GB2278051A - Thermally activated safety device for attachment to hot water tap - Google Patents

Abstract

Apparatus for limiting the temperature of water in a sink, bath or like reservoir, comprises valve 5, attachment means 4 for attaching the valve to a hot water tap, and activating means adapted to close the valve, thereby impeding the flow of hot water from the tap when the water in the reservoir exceeds a predetermined temperature. Preferably the valve has a first chamber having an inlet and an outlet and housing a sealing means operable between an open and a closed position in response to a pressure differential across it, and a second chamber communicating with the activating means and the first chamber. Suitably the activating means includes a sensor adapted to be immersed in the water contained in the reservoir and a hose which provides communication of the sensor with the second chamber of the valve. <IMAGE>

Description

"Thermally Activated Safety Device" This invention relates to a safety device which finds application in preventing injury or even death through scalding in domestic baths, water basins, sinks and the like. The device may be used in domestic residences, institutions and homes for the elderly or disabled, nurseries and in many other environments.

The invention particularly relates to a device which includes a valve for controlling the supply of hot water.

Frequently, water supply from a hot water tap is too hot for the user and must be mixed with a cold water supply. This is especially the case where the water is required to bathe infants, disabled or elderly people.

Disabled people are not always able to determine the temperature of the water, possibly due to loss of feeling in their limbs. Thus, attempts have been made to prevent or mitigate dangerous situations occurring as a result of excessive water temperatures. Such attempts have included a number of alternative methods, including limiting the water supply temperature, or where the water temperature exceeds a predetermined level, either isolating the water supply, activating an alarm signal or limiting the supply temperature.

However, in the invention it is found that some of these methods are inherent with disadvantages. For example, limiting the supply temperature can lead to the growth of bacteria and limits the availability of water. Such methods also require the adaption of existing fittings, which incurr associated fitting costs. Moreover, alarm signals are non-preventative and hence are not suitable to all of the above applications. Alarms need to be energised and the use of batteries or the like render some unreliability due to energy failure from the source.

An object of the present invention is therefore to obviate or at least mitigate the above disadvantages by providing a safety device which more adequately prevents injury through scalding, and yet is easy to install, does not incur fitting costs and is cheap to produce.

According to the invention there is provided apparatus for limiting the temperature of water in a sink, bath or like reservoir, comprising a valve, attachment means for attaching the valve to a hot water tap, and activating means adapted to close the valve, thereby impeding the flow of hot water from the tap when the water in the reservoir exceeds a predetermined temperature.

Preferably, the valve has a first chamber having an inlet and an outlet and housing a sealing means operable between an open and a closed position in response to a pressure differential across it, and a second chamber communicating with the activating means and the first chamber.

Preferably, the activating means includes a sensor adapted to be immersed in the water contained in the reservoir and a hose which provides communication of the sensor with the second chamber of the valve.

Preferably, when the sealing means is in an open position, hot water is able to flow from the tap into the reservoir via the outlet of the first chamber and through the hose via the second chamber.

The sensor preferably has a thermostatic element containing a substance that undergoes a change in volume or shape at the predetermined temperature, the change causing the flow of water through the hose to be substantially prevented and thereby effecting an increase in pressure in the second chamber so as to create a larger pressure on the inlet side of the sealing means than on the outlet side of the sealing means so as to cause the sealing means to move to the closed position.

Alternatively, the thermostatic element upon expansion or change in the volume or shape, mechanically operates the sealing means towards the closed position.

The hose preferably fits to the hot tap without the tap requiring modification by use of a universal bracket and without the use of skilled labour, or tools that could not be found within a domestic environment.

Embodiments of the invention will now be described, by way of example only, with reference to the accompanying Figures, in which: Fig. 1 is a sectional elevation of a device comprising a sensor, valve and actuating means; Fig. 2 shows sectional drawings of a valve; Fig. 3 shows a sectional arrangement drawing of a sensor; and Fig. 4 shows an assembly of a device in accordance with the invention.

