GB2380796A

GB2380796A - Domestic bath level warning or control device

Info

Publication number: GB2380796A
Application number: GB0208910A
Authority: GB
Inventors: Malachi Christopher Mckenna
Original assignee: Individual
Current assignee: Individual
Priority date: 2001-04-18
Filing date: 2002-04-18
Publication date: 2003-04-16
Anticipated expiration: 2022-04-18
Also published as: GB0208910D0; GB0109552D0; GB2380796B

Abstract

A device for determining when a bath 101 has been filled to a predetermined level comprises a flow diverter (in chamber C of mixer tap 15) which diverts a control flow 52 of water along a pipe 20 into a control chamber 40, and sensing means 42 which determines when the control chamber 40 is full, and operates an alarm or turns off flow to the tap. As shown a float 42 with a magnet 43 operates reed switch 46 to actuate an audible or visual alarm or close hot and cold solenoid valves 11a, 11b. The level to which the bath fills may be varied by an adjustable constriction 30 which varies the rate at which the control chamber 40 fills. Depending on the position of the level selector 32 the bath may contain 100, 90 or 75 litres of water when the control chamber 40 is full. Alternatively the float may actuate one of three reed switches. In Fig 5, a float (142) in a sector-shaped control chamber (140) actuates via swing arm a rotary valve (111) in inlet pipe (110) to close off flow to the bath when the control chamber is full. The float may be replaced by optical or capacitive sensors or load cells.

Description

BATH FILLING CONTROL SYSTEM This invention relates to an apparatus and a method for automatically filling a container, more particularly but not exclusively a bathtub, with liquid to a substantially predetermined level.

In many circumstances it is inconvenient for a bather to have to supervise the running of water into a bathtub as the user must remain in the vicinity of the bathtub until it is filled to the level desired by the bather. If the bather does not monitor the entry of water into the bathtub with sufficient diligence, then the bathtub may become overfilled with water. Overfilling a bathtub generally entails wasted energy as warm water is discharged to a drain. In more extreme cases of overfilling the water may be discharged through an overflow outlet in the bathtub or if the outlet is blocked, over the sides of the bathtub and onto the floor.

Accordingly, there is a need for an apparatus to allow a bathtub to be automatically filled to a predetermined level.

According to the present invention there is provided an

apparatus for inferring the level of liquid in a vessel, the apparatus comprising: a storage vessel for storing liquid; a flow division means for separating a substantially predetermined proportion of a flow of liquid into the vessel away from a remainder of the flow, and passing the predetermined proportion of the flow into the storage vessel; and sensing means for sensing the amount of liquid accumulated in the storage vessel and outputting a signal indicative of said amount.

There is also provided a method for controlling the entry of liquid into a vessel by sensing the amount of liquid accumulated in a storage vessel.

Preferred embodiments of the present invention will now be described by way of example only and with reference to the following drawings, in which: Figure 1 shows a schematic perspective view of the principal components of a first embodiment of the invention; Figure 2 shows a cross-section, in a vertical plane XX, through an installation including the principal

components illustrated in Figure 1 ; Figure 3a shows a cross-section through an adjustable constriction in a first position; Figure 3b shows a cross-section through the adjustable constriction in a second position; Figure 3c shows a cross-section through the adjustable constriction in a third position; Figure 4 shows a block diagram of a control system for the embodiment illustrated in Figures 1 and 2; Figure 5a shows a cross-sectional view of the principal components in a second embodiment of the invention; and Figure 5b shows in more detail the region designated Y in Figure 5a.

Figure 1 shows a filling system 1 for allowing a predetermined quantity of water to fill a bathtub 101 (only a part of the rim of which is shown). Hot and cold water from feed pipes 10a, lOb, respectively, is allowed to pass through respective solenoid valves lla, lib and stub pipes 12a, 12b to a mixer tap 15. The solenoid

valves lla, 11b open and close in response to an electric current which is supplied by solenoid valve leads 13a, 13b respectively, from a control system (which will be discussed below).

The mixer tap 15 has a tap handle 16a for controlling the rate at which hot water is allowed into the bathtub and a tap handle 16b for controlling the rate of the cold water. The mixer tap 15 also has a spout 17 from which bathtub water 18 is shown entering the bathtub 101.

