GB2256047A - Temperature sensor - Google Patents
Temperature sensor Download PDFInfo
- Publication number
- GB2256047A GB2256047A GB9210158A GB9210158A GB2256047A GB 2256047 A GB2256047 A GB 2256047A GB 9210158 A GB9210158 A GB 9210158A GB 9210158 A GB9210158 A GB 9210158A GB 2256047 A GB2256047 A GB 2256047A
- Authority
- GB
- United Kingdom
- Prior art keywords
- sensor
- mounting plate
- temperature
- wax
- sensitive indicator
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Withdrawn
Links
Classifications
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01H—ELECTRIC SWITCHES; RELAYS; SELECTORS; EMERGENCY PROTECTIVE DEVICES
- H01H37/00—Thermally-actuated switches
- H01H37/74—Switches in which only the opening movement or only the closing movement of a contact is effected by heating or cooling
- H01H37/76—Contact member actuated by melting of fusible material, actuated due to burning of combustible material or due to explosion of explosive material
- H01H37/767—Normally open
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01K—MEASURING TEMPERATURE; MEASURING QUANTITY OF HEAT; THERMALLY-SENSITIVE ELEMENTS NOT OTHERWISE PROVIDED FOR
- G01K11/00—Measuring temperature based upon physical or chemical changes not covered by groups G01K3/00, G01K5/00, G01K7/00 or G01K9/00
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01K—MEASURING TEMPERATURE; MEASURING QUANTITY OF HEAT; THERMALLY-SENSITIVE ELEMENTS NOT OTHERWISE PROVIDED FOR
- G01K11/00—Measuring temperature based upon physical or chemical changes not covered by groups G01K3/00, G01K5/00, G01K7/00 or G01K9/00
- G01K11/06—Measuring temperature based upon physical or chemical changes not covered by groups G01K3/00, G01K5/00, G01K7/00 or G01K9/00 using melting, freezing, or softening
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01K—MEASURING TEMPERATURE; MEASURING QUANTITY OF HEAT; THERMALLY-SENSITIVE ELEMENTS NOT OTHERWISE PROVIDED FOR
- G01K3/00—Thermometers giving results other than momentary value of temperature
Landscapes
- Physics & Mathematics (AREA)
- General Physics & Mathematics (AREA)
- Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Combustion & Propulsion (AREA)
- Fire-Detection Mechanisms (AREA)
Abstract
A temperature sensor comprises a mounting plate (1) made of a thermally-conductive material e.g. Cu, and a temperature sensitive indicator (3) positioned on one surface of the mounting plate. The temperature sensitive indicator is constituted by a solid material (3) which melts at a predetermined temperature, and the sensor is such that melting of the solid material results in said material flowing away from its original position thereby providing an indication that the mounting plate (1) has attained said predetermined temperature. The indication may be visible, when wax (3) melts and exposes a plate (2) of different appearance. The area (1a) may form a groove lower than the surface (2). Alternatively the sensor comprises a switch and when the wax melts a spring loaded contact is allowed to move. In another embodiment the indicator is located between the ends of two aligned fibre optics connecting an LED and a photodelector. <IMAGE>
Description
TEMPERATURE SENSOR
This invention relates to a temperature sensor, and in particular to a sensor for providing an indication that a predetermined temperature has been exceeded.
There are many available devices which are designed to monitor and sense heat (temperature), for example thermometers, thermocouples, thermistors, reactive and chemical strips, and bi-metal devices. All these known devices have disadvantages. Thus, thermometers such as maximum and minimum thermometers are fragile, are inaccurate when subjected to vibrations, can only be read at close range, are susceptible to mis-reading, are precluded from use in the food industry (as they incorporate mercury or alcohol), have a limited temperature range, and cannot usually be fixed to equipment whose temperature is to be monitored.Similarly, thermocouples and thermistors are costly, require a dedicated power supply, are not intrinsically safe, are difficult to read in poor light, need skilled interpretation, are prone to accidental re-setting of the maximum temperature, and are limited in the places they can be used. Reactive and chemical strips have poor accuracy, are difficult to interpret, are not weatherproof, have a low working temperature range, and are limited in the places they can be used. Similarly, bi-metal devices' are costly, have limited accuracy, are easily damaged, and require special fittings.
The aim of the invention is to provide a temperature sensor which is simple to use, inexpensive to manufacture, and be usable with a wide range of industrial and domestic appliances.
