CA2093678C - Carbon monoxide activated safety shut-off system for gas appliances - Google Patents
Carbon monoxide activated safety shut-off system for gas appliancesInfo
- Publication number
- CA2093678C CA2093678C CA002093678A CA2093678A CA2093678C CA 2093678 C CA2093678 C CA 2093678C CA 002093678 A CA002093678 A CA 002093678A CA 2093678 A CA2093678 A CA 2093678A CA 2093678 C CA2093678 C CA 2093678C
- Authority
- CA
- Canada
- Prior art keywords
- connector
- gas
- valve control
- conducting strip
- thermocouple
- 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.)
- Expired - Fee Related
Links
Classifications
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
- F23D—BURNERS
- F23D14/00—Burners for combustion of a gas, e.g. of a gas stored under pressure as a liquid
- F23D14/46—Details, e.g. noise reduction means
- F23D14/72—Safety devices, e.g. operative in case of failure of gas supply
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
- F23N—REGULATING OR CONTROLLING COMBUSTION
- F23N5/00—Systems for controlling combustion
- F23N5/003—Systems for controlling combustion using detectors sensitive to combustion gas properties
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
- F23N—REGULATING OR CONTROLLING COMBUSTION
- F23N5/00—Systems for controlling combustion
- F23N5/24—Preventing development of abnormal or undesired conditions, i.e. safety arrangements
- F23N5/242—Preventing development of abnormal or undesired conditions, i.e. safety arrangements using electronic means
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
- F23N—REGULATING OR CONTROLLING COMBUSTION
- F23N2221/00—Pretreatment or prehandling
- F23N2221/10—Analysing fuel properties, e.g. density, calorific
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
- F23N—REGULATING OR CONTROLLING COMBUSTION
- F23N2231/00—Fail safe
- F23N2231/20—Warning devices
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
- F23N—REGULATING OR CONTROLLING COMBUSTION
- F23N5/00—Systems for controlling combustion
- F23N5/02—Systems for controlling combustion using devices responsive to thermal changes or to thermal expansion of a medium
- F23N5/10—Systems for controlling combustion using devices responsive to thermal changes or to thermal expansion of a medium using thermocouples
Abstract
A shut-off system interconnected to a propane powered internally vented appliance that is capable of terminating the flow of propane to the burner of the appliance when the level of CO emissions exceeds a predetermined amount. The system consists of a sensor assembly that detects the level of CO
emissions, a coupler for electrically coupling a switching circuit with a electromagnetic valve assembly, which controls a valve in the gas control unit, and a thermocouple. In use, the system switches the voltage across the electromagnetic valve to 0 volts such that the flow of propane to the burner is terminated to provide an added measure of safety in the operation of propane powered appliance.
emissions, a coupler for electrically coupling a switching circuit with a electromagnetic valve assembly, which controls a valve in the gas control unit, and a thermocouple. In use, the system switches the voltage across the electromagnetic valve to 0 volts such that the flow of propane to the burner is terminated to provide an added measure of safety in the operation of propane powered appliance.
Description
209~678 Carbon Monoxide Activated Safety Shut-Off System for Gas Appliances Field of the Invention This invention relates to the field of gas appliances, and more particularly, to propane powered internally vented appliances, such as refrigerators.
Background of the Invention Gas powered appliances that vent the products of combustion internally into the dwelling in which the appliance is located can result in the accumulation of unacceptable levels of carbon monoxide (CO). For example, propane powered refrigerators that are not vented to the outdoors by a chimney or flue, which are commonly being used in homes, cottages and trailers etc., can emit harmful levels of CO into the dwelling.
Under normal operating conditions the level of CO emissions will be below acceptable limits of approximately 100 parts per million (ppm). However, if there is an imbalance during combustion, such as a decrease in the available oxygen, the level of CO can increase beyond the acceptable limit. High levels of CO can cause severe physical damage to the occupants of the dwelling, if the level of CO remains undetected for an unacceptable period of time. Consequently, there is a need for automatically controlling the operation of this type of appliance based on the level of CO emissions.