Hot and cold water from the stub pipes 12a, 12b mixes in a chamber C within the mixer tap 15 and exits via the spout 17. Water from chamber C also passes along a sense pipe 20 to an adjustable constriction 30.

The adjustable constriction 30 has a level selector 32 which selects one of three aperture settings for the adjustable constriction 30 and hence selects one of three flow rates of water, from the chamber C via the sense pipe 20, through an accumulation pipe 21. The accumulation pipe 21 conveys water from the adjustable constriction 30 to an accumulation chamber 40. The three flow rates correspond to three predetermined levels of water in the bathtub 101.

The adjustable constriction 30 divides away a predetermined proportion of the water flowing through the chamber C and passes the divided water to the accumulation chamber 40. In this embodiment the ratio of the flow rate of bathtub water 18 to that of divided water is 100: 1. In other words, if 100 litres of water enters the bathtub then 1 litre of water will enter the accumulation chamber 40.

At the top of the accumulation chamber 40 there is provided an air vent pipe 45 which vents the accumulation chamber 40 to the atmosphere. Also shown is a reed switch 46 (having reed switch leads 48) mounted towards the top of the accumulation chamber. An accumulation chamber drain valve 47 allows the bather to drain water from the accumulation chamber 40 via a drain pipe 44.

Figure 2 shows the principal parts of the filling system 1 in a cross-sectional view. The cross-section is in a vertical plane along the line XX (the centreline of the bathtub 101) of Figure 1. Note that although the feed pipes lOa, lOb, solenoid valves lla, llb, stub pipes 12a, 12b and solenoid valve leads 13a, 13b are not in the cross-sectional plane they are nonetheless shown in dashed lines to facilitate understanding of the invention. Parts shown in Figure 2 that are also shown

in Figure 1 are identified by the same reference numerals.

Figure 2 also shows a flow of water 50 from the chamber C. The water 50 is separated into two streams. One stream is a stream 51 of bathtub water 18 that flows along the spout 17, out of a tap nozzle 19 and then falls into the bathtub 101. The other stream is a stream 52 of sense water 55 that flows through the sense pipe 20 and through the adjustable constriction 30. Sense water 55 leaving the adjustable constriction 30 then flows through the accumulation pipe 21 and drips into the accumulation chamber 40 as a series of drops of water 53.

The drops of water 53 gradually accumulate as accumulated water 54 within the accumulation chamber 40 and cause the float 42 to rise gradually. The float 42 comprises a magnet 43 and once the float 42 has risen to an actuation position 42' (shown in dashed lines), the magnetic field from the magnet 43 closes the contacts of the reed switch 46. As is discussed later, the closing of the reed switch 46 contacts is used as a signal to cause the closure of the hot and cold solenoid valves lla, llb.

In this embodiment the float 42 will reach the actuation position 42'when the accumulation chamber contains 1

litre of accumulated water 54. Due to the 100: 1 division ratio between the stream 51 and the stream 52, respectively, if bathtub water 18 enters the bathtub at a rate of 20 litres a minute (for example) then sense water 55 will accumulate within the accumulation chamber 40 at a rate of 0.2 litres per minute.

The level selector 32 is a cylindrical bar with a handle at one end to allow a bather to move it longitudinally along a bore 34 defined in the adjustable constriction 30. The level selector 32 may be moved to one of three positions with respect to the bore 34. One of these positions corresponds to the aforesaid 100: 1 division ratio while the other positions correspond to ratios of 90: 1 and 75: 1. Three parallel passages 33a, 33b, 33c are provided in the adjustable constriction 30. Each of the passages 33a, 33b, 33c intersects at right angles to the longitudinal axis of the bore 34 and each is connected at one end to the sense pipe 20 and at the other end to the accumulation pipe 21.

Figures 3a, 3b and 3c show the adjustable constriction 30 with the level selector 32 in first, second and third positions respectively.

In Figure 3a, only the first passage 33a is unobstructed

by the level selector 32. The first passage 33a has a flow rate that is 0.01 of the flow rate of the spout 17 and tap nozzle 19, thus giving a division ratio of 100: 1.

In Figure 3b, the level selector 32 is in the second position in which the first and second passages 33a, 33b are unobstructed whilst the third passage 33c is obstructed. The second passage 33b has a flow rate that is 0.0011 of the flow rate of the spout 17 and tap nozzle 19. Thus the combination of the first and second passages 33a, 33b gives an aggregate flow rate which is 0.0111 of the flow rate through the spout 17 and tap nozzle 19. Consequently, the division ratio is reduced from 100: 1 (in Figure 3a) to 90: 1.