The present invention provides a temperature sensor comprising a mounting plate made of a thermally-conductive material, and a temperature sensitive indicator positioned on one surface of the mounting plate, the temperature sensitive indicator being constituted by a solid material which melts at a predetermined temperature, and the sensor being such that melting of the solid material results in said material flowing away from its original position thereby providing an indication that the mounting plate has attained said predetermined temperature.
Advantageously, the sensor further comprises a cover plate which overlies the temperature sensitive indicator, the cover plate and the mounting plate defining a sealed unit surrounding the temperature sensitive indicator.
Preferably, the temperature sensitive indicator is positioned substantially centrally with respect to said one surface of the mounting plate, and the mounting plate and the cover plate are shaped to define a chamber surrounding the temperature sensitive indicator. Conveniently, the cover plate is made of a heat-insulating substance such as a polycarbonate material, preferably a transparent material; and the mounting plate is made of a metal such as copper.
Preferably, that surface of the mounting plate opposite to said one surface constitutes a fixing surface for fixing the sensor to an article whose temperature is to be sensed. Advantageously, the fixing surface is provided with a coating of epoxy resin.
In a preferred embodiment, the sensor further comprises an indicator plate fixed to said one surface of the mounting plate, the temperature sensitive indicator being positioned on the indicator plate. Advantageously, the indicator plate and the temperature sensitive indicator have different visual characteristics. For example, the indicator plate may be striped (preferably red and silver) and the temperature sensitive indicator may be a monochrome material.
The solid material constituting the temperature sensitive indicator may be a wax material, preferably a technically graded wax having a paraffin filler, the amount of paraffin filler being chosen to control said predetermined temperature at which the wax melts, whereby the sensor can be pre-set for the wax to melt at any desired temperature within a given temperature range. The wax material may also include a colourant.
In another preferred embodiment, the mounting plate is made of an electrically-conductive material, and the sensor further comprises an electrical contact member one portion of which is fixed to the cover plate, the electrical contact member being made of a resilient material and being mounted within the sensor in such a manner that another portion of the electrical contact member is resiliently biased towards the mounting plate, the electrical contact member and the mounting plate being included in an electrical circuit also including an electrical power source and an alarm device, electrical contact between said another portion of the electrical contact member and the mounting plate being prevented, when the temperature of the mounting plate is below said predetermined temperature, by the solid material constituting the temperature sensitive indicator, and said another portion of the electrical contact member electrically contacting the mounting plate when the mounting plate has attained said predetermined temperature and the material constituting the temperature sensitive indicator has melted and flowed away, whereby said electrical circuit is completed thereby triggering the alarm device.
Advantageously, the alarm device is a visual alarm device such as a LED, or an audible alarm device such as a buzzer.
In yet another preferred embodiment, the sensor further comprises first and second optical fibres, one end of each of the optical fibres being fixed within the solid material constituting the temperature sensitive indicator with said ends in an axially-aligned orientation, said optical fibre ends being spaced apart with said solid material substantially filling the gap between said optical fibre ends, the other end of the first optical fibre being connected to a light source, and the other end of the second optical fibre being connected to a light operable alarm device, whereby, when the temperature of the mounting plate is below the predetermined temperature, the solid material in said gap prevents light passing from the first optical fibre to the second optical fibre, and, when the mounting plate has attained said predetermined temperature and the solid material in said gap has melted and flowed away, light can pass from the first optical fibre to the second optical fibre thereby to trigger the alarm device.
Preferably, the light source is a LED and the alarm device is a photodiode.
Three forms of temperature sensor, each of which is constructed in accordance with the invention, will now be described, by way of example, with reference to the accompanying drawings, in which:
FIGURE 1 is an exploded perspective view of the
first form of temperature sensor;
FIGURE 2 is a diametrical cross-section taken
through the sensor of Figure 1;
FIGURE 3 is a diametrical cross-section taken
through the second form of temperature
sensor, the sensor being shown in a
first operative condition;
FIGURE 4 is a cross-section similar to that of
Figure 3, but showing the sensor in a
second operative condition; and
FIGURE 5 is a schematic plan view of the third
form of temperature sensor.
