AU3007500A - Oxygen depletion sensor - Google Patents
Oxygen depletion sensor Download PDFInfo
- Publication number
- AU3007500A AU3007500A AU30075/00A AU3007500A AU3007500A AU 3007500 A AU3007500 A AU 3007500A AU 30075/00 A AU30075/00 A AU 30075/00A AU 3007500 A AU3007500 A AU 3007500A AU 3007500 A AU3007500 A AU 3007500A
- Authority
- AU
- Australia
- Prior art keywords
- flame
- thermocouple
- oxygen
- gaseous fuel
- combustion air
- 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.)
- Abandoned
Links
Classifications
-
- 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
- F23N5/006—Systems for controlling combustion using detectors sensitive to combustion gas properties the detector being sensitive to oxygen
-
- 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
- F23N5/107—Systems for controlling combustion using devices responsive to thermal changes or to thermal expansion of a medium using thermocouples using mechanical means, e.g. safety valves
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
- F23N—REGULATING OR CONTROLLING COMBUSTION
- F23N2227/00—Ignition or checking
- F23N2227/22—Pilot burners
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
- F23N—REGULATING OR CONTROLLING COMBUSTION
- F23N2235/00—Valves, nozzles or pumps
- F23N2235/12—Fuel valves
- F23N2235/14—Fuel valves electromagnetically operated
Landscapes
- Engineering & Computer Science (AREA)
- Chemical & Material Sciences (AREA)
- Combustion & Propulsion (AREA)
- Mechanical Engineering (AREA)
- General Engineering & Computer Science (AREA)
- Control Of Combustion (AREA)
- Regulation And Control Of Combustion (AREA)
Description
WO 00/50815 PCT/US00/04851 OXYGEN DEPLETION SENSOR BACKGROUND OF THE INVENTION The present invention generally relates to controlling the flow of gas to a gas-fired appliance and more particularly pertains to an oxygen depletion sensor that enables a gas controller to shut off the supply of gas to the appliance when the oxygen content of the 5 combustion air falls below a preselected value. Obviating the need to vent a gas burning appliance provides a number of advantages for various applications. First and foremost, it obviates the need to route combustion gases to the outside of a building or room thereby greatly simplifying the installation of certain appliances. Additionally, elimination of a vent may enhance the efficiency of certain gas 10 fired appliances as it precludes the escape of heat through such vent. Combustion of certain gases such as natural gas (methane) or liquified petroleum gas can yield very clean, substantially toxin-free exhaust gases, essentially limited to CO2 and H20, if the supplied combustion air has an adequate oxygen content. However, as the oxygen content drops below a critical level, an increasing amount of undesirable pollutants 15 are created during the combustion of the fuel. Additionally, as the oxygen is depleted in an WO 00/50815 PCT/US00/04851 enclosed space, less and less will be available for the occupants thereof to breathe as well. It is therefore most desirable for combustion in a non-vented gas-fired appliance to immediately and automatically be discontinued should the oxygen content ofthe combustion air fall below a critical level. 5 A number of different approaches have been devised in an effort to address this problem. In its most fundamental form, a standard pilot light and thermocouple combination may serve as a crude oxygen depletion sensor in view of the fact that a substantial drop in the oxygen level will eventually cause a pilot flame to extinguish. This in turn will cause the voltage generated by the thermocouple to drop below the threshold level required for 10 maintaining the associated gas valve in its open position. However, substantially more sensitivity is desirable and indeed is required by currently applicable industry standards. One approach that has been employed in an effort to enhance the sensitivity of the pilot light/thermocouple combination to low oxygen levels has exploited the fact that the pilot flame temperature decreases as the oxygen level drops off. By enhancing the sensitivity 15 of the gas valve to respond to the slightly reduced voltage generated by a thermocouple being subjected to a slightly cooler flame, the gas supply can be shut off long before a drop in 2 WO 00/50815 PCT/US00/04851 oxygen level would actually cause the pilot flame to become extinguished. However, such devices nonetheless suffer from certain disadvantages. As an example, the heightened sensitivity of the valve to slightly reduced thermocouple voltages may give rise to unnecessary shut downs when a slight reduction in voltage is caused by something other than 5 an unacceptably low oxygen level. A shifting of the thermocouple relative to the pilot flame could cause the thermocouple to be subjected to a cooler region of the flame. Conversely, a shifting of the flame relative to the thermocouple, such as when it is distorted by a draft, could similarly cause the thermocouple to be subjected to a cooler region of the flame. In either event, a slightly reduced voltage is the result that may not be distinguishable from the 0 reduced voltage that results from an overall cooling of the flame caused by a decrease in the oxygen level. Additionally, such systems are vulnerable to the radiated heat generated by the main burner of a gas-fired device as the temperature actually sensed by the thermocouple may therefore be higher than that actually generated by the pilot flame and as a result, a cooling of the pilot flame caused by a drop in the oxygen level could go undetected. 