There are currently passive CO sensors available that can be mounted near the exhaust flue of an internally vented appliance to monitor the level of CO being emitted. However, these sensors merely sound an alarm when the level of CO
exceeds a predetermined maximum. Someone must then physically turn off the flow of gas to stop the combustion thereby eliminating the CO emissions. This is an unacceptable method of monitoring and controlling CO emissions because it requires ~.
,~.
_ 2 human intervention to (a) hear the alarm from the sensor and (b) turn off the flow of gas to stop combustion.
As a result, there is a need for a safety shut-off system that is capable of (a) monitoring the level of CO emitting from the flue of an internal vented gas powered appliance and (b) capable of automatically turning off the flow of gas to stop combustion when the level of C0 exceeds a predetermined maxlmum .
Summary of the Invention An object of the preferred embodiment of the present invention is to provide a gas shut-off system that is capable of terminating the flow of gas to a burner of an appliance when the level of Co emissions exceeds a predetermined amount.
In accordance with one aspect of the invention there is provided an apparatus for terminating a supply of gas to a gas powered internally vented appliance having a burner, a valve control means and a thermocouple, said apparatus comprising:
sensing means for monitoring carbon monoxide levels being emitted from the burner; signal generating means connected to the sensing means for providing a electrical signal when the level of carbon monoxide emissions is above a predetermined level; and switching means, connected between the signal generating means and the valve control means, responsive to the electrical signal, for operating the valve control means to terminate the supply of gas to the burner.
In accordance with another aspect of the invention there is provided in a gas powered appliance having a burner, a valve control means and a thermocouple; an apparatus for terminating the supply of gas to the burner comprising: means for providing an electrical signal responsive to the level of carbon monoxide being emitted from the appliance, and means responsive to the electrical signal for terminating the supply of gas to the burner when the level of carbon monoxide exceeds a predetermined level.
In accordance with another aspect of the invention there is provided an apparatus for terminating a supply of gas to a gas burner having an exhaust flue comprising: a thermocouple adapted to produce an electrical signal in the presence of a flame from the gas burner; valve means for controlling the supply of gas to the gas burner, the valve means being maintained in an open position when subjected to the electrical signal; sensing means for detecting the presence of carbon monoxide in an area adjacent the exhaust flue, and adapted to produce an electrical control signal when the level of carbon monoxide is detected above a predetermined level;
and switch means controlled by the electrical control signal, the switch means being connected between the thermocouple and the valve means, whereby in the presence of carbon monoxide above the predetermined level the electrical signal is removed from the valve means closing the valve means and terminating the supply of gas to the gas burner.
Brief Description of the Drawings An embodiment of the invention will be described by way of example in conjunction with the drawings in which:
Fig. 1 illustrates a perspective view of a refrigerator showing mainly the back with the gas shut-off system of the present invention mounted thereon;
Fig. 2 illustrates a schematic representation of a typical gas control valve;
Fig. 3A illustrates a perspective exploded view of the gas control valve of Fig. 2 interconnected with the gas shut-off system of the present invention;
Fig. 3B illustrates a cross sectional view of a split adapter interconnecting various components of the gas shut-off system of the present invention;
~, 2(3~6 78 Fig. 4 illustrates a block diagram of the main components of a CO sensor interconnected with the gas shut-off system of the present invention; and Fig. 5 illustrates the switching circuit of the present invention.
Detailed Description of An Embodiment of the Invention Fig. 1 illustrates the back of a refrigerator 10 with a gas shut-off system 12 mounted to the refrigerator 10 and interconnected with a gas control valve 18. The shut-off system 12 includes a carbon monoxide (C0) sensor 14 and a split adapter 16. The sensor 14 has a pair of wires 22 extending therefrom to the adapter 16 for providing a gas shut-off signal to the gas control valve 18 in the event that excessive levels of CO are discharged into the dwelling. The details of this operation will be discussed in conjunction with Figs. 4 and 5.