Firstly, referring to Fig. 1, thermostatic safety apparatus, generally described at 1, comprises a bracket 2 dimensioned to fit a range of tap sizes and shapes and provides a securing arrangement for connection of a hose 4. The hose 4 may be manufactured of a rigid, semi-rigid or flexible material. The length of the hose 4 is such that its down stream end is terminated at a point to suit the function of the remainder of the apparatus or the size of the sink, -bath or the like.

Attached to the hose 4, is a valve 5 arranged to block the flow of water through the hose 4 at a predetermined temperature. The valve 5 contains a spring 6, that is compressed when the valve 5 is in the open position.

When released, the spring 6 contains sufficient energy to stop the flow of water through the tap 7.

Connected to the spring 6 is a plug 8. The plug 8 is arranged so that, when forced by the spring 6, it will block the flow of water, through the valve 5. The plug 8 is provided with a button 9, that allows a person to push the plug 8 against the spring 6 until the plug 8 is at its original position.

Associated with the valve 5 is an activating means including a catch 10, that maintains the plug 8 in the open position against the force of the spring 6. When operated, the catch 10 releases the plug 8 allowing it to move to the closed position thus blocking the flow of water.

Connected to the catch 10 is a sensor including a thermostatic element 11. The thermostatic element 11 is positioned within the lower part of the sink, bath or the like, so that it is able to sense the ambient temperature of water contained within the sink, bath or the like. When the water within the sink, bath or the like reaches a predetermined temperature the thermostatic element 11 releases the cath 10, allowing the plug 8 to block the flow of water through the tap 7. The thermostatic element 11 is contained within a housing 12. The housing 12 comprises a series of apertures 13, which ensure that the water may freely flow around the thermostatic element 11.

In use, when hot water is allowed to enter a sink, bath or the like, that may already contain a quantity of water, the ambient temperature of the water within the sink, bath or the like, will rise towards the temperature of the hot water entering through the tap 7. At the said predetermined temperature, the thermostatic element 11 undergoes a change in shape or volume thus causing the catch 10 to release the plug 8.

The plug 8 blocks the flow of water through the pipe 4 and thus through the tap 7. If sufficient time is allowed to pass or if cold water is allowed to enter the sink, bath or the like, the ambient temperature of the water will fall until it is below the predetermined temperature. The water surrounding the thermostatic element 11 will remove heat from the thermostatic element 11 until it is below the predetermined temperature, at which time it will undergo a change in shape or volume. This, in turn, allows the catch 10 to reset. If the plug 8 is now returned to its original position by operation of the button 9, the catch 10 will locate in the plug 8, thus preventing it from moving towards the closed position. It is not possible for the catch 10 to locate in the plug 8 until the thermostatic element 11 is below the predetermined temperature.

The plug 8, in accordance with the invention, may not act directly to block the water passing through the hose 4, but may act against the wall of the hose 4 with sufficient force to collapse the hose 4 thus preventing the water from passing through the hose 4.

It is realised in the invention that the embodiment described hereinbefore may be adapted without departing from the invention herein intended. Components of a more preferable embodiment are shown in Figs. 2, 3 and 4. In Fig. 2 there is illustrated a thermostatic valve which has a first chamber 20 and a second chamber 21.

The first chamber 20 has an inlet 22 and an outlet 23 between which is located a sealing means 24 comprising a diaphragm 25 and a valve plate 26. The sealing means 24 is operable between a closed position as shown in section A-A and an open position as shown in section B-B of Fig. 2.

The diaphragm 25 has a number of small orifices set into its convolutions through which water may pass into the second chamber 21 due to any pressure difference that might exist across the diaphragm 25.

The second chamber 21 communicates with a hose 4 which provides a means for water to pass from the second chamber 21 to the reservoir (not shown). At the end of the hose 4 is provided a sensor 28 which is illustrated in Fig. 3. The sensor 28 forms a pilot valve that can block the path of water passing through the hose 4.

Preferably, this happens when the temperature of the water in the reservoir exceeds 42 degrees celsius.

The sensor 28 comprises a valve 30 which is moveable in response to a change in shape or volume of a thermally sensitive material 31. This may be, for example, a shape memory alloy. When the temperature exceeds a predetermined level the valve 30 is caused to block the passage 32, thereby preventing the escape of water from the hose 4 into the reservoir. The sensor may also be provided with a thermal barrier 33 which prevents the heat from the hot water passing through the hose 4 to interfere with the temperature sensed by the thermally sensitive material 31.