5 The device described in USPN 5,674,065 to Grando et al. appears to be a representative example of heretofore known thermocouple and oxygen depletion sensor configurations and as such would suffer from the disadvantages described above. The 3 WO 00/50815 PCT/US00/04851 thermocouple is described as being conventionally installed as part of an oxygen depletion safety device wherein the thermocouple is positioned so as to be heated by the gas flame of the pilot. When the flame becomes unstable or diminished in size due to a reduction in the oxygen level, its temperature drops off causing a commensurate reduction in the voltage 5 generated by the thermocouple. Any voltage reduction below the 14-22 open circuit millivolt range will cause the gas valve to close. As a consequence, a reduction of the output voltage to slightly below the nominal range for any reason would cause the shut down of the gas supply even if the oxygen level were not significantly depleted. Conversely, the sensitivity of such system could conceivably allow the radiant heat of the burner to maintain the output 10 voltage within the nominal range even if the oxygen level were depleted to an unacceptable level. Either situation is undesirable. Other disadvantages inherent in prior art devices are that they generally require a substantial reconfiguration in order to accommodate the use of different gaseous fuels. Different nozzles and different relative positions of the nozzle and thermocouple require a 15 multiplication of the number of parts that must be manufactured and on hand for the various applications. As an example, in the apparatus described in Grando et al, the thermocouple 4 WO 00/50815 PCT/US00/04851 must be repositioned from out in front of the pilot to an attachment point directly on the side of the pilot in order to accommodate a change from natural gas to liquified petroleum gas. A simple, reliable oxygen depletion sensor is needed that overcomes the shortcomings of the heretofore known sensors. Such sensor should be easy to manufacture and should be 5 readily installable into existing appliance configurations. SUMMARY OF THE INVENTION The present invention provides an oxygen depletion sensor that offers substantial advantages over previously known devices. The sensor is easily manufactured, very reliably responds to a drop in the oxygen content to below a preselected level, is substantially 0 unresponsive to slight shifts in pilot flame or thermocouple positions and additionally provides a visual indication of the oxygen level. In general terms, the present invention takes advantage of the effect that the oxygen content of combustion air has on flame velocity and causes the difference between the voltage generated by thermocouple during high and during low oxygen level conditions to be greatly exaggerated. In contrast to the previously known 15 devices wherein the thermocouple output gradually drops off as the oxygen level is depleted 5 WO 00/50815 PCT/US00/04851 and the difference between the voltage that is generated during combustion at acceptable oxygen levels and at unacceptable oxygen level conditions is very slight, the device of the present invention needs only to recognize a substantial drop in the generated voltage. The flame velocity of a particular gaseous fuel is indicative of how fast such gas burns 5 and depends to a large extent on the amount of oxygen that is available for combustion. Flame velocity is therefore a direct function of the oxygen/fuel ratio in a mixture subject to combustion. By holding the air/fuel ratio constant, the flame velocity becomes a direct function of the oxygen content in the combustion air. During combustion, the position of the flame, or more accurately, the periphery of the 10 base of such flame will stabilize where the flow velocity of the combustible mixture substantially equals the flame velocity. As the oxygen level decreases, the flame velocity drops off causing the base of the flame to move away from the nozzle emitting the combustible mixture. The unburned zone will tend to increase as the oxygen level continues to decrease until eventually, the flame is extinguished. 6 WO 00/50815 PCT/US00/04851 The velocity of a gas flowing from a nozzle is substantially a function of the volume of the gas flow and of the cross-sectional area of the nozzle through which such gas flow issues. The amount of combustion air that is drawn into a flow of gaseous fuel prior to its emission from a nozzle is substantially dependent upon the pressure drop generated by the 5 flow as it passes through a mixing chamber and upon the size of the primary air intake opening through which air is drawn into such mixing chamber in response to the pressure drop. The volume and velocity of the gaseous fuel flowing into and through such mixing chamber will determine the pressure drop relative to ambient conditions. The pressure at which the gaseous fuel is supplied and the size of the inlet orifice through which the fuel 10 flows into a mixing chamber will in turn determine the volume and velocity of the gaseous fuel as it passes through the mixing chamber. The combination of all these parameters will determine where the flame resulting from the combustion of the air/fuel mixture issuing from the nozzle will be positioned relative to such nozzle. As the oxygen content of the combustion air is decreased, the flame will move away from the nozzle. 