GB2356564A - Overflow control fitting for a bath - Google Patents

Description

2356564 OVERFLOW SYSTEM This invention relates to an apparatus for

preventing the overfilling of a vessel with fluid and in particular but not exclusively to an apparatus for preventing the overfilling of a bathtub with water.

It is well known that the pressure of the mains water supply to a building depends upon both the distance of the nearest water tower to the building and upon the head of water from the water tower to the building. The pressure of a water supply within a building may also vary. For example, a hotel may be provided with a water tank in the loft for supplying water to the individual rooms, in which case the pressure of the water supply to a particular room will depend on how many floors below the water tank the room is situated. Each hotel room is typically provided with a bathroom and a bathtub and, due to the variation of the pressure of the water supply, on different floors the taps used for filling the bathtub will have different maximum flow rates. Although bathtubs are conventionally provided with an overflow to convey excess water from the bathtub to a drain, for some bathtubs the flow rate of the water f rom the taps into the bathtub exceeds the rate at which the overflow can 2 convey excess water to the drain. Thus there is a risk that if the taps should inadvertently be left on, or if a tap fails in the open position, that water will overflow the sides of the bath with consequential economic loss and structural damage. Accordingly there is a need to prevent such overflow.

According to one aspect of the present invention there is provided a flow control system for a vessel comprising a liquid supply means and a drain, the flow control system comprising:

overflow means situated at a predetermined height in the vessel for drawing liquid from the vessel; a flow rate sensor associated with the overflow means, the sensor being operable to provide an output when the flow rate through the overflow exceeds a predetermined flow rate; and control means responsive to the sensor output for controlling the liquid supply to the vessel.

An advantage of such an apparatus is that it prevents a bathtub from inadvertently being overfilled. A further advantage of such an apparatus is that it allows a person to start filling their bathtub and then leave the apparatus to turn of f the water supply to the bath 3 without danger of overfilling the bathtub.

Preferred embodiments of the present invention will now be described by way of example only and with reference to the following drawings of which:

Figure 1 shows a cross-section, in a vertical plane along the centre line of a bathtub, of the plumbing arrangements for a bath system according to a first embodiment of the present invention; Figure 2 shows a portion of the bath system of Figure 1 in more detail in the condition in which the bath system is overflowing; Figure 3 shows a schematic diagram of a control system suitable for use in conjunction with the bath system of Figure 1; and Figure 4 shows a cross-section, in a vertical plane along the centre line of a bathtub, of a second and preferred embodiment of the invention and also shows a portion of the bathtub to which the alternative embodiment is mounted. 25 4 Figure 1 shows a bath system 1 comprising a bathtub 3.

A cold tap 7 is connected to a cold water supply pipe 11 via a solenoid valve 9. Water 5 may be introduced into the bathtub 3 via the cold tap 7.

The nominal capacity of the bathtub 3, illustrated by the level of the water 5, is defined by the vertical offset of an overflow duct 17 above a water drainpipe 13. The overflow duct 17 allows water that is above the level of the overf low duct 17 to flow to a mains drainage system (not shown). The water drainpipe 13 connects to a mains drainage system (not shown) and allows water to be drained from the bathtub 3 when a bathplug 15 is removed from the water drainpipe 13.

An overflow assembly 19 connects the overflow duct 17 to the water drainpipe 13; water enters the overflow assembly 19 through an inlet duct 23 and leaves via an outlet duct 25. Mounted within the overflow assembly 19 are a magnetic float 27, a float cage 29 and a reed switch 3 1. An overflow strainer 21 prevents detritus from entering the overflow duct 17.

Note that whereas the cold tap 7 is mounted on the centre line of the bathtub 3, mounted to one side of the centre line and thus not visible in Figure I is a hot tap 33 (seen in Fig. 3) connected to a hot water supply pipe 37 via a normally open solenoid valve 35. Note also that the cold tap 7 has been shown at the end of the bathtub 3 remote from the water drainpipe 13 in order to improve the clarity of Figure 1; the taps 7, 33 may, more conventionally, be mounted at the same end of the bathtub 3 adjacent the water drainpipe 13.