When the passage of water through the hose 4 is blocked, the pressure in the second chamber 21 is caused to rise and the sealing means 24 is caused to assume a closed position preventing or at least substantially impeding the flow of water from the outlet 23. This effect is enhanced by the flow of any water underneath the sealing means 24 through the outlet under gravity, as this forms a slight negative pressure immediately below the valve plate 26. The result is an average pressure above the sealing means 24 and (in particular the diaphragm 25) which is higher than the average pressure below the diaphragm 25. The sealing means 24 is caused to move downwards, thereby assuming its closed position.

If cold water is now run into the reservoir so that the temperature falls below 42 degrees celsius, the sensor 28 will vent the water in the second chamber 21 into the reservoir allowing the sealing means 24 to rise, opening the valve.

The valve body may also include a small hole 29 as shown near the outlet in section B-B. When the valve is closed, but the hot water tap is left on, a small jet of water will be seen entering the bath or reservoir which provides a reminder that the tap is still turned on.

The valve and bracket may be shielded by a cosmetic cover 46 (Fig. 4) providing a smooth exterior with aesthetic appeal and preventing injury from an unforseen leak or spray which may be inadvertantly jetted from the valve or bracket.

The apparatus, in accordance with the invention, may also be provided with a chain fitting 14 and a chain 15 attached to the sink, bath or the like so as to prevent a child from forcibly removing the apparatus from the tap 7. The sensor may also be connected to the bath plug so that it is not possible to fill the bath without the sensor 28 being positioned in the bottom of the bath or reservoir.

Thus, embodiments of the invention may be produced cheaply and provide a significant advantage in that no adaption to existing plumbing or fittings is required.

Use of the invention merely involves attaching the apparatus to the hot water tap or inlet.

Preliminary tests have indicated that the invention is effective, with the thermostatic element responding to excessive temperature in a relatively short period of time, that is within a few seconds.

Further modifications and improvements may be incorporated.

Claims (9)

1 Apparatus for limiting the temperature of water in a sink, bath or like reservoir, comprising a valve, attachment means for attaching the valve to a hot water tap, and activating means adapted to close the valve, thereby impeding the flow of hot water from the tap when the water in the reservoir exceeds a predetermined temperature.

2 Apparatus as claimed in Claim 1 wherein the valve has a first chamber having an inlet and an outlet and housing a sealing means operable between an open and a closed position in response to a pressure differential across it, and a second chamber communicating with the activating means and the first chamber.

3 Apparatus as claimed in Claim 1 or Claim 2 wherein the activating means includes a sensor adapted to be immersed in the water contained in the reservoir and a hose which provides communication of the sensor with the second chamber of the valve.

4 Apparatus as claimed in Claim 2 or Claim 3, wherein when the sealing means is in an open position, hot water is able to flow from the tap into the reservoir via the outlet of the first chamber and through the hose via the second chamber.

5 Apparatus as claimed in any one of the preceding Claims, wherein the sensor preferably has a thermostatic element containing a substance that undergoes a change in volume or shape at the predetermined temperature, the change causing the flow of water through the hose to be substantially prevented and thereby effecting an increase in pressure in the second chamber so as to create a larger pressure on the inlet side of the sealing means than on the outlet side of the sealing means so as to cause the sealing means to move to the closed position.

6 Apparatus as claimed in Claim 4, wherein the thermostatic element, upon expansion or change in the volume or shape, mechanically operates the sealing means towards the closed position.

7 Apparatus as claimed in any one of Claims 2 to 5, wherein the hose fits to the hot tap without the tap requiring modification by use of a universal bracket and without the use of skilled labour, or tools that could not be found within a domestic environment.

8 Apparatus as claimed in any one of Claims 3 to 7, wherein said hose is of a flexible material, the length of which can be easily altered to suit the depth of the sink, bath or the like.

9 Apparatus substantially as hereinbefore described with reference to the accompanying drawings.