In Figure 3c the level selector 32 is in the third position in which the first, second and third passages 33a, 33b, 33c are all unobstructed. The third passage 33c has a flow rate that is 0.0022 of the flow rate of the spout 17 and tap nozzle 19. Thus the combination of the three passages gives an aggregate flow rate which is 0.0133 of the flow rate through the spout 17 and tap nozzle 19. Consequently, the division ratio is reduced from 90: 1 (in Figure 3b) to 75: 1.

The cross sectional areas and/or the effective lengths

of the first, second and third passages 33a, 33b, 33c are different from each other in order to give the division ratios mentioned above. Of course, the flow rates of the first, second and third passages 33a, 33b, 33c are all much lower than the flow rate through the spout 17 and tap nozzle 19.

With the level selector 32 in the first position, the accumulation chamber will contain one litre of accumulated water 54 (at which point the contacts of the reed switch 46 will close) when the bathtub 101 contains 100 litres of bathtub water 18. With the level selector 32 in the second and third positions, respectively, the bathtub 101 will contain 90 and 75 litres of water when the contacts of the reed switch 46 become closed.

Thus depending on the position of the level selector 32, the adjustable constriction 30 allows a bather to select whether the bathtub is automatically filled with 100,90 or 75 litres of water.

Note that in this embodiment the adjustable constriction 30 is arranged so that the first passage 33a cannot be obstructed by the level selector 32. Therefore, the maximum amount of water with which the bathtub may be filled is 100 litres and it is not possible for a user

to inadvertently overfill the bathtub 101. By moving the level selector 32 to one of its other two positions, the second and third passages 33b, 33c may also be unobstructed so that the bathtub 101 may instead be filled to a lower water level (either 75 or 90 litres) of water. Thus, in effect, the filling system 1 provides a system for preventing the overfilling of the bathtub 101 (which could otherwise result in water overflowing the rim of the bathtub if the mains water pressure is such that water can enter the bathtub faster than it can be drained away by a safety overflow (not shown) ) and also provides a system for allowing a user to select the level to which the bathtub 101 is automatically filled.

A seal (not shown) prevents water escaping from around the stem of the level selector 32 and the bore 34.

Figure 4 shows a control system 60 which controls the solenoid valves lla, llb in response to the closing of the reed switch 46. A power supply 62 takes a 240 volt 50 hertz mains input and reduces this using a transformer to an isolated 12 volt DC output which powers a control unit 61. An advantage of using an isolated low voltage supply is that it reduces the risk of electric shock to a bather should a fault inadvertently develop. When the contacts of the reed switch 46 are closed then the

control unit 61 energises the solenoid valves lla, lib in order to shut off the water supply to the mixer tap 15, thereby preventing any further water 18 from entering the bathtub 101 or accumulation chamber 40.

The control unit 61 also activates an alarm sounder 63 for a period of one minute. Should the bather not be in the immediate vicinity of the bathtub 101, the alarm sounder 63 will alert the bather that the bathtub 101 contains water to the desired level and that the bather may commence bathing.

Once the contacts of the reed switch 46 have been closed the solenoid valves lla, lib will remain closed unless the float 42 descends inside the accumulation chamber 40.

As shown in Figure 2, a drain pipe 44 and drain valve 47 are provided to allow water to be drained from the accumulation chamber 40. By using the drain valve 47 to drain the water from the accumulation chamber 40, a bather may top up the bathtub 101 with more hot water. In this embodiment the drain valve 47 is operated by a non-latching pushbutton so that the drain valve 47 cannot inadvertently be left open whilst the bathtub 101 is being filled with water.

The drain valve 47 also allows the accumulation chamber

40 to be completely drained, thus resetting the filling system 1 so that the bathtub 101 may once again be automatically filled to a level determined by the level selector 32.

The air vent 45 allows air to enter or escape the accumulation chamber 40 during the discharge or entry, respectively, of accumulated water 54 from the accumulation chamber 40.

Figure 5a shows a cross-section, in a vertical plane, of a filling system 2 according to a second embodiment of the invention. There is shown a bathtub 101 with an overflow aperture 170 leading to an overflow conduit 171.