To prepare the bathtub 3 for bathing, a user inserts the bath plug 15 into the water drainpipe 13, opens the taps 7 and 33, and waits until there is sufficient water in the bath. At this point the user would normally close the taps 7, 33. If the user does not close the taps 7, 33 then the bathtub 3 will continue filling until it reaches its nominal capacity of water 5 beyond which the excess water will flow via the overflow duct 17 and the overflow assembly 19 to the water drainpipe 13. 20 Figure 2 depicts a situation in which excess water is being added to a bathtub 3 which is already nominally full of water 5 and shows in more detail the junction between the inlet duct 23 and the outlet duct 25, and also illustrates outlet water 52 within the outlet duct 6 25, overflow water 50 falling down the inlet duct 23, backed-up water 5 1, the f loat cage 2 9, the magnetic f loat in an alternative position 271 and the reed switch 31.

As shown, the overflow water 50 passes through the overflow duct 17 and subsequently falls down the inlet duct 23 into a region of backed-up water 51. The backedup water 51 extends from the outlet duct 25 into the inlet duct 23 and arises because the cross-sectional 10 area, al, of the inlet duct 23, and of the overflow duct 17, is greater than the cross-sectional area, a2, of the outlet duct 25. At low f low rates all of the overflow water 50 will pass 15 as outlet water 52 through the outlet duct 25. However, at moderate flow rates the reduced cross-sectional area, a2, of the outlet duct 25 impedes the f low of the outlet water 52 and thus backed-up water 51 will accumulate. The surface of the backed-up water 51 is higher than the 20 level of the outlet duct 25 and results in a head of water, hl, which exerts a small pressure upon the outlet water 52 in the outlet duct 25. This small pressure acts to increase the flow rate of the outlet duct 25, bringing the flow rates of the overflow water 50 and the outlet water 52 into equilibrium.Higher overflow water 50 flow 7 rates will increase the extent to which the backed-up water 51 rises up into the inlet duct 23 until, at a sufficiently great flow rate, the entire inlet duct 23 becomes full of water and there is no longer any distinction between the overflow water 50 and the backed up water 51.

The float cage 29 is provided at the junction of the inlet duct 23 and the outlet duct 25 and constrains the magnetic float 27 to move vertically in response to the level of any backed-up water 51. Apertures which communicate with the inlet duct 23 and with the outlet duct 25 are provided in the float cage 29, so that as the level of the backed-up water 51 rises it can displace air from within the float cage 29.

At low overflow water 50 flow rates, the magnetic float 27 rests on the bottom of the float cage 29. As the flow rate of the overflow water 50 increases to moderate, backed-up water 51 will develop and the level of this backed-up water 51 will gradually increase, floating the magnetic float 27 until (with a sufficiently high flow rate) it comes to rest against the top of the f loat cage 29 in the position 27'. In the position 27, the magnetic field of the magnetic float 27 causes the reed switch 31

8 to become closed with the result that the solenoid valves 9, 35 are actuated to prevent any more water entering the bathtub 3 via the taps 7, 33.

Figure 3 is a block diagram of a control system 39, suitable for use in conjunction with the bath system 1, comprising a control unit 41, an isolating transformer 43 and an alarm sounder 45. Also illustrated is the cold tap 7, the hot tap 33, the solenoid valves 9, 35, the 10 cold water supply pipe 11 and the hot water supply pipe 37. For safety reasons, the control system 39 is not powered directly from the 240 volts AC mains electricity supply (in case an electrical connection inadvertently arises between the control system 39 and the water 5 in 15 the bathtub 3). In this embodiment, the isolating transformer 43 is used to provide a 12 volt DC supply to the control system 39. The control unit 41 comprises a relay and is operable to 20 energise the solenoid valves 9, 35, and to activate the alarm sounder 45 for a predetermined period, in response to the reed switch 31 becoming closed. The control unit 41 includes a latch circuit so that the solenoid valves 91 35 remain energised indefinitely; this latching 25 mechanism can only be reset by removing power from the 9 control unit 41.

The control unit 41 also includes a mechanism to close the solenoid valves 9, 35 for a predetermined period, for example five seconds upon the application of power to the control unit 41. This is because most solenoid valves require periodic operation in order to prevent them from seizing up and so this power-on mechanism allows the solenoid valves 9, 35 to be actuated simply by momentarily interrupting the mains electricity supply to the isolating transformer 43. of course, the solenoid valves 9, 35 could also be activated by deliberately allowing the bathtub 3 to become overfilled but this is unlikely to be a convenient way of performing the requisite actuation.

Figure 4 shows a portion of a bath system 101, according to a second and preferred embodiment of the invention, comprising an overflow adaptor 119, an O-ring seal 104 and a portion of a vertical sidewall of a bathtub 103.