Referring to the drawings, Figures 1 and 2 show a temperature sensor having a copper mounting plate 1 having a circular base la and an upstanding circumferential wall lb. A circular overheat signal disc 2, which is striped and coloured red and silver, is fixed to the circular base la centrally thereof. A wax disc 3, which is coloured green (or any other monochrome colour except red), is positioned above the signal disc 2. An annular insulation shield 4, which is made of polycarbonate, surrounds the wax disc 3 and is supported on the base la by a peripheral flange 4a.
The sensor is completed by a transparent polycarbonate dial (or lid) 5 having a generally annular upper surface Sa, a recessed central upper portion 5b which constitutes a dioptric lens, a pair of downwardly-extending, peripheral, annular flanges 5c, and a downwardly-extending, annular flange 5d which lies adjacent to the dioptric lens.
The wax disc 3 is made from a technically graded wax having a paraffin filler and a green (or other monochrome) colourant. The proportion of paraffin filler is chosen to control the temperature at which the wax melts, whereby the sensor can be pre-set for the wax to melt at any desired temperature within a wide temperature range.
In use, the sensor is fixed, for example by an epoxy adhesive, to a device (or appliance) in danger of overheating. The adhesive may be applied to that surface of the base la of the mounting plate opposite to that to which the signal disc 2 is fixed. The sensor is fixed to the device so as to be generally in a vertical or upright position, that is to say in the configuration shown in
Figure 1. The composition of the wax in the wax disc 3 is chosen so that it will melt when the device reaches a predetermined temperature which is slightly less than the 'overheat' temperature. As long as the device is not overheated, therefore, the wax disc 3 will remain solid, so that the sensor will display a green, safe, indication.If, however, overheating occurs, the wax will melt and run down into the lower part of the copper mounting plate 1, thereby exposing the signal disc 2, and so providing a red/silver danger indication. The sensor needs to be positioned in a position which is sufficiently upright to permit this wax flow to occur. The change from green (or other monochrome) colour to the red/silver striped indication has the advantage of providing an easilyrecognisable visual indication of overheating even to people who are colour blind. This indication would be readily apparent to observers, and would persist even after the device has cooled down. Thus, not only does the temperature sensor provide a reliable indication of when the device is overheated, but it also indicates that the device has been overheated (and possibly been damaged) even if subsequent cooling has occurred.
Figures 3 and 4 show a modified form of temperature sensor including a copper mounting plate 11 having a circular base 11a and an upstanding circumferential wall llb. A wax disc 13 is fixed to the circular base lia centrally thereof. A polycarbonate lid 15 is fixed to the wall lib of the mounting plate 11, the lid including an annular surface 15a and a recessed central portion 15b. The portion 15b overlies the wax disc 13. An electrical contact bar 16 is fixed to the inside of the lid surface 15a, the contact bar being made of spring copper which is prestressed so as to bias its free end portion 16a towards the circular base 11a of the mounting plate 1. An electrical lead 17 is fixed to the contact bar 16, and a further electrical lead 18 is fixed to the mounting plate 11.The leads 17 and 18 form part of an electrical circuit which also includes a battery (not shown) and an indicator (not shown) such as a light bulb, a light emitting diode (LED) or an audible alarm device such as a buzzer.
The wax disc 13 is made from a technically graded wax having a paraffin filler. The proportion of paraffin filler is chosen to control the temperature at which the wax melts, whereby the sensor can be pre-set for the wax to melt at any desired temperature within a wide temperature range.
In use, the sensor is fixed, for example by an epoxy adhesive, to a device (or appliance) in danger of overheating. The composition of the wax in the wax disc 13 is chosen so that it will melt when the device reaches a predetermined temperature which is slightly less than the 'overheat' temperature. As long as the device is not overheated, therefore, the wax disc 13 will remain solid, so that the wax prevents the free end portion 16a of the contact bar 16 touching the base lia of the mounting plate 11. Consequently, the electrical circuit containing the visible or audible alarm remains open circuit. If, however, overheating occurs, the wax will melt, thereby releasing the contact bar 16 so that its free end portion 16a bears against the mounting plate base lla, thereby completing the electrical circuit and triggering the alarm.Here again, the sensor needs to be positioned in a position which is sufficiently upright to permit this wax flow to occur.
The advantage of the sensor of Figures 3 and 4 is that the sensor proper can be fixed to the device (or appliance) in danger of overheating even where that device (or appliance) is not easily accessible for observation, the alarm device of the associated electrical circuit being positionable in an easily-observable location.