The overflow conduit 171 conveys any water that overflows through the overflow aperture 170 to aU-bend 172. The top of the U-bend 172 is shown sealed by an ejectable plug 173 which rests on a push rod 184. The push rod 184 passes through the bottom of the U-bend 172 via a watertight seal 174 and is connected to a bar 182 which is centrally pivoted about a pivot 183. The end of the bar 182 opposite to the push rod 184 is connected to a second push rod 180 and the second push rod 180 passes through the top of the bathtub 101 and ends in a knob 181. The second push rod 180 also connects to a crank 185.

In Figure 5a the second push rod 180 and connected parts are shown in a first position in which the ejectable plug 173 forms a seal with the bathtub 101. If the bather pushes down on the knob 181 then the bar 182 and crank 185 will move to a second position, shown in dotted lines at 182'and 185', in which the ejectable plug 173 is raised to an open position and no longer seals the bathtub 101, thus allowing bathtub water 118 to leave the bathtub via the U-bend 172.

A feedpipe 110 conveys water from a mains supply to a rotary valve 111 and from there via a stub pipe 112 to a tap 115. The tap 115 is operated by a tap handle 116 allowing water to pass along a spout 117.

A flow divider 130 is attached to the spout 117 by means of a push fit and divides the water leaving the spout 117 into a portion 118 for the bathtub 101 and a smaller portion for an accumulation chamber 140. The flow divider 130 is shown in more detail in Figure 5b.

Figure 5b shows an enlarged view of the flow divider 130 attached to the discharge end of the spout 117. The flow divider 130 has a discharge orifice 119 having a crosssectional area al, and a sense aperture 133 having a

cross-sectional area a2. The ratio of al: a2, in this embodiment, is 100: 1 and thus when water flows out of the discharge orifice 119 and into the bathtub 101, a proportionally smaller flow passes through the sense aperture 133. The sense aperture 133 is connected via a sense pipe 121 to the accumulation chamber 140. The sense pipe 121 has a greater cross-sectional area than the sense aperture 133 in order to ensure that the division ratio of the flow divider 130 is substantially independent of the length of the sense pipe 121.

The accumulation chamber 140 is formed as a chamber enclosing the rotary valve 111 and contains a float 142 mounted at one end of a swing arm 141. The accumulation chamber 140 has a sectorial shape and, as shown, extends over a quadrant. The other end of the swing arm 141 is pivoted about a horizontal axis of the rotary valve 111 and therefore vertically arcuate motion of the float 142 within the accumulation chamber 140 will be converted by the swing arm 141 into rotary motion at the rotary valve 111. Thus the rotary valve 111 opens and closes in response to the position of the float 142.

Figure 5 also shows drips 153 of water from the sense pipe 121 accumulating as accumulated water 154 in the accumulation chamber 140. An air vent 145 allows air

displaced by the entry of the drops 153 to escape the accumulation chamber 140. As more and more water accumulates in the accumulation chamber 140 during the filling of the bathtub 101, the float 142 gradually rises, and the swing arm 141 gradually rotates the valve of the rotary valve 111, until eventually the float 142 rises to a position 142' (shown in dotted lines). In the position 142'the float 142 fully closes the rotary valve 111, preventing any further water 118 from entering the bathtub 101.

The full angular range of the swing arm 141, as the float 142 moves from the bottom to the top of the accumulation chamber 140, is 900. However, to ensure that the bathtub 101 is rapidly filled with water to the predetermined level the rotary valve 111 is only operated during the uppermost 100 of travel of the swing arm 141. Thus the bathtub 101 will rapidly fill to near the predetermined level and then will fill progressively more slowly until the predetermined level is attained.

The volume of the accumulation chamber 140 is 0.8 litres and thus, as the division ratio is 100: 1, the filling system 2 automatically fills the bathtub 101 with 80 litres of water.

The bottom of the accumulation chamber 140 is connected via a drain pipe 144 to a rotary drain valve 147 and from thence to the overflow conduit 171. The drain valve 147 is controlled by the crank 185 and is closed when the second push rod 180 is in the position shown in Figure 5a. However, when the knob 181 is pushed downwards to eject the ejectable plug 173, the crank 185 moves to the second position 185'in which the drain valve 147 is opened thus draining the accumulation chamber 140.