Formed in the sidewall of the bathtub 103 is an overflow orifice 102 into which the overflow adaptor 119 is mounted.

The preferred embodiment allows the overflow adaptor 119 to be readily connected to the plumbing of the bathtub 103 and also allows the overflow adaptor 119 to be mounted with a stable orientation.

The overflow adaptor 119 comprises an overflow body 115 which may be formed from injection moulded plastic and which principally provides three functional regions:

(i) an inlet duct 123; (ii) an outlet duct 125; and (Iii) a float chamber 129.

The overflow orifice 102 in the bathtub 103 defines the nominal maximum capacity of the bathtub 103 (the overflow orifice 102 is thus similar to the overflow duct 17 illustrated in Figure 1). The overflow adaptor 119 comprises a flange 105 and is mounted on the bathtub 103 so that the flange 105 compresses the O-ring seal 104 against the exterior of the bathtub 103 and so that the inlet duct 123 protrudes into the bathtub 103. The inlet duct 123 is provided with a threaded portion 124 so that an integrated securing nut and overflow strainer (not shown) may be used to secure the overflow adaptor 119 to the bathtub 103.

The inlet duct 123 receives overflow water from the 11 bathtub 103 and conveys this excess water to the outlet duct 125. Located within the inlet duct 123 is a feeder tube 110 which is arranged so that it lies at the top of the inlet duct 123 when the overflow adaptor 119 is mounted in its normal orientation. one end of the feeder tube 110 is co-terminous with the inlet duct 123, the other end opens into the f loat chamber 129 so that, if the level of water in the bathtub 103 rises to the top of the inlet duct 123, water may pass through the feeder tube 110 into the float chamber 129. In this embodiment, the inlet duct 123 has a bore of 34mm and the feeder tube has a bore of 6mm.

Water that enters the overflow body 115 via the inlet duct 123 is able to leave via the outlet duct 125. The outlet duct 125 is a circular tube with a bore of 19mm and is provided at its extremity with an annular lip 126.

overflow water from the bathtub 103 may pass through the outlet duct 125 to a mains drainage system (not shown) via a corrugated plastic pipe (not shown). one end of the plastic pipe connects to the outlet duct 125 whilst the other end connects to a water drainpipe (not shown) that is similar to the water drainpipe 13 of Figure 1.

The corrugated plastic pipe is retained on the outlet duct 125 by the annular lip 126 which allowsthe 12 corrugated plastic pipe to be relatively easily pushed onto the outlet duct 125 but makes removal of the corrugated plastic pipe more difficult.

A portion of the overflow body 115 is adapted to form the float chamber 129. The float chamber 129 is a cylindrical chamber and is arranged so that its axis is vertical when the overflow adaptor 119 is mounted for normal use. Water may enter the float chamber 129 via the feeder tube 110 which extends radially a small distance into the float chamber 129. The top face of the f loat chamber is open. A reed switch 131 is glued onto the bottom of the float chamber 129, so as to form a waterproof seal, and extends along the axis to the top of the float chamber 129. In this embodiment the float chamber 129 has a height of 30mm.

An annular magnet 128 is centrally and coaxially mounted within a magnetic float 127. The magnetic float 127, and hence the annular magnet 128, is free to move vertically about the reed switch 131 in response to the level of any water which may be present within the float chamber 129.

A ci-rclip 133 prevents the magnetic float 127 from becoming detached from the reed switch 131. Lead out wires132 connect the reed switch 131 to the control 13 system 39 described above in connection with Figure 3.

In use, if the bathtub 103 becomes overfilled with water then the excess water will f low through the inlet duct 123 and out of the outlet duct 125 to the mains drainage system. If the level of water in the bathtub 103 continues to rise then eventually the water will reach the level of the feeder tube 110 (at the top of the inlet duct 123) and will flow into the float chamber 129 until at some level the magnetic float 127 will raise the annular magnet 128 sufficiently far up the reed switch 131 to open/close the contacts of the reed switch 131, thereby causing the control system 39 to activate the solenoid valves 9, 35 and stop the flow of water into the bathtub 103.

Modifications to the bath systems 1, 101 and the control system 39 hitherto presented will now be discussed.