In general, when the refrigerator is operating under normal conditions, a burner assembly 31 supports a flame 46 and combustion of propane occurs in a combustion chamber 24 of the refrigerator 10 with the products of combustion being exhausted through a flue 26 into a room (not shown) in which the refrigerator 10 is located.
2~
When there is a requirement to cool down the refrigerator 10, flame 46 is fed with a relatively large gas supply which provides the necessary energy to cool the refrigerator 10.
When the refrigerator 10 is at the required temperature, the intensity of the flame 46 is dramatically reduced by reducing the supply of gas to the burner 31.
A schematic representation of a typical gas control valve 18 commonly used in propane powered refrigerators is detailed in Fig. 2. The gas control valve 18 includes a chamber 34 having a pair of baffles 36 for directing the flow of gas through the chamber 34; a reset button 32; a valve plate 38 connected to a .~, electromagnetic valve assembly 44 which is biased by a spring 40. A gas inlet pipe 28 provides the supply of propane and a gas outlet pipe 30 supplies the propane to the burner assembly 31.
The operation of the control valve 18 will be discussed with reference to Fig. 2 without the interconnection of the shut-off system 12 of the present invention.
When the thermocouple 20 is heated by the flame 46, the thermocouple 20 generates a small electrical charge (approximately 27 mV) which energizes the electromagnetic valve assembly 44 which in turn holds the valve plate 38 in a gas flow position. Specifically, the valve plate 38 is oriented to allow the flow of propane from the inlet pipe 28 to the outlet pipe 30 by passing between the space in the baffles 36.
If the flame 46 becomes extinguished the electromagnetic valve assembly 44 is no longer energized, since the thermocouple 20 no longer generates the required voltage. Consequently, the electromagnetic valve assembly 44 drops the valve plate 38 on portions of the baffles 36. As a result, the flow of propane from the inlet pipe 28 to the outlet pipe 30 is terminated.
To restart the flow of propane, the reset button 32 is depressed, which pushes the valve plate 38 against the bias of spring 40 of the electromagnetic valve assembly 44 and lifts the valve plate 38 above the baffles 36. This allows the flow of propane to reach burner 31. The flame 46 is then lit to heat the thermocouple 20 which eventually will generate enough electricity to charge the electromagnetic valve assembly 44 to maintain the valve plate 38 in a gas flow position. At this stage the reset button 32 is released and propane will continue to flow from the inlet pipe 28 to the outlet pipe 30 by passing between the space in the baffles 36.
.
Fig. 3A illustrates the interconnection of the shut-off system 12 of the present invention with the control valve 18 and the thermocouple 20.
The adapter 16 (detailed in Fig. 3B) includes an external threaded protrusion 54 at one end and an internally threaded portion 55 at the other end. A conducting element 56 extends outwardly from the protrusion 54 and inwardly to a cavity 59 in the adapter 16. The conducting element 56 is insulated from the body of the adapter 16 by an insulating sheath 58.
The body of the adapter 16 is provided with an aperture 60 that extends through the sides of the adapter to expose a portion of the conducting element 56.
The protrusion 54 of adapter 16 is threaded into an interface 50 of the control valve 18. The wires 22 from the sensor 14 have a bi-polar connector 48 located at its end. The connector 48 has two electrically separated metal strips 49.
The connector 48 is inserted into the aperture 60 of the adapter 16 such that one of the metal strips 49 makes electrical contact with the portion of the conducting element 56 that extends into the cavity 59 of the adapter 16. The thermocouple 20 having a threaded end 52 is threaded into the internally threaded portion 55 of the adapter 16. A portion of the threaded end 52 of the thermocouple 20 makes electrical contact with one of the metal strips 49, i.e. the metal strip opposite the strip contacting the conducting element 56.
Fig. 4 illustrates the CO sensor 14 having a CO analyzer 62, a sensor processor 64 and a speaker 66. These are all known elements and will not be discussed in detail since they are commonly available items. A switching circuit 70 in the form of a MOSFET (metal-oxide-semiconductor field-effect transistor) is added to the CO sensor 14 to provide the necessary signals to the electromagnetic valve assembly 44 in the control valve 18 to terminate the flow of propane to the A-~
..