15 The oxygen depletion sensor of the present invention exploits these fluid dynamic principles of gas flow and flame velocity. By advantageously positioning a thermocouple adjacent to an appropriately configured nozzle emitting an air/fuel mixture, such that the 7 WO 00/50815 PCT/US00/04851 thermocouple is enveloped by the flame during combustion of such mixture at oxygen levels above a preselected value and is wholly outside the flame at oxygen levels below such preselected level, a very substantial change in output voltage is thereby realized as a function of only a relatively minor change in the combustion air's oxygen content. An associated 5 valve that controls the flow of gas to the appliance is configured such that only a voltage in the range generated by the thermocouple while enveloped by the flame is sufficient to hold the valve in its open position. The substantially lower voltage generated by the thermocouple when located in the unburned zone is substantially below the threshold voltage required for maintaining the valve in its open position. Such system is substantially 10 impervious to slight shifts in the relative positions of the thermocouple and pilot flame as the voltage generated in even the coolest region of the flame is still well above the threshold temperature at which the valve shuts off. Conversely, the heat radiated by the main burner is incapable of raising the voltage generated by the thermocouple while positioned outside the flame to a level sufficient to maintain the valve in its open position. Only the substantial 15 drop in output voltage commensurate with the temperature differential between a location inside and a location outside the flame is recognized as being indicative of an unacceptable drop in oxygen content. 8 WO 00/50815 PCT/US00/04851 The present invention provides an additional benefit in that the position of the flame relative to the thermocouple gives a visual indication of the oxygen content of the combustion air. The oxygen content will be at or above an acceptable level when the thermocouple is observed as being fully enveloped by the flame. Any shift of the periphery 5 of the flame toward the thermocouple that is apparent or any obvious instability or lifting of the flame is an indication of a depleted oxygen level. A gap between the flame and the thermocouple during for example manual override of an automatic shutoff valve is an indication of an unacceptably low oxygen level. Finally, the present invention provides the additional advantage of being readily 10 adaptable for use with different gaseous fuels. Rather than requiring the use of a different nozzle configuration and/or the repositioning of the thermocouple relative to the nozzle in order to accommodate the use of a different gas, the same nozzle and the same relative placement of the nozzle and thermocouple may be employed by simply resizing the inlet orifice and air hole sizes. 15 These and other features and advantages of the present invention will become apparent from the following detailed description of a preferred embodiment which, taken in 9 WO 00/50815 PCT/US00/04851 conjunction with the accompanying drawings, illustrates by way of example the principles of the invention. BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is semi-schematic view of an oxygen depletion sensor of the present invention 5 as used in a gas-fired appliance; Fig. 2 is an enlarged cross-sectional view of the flame forming component of the sensor shown in Fig. 1; Fig. 3 is side view of the oxygen depletion sensor of the present invention with a pilot flame burning in combustion air having a high level of oxygen content; 10 Fig. 4 is a side view of the oxygen depletion sensor of the present invention with a pilot flame burning in combustion air having a low level of oxygen content; and 10 WO 00/50815 PCT/US00/04851 Fig. 5 is a graphic plot of the voltage versus oxygen level for a device constructed in accordance with the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The Figures generally illustrate the present invention and more particularly, are 5 directed to a preferred embodiment thereof. The oxygen depletion sensor of the present invention simultaneously serves as a pilot light for a gas-fired appliance and functions to shut off the flow of gas to such appliance should the oxygen content of the combustion air fall below a preselected level. The device is readily adaptable for use with different gaseous fuels. Additionally, the device provides a visual indication of the oxygen content that is 0 present in the combustion air. Fig. 1 is a semi-schematic representation of a preferred embodiment of the oxygen sensor device 12 of the present invention as used in a gas-fired appliance. A bracket 14 maintains a thermocouple 16 in position adjacent the mouth of nozzle 18 of a flame forming component 20. A gas valve 22 controls the flow of gas from a supply line 21 to both the 11 WO 00/50815 PCT/US00/04851 flame forming component 20 via line 24 and to