In the embodiments previously discussed, the overflow duct 17 and the inlet duct 23 were substantially horizontal. In alternative embodiments, they may instead be inclined, either upwards or downwards. 25 In a modification to the overflow adaptor 119, the float chamber 129 is dispensed with and the magnetic float 127, together with the reed switch 131, is positioned in the inlet duct 123. A suitable position in the inlet duct 123 is indicated by the line AA, in Figure 4. The overflow body 115 may conveniently be sealed across the line BBI in Figure 4, and the feeder tube 110 may be dispensed with. An advantage of this modification is that the overflow adaptor is simplified by the omission of the float chamber 129, and that the overflow adaptor becomes watertight from the inlet duct 123 through to the outlet duct 125.

In a further modification to the overflow adaptor 119, the feeder tube 110 and the float chamber 129 may be retained but the feeder tube 110 (and, correspondingly, the float chamber 129) may be located at an alternative position, for example half way up, or at the bottom of, the inlet duct 123. These alternative positions for the feeder tube 110 and the float chamber 129 would allow the reed switch 131 to be activated when the inlet duct 123 is only partially full of overflowing water.

In a yet further embodiment of the overflow adaptor, the outlet duct may have a greater bore, and hence flow capacity, than the inlet duct.For this yet further embodiment, the feeder tube 110 -is preferably modified so that it is no longer co-terminous with the plane of the inlet duct but instead extends beyond the inlet duct into the bathtub 103. This extension of the inlet tube would allow the level of the water in the bathtub 103 to be sensed even though the constriction (referred to in an earlier embodiment in terms of al and a2) is now provided by the inlet duct.

In alternative bath systems, the control unit may be directly connected to the mains electricity supply or may be powered by batteries.

The solenoid valves 9, 35 are of the normally open type although, with suitable modifications to the control unit 41, normally closed solenoid valves could be used instead. An advantage of using normally open solenoid valves is that the Water Research Council (WRC), which is the body responsible in the UK for approving components for connection to the water supply, has a preference for normally open valves as these are less likely to stagnate and accumulate bacteria than normally closed valves.

Another advantage of using a normally open solenoid valve is that such a valve may be directly connected to the reed switch 31 and isolating transformer 43, in which 16 case the reed switch 31 would itself act as a control unit. However an advantage of using normally closed solenoid valves is that in the event of a power cut they will close and prevent water from being introduced into the bathtub 3.

other types of valve may be used instead of solenoid valves, for example, motorised butterfly valves. In some situations the water may be supplied to the taps 7, 33, by an electric pump in which case solenoid valves would not be required as the f low of water could be stopped by using the reed switch 31 to control the supply of power to the electric pump.

Although in the embodiment previously described, solenoid valves 9, 35 were used which completely stopped the flow of water through them, in an alternative embodiment a different type of solenoid valve is used which merely restricts the flow of water. The overriding requirement to prevent the bathtub 3 from being overfilled is that the (combined) f low rate of the taps 7, 33 is reduced to below the f low rate of the outlet duct 25, thereby ensuring that the overflow duct 17 and overflow assembly 19 can discharge any excess water in the bathtub 3 and any extra water flowing from the taps 7, 33 to the water 17 drainpipe 13.

In a further embodiment, the solenoid valves 7, 35 are dispensed with and an electric pump Is used to pump the excess water out of the bathtub 3, thereby augmenting the overflow assembly 19 so that the total flow rate of water out of the bathtub 3 exceeds the f low rate of the taps 7, 33.

In a modified control unit the activation of the solenoid valves 9, 35 is not latched. If the bathtub 3 overfills for this modified embodiment, the solenoid valves 9, 35 will be brief ly actuated, until the level of the backed up water 51 drops below the outlet duct 25, at which point the solenoid valves 9, 35 will open again and the bathtub 3 will start refilling until an excessive level of backed-up water 51 is produced again. This cycle may continue indefinitely.

As an alternative to the reed switch 31, a Hall effect sensor may be used to detect the position of the magnetic float 27. A Hall sensor with a proportional output may be used to indicate the position of the magnetic float 27 (instead of merely indicating if a threshold level has been reached) and may thus be used to actuate the 18 solenoid valves in proportion to the water level.

Differential and integral responses could also be used, in addition or alternatively, to actuate the solenoid valves.