7 209s678 outlet pipe 30 in the event that excessive amounts of CO
emissions are detected.
The precise acceptable limits of carbon monoxide vary depending on the specific safety regulations in force in the district of interest. For example, the Ontario Fuel Safety Branch, in Canada, has established that 100 ppm of CO is the upper acceptable limit before the occupant may become at risk.
The switching circuit 70 is electrically connected to the processor of the sensor 14 such that when a predetermined level of CO is detected the circuit 70 will effectively drop the voltage across the electromagnetic valve assembly 44 to 0 volts, which in turn will close the valve 38 to terminate flow of propane to the outlet pipe 30.
More specifically, Fig. 5 illustrates a typical MOSFET circuit connected at the drain (D) to the thermocouple 20 and at the source (S) to the electromagnetic valve assembly 44. The gate (G) is attached to a DC voltage source supplied by the sensor 14. The following three operating conditions will be encountered and accommodated by the shut-off system 12:
1. Normal APPliance Operation CO Below Limit & Flame On In this situation VGS is greater than the threshold voltage of the MOSFET, or approximately +5 Volts. This situation will induce a current iD that is greater than 0 amperes resulting in a "short" circuit which in turn causes the voltage induced in the thermocouple (approximately 27 mV) to be applied to the electromagnetic valve assembly 44. When the electromagnetic valve assembly 44 is energized the valve 38 is maintained in a gas flow position (i.e. above baffles 36) to continue the flow of propane to the outlet pipe 30 to provide fuel to the burner assembly 31.
~093678 2. Carbon Monoxide Hazard Excessive Levels of CO Detected & Flame On In this situation the sensor processor 64 will reduce the VGS voltage from +5 volts to approximately 0 volts. This situation will in turn reduce the current iD to 0 amperes resulting in an "open" circuit such that the voltage induced in the thermocouple 20 is not applied to the electromagnetic valve assembly 44 so that the valve 38 drops into a position in which the flow of propane is terminated (i.e. the valve 38 rests on the baffles 36).
The flame 46 will be extinguished and eventually the thermocouple 20 will cool down such that no voltage is generated by the thermocouple 20.
Background of the Invention Gas powered appliances that vent the products of combustion internally into the dwelling in which the appliance is located can result in the accumulation of unacceptable levels of carbon monoxide (CO). For example, propane powered refrigerators that are not vented to the outdoors by a chimney or flue, which are commonly being used in homes, cottages and trailers etc., can emit harmful levels of CO into the dwelling.
Under normal operating conditions the level of CO emissions will be below acceptable limits of approximately 100 parts per million (ppm). However, if there is an imbalance during combustion, such as a decrease in the available oxygen, the level of CO can increase beyond the acceptable limit. High levels of CO can cause severe physical damage to the occupants of the dwelling, if the level of CO remains undetected for an unacceptable period of time. Consequently, there is a need for automatically controlling the operation of this type of appliance based on the level of CO emissions.
There are currently passive CO sensors available that can be mounted near the exhaust flue of an internally vented appliance to monitor the level of CO being emitted. However, these sensors merely sound an alarm when the level of CO
exceeds a predetermined maximum. Someone must then physically turn off the flow of gas to stop the combustion thereby eliminating the CO emissions. This is an unacceptable method of monitoring and controlling CO emissions because it requires ~.
,~.
_ 2 human intervention to (a) hear the alarm from the sensor and (b) turn off the flow of gas to stop combustion.
As a result, there is a need for a safety shut-off system that is capable of (a) monitoring the level of CO emitting from the flue of an internal vented gas powered appliance and (b) capable of automatically turning off the flow of gas to stop combustion when the level of C0 exceeds a predetermined maxlmum .
Summary of the Invention An object of the preferred embodiment of the present invention is to provide a gas shut-off system that is capable of terminating the flow of gas to a burner of an appliance when the level of Co emissions exceeds a predetermined amount.
