GB2124339A

GB2124339A - Improvements in or relating to Anti-scald devices

Info

Publication number: GB2124339A
Application number: GB08311550A
Authority: GB
Inventors: Geoffrey Alan Chadwick
Original assignee: Individual
Current assignee: Individual
Priority date: 1982-06-26
Filing date: 1983-04-28
Publication date: 1984-02-15
Also published as: GB8311550D0; GB2124339B

Abstract

An anti-scald device for a domestic shower unit comprises a heat responsive valve consisting of a laminated bi-metallic dished disc N provided to snap from a first curvature condition which it exhibits below a pre-determined temperature to a second curvature condition as said pre-determined temperature is exceeded. The dished disc is attached to a member providing a valve seating surface into which a plurality of ports 6, 7 open, which ports are open when the dished disc is in its first curvature condition and closed over when said dished disc snaps to its second curvature condition upon said predetermined temperature being exceeded. <IMAGE>

Description

SPECIFICATION Improvements in or relating to anti-scald devices This invention relates to anti-scald devices and more particularly to such devices for use in a domestic water system in which heated water is used directly from a water outlet for washing or showering.

One object of the present invention is to provide an improved such device which is operative to reduce the flow of heated water from said outlet when the temperature of the water flowing exceeds a pre-determined temperature.

According to this invention an anti-scald device comprises means comprising a passage for liquid from a source of heated liquid to a liquid outlet and a heat responsive, liquid restrictive valve within said passage means, said valve including a dished laminated member comprised of two laminae each of material having different temperature coefficients of expansion and arranged such that said dished member tends to change from a first curvature condition which it exhibits below a predetermined temperature to a second curvature condition as said predetermined temperature is exceeded, said dished member being arranged to present an increased impedance to liquid passing through said valve in said second curvature condition compared to that presented in said first curvature condition.

Preferably said dished member comprises two metallic laminae each of a different metallic composition providing different temperature coefficients of expansion.

Preferably said valve comprises said dished member and a valve seat member, said dished member being fastened to said valve seat member such that when said dished member is in its first condition of curvature, its surface facing said valve seat member curves away from the same from the point of attachment thereto to open a port within said valve seat member, through which port liquid may pass, the arrangement being such said port is obstructed if and when the temperature of said dished member increases beyond said predetermined temperature and said member changes to its second condition of curvature.

There may be more than one such port in said valve seat member, each being open when said dished member is in its first state of curvature.

The obstruction of said port or ports in said valve seat when said dished member changes into its second condition of curvature may be partial, complete or substantially complete. In some cases it may be desired to allow some leakage in order to aid recovery of said dished member to its first condition by cooling as hot water is displaced by cooler water from said source.

The valve seat member and the passage means may be formed of a hard material such as brass or a hard plastics material. Normally it is not preferred to provide any aid to sealing such as a neoprene or rubber washer. It is normally preferred to rely upon contact between said dished member and the valve seat member to provide the required obstruction.

Preferably said dished member is a dished disc fastened by means of a bolt or screw passing through a central hole therein and into a short post upstanding from a generally planar face of said valve seat member into which said port or ports open, said dished member covering said port or ports viewed in the direction of liquid flow.

In a preferred construction four ports are provided in said valve seat member distributed uniformly around said upstanding post.

The invention is particularly applicable to a domestic water system in which heated water is used directly from a water outlet for washing or showering. One example of such a system is the subject of my United Kingdom Patent No.

1320105 and according to a feature of this invention a shower unit as claimed in claim 1 or U.K. Patent No. 1320105 includes an anti-scald device as described above.

It will be appreciated however that the invention is applicable to other types of domestic water heating systems and indeed to other liquid heating systems in which anti-scald protection is desired to reduce the possibility of damage to an object sensitive to heat or injury or discomfort to a human.

The invention is illustrated in and further described with reference to the accompanying drawing in which Figure 1 is a longitudinal section through part of one example of anti-scald device in accordance with the present invention and Figure 2 is a section along the line X... X of Figure 1.

Referring to the drawing, a moulded plastic body 1 provides a passage 2 for heated water from a source of heated water (not shown but to the left as viewed in Figure 1) to a heated water outlet (not shown but to the right as viewed in Figure 1). The direction of water flow is in the direction of the arrow 3. In this example the source of heated water may be taken to be as described in the specification of my United Kingdom Patent No. 1320105. Accordingly the anti-scald device described herein may be taken to be located between the pipe 1 0a and the shower head 1 6 of the shower system described with reference to the drawing in said earlier specification.