the main burner 26 of the appliance via line 28. The valve is configured such that the range of voltages generated by the thermocouple while subject to temperatures encountered within a pilot flame is sufficient to hold the valve in its open position while voltages generated by the thermocouple at temperatures below 5 those encountered within a pilot flame are insufficient to hold the valve open and therefore allow the valve to close and shut off the flow of gas to the appliance. The general configuration of such a valve may conform to that which is well known in the art wherein a spring loaded valve element is held in its open position by an electromagnet that is energized by the thermocouple. The particular performance parameters of such valve 10 configuration are selected such that the threshold voltage for holding the valve open is below the voltage generated by the thermocouple while positioned in a pilot flame and above the voltage generated by such thermocouple while positioned in the unburned zone adjacent a pilot flame. The bracket may additionally hold an ignitor 30 in position so as to enable the gaseous 15 mixture issuing from the nozzle to be ignited to establish a pilot flame. Additionally, the bracket may hold a thermopile 32 in position above the flame. The voltage generated by the thermopile may be used by the valve 22 to regulate the flow of gas to the main burner 26. 12 WO 00/50815 PCT/US00/04851 Fig. 2 is a cross sectional view of the flame controlling component 20 of the oxygen depletion sensor and illustrates its essential features. Gas line 24 supplies the component with gaseous fuel which enters a mixing chamber 34 through inlet orifice 36. An air hole 38 is formed in the wall of the mixing chamber and the gaseous fuel flowing from inlet orifice 5 as well as the air drawn in through the air hole exits through nozzle 18. The line pressure of the gas and the cross-sectional area of inlet orifice 36 dictate the velocity with which the gas emanates from the orifice. The velocity of the gas flow and size of the cross-sectional area of the air hole in turn determines the rate at which combustion air is drawn into the mixing chamber. The respective flow rates of the gaseous fuel and the combustion air in turn 10 determine the air/fuel ratio of the resultant mixture. Finally, the diameter of the nozzle determines the velocity with which the air/fuel mixture issues from the nozzle. By properly selecting the various parameters, i.e. type of gaseous fuel, line pressure, inlet orifice size, air hole size and nozzle size, a stable flame forms adjacent the mouth of the nozzle upon combustion of the mixture issuing from the nozzle. As the oxygen content of 15 the combustion air that is drawn in through the air hole decreases, the position of the flame shifts away from the end of the nozzle. Thermocouple 16 is positioned so as to be located within the flame in the position the flame assumes when the combustion air contains what 13 WO 00/50815 PCT/US00/04851 is considered to be an adequate oxygen content and outside of the periphery of the flame, i.e in the unburned zone, when the flame is in the position it assumes when the combustion air contains what is considered to be an inadequate oxygen content. The following dimensions and relationships are representative of a configuration that 5 functions in accordance with the present invention: gas type: methane inlet pressure: 3.5 to 10.5" water column inlet orifice: 0.013" diameter air hole: 0.166" diameter 10 nozzle: 0.125" diameter TC from nozzle: 0.35" TC output at 600-700 F: 13mV - 16mV min. to hold valve open: 2.5mV .5 An oxygen depletion sensor constructed in accordance with the above specifications has been found to automatically shut off the flow of gas when the oxygen content in the 14 WO 00/50815 PCT/US00/04851 combustion air drops from the normal 20.8% to between 18.2 - 19.4%. Further depletion of the oxygen content is thereby curtailed to prevent the formation of noxious products of combustion and to leave an adequate oxygen content for breathing. Fig. 3 illustrates the oxygen depletion sensor 12 in operation when the combustion air 5 contains an adequate content of oxygen. The pilot flame 40 forms and stabilizes a short distance adjacent to the mouth of nozzle 18. The base of the flame, or more accurately, the proximal end of the periphery of the flame approximately conforms to the loci of where the flame velocity is substantially equal to the flow velocity of the combustible mixture of gaseous fuel and combustion air issuing from the nozzle. The thermocouple 16 is positioned 0 within the flame and generates a voltage commensurate with the 600-700 F temperature it is thereby subjected to. Such voltage is well above the threshold voltage selected to hold the valve 22 in its open position thus allowing it to supply gas to the flame forming component 20 as well as to the main burner 26 as needed. The configuration ofthe device has the added benefit of maintaining a fairly high flow 5 velocity of the combustible mixture which allows the main burner 26 to be distanced further away from the nozzle 18 and thermocouple 16 than is possible when using a low velocity 15 WO 00/50815 PCT/US00/04851 configuration. This serves to reduce the amount of radiated heat sensed by the thermocouple. Additionally, the higher