Figure 5 is a schematic representation of another form of temperature sensor that can provide an indication of overheating to a remote location. In this case, a copper mounting plate 21 is provided with a wax disc 23 fixed centrally thereof. A pair of axially-aligned optical fibres 24 and 25 are fixed to the sensor by being embedded in the wax disc 23. The free ends 24a and 25a of the fibres 24 and 25 terminate a short distance apart within the wax of the disc 23, wax filling the gap between the free fibre ends.
The other end of the fibre 24 is connected to a LED (not shown), and the other end of the fibre 25 is connected to a light-sensitive photodiode (not shown). This sensor will preferably be a sealed unit similar in construction to the sensor of Figures 3 and 4, and so will be provided with a lid (not shown).
The wax disc 23 is made from a technically graded wax having a paraffin filler. The proportion of paraffin filler is chosen to control the temperature at which the wax melts, whereby the sensor can be pre-set for the wax to melt at any desired temperature within a wide temperature range.
In use, the sensor is fixed, for example by an epoxy adhesive, to a device (or appliance) in danger of overheating. The composition of the wax in the wax disc 23 is chosen so that it will melt when the device reaches a predetermined temperature which is slightly less than the 'overheat' temperature. As long as the device is not overheated, therefore, the wax disc 23 will remain solid, so that the wax in the gap between the fibre ends 24a and 25a prevents light emitted by the LED and passing along the fibre 24 from reaching the fibre 25. Consequently, light does not reach the photodiode to provide a visual indication.If, however, overheating occurs, the wax will melt and flow away, thereby permitting light to pass from the fibre end 24a to the fibre end 25a, and hence to reach the photodiode via the fibre 25, thereby providing a visual indication of overheating. Here again, the sensor needs to be positioned in a position which is sufficiently upright to permit this wax flow to occur.
The sensor of Figure 5 not only has the advantage of the sensor of Figures 3 and 4, namely that the alarm device (the photodiode) can be remote from the sensor proper, but it also has the advantage of being usable in locations where an electrical current could present dangers, for example of an explosion caused by an electrical spark. This form of sensor does, therefore, provide an intrinsicallysafe remote indication of overheating.
The sensors of Figures 3 and 4 and of Figure 5 also have the advantage of the sensor of Figures 1 and 2, namely they each provide an indication that the associated device has been overheated (and possibly damaged) even if subsequent cooling has occurred.
Claims (22)
1. A temperature sensor comprising a mounting plate made of a thermally-conductive material, and a temperature sensitive indicator positioned on one surface of the mounting plate, the temperature sensitive indicator being constituted by a solid material which melts at a predetermined temperature, and the sensor being such that melting of the solid material results in said material flowing away from its original position thereby providing an indication that the mounting plate has attained said predetermined temperature.
2. A sensor as claimed in claim 1, further comprising a cover plate which overlies the temperature sensitive indicator, the cover plate and the mounting plate defining a sealed unit surrounding the temperature sensitive indicator.
3. A sensor as claimed in claim 2, wherein the temperature sensitive indicator is positioned substantially centrally with respect to said one surface of the mounting plate, and wherein the mounting plate and the cover plate are shaped to define a chamber surrounding the temperature sensitive indicator.
4. A sensor as claimed in claim 2 or claim 3, wherein the cover plate is made of a heat-insulating substance such as a polycarbonate material.
5. A sensor as claimed in claim 4, wherein the cover plate is made of a transparent material.
6. A sensor as claimed in any one of claims 1 to 5, wherein the mounting plate is made of metal.
7. A sensor as claimed in claim 6, wherein the mounting plate is made of copper.
8. A sensor as claimed in any one of claims 1 to 7, wherein that surface of the mounting plate opposite to said one surface constitutes a fixing surface for fixing the sensor to an article whose temperature is to be sensed.
9. A sensor as claimed in claim 8, wherein the fixing surface is provided with a coating of epoxy resin.
10. A sensor as claimed in any one of claims 1 to 9, further comprising an indicator plate fixed to said one surface of the mounting plate, the temperature sensitive indicator being positioned on the indicator plate.
11. A sensor as claimed in claim 10, wherein the indicator plate and the temperature sensitive indicator have different visual characteristics.
12. A sensor as claimed in claim 11, wherein the indicator plate is striped and the temperature sensitive indicator is a monochrome material.