A wall 4 across passage 2 has a planar face 5 which forms a valve seating. Through the wall 4 extend four ports 6, 7, 8, 9 which open out into the face 5. Ports 6, 7, 8, 9 are distributed regularly around a short post 10 upstanding from the face 5.

Secured to the post 10 by means of centrally located screw is a laminated dished disc 11 which consists of two laminae (not separately shown) of different metallic compositions providing different temperature coefficients of expansion such that dished disc 11 tends to snap from a first curvature condition (as shown), which it exhibits below a predetermined temperature, to a second curvature condition (as represented in dashed outline) as said predetermined temperature is exceeded.

Dished disc 11 is secured to post 10 in such manner that when disc 11 is in its first curvature condition (i.e. when its temperature as determined by the temperature of the water is below said predetermined temperature) its surface facing valve seating planar surface 5 curves away from the same from the point of attachment to the post 10. Thus ports 6, 7, 8 and 9 are open and heated water may pass through the valve. If and when the temperature of dished disc 11 (as determined by the temperature of the water passing past it) exceeds said predetermined temperature it snaps into its second condition of curvature and thus closes over the openings of ports 6, 7, 8 and 9 and thus obstructs the passage of water through the valve.The length of post 10 (i.e. extent to which it extends out of surface 50 is chosen with this action in mind. Sealing of the periphery of the disc 11 against the surface 5 may not be perfect.

However provided it is sufficient satisfactorily to reduce the risk of injury due to scalding, some leakage may be desirable in order to allow hot water to be displaced by cooler water coming from said source of heated water and thus, by cooling, assist in the recovery of the dished disc to its first condition as the temperature of the water is reduced.

Whilst not illustrated, should it be desired further to increase leakage in order to aid recovery, one or more small bleed holes may be provided in dished disc 11 or through a part of wall 4 not covered by disc 11.

In the example described with reference to the accompanying drawing the predetermined temperature is set by the characteristics of the laminated dished disc.

The metallic compositions used for the individual laminae and the thicknesses of the last mentioned may be chosen empirically or by calculation. No provision is made for adjustment in this example (save possibly by changing the dished disc for another). However, this is not regarded as disadvantageous in view of its function as a safety device the operation of which might be deranged if some means for adjustment were provided.

Whilst not illustrated, if desired the laminated disc 11 may be covered by plating or some other suitable protective covering.

Claims

1. An anti-scald device comprising means providing a passage for liquid from a source of heated liquid to a liquid outlet and a heat responsive, liquid restrictive valve within said passage means, said valve including a dished laminated member comprised of two laminae each of material having different temperature coefficients of expansion and arranged such that said dished member tends to change from a first curvature condition which it exhibits below a predetermined temperature to a second curvature condition as said predetermined temperature is exceeded, said dished member being arranged to present an increased impedance to liquid passing through said valve in said second curvature condition compared to that presented in said first curvature condition.

2. A device as claimed in claim 1 and wherein said dished member comprises two metallic laminae each of a different metallic composition providing different temperature coefficients of expansion.

3. A device as claimed in claim 1 or 2 and wherein said valve comprises said dished member and a valve seat member, said dished member being fastened to said valve seat member such that when said dished member is in its first condition of curvature, its surface facing said valve seat member curves away from the same from the point of attachment thereto to open a port within said valve seat member, through which port liquid may pass, the arrangement being such said port is obstructed if and when the temperature of said dished member increases beyond said predetermined temperature and said member changes to its second condition of curvature.

4. A device as claimed in claim 3 and wherein there are more than one such port in said valve seat member each being open when said dished member is in its first state of curvature.

5. A device as claimed in any of the above claims and wherein said valve seat and said passage means are formed of brass.

6. A device as claimed in any of the above claims 1 to 4 and wherein said valve seat and said passage means are formed of a hard plastics material.

7. A device as claimed in any of the above claims and wherein said dished member is a dished disc fastened by means of a bolt or screw passing through a central hole therein and into a short post upstanding from a generally planar face of said valve seat member into which said port or ports open, said dished member covering said port or ports viewed in the direction of liquid flow.

8. A device as claimed in claim 7 and wherein four ports are provided in said valve seat member distributed uniformly around said upstanding post.

9. An anti-scald device substantially as herein described and illustrated in the accompanying drawing.

10. A domestic water system in which heated water is used directly from a water outlet for washing or showering and including an anti-scald device as claimed in any of the above claims.

11. A shower unit as claimed in claim 1 of U;K.

Patent No. 1320105 and including an anti-scald device as claimed in any of the above claims 1 to 9.