In accordance with one aspect of the invention there is provided an apparatus for terminating a supply of gas to a gas powered internally vented appliance having a burner, a valve control means and a thermocouple, said apparatus comprising:
sensing means for monitoring carbon monoxide levels being emitted from the burner; signal generating means connected to the sensing means for providing a electrical signal when the level of carbon monoxide emissions is above a predetermined level; and switching means, connected between the signal generating means and the valve control means, responsive to the electrical signal, for operating the valve control means to terminate the supply of gas to the burner.
In accordance with another aspect of the invention there is provided in a gas powered appliance having a burner, a valve control means and a thermocouple; an apparatus for terminating the supply of gas to the burner comprising: means for providing an electrical signal responsive to the level of carbon monoxide being emitted from the appliance, and means responsive to the electrical signal for terminating the supply of gas to the burner when the level of carbon monoxide exceeds a predetermined level.
In accordance with another aspect of the invention there is provided an apparatus for terminating a supply of gas to a gas burner having an exhaust flue comprising: a thermocouple adapted to produce an electrical signal in the presence of a flame from the gas burner; valve means for controlling the supply of gas to the gas burner, the valve means being maintained in an open position when subjected to the electrical signal; sensing means for detecting the presence of carbon monoxide in an area adjacent the exhaust flue, and adapted to produce an electrical control signal when the level of carbon monoxide is detected above a predetermined level;
and switch means controlled by the electrical control signal, the switch means being connected between the thermocouple and the valve means, whereby in the presence of carbon monoxide above the predetermined level the electrical signal is removed from the valve means closing the valve means and terminating the supply of gas to the gas burner.
Brief Description of the Drawings An embodiment of the invention will be described by way of example in conjunction with the drawings in which:
Fig. 1 illustrates a perspective view of a refrigerator showing mainly the back with the gas shut-off system of the present invention mounted thereon;
Fig. 2 illustrates a schematic representation of a typical gas control valve;
Fig. 3A illustrates a perspective exploded view of the gas control valve of Fig. 2 interconnected with the gas shut-off system of the present invention;
Fig. 3B illustrates a cross sectional view of a split adapter interconnecting various components of the gas shut-off system of the present invention;
~, 2(3~6 78 Fig. 4 illustrates a block diagram of the main components of a CO sensor interconnected with the gas shut-off system of the present invention; and Fig. 5 illustrates the switching circuit of the present invention.
Detailed Description of An Embodiment of the Invention Fig. 1 illustrates the back of a refrigerator 10 with a gas shut-off system 12 mounted to the refrigerator 10 and interconnected with a gas control valve 18. The shut-off system 12 includes a carbon monoxide (C0) sensor 14 and a split adapter 16. The sensor 14 has a pair of wires 22 extending therefrom to the adapter 16 for providing a gas shut-off signal to the gas control valve 18 in the event that excessive levels of CO are discharged into the dwelling. The details of this operation will be discussed in conjunction with Figs. 4 and 5.
In general, when the refrigerator is operating under normal conditions, a burner assembly 31 supports a flame 46 and combustion of propane occurs in a combustion chamber 24 of the refrigerator 10 with the products of combustion being exhausted through a flue 26 into a room (not shown) in which the refrigerator 10 is located.
2~
When there is a requirement to cool down the refrigerator 10, flame 46 is fed with a relatively large gas supply which provides the necessary energy to cool the refrigerator 10.
When the refrigerator 10 is at the required temperature, the intensity of the flame 46 is dramatically reduced by reducing the supply of gas to the burner 31.
A schematic representation of a typical gas control valve 18 commonly used in propane powered refrigerators is detailed in Fig. 2. The gas control valve 18 includes a chamber 34 having a pair of baffles 36 for directing the flow of gas through the chamber 34; a reset button 32; a valve plate 38 connected to a .~, electromagnetic valve assembly 44 which is biased by a spring 40. A gas inlet pipe 28 provides the supply of propane and a gas outlet pipe 30 supplies the propane to the burner assembly 31.
The operation of the control valve 18 will be discussed with reference to Fig. 2 without the interconnection of the shut-off system 12 of the present invention.