13. A sensor as claimed in claim 12, wherein the stripes of the indicator plate are red and silver.
14. A sensor as claimed in any one of claims 1 to 13, wherein the solid material constituting the temperature sensitive indicator is a wax material.
15. A sensor as claimed in claim 14, wherein the wax material is a technically graded wax having a paraffin filler, the amount of paraffin filler being chosen to control said predetermined temperature at which the wax melts, whereby the sensor can be pre-set for the wax to melt at any desired temperature within a given temperature range.
16. A sensor as claimed in either of claims 14 and 15 when appendant to either of claims 12 and 13, wherein the wax material includes a colourant.
17. A sensor as claimed in any one of claims 2 to 9, or in either of claims 14 and 15 when appendant to any one of claims 2 to 9, wherein the mounting plate is made of an electrically-conductive material, and the sensor further comprises an electrical contact member one portion of which is fixed to the cover plate, the electrical contact member being made of a resilient material and being mounted within the sensor in such a manner that another portion of the electrical contact member is resiliently biased towards the mounting plate, the electrical contact member and the mounting plate being included in an electrical circuit also including an electrical power source and an alarm device, electrical contact between said another portion of the electrical contact member and the mounting plate being prevented, when the temperature of the mounting plate is below said predetermined temperature, by the solid material constituting the temperature sensitive indicator, and said another portion of the electrical contact member electrically contacting the mounting plate when the mounting plate has attained said predetermined temperature and the material constituting the temperature sensitive indicator has melted and flowed away, whereby said electrical circuit is completed thereby triggering the alarm device.
18. A sensor as claimed in claim 17, wherein the alarm device is a visual alarm device such as a LED.
19. A sensor as claimed in claim 17, wherein the alarm device is an audible alarm device such as a buzzer.
20. A sensor as claimed in any one of claims 2 to 9, or in either of claims 14 and 15 when appendant to any one of claims 2 to 9, further comprising first and second optical fibres, one end of each of the optical fibres being fixed within the solid material constituting the temperature sensitive indicator with said ends in an axially-aligned orientation, said optical fibre ends being spaced apart with said solid material substantially filling the gap between said optical fibre ends, the other end of the first optical fibre being connected to a light source, and the other end of the second optical fibre being connected to a light-operable alarm device, whereby, when the temperature of the mounting plate is below the predetermined temperature, the solid material in said gap prevents light passing from the first optical fibre to the second optical fibre, and, when the mounting plate has attained said predetermined temperature and the solid material in said gap has melted and flowed away, light can pass from the first optical fibre to the second optical fibre thereby to trigger the alarm device.
21. A sensor as claimed in claim 20, wherein the light source is a LED and the alarm device is a photodiode.
22. A temperature sensor substantially as hereinbefore described with reference to, and as illustrated by, Figures 1 and 2, Figure 3 and 4, or Figure 5 of the accompanying drawings.
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB919110741A GB9110741D0 (en) | 1991-05-13 | 1991-05-13 | Overheating monitor |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| GB9210158D0 GB9210158D0 (en) | 1992-06-24 |
| GB2256047A true GB2256047A (en) | 1992-11-25 |
Family
ID=10695192
Family Applications (2)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| GB919110741A Pending GB9110741D0 (en) | 1991-05-13 | 1991-05-13 | Overheating monitor |
| GB9210158A Withdrawn GB2256047A (en) | 1991-05-13 | 1992-05-12 | Temperature sensor |
Family Applications Before (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| GB919110741A Pending GB9110741D0 (en) | 1991-05-13 | 1991-05-13 | Overheating monitor |
Country Status (1)
| Country | Link |
|---|---|
| GB (2) | GB9110741D0 (en) |
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP0833354A2 (en) * | 1996-09-27 | 1998-04-01 | Emerson Electric Co. | Thermal cutoff |