One end of the air vent pipe 145 connects to the top of the accumulation chamber 140 whilst the other end connects to the overflow conduit 171 in the vicinity of the overflow aperture 170. This arrangement ensures that, should the accumulation chamber 140 become over filled due to a fault, water may harmlessly escape via the overflow conduit 171.

As those skilled in the art will appreciate, a variety of modifications may be made to the filling systems 1, 2 described earlier. For example, the adjustable constriction 30 had three alternative settings. In an alternative embodiment a single passage may intersect with the bore 34 and the level selector 32 may be threaded so that by rotating the level selector 32 relative to the adjustable constriction 30, the degree

to which the level selector 32 obstructs the bore 34 may be continuously adjusted. Such a modification would allow, for example, the predetermined amount of bathtub water 18 to be continuously varied between 40 and 120 litres. Alternatively, the effective volume of the accumulation chamber 40 may be varied by moving the reed switch 46 vertically with respect to the accumulation chamber 40.

Another way of providing three settings is to provide the accumulation chambers 40,140 with three reed switches, at different heights. A bather would select a bath level by using a switch to select the corresponding reed switch. Four settings could be provided by using two reed switches in conjunction with two different constrictions.

In the embodiments described earlier the adjustable constriction 30 and mixer tap 15, and the flow divider 130 and the tap 115, were separate. In alternative embodiments these may be integrated into a single unit. Furthermore, although preferably both the hot and cold water are controlled by a filling system according to the present invention, the system may be used to control hot water only or cold water only.

In a modification to the filling system 2 shown in Figure 5a, the rotary valve 111 is replaced by a section of resilient pipe and the swing arm 141 is arranged to squeeze and thereby constrict the resilient section as the float 142 rises within the accumulation chamber 140.

Such an embodiment offers the potential advantage of lower manufacturing costs. Instead of the adjustable constriction 30, a resilient section of pipe between the sense pipe 20 and accumulation pipe 21 could be used, in an alternative embodiment, in conjunction with an adjustable clamp to provide a continuous range of predetermined levels of water in the bathtub 101.

In another modification to the filling system 2, provision is made to allow a bather to top up the bathtub 101 with more water. This may be done by allowing the bather to drain some of the accumulated water 154 from the accumulation chamber 140 using either a spring loaded valve (having the same effect as the drain valve 47 of the filling system 1) or by allowing the bather to push the float 142 down inside the accumulation chamber 140 (for example by using a push rod).

Another way in which the filling system 1 could allow the bathtub 101 to be topped up with more water is through the use of an electrical switch, instead of through the

use of the drain valve 47. The electrical switch would be wired in series with the reed switch 46 and would cause the solenoid valves lla, llb, to open, thereby allowing more water into the bathtub 101. The electrical switch would preferably be non-latching to prevent it from inadvertently being left in the open position.

The control system 60 closed the solenoid valves lla, lib and also activated the alarm sounder 63. In an alternative embodiment the solenoid valves lla, lib are dispensed with and the alarm sounder 63 is activated to alert the bather that the bathtub 101 contains water 18 to the predetermined level.

Hitherto, the amount of water in the accumulation chambers 40,140 has been detected by sensing the level of the floats 42,142. In alternative embodiments optical or capacitive sensors may be used to determine the level of the accumulated water 54,154.

Alternatively, the weight of the accumulated water 54, 154 within the accumulation chambers 54,154 could be sensed using electronic load cells. Furthermore, the accumulation chambers 54,154 need not be rigid but may instead be flexible bladders. The use of bladders removes the need for air vents 45,145. In yet another embodiment, the accumulation chambers 40,140 are not

drained by gravity but are instead emptied using an electrically-powered pump.

The accumulation chambers 40,140 have been shown mounted beneath the rim of the bathtub 101. In alternative embodiments, the accumulation chambers 40,140 may be mounted above the rim of the bathtub 101, and may conveniently be used as a pedestal on which the taps 15, 115 are mounted. Preferably, at least a portion of the accumulation chambers 40,140 is sufficiently transparent to allow a bather to monitor the progress of the filling of the bathtub 101 without having to stand over the bathtub 101.

Although the filling systems 1,2 have been described in terms of controlling the entry of water into a bathtub 101, it is also anticipated that, for example, sinks or other sanitary vessels may be automatically filled with water using the filling systems 1,2.