When the thermocouple 20 is heated by the flame 46, the thermocouple 20 generates a small electrical charge (approximately 27 mV) which energizes the electromagnetic valve assembly 44 which in turn holds the valve plate 38 in a gas flow position. Specifically, the valve plate 38 is oriented to allow the flow of propane from the inlet pipe 28 to the outlet pipe 30 by passing between the space in the baffles 36.
If the flame 46 becomes extinguished the electromagnetic valve assembly 44 is no longer energized, since the thermocouple 20 no longer generates the required voltage. Consequently, the electromagnetic valve assembly 44 drops the valve plate 38 on portions of the baffles 36. As a result, the flow of propane from the inlet pipe 28 to the outlet pipe 30 is terminated.
To restart the flow of propane, the reset button 32 is depressed, which pushes the valve plate 38 against the bias of spring 40 of the electromagnetic valve assembly 44 and lifts the valve plate 38 above the baffles 36. This allows the flow of propane to reach burner 31. The flame 46 is then lit to heat the thermocouple 20 which eventually will generate enough electricity to charge the electromagnetic valve assembly 44 to maintain the valve plate 38 in a gas flow position. At this stage the reset button 32 is released and propane will continue to flow from the inlet pipe 28 to the outlet pipe 30 by passing between the space in the baffles 36.
.
Fig. 3A illustrates the interconnection of the shut-off system 12 of the present invention with the control valve 18 and the thermocouple 20.
The adapter 16 (detailed in Fig. 3B) includes an external threaded protrusion 54 at one end and an internally threaded portion 55 at the other end. A conducting element 56 extends outwardly from the protrusion 54 and inwardly to a cavity 59 in the adapter 16. The conducting element 56 is insulated from the body of the adapter 16 by an insulating sheath 58.
The body of the adapter 16 is provided with an aperture 60 that extends through the sides of the adapter to expose a portion of the conducting element 56.
The protrusion 54 of adapter 16 is threaded into an interface 50 of the control valve 18. The wires 22 from the sensor 14 have a bi-polar connector 48 located at its end. The connector 48 has two electrically separated metal strips 49.
The connector 48 is inserted into the aperture 60 of the adapter 16 such that one of the metal strips 49 makes electrical contact with the portion of the conducting element 56 that extends into the cavity 59 of the adapter 16. The thermocouple 20 having a threaded end 52 is threaded into the internally threaded portion 55 of the adapter 16. A portion of the threaded end 52 of the thermocouple 20 makes electrical contact with one of the metal strips 49, i.e. the metal strip opposite the strip contacting the conducting element 56.
Fig. 4 illustrates the CO sensor 14 having a CO analyzer 62, a sensor processor 64 and a speaker 66. These are all known elements and will not be discussed in detail since they are commonly available items. A switching circuit 70 in the form of a MOSFET (metal-oxide-semiconductor field-effect transistor) is added to the CO sensor 14 to provide the necessary signals to the electromagnetic valve assembly 44 in the control valve 18 to terminate the flow of propane to the A-~
..
7 209s678 outlet pipe 30 in the event that excessive amounts of CO
emissions are detected.
The precise acceptable limits of carbon monoxide vary depending on the specific safety regulations in force in the district of interest. For example, the Ontario Fuel Safety Branch, in Canada, has established that 100 ppm of CO is the upper acceptable limit before the occupant may become at risk.
The switching circuit 70 is electrically connected to the processor of the sensor 14 such that when a predetermined level of CO is detected the circuit 70 will effectively drop the voltage across the electromagnetic valve assembly 44 to 0 volts, which in turn will close the valve 38 to terminate flow of propane to the outlet pipe 30.