| EP0833355A2 (en) * | 1996-09-27 | 1998-04-01 | Emerson Electric Co. | Thermal cutoff |
| WO2007117163A1 (en) * | 2006-04-12 | 2007-10-18 | Abb Sp. Z O.O. | Surge arrester comprising an optical fault indicator |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN107024300A (en) * | 2016-01-29 | 2017-08-08 | 深圳带路科技有限公司 | A kind of apparatus overheat alarm |
Citations (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB1332410A (en) * | 1970-12-31 | 1973-10-03 | Artech Corp | Device for indicating that a refrigerated objects has undergone rewarming |
| US3827014A (en) * | 1973-09-24 | 1974-07-30 | Portage Electric Prod Inc | Thermal protector |
| US4145918A (en) * | 1976-09-07 | 1979-03-27 | Akzona Incorporated | Freeze-thaw indicator |
| GB2027995A (en) * | 1978-06-15 | 1980-02-27 | Inter Control Koehler Hermann | Temperature-responsive cut-out employing fusible material |
| GB2132021A (en) * | 1982-11-11 | 1984-06-27 | Soc Corp | Thermal switch |
| GB2203244A (en) * | 1987-02-13 | 1988-10-12 | Provera Gmbh | Indicator for monitoring the temperature of chilled or frozen products |
-
1991
- 1991-05-13 GB GB919110741A patent/GB9110741D0/en active Pending
-
1992
- 1992-05-12 GB GB9210158A patent/GB2256047A/en not_active Withdrawn
Patent Citations (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB1332410A (en) * | 1970-12-31 | 1973-10-03 | Artech Corp | Device for indicating that a refrigerated objects has undergone rewarming |
| US3827014A (en) * | 1973-09-24 | 1974-07-30 | Portage Electric Prod Inc | Thermal protector |
| US4145918A (en) * | 1976-09-07 | 1979-03-27 | Akzona Incorporated | Freeze-thaw indicator |
| GB2027995A (en) * | 1978-06-15 | 1980-02-27 | Inter Control Koehler Hermann | Temperature-responsive cut-out employing fusible material |
| GB2132021A (en) * | 1982-11-11 | 1984-06-27 | Soc Corp | Thermal switch |
| GB2203244A (en) * | 1987-02-13 | 1988-10-12 | Provera Gmbh | Indicator for monitoring the temperature of chilled or frozen products |
Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP0833354A2 (en) * | 1996-09-27 | 1998-04-01 | Emerson Electric Co. | Thermal cutoff |
| EP0833355A2 (en) * | 1996-09-27 | 1998-04-01 | Emerson Electric Co. | Thermal cutoff |
| EP0833355A3 (en) * | 1996-09-27 | 1999-01-27 | Emerson Electric Co. | Thermal cutoff |
| EP0833354A3 (en) * | 1996-09-27 | 1999-01-27 | Emerson Electric Co. | Thermal cutoff |
| WO2007117163A1 (en) * | 2006-04-12 | 2007-10-18 | Abb Sp. Z O.O. | Surge arrester comprising an optical fault indicator |
Also Published As
| Publication number | Publication date |
|---|---|
| GB9210158D0 (en) | 1992-06-24 |
| GB9110741D0 (en) | 1991-07-10 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| US6700497B2 (en) | System and method for identifying unsafe temperature conditions | |
| US7808760B2 (en) | Electrical fire prevention from over-temperature conditions | |
| CA1172300A (en) | Warning lights for electric cookers | |
| US4354105A (en) | Control system including a temperature-responsive variable optical parameter sensor | |
| US3513292A (en) | Electric kettle | |
| US4083224A (en) | Phase transition detector | |
| GB2256047A (en) | Temperature sensor | |
| US3916691A (en) | Electrically actuated cold junction compensating device | |
| EP0259412B1 (en) | Fibre-optic thermometer or temperature alarm device | |
| US3614345A (en) | Thermal sensing device | |
| NO860209L (en) | OVER HEATING ALARM. | |
| FR2365202A1 (en) | FUSE WITH FUSION INDICATOR | |
| GB2159940A (en) | Remote optical sensors | |
| US6456379B1 (en) | Optical smoke detector operating in accordance with the extinction principle and method for compensating its temperature drift | |
| GB2302586A (en) | Temperature indicator for mounting on a door or wall | |
| US4106339A (en) | Wind chill meter and method of measuring wind chill effect | |
| CN108917949B (en) | Signal controller for temperature alarm | |
| US4196428A (en) | Device for monitoring operational readiness of a gas-measuring instrument | |
| GB2083327A (en) | Warning light for electric cookers | |
| GB2122346A (en) | Combined thermometer-fire alarm device | |
| US2686908A (en) | Temperature indicating device | |
| JPH0432730A (en) | Temperature monitor device | |
| JPH0129676Y2 (en) | ||
| US3538770A (en) | Humidity meters | |
| GB1104330A (en) | Heat detection system |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| WAP | Application withdrawn, taken to be withdrawn or refused ** after publication under section 16(1) |