As an alternative to constraining the magnetic float 27 within the float cage 29, a float with an optically reflective portion on its top may be attached via a lateral cantilever to a modified inlet duct and the position of this reflective float may be sensed by an optical proximity sensor via a transparent portion provided in the overflow assembly. In a yet f urther embodiment, the float could be dispensed with altogether and an optical sensor, f or example of the total internal reflection type, could be used to detect the level of any backed-up water 51 within the inlet duct 23.

In the embodiment of the bath system 1, the overflow assembly 19 was provided with an inlet duct 23 having a cross-sectional area, al, greater than that, a2, of the outlet duct 25. However, the overriding requirement is that the maximum flow rate of the overflow duct 17, and of the inlet duct 23, is greater than the maximum f low rate of the outlet duct 25. This could alternatively be achieved by using a modified overflow assembly in which, 19 instead of having a distinct inlet duct 23 and outlet duct 25, the bore of the modified overflow assembly continuously tapers from the overflow duct 17 to the water drainpipe 13 (narrowing towards the water drainpipe 13). In a yet further alternative, an overflow assembly may have a uniform cross-section from the overflow duct 17 to the water drainpipe 13 but be provided with an extended outlet duct of such great length that viscous fluid effects of the water result in the extended outlet duct having a reduced flow rate (compared to the relatively short inlet duct 23 in the vicinity of the magnetic float 27), thereby causing water to become backed up in the inlet duct. In another modification, the bores of the inlet duct 23 and outlet duct 25 are identical but an obstruction mounted in the outlet duct reduces the flow rate of the outlet duct 25.

In a further embodiment, a modified overflow assembly does not connect to the water drainpipe 13 but instead has a separate connection to a mains drainage system.

The above-described overflow assemblies are suitable for either replacing the overflow conduit of a bath system or are suitable for connection between a bath and an overflow conduit. In an alternative embodiment, which is particularly suitable for retro-fitting to existing bath systems, the overflow conduit may be cut and the overflow flow rate sensor may be inserted in-line between the two pieces of the cut conduit. 5 Although the overflow system according to the present invention has been described in terms of a bath system, it may also be applied, for example, to showers, sinks and bidets. Furthermore, the overflow system may also be used in conjunction with fluids other than water.

21 claims 1. An overflow control system comprising:

a vessel comprising an overflow at a predetermined level for discharging liquid from the vessel and a drain for draining liquid from the vessel; an overflow detector for detecting a condition in which liquid f lows out of the overflow at a f low rate that exceeds a predetermined f low rate; a liquid control means for reducing the rate at which liquid accumulates in the vessel; and a control unit operable to activate the liquid control means in response to a signal from the overflow detector.

2. An overflow control system according to claim 1, further comprising an inlet for introducing liquid into the vessel and wherein the liquid control means comprises a solenoid valve for reducing the f low rate of liquid through the inlet.

3. An overflow control system according to claim 1 or claim 2, wherein the control unit comprises a latch means.

22 4. An overflow control system according to any of claims 1 to 3, wherein the vessel is a bathtub.

5. An overflow detector for use in an overflow control system according to claim 1, comprising:

a conduit comprising an inlet for connection to the overflow, and an outlet for draining liquid from the conduit; and a sensor for sensing a condition in which liquid flows through the conduit at a flow rate that exceeds a predetermined flow rate.

6. An overflow detector according to claim 5, wherein the sensor is located inside the conduit.

7. An overflow detector according to claim 5 or claim 6, wherein the sensor is operable to sense the condition via a tube.

8. An overflow detector according to any of claims 5 to 7, wherein the conduit comprises a constriction.

9. An overflow detector according to claim 8, wherein the constriction is at the inlet.

23 10. An overflow detector according to any of claims 5 to 9, wherein the sensor comprises a f loat.

11. An overflow detector according to claim 10, wherein the float is magnetic.

12. An overflow detector according to claim 11, wherein the sensor comprises a reed switch.

13. An overflow detector according to any of claims 5 to 12, wherein said overflow control system further comprises a conduit for connecting the overflow to a mains drain, and wherein the overflow detector is adapted for in-line insertion into the conduit.

14. The combination of:

a vessel comprising an overflow at a predetermined level for discharging liquid from the vessel and a drain for draining liquid from the vessel; and an overflow detector according to any of claims 5 to 13.

15. The combination according to claim 14, wherein the overflow detector is an integral part of -the vessel. 25 24 16. An overflow detector as hereinbef ore described with reference to or as shown in Figures 1, 2 or 4.

17. An overflow control system as hereinbef ore described with reference to or as shown in Figure 3.