More specifically, Fig. 5 illustrates a typical MOSFET circuit connected at the drain (D) to the thermocouple 20 and at the source (S) to the electromagnetic valve assembly 44. The gate (G) is attached to a DC voltage source supplied by the sensor 14. The following three operating conditions will be encountered and accommodated by the shut-off system 12:
1. Normal APPliance Operation CO Below Limit & Flame On In this situation VGS is greater than the threshold voltage of the MOSFET, or approximately +5 Volts. This situation will induce a current iD that is greater than 0 amperes resulting in a "short" circuit which in turn causes the voltage induced in the thermocouple (approximately 27 mV) to be applied to the electromagnetic valve assembly 44. When the electromagnetic valve assembly 44 is energized the valve 38 is maintained in a gas flow position (i.e. above baffles 36) to continue the flow of propane to the outlet pipe 30 to provide fuel to the burner assembly 31.
~093678 2. Carbon Monoxide Hazard Excessive Levels of CO Detected & Flame On In this situation the sensor processor 64 will reduce the VGS voltage from +5 volts to approximately 0 volts. This situation will in turn reduce the current iD to 0 amperes resulting in an "open" circuit such that the voltage induced in the thermocouple 20 is not applied to the electromagnetic valve assembly 44 so that the valve 38 drops into a position in which the flow of propane is terminated (i.e. the valve 38 rests on the baffles 36).
The flame 46 will be extinguished and eventually the thermocouple 20 will cool down such that no voltage is generated by the thermocouple 20.
3. ProPane Leak Hazard Co Below Limit and Flame is Extinguished In this situation VGS remains at +5 volts and the MOSFET
is "short" circuited. However, the voltage generated by the thermocouple 20 drops to zero since it cools down with no flame 46. This voltage, or more particularly the lack of voltage, is applied across the electromagnetic valve assembly 44 such that the valve 38 drops into a position in which the flow of propane is terminated (i.e.
the valve 38 rests on the baffles 36).
In summary, the shut-off system 12 does not affect the normal operation of the thermocouple 20, but includes the additional feature of safely terminating the flow of propane to the outlet pipe 30 in the event that the CO emissions exceed a predetermined level.
The present invention provides a simple gas safety shut-off system that can be easily retrofitted to many existing refrigerators by merely unscrewing the thermocouple, inserting the adapter and the connector from the CO sensor and then screwing the thermocouple into the adaptor. The resulting arrangement provides an added measure of safety in the event , ~
._ of excess levels of CO being emitted from the flue of the refrigerator.
is "short" circuited. However, the voltage generated by the thermocouple 20 drops to zero since it cools down with no flame 46. This voltage, or more particularly the lack of voltage, is applied across the electromagnetic valve assembly 44 such that the valve 38 drops into a position in which the flow of propane is terminated (i.e.
the valve 38 rests on the baffles 36).
In summary, the shut-off system 12 does not affect the normal operation of the thermocouple 20, but includes the additional feature of safely terminating the flow of propane to the outlet pipe 30 in the event that the CO emissions exceed a predetermined level.
The present invention provides a simple gas safety shut-off system that can be easily retrofitted to many existing refrigerators by merely unscrewing the thermocouple, inserting the adapter and the connector from the CO sensor and then screwing the thermocouple into the adaptor. The resulting arrangement provides an added measure of safety in the event , ~
._ of excess levels of CO being emitted from the flue of the refrigerator.
Claims (8)
1. An apparatus for terminating a supply of gas to a gas powered internally vented appliance having a burner, a valve control means and a thermocouple, said apparatus comprising:
(a) sensing means for monitoring carbon monoxide levels being emitted from the burner;
(b) signal generating means connected to the sensing means for providing an electrical signal when the level of carbon monoxide emissions is above a predetermined level; and (c) switching means, connected between the signal generating means and the valve control means, responsive to the electrical signal, for operating the valve control means to terminate the supply of gas to the burner; said switching means includes:
(i) a switching circuit having a connector, said connector having a first conducting strip and a second conducting strip separated by an insulating strip such that the first and second conducting strips are not directly electrically connected; and (ii) coupling means for electrically coupling the connector of the switching circuit, the thermocouple and the valve control means.
