GB2483508A

GB2483508A - Safety device

Info

Publication number: GB2483508A
Application number: GB1015180.1A
Authority: GB
Inventors: Colin Philip
Original assignee: Individual
Current assignee: Individual
Priority date: 2010-09-11
Filing date: 2010-09-11
Publication date: 2012-03-14
Also published as: GB201015180D0

Abstract

A safety device comprises a heat conductive outer casing 100 for contacting a body of water (e.g. in a bathtub), a valve 105 comprising a piston 107 and return spring 116, and a substantially airtight capillary tube 115 having a first end 104 connected to the outer casing and a second end 110 connected to the valve. When the water temperature exceeds a predetermined value, a pressurized gas 111 in the tube 115 expands to push piston 107 and stopper 108 into water supply pipe 104 to close off the water supply.

Description

Temperature sensitive hot water cut-off valve

Background of the Invention

[1] The present invention relates to water temperature control for bathtubs.

[2] Safety valves for preventing bathtub water from exceeding a predetermined temperature are known in the art. For example, CN87208673 to Fanbin discloses a shower or bath valve for automatic temperature regulation by thermal control. The relative proportions of cool and hot water supplied are controlled by the thermosensitive effect of a double-metal piece which is made of two adhered metal thin pieces whose thermal expansion coefficients are largely different, such that the valve will open and close at predetermined temperatures.

[3] US 2002148501 to Shieh discloses a valve device which includes a cold water inlet and a hot water inlet communicating with a chamber, and one or more ports. The valve housing comprises a channel for receiving a safety valve. A valve element is engaged in the valve housing for controlling the flow of hot and cold water through the port or ports. The safety valve may be used for shutting off the hot water when the cold water is shut of f inadvertently, so as to prevent the users from being hurt by the hot water inadvertently.

[4] CN 2090904 to Jie discloses a water heating facility. A safety valve is disclosed which comprises a valve body and a valve core. The safety valve is characterized in that a shape memory alloy spring is fixed on the valve core. The spring is highly responsive to changes in water temperature and when the water temperature reaches a predetermined level, the spring drives the valve core to close the valve, and water flow is cut off. Conversely, when the water temperature drops below the set temperature, the spring contracts to disengaged the valve core, and the water flows. The safety valve, which is intended to be installed on the water pipe of a shower spray head, reduces the risk of scalding by hot water from the shower.

Brief Summary of the_Invention

[5] It can be seen from the forgoing that a need has arisen for means to prevent scalding by bathwater. It would be advantageous to provide a means for recognizing when a bathtub temperature exceeds a safe level. It would be further advantageous to provide a means for shutting off a hot water tap upon such an eventuality.

[6] It is therefore an object of the present invention to provide a means for shutting off a hot water supply when a temperature in a bathtub exceeds a predetermined level. It is a further object to provide such a means which does not depend on an external power supply.

[7] To this end, a safety device is disclosed comprising: a heat conductive outer casing for contacting a body of water; a valve comprising a piston; a substantially airtight cavity having a first end connected to said outer casing and a second end connected to said valve; a pressurized gas in said cavity; wherein said piston in a first position opens, and in a second position closes, a hot water supply pipe.

(8] An advantage of the present invention is that when the temperature of a bathtub approaches dangerously high levels, hot water is shut off, preventing the temperature from rising further. A yet further advantage is that since the device relies on heat energy to operate a mechanical valve, it does not require an external power supply.

Brief Description of the Several Views of the Drawins [9) The invention can be better understood with reference to the following drawings, in which: [10] Figure 1 shows the preferred embodiment of the invention; and [11] Figure 2 shows a cross sectional view of the preferred embodiment.

Detailed Description of the Invention

[12] In a preferred embodiment of the invention, shown in Figures 1 and 2 wherein like numerals refer to like components, a safety device is disclosed comprising: a heat conductive outer casing 100 for contacting a body of water; a valve 105 comprising a piston 107; a substantially airtight cavity 115 having a first end 109 connected to said outer casing and a second end 110 connected to said valve; a pressurized gas 111 in said cavity; wherein said piston in a first position opens, and in a second position closes, a hot water supply pipe.

