and a stem portion configured to support the head portion in the draining position, wherein the stem portion comprises a bias configured to: yield to an external force applied to the head portion to move the head portion against the bias from the draining position to the blocking position; and urge the head portion from the blocking position to the draining position when the external force is removed.

2. The plug of claim 1, wherein the stem portion comprises: a lower end configured to engage a plug support of the drain below the level of the drain; and an upper end fixed to the head portion to support the head portion.

3. The plug of claim 2, wherein the plug is for a drain having an actuation mechanism configured to move the plug support between an upper position and a lower position, wherein the stem portion of the plug is configured to support the head portion in the draining position when the plug support is in the upper position, and wherein the head portion of the plug falls into the blocking position under gravity when the plug support is in the lower position.

4. The plug of any preceding claim, wherein the bias comprises a helical spring.

5. The bath plug of any preceding claim, wherein the head portion further comprises a deformable elastic seal around a perimeter of the head portion to facilitate an interference fit between the head portion and the drain and thereby block flow of water down the drain.

6. The plug of any preceding claim, wherein an unbiased length of the stem portion is adjustable.

7. The plug of claim 6, wherein the stem comprises a threaded portion and a corresponding threaded socket, which are rotatable relative to each other to adjust the unbiased length of the stem portion.

8. The plug of claim 7, wherein the threaded socket comprises a nut. 9, The plug of claim 8, wherein the nut is a first nut, wherein the stem further comprises a second nut adjacent to the first nut.

10. The plug of any preceding claim, wherein the stem portion further comprises a cover over the bias.

11. The plug of any preceding claim, wherein the plug is a bath plug for a bath drain.

12. A kit of parts for assembly to form a plug for a drain, the kit of parts comprising: a head portion configured to block flow of water down the drain when the head portion isin a blocking position level with the drain and configured to permit flow of water down the drain when the head portion is in a draining position above the level of the drain; a stem portion fixed to the head portion or fixable to the head portion so that the stem supports the head portion in the draining position; a bias fixed to the stem or fixable to the stem so that the bias is configured to: yield to an external force applied to the head portion to move the head portion against the bias from the draining position to the blocking position; and urge the head portion from the blocking position to the draining position when the external force is removed.

13. A plug system comprising: a plug according to any of claims 1 to 11; and a drain comprising a plug support and an actuation mechanism configured to move the plug support between an upper position and a lower position.

14. An over-bath showering system comprising: a shower; a bath; a plug system according to claim 13. 15; A method of manufacturing a plug, the method comprising: providing a head portion; fixing a stem portion to the head portion, wherein the stem portion has a longitudinal axis defining an upward and a downward direction, wherein the head portion is fixed to an upper end of the stem portion; and providing a bias in the stem portion, wherein the bias is configured to: yield to an external force applied to the head portion in the downward direction to move the head portion against the bias in the downward direction; and urge the head portion in the upward direction when the external force is removed. CLAIMS:

1. A plug for a drain having an actuation mechanism configured to move a plug support between an upper position and a lower position, the plug comprising: a head portion configured to block flow of water down the drain when the head portion is in a blocking position level with the drain and configured to permit flow of water down the drain when the head portion is in a draining position above the level of the drain; and a stem portion configured to support the head portion in the draining position, wherein an unbiased length of the stem portion is adjustable, wherein the stem portion comprises: a lower end configured to engage the plug support of the drain below the level of the drain; an upper end fixed to the head portion to support the head portion, wherein the stem portion of the plug is configured to support the head portion in the draining position when the plug support is in the upper position, and wherein the head portion of the plug falls into the blocking position under gravity when the plug support is in the lower position; and a bias configured to: yield to an external force applied to the head portion to move the head portion against the bias from the draining position to the blocking position; and urge the head portion from the blocking position to the draining position when the external force is removed.

2. The plug of any preceding claim, wherein the bias comprises a helical spring.

3. The plug of any preceding claim, wherein the head portion further comprises a deformable elastic seal around a perimeter of the head portion to facilitate an interference fit between the head portion and the drain and thereby block flow of water down the drain.

4. The plug of any preceding claim, wherein the stem portion comprises a threaded portion and a corresponding threaded socket, which are rotatable relative to each other to adjust the unbiased length of the stem portion.

5. The plug of claim 4, wherein the threaded socket comprises a nut.

6. The plug of claim 5, wherein the nut is a first nut, wherein the stem portion further comprises a second nut adjacent to the first nut.

7. The plug of any preceding claim, wherein the stem portion further comprises a cover over the bias.

8. The plug of any preceding claim, wherein the plug is a bath plug for a bath drain.

9. A kit of parts for assembly to form a plug for a drain having an actuation mechanism configured to move a plug support between an upper position and a lower position, the kit of parts comprising: a head portion configured to block flow of water down the drain when the head portion is in a blocking position level with the drain and configured to permit flow of water down the drain when the head portion is in a draining position above the level of the drain; a stem portion fixed to the head portion or fixable to the head portion so that the stem portion supports the head portion in the draining position, wherein an unbiased length of the stem portion is adjustable, wherein the stem portion comprises: a lower end configured to engage the plug support of the drain below the level of the drain; an upper end fixed to or fixable to the head portion to support the head portion, wherein the stem portion of the plug is configured to support the head portion in the draining position when the plug support is in the upper position, and wherein the head portion of the plug falls into the blocking position under gravity when the plug support is in the lower position; and a bias fixed to the stem or fixable to the stem so that the bias is configured to: yield to an external force applied to the head portion to move the head portion against the bias from the draining position to the blocking position; and urge the head portion from the blocking position to the draining position when the external force is removed.

10. A plug system comprising: a plug according to any of claims 1 to 8; and a drain comprising a plug support and an actuation mechanism configured to move the plug support between an upper position and a lower position.

11. An over-bath showering system comprising: a shower; a bath; a plug system according to claim 10.

12. A method of manufacturing a plug for a drain having an actuation mechanism configured to move a plug support between an upper position and a lower position, the method comprising: providing a head portion; fixing a stem portion to the head portion, wherein an unbiased length of the stem portion is adjustable, wherein the stem portion has a longitudinal axis defining an upward and a downward direction, wherein a lower end of the stem portion is configured to engage a plug support of a drain below the level of the drain, wherein the head portion is fixed to an upper end of the stem portion configured to support the head portion in a draining position when the plug support is in the upper position, and wherein the head portion of the plug falls into a blocking position under gravity when the plug support is in the lower position; and providing a bias in the stem portion, wherein the bias is configured to: yield to an external force applied to the head portion in the downward direction to move the head portion against the bias in the downward direction; and urge the head portion in the upward direction when the external force is removed.

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