(a) sensing means for monitoring carbon monoxide levels being emitted from the burner;
(b) signal generating means connected to the sensing means for providing an electrical signal when the level of carbon monoxide emissions is above a predetermined level; and (c) switching means, connected between the signal generating means and the valve control means, responsive to the electrical signal, for operating the valve control means to terminate the supply of gas to the burner; said switching means includes:
(i) a switching circuit having a connector, said connector having a first conducting strip and a second conducting strip separated by an insulating strip such that the first and second conducting strips are not directly electrically connected; and (ii) coupling means for electrically coupling the connector of the switching circuit, the thermocouple and the valve control means.
2. The apparatus of claim 1, wherein the coupling means includes a body having an aperture for receiving the connector such that the first conducting strip of the connector is in electrical contact with the valve control means and the second conducting strip of the connector is in electrical contact with the thermocouple.
3. The apparatus of claim 2, wherein the coupling means further includes a conducting element positioned between the valve control means and the first conducting strip of the connector such that the first conducting strip electrically communicates with the valve control means through the conducting element.
4. The apparatus of claim 3, wherein the switching circuit is a metal-oxide-semiconductor field-effect transistor.
5. An apparatus for terminating a supply of gas to a gas burner having an exhaust flue comprising:
a thermocouple adapted to produce an electrical signal in the presence of a flame from the gas burner;
valve means for controlling the supply of gas to the gas burner, the valve means being maintained in an open position when subjected to the electrical signal;
sensing means for detecting the presence of carbon monoxide in an area adjacent the exhaust flue, and adapted to produce an electrical control signal when the level of carbon monoxide is detected above a predetermined level; and switch means controlled by the electrical control signal, whereby in the presence of carbon monoxide above the predetermined level the electrical signal is removed from the valve means closing the valve means and terminating the supply of gas to the gas burner; said switch means includes:
(i) a switching circuit having a connector, said connector having a first conducting strip and a second conducting strip separated by an insulating strip such that the first and second conducting strips are not directly electrically connected; and (ii) coupling means for electrically coupling the connector of the switching circuit, the thermocouple and the valve control means.
a thermocouple adapted to produce an electrical signal in the presence of a flame from the gas burner;
valve means for controlling the supply of gas to the gas burner, the valve means being maintained in an open position when subjected to the electrical signal;
sensing means for detecting the presence of carbon monoxide in an area adjacent the exhaust flue, and adapted to produce an electrical control signal when the level of carbon monoxide is detected above a predetermined level; and switch means controlled by the electrical control signal, whereby in the presence of carbon monoxide above the predetermined level the electrical signal is removed from the valve means closing the valve means and terminating the supply of gas to the gas burner; said switch means includes:
(i) a switching circuit having a connector, said connector having a first conducting strip and a second conducting strip separated by an insulating strip such that the first and second conducting strips are not directly electrically connected; and (ii) coupling means for electrically coupling the connector of the switching circuit, the thermocouple and the valve control means.
6. The apparatus of claim 5, wherein the coupling means comprises a body having an aperture for receiving the connector such that the first conducting strip of the connector is in electrical contact with the valve control means and the second conducting strip of the connector is in electrical contact with the thermocouple.
7. The apparatus of claim 6, wherein the coupling means further includes a conducting element positioned between the valve control means and the first conducting strip of the connector such that the first conducting strip electrically communicates with the valve control means through the conducting element.
8. The apparatus of claim 6, wherein the switching circuit is a metal-oxide-semiconductor field-effect transistor.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA002093678A CA2093678C (en) | 1993-04-08 | 1993-04-08 | Carbon monoxide activated safety shut-off system for gas appliances |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA002093678A CA2093678C (en) | 1993-04-08 | 1993-04-08 | Carbon monoxide activated safety shut-off system for gas appliances |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2093678C true CA2093678C (en) | 1995-05-23 |
Family
ID=4151435
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA002093678A Expired - Fee Related CA2093678C (en) | 1993-04-08 | 1993-04-08 | Carbon monoxide activated safety shut-off system for gas appliances |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA2093678C (en) |
-
1993
- 1993-04-08 CA CA002093678A patent/CA2093678C/en not_active Expired - Fee Related
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| Date | Code | Title | Description |
|---|---|---|---|
| EEER | Examination request | ||
| MKLA | Lapsed |