[13] It is envisaged that the surrounding body of water will be water in a bathtub, although the invention is not limited to this and there may be other applications in bodies of water other than a bathtub.

[14] The cuter casing preferably comprises thin copper since this is highly heat conductive and enables maximum sensitivity to temperature changes in the surrounding body of water.

Alternatively other heat conducting materials may be used. In a preferred embodiment, the outer casing is shaped as a spherical segment as shown in the figures, an advantage of this being that heat from the body of water is distributed evenly over the casing and therefore absorbed evenly into the gas. However, alternatively, the casing may comprise any shape, and may comprise a large surface area to aid absorption of heat.

[15] The valve preferably comprises a piston 107, a cylinder 106, and a stopper 108 for stopping the flow in a hot water supply pipe. A spring 116 may be disposed in the cylinder to return the piston to its original position. These components are known in the art and therefore not described herein in detail except for their functionality. It will be readily understood that commercially available valves are more complex than that described and depicted herein and the description given here details only the minimal requirements for operation. The valve operates as follows. When the body of water is cool, the gas in the airtight cavity is cool, the piston is in a first position, and the valve is open. When the temperature of the body of water exceeds a predetermined value, gas in the airtight cavity expands sufficiently to push the piston along the cylinder into a second position, which in turn pushes the stopper into the hot water supply pipe to close the pipe. When the temperature of the body of water cools below the safe value, the pressurized gas contracts until the force in the spring overcomes that from the gas in the capillary tube and pulls the cylinder back into the first position, pulling the stopper out of the hot water pipe, opening the pipe. Alternatively any type of pressure activated shut off valve may be used.

[161 The airtight cavity has a first end connected to said outer casing and a second end connected to said valve. Preferably the airtight cavity comprises a capillary tube 115, since the thin nature of a capillary tube enables maximal sensitivity to pressure changes in the pressurized liquid. The cavity may exclusively comprise a capillary tube or may comprise a capillary tube in conjunction with other spaces, such as one or more hollow sections, for example hollow section 101 inside the outer casing.

An advantage of having a hollow section and a capillary section is that the hollow section acts as a pressurized gas temperature sensor, having a greater volume of gas in thermal contact with the body of water, thereby enabling faster response to temperature changes. Furthermore the increased volume of gas this arrangement enables provides greater changes in volume (therefore greater sensitivity) compared with a smaller volume of gas. The cavity may be directly or indirectly connected to the valve, and may comprise or be connected to the cylinder of the valve, such that a change in volume of the pressurized gas pushes the piston along the cylinder. A further hollow may be disposed at the second end of the cavity where the cavity contacts the cylinder.

[17] The pressurized gas may be any gas known in the art.

[18] The device is preferably connected to the hot water supply pipe 104 close to the bathtubf such that it will stop the flow of water quickly. The device may comprise a section of pipe 114, to which the valve is pre-fitted, with which an existing section of hot water supply pipe can be replaced. An advantage of this is that it enables easy retrofitting of the device.

Alternatively the device may not comprise a section of pipe and the valve may require fitting as known in the art to the existing hot water supply pipe.

[19] The device may alternatively be fitted in any way and in any position to a hot water supply pipe of a bathtub, sink, or any other fixture for containing a body of water.

[20] The outer casing is preferably fitted to the bathtub as shown in the figures, with a screw thread 112 connected to the outer casing for passing through a hole drilled or otherwise made in the bath. A tubular hollow in the screw thread enables the capillary tube to pass therethrough. Washers 113 on each side of the bathtub create a watertight seal to prevent the body of water from escaping. Alternatively the device may be connected by any means to the bathtub.

Claims

claims 1. A safety device comprising: a heat conductive outer casing for contacting a body of water; a valve comprising a piston; a substantially airtight cavity having a first end connected to said outer casing and a second end connected to said valve; a pressurized gas in said cavity; wherein said piston in a first position opens, and in a second position closes, a hot water supply pipe.
2. The device of claim 1 wherein said casing is shaped to form a spherical segment, whereby heat is distributed evenly.
3. The device of claim 1 wherein said cavity comprises at least one hollow section and a capillary section.