Furthermore, although it is preferred that the flow of water into the bathtub 101 ceases once the predetermined level has been reached, in alternative embodiments the flow rate of the water is instead reduced. As long as the bather returns to the bathtub 101 within a sufficiently brief period after the reduction of the

flow, the level of water in the bathtub 101 will substantially be at the predetermined level.

In an earlier embodiment, an audible alarm was raised once the predetermined level was attained. In an alternative embodiment the alarm is signalled by the flashing of a strobe lamp to alert the bather.

In the filing system 2, a mechanical linkage was used between the pushrod 184 and the drain valve 147. In an alternative embodiment the linkage may be made using an electrical circuit and solenoid actuators to move the respective parts.

Claims

CLAIMS 1. An apparatus for determining whether a substantially predetermined quantity of liquid has flowed into a vessel, the apparatus comprising: a storage chamber for containing liquid; a flow divider for receiving a flow of liquid and dividing the flow of liquid into a first portion and a second portion, the first portion being directed into the vessel and the second portion being directed into the storage chamber; and sensing means for sensing whether the storage chamber contains a predetermined quantity of liquid and outputting a signal when the storage chamber contains said predetermined quantity of liquid.
2. An apparatus according to claim 1, wherein the sensing means is operable to sense the volume of liquid contained by the storage chamber.
3. An apparatus according to claim 1 or 2, wherein the second portion is a fixed proportion of the flow of liquid into the vessel.
4. An apparatus according to claim 1 or 2, further comprising adjusting means for adjusting the ratio of the

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first portion to the second portion.
5. An apparatus according to claim 4, wherein the adjusting means is operable to adjust the ratio to one of three discrete ratios.
6. An apparatus according to claim 4, wherein the adjusting means is operable to adjust the ratio to a ratio within a predetermined range of ratios.
7. An apparatus according to any preceding claim, wherein the sensing means comprises a float, located within the storage chamber and bearing a magnet, and a reed switch for sensing the position of the magnet.
8. An apparatus according to any preceding claim, further comprising means for adjusting the predetermined quantity of liquid sensed by the sensing means.
9. An apparatus according to any preceding claim, wherein the storage chamber comprises a variable-volume bladder.
10. An apparatus according to any preceding claim, wherein the storage means is adapted for mounting onto the rim of a sanitary vessel.

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11. An apparatus according to any preceding claim, wherein at least a portion of the storage means is at least partially transparent.
12. An apparatus according to any preceding claim, further comprising discharge means for discharging liquid from the storage chamber.
13. An apparatus according to claim 12, wherein the discharge means comprises a valve.
14. An apparatus according to claim 12 or 13, further comprising drain means, for allowing liquid to drain from the vessel, linked to the discharge means by a linkage, wherein the linkage is operable to cause liquid to be discharged from the storage chamber when the drain means allows liquid to drain from the vessel.
15. An apparatus according to claim 14, wherein the linkage is a mechanical linkage.
16. An apparatus according to any preceding claim, wherein the flow divider is adapted to be removably mountable to the spout of a tap.
17. An apparatus according to any preceding claim,

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wherein the signal is an audible signal.
18. An apparatus for filling a vessel with a substantially predetermined quantity of liquid, comprising an apparatus according to any preceding claim and further comprising: valve means for controllably providing a flow of liquid to the flow divider; and actuation means for closing the valve means in response to the signal from the sensing means.
19. An apparatus according to claim 18, wherein the valve means is fully closeable by the actuation means.
20. An apparatus according to claim 18 or 19, wherein the actuation means is operable to progressively close the valve means as the quantity of water in the storage chamber approaches the predetermined quantity.
21. An apparatus according to any of claims 18 to 20, wherein the actuation means comprises an electrical circuit.
22. An apparatus according to claim 21, wherein the valve means comprises a solenoid valve.

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23. An apparatus according to claim 21 or 22, further comprising a switch for causing the actuation means to open the valve means.
24. A method of determining whether a substantially predetermined quantity of liquid has flowed into a vessel, the method comprising the steps of: providing a flow of liquid; using a flow divider to divide the flow of liquid into a first portion and a second portion, the first portion being directed into the vessel and the second portion into a storage chamber; and using a sensing means to sense whether the storage chamber contains a predetermined quantity of liquid and outputting a signal when the storage chamber contains said predetermined quantity of liquid.