velocity stabilizes the flame which is thereby less susceptible to distortion by drafts and less susceptible to buoyancy effects making it feasible to mount the device in inclined and even vertical orientations as well as the illustrated horizontal 5 orientation. Fig. 4 illustrates the oxygen depletion sensor 12 in operation in an environment wherein the combustion air has a depleted oxygen content. The flame 40a forms at a position further removed from the mouth of the nozzle 18 which causes the thermocouple 16 to be positioned outside the flame in the unburned zone. The temperature outside the periphery 3 of the flame is substantially less than inside the flame, on the order of several hundred degrees Fahrenheit, resulting in a commensurately reduced voltage output. The lower voltage output is well below the threshold voltage required to maintain the gas valve 22 in its open position which causes it to shut off all gas flow. Additionally, a visual inspection of the pilot flame offers a clear indication of the oxygen content by virtue of the position of 5 the flame relative to the thermocouple. Any gap between the visible periphery of the pilot flame and the thermocouple or any instability or lifting of the pilot flame is an indication of an unacceptably low oxygen content and that shut off is imminent. 16 WO 00/50815 PCT/US00/04851 Fig. 5 is a representative plot of thermocouple voltage versus oxygen content of the combustion air for a oxygen sensor device of the present invention. As is apparent, the voltage generated by the thermocouple gradually decreases as the oxygen content of the combustion air becomes depleted. In the zone identified by reference numeral 50, the 5 thermocouple is enveloped by the flame and therefore subject to very high temperatures, as is evidenced by the relatively high voltage output. As the oxygen content is depleted, the flame velocity of the mixture decreases which causes the flame temperature to drop off slightly as is evidenced by the slight slope in the curve. The depletion of the oxygen content also causes the flame to gradually move away from the nozzle and thermocouple until its 0 periphery is substantially aligned with the thermocouple. At such point, the temperature sensed by the thermocouple is subject to a precipitous decline as is evidenced by the abrupt drop in the voltage in zone 52. Further depletion of the oxygen content would cause the voltage to continue to decrease (zone 54) as the flame moves further away from the thermocouple and its temperature continues to decrease. The flame forming component of 5 the present invention is configured such that the abrupt transition zone 52 substantially includes the preselected limit 56 below which the oxygen content is considered unacceptable. Additionally, the gas valve is configured such that the threshold voltage necessary to maintain the valve in its open position is selected to correspond to a voltage 58 encountered 17 WO 00/50815 PCT/US00/04851 in the transition zone 52. As a consequence, maximum sensitivity and repeatability is simultaneously achieved. The oxygen depletion of the sensor of the present invention can be readily modified to accommodate the use other gaseous fuels by either altering the inlet orifice diameter, the 5 air hole diameter, or both. The same thermocouple may be used, the same spacing between the thermocouple and the mouth of the nozzle may be maintained and the same overall flame forming component may be employed. While a particular form of the invention has been illustrated and described, it will also be apparent to those skilled in the art that various modifications can be made without 10 departing from the spirit and scope of the invention. Accordingly, it is not intended that the invention be limited except by the appended claims. 18
Claims (11)
1. An oxygen depletion sensor device for discontinuing the flow of a gaseous fuel to a fuel-burning appliance when the oxygen content of combustion air available for the combustion of said gaseous fuel falls below a preselected limit, comprising: a flame forming component for providing a flame of combusting gas adjacent 5 thereto, said flame being subject to a change in position as a function of the oxygen content of combustion air available for combustion of said gaseous fuel, wherein said flame shifts away from said flame forming component as said oxygen content decreases; a thermocouple positioned so as to be located within said flame when said oxygen content is above said preselected limit and adjacent such flame when said oxygen 0 content is below said preselected limit, wherein voltage generated by said thermocouple while said thermocouple is within said flame is greater than a threshold level and voltage generated by said thermocouple while said thermocouple is adjacent said flame is below said threshold level; and a valve for controlling the flow of gaseous fuel to said appliance, wherein said 5 valve is responsive to voltage generated by said thermocouple such that said flow is discontinued when the voltage generated by said thermocouple is below said threshold level. 19 WO 00/50815 PCT/US00/04851
2. The oxygen depletion sensor of claim 1, wherein said flame forming component comprises: a mixing chamber; an inlet orifice formed in said mixing chamber for allowing said gaseous fuel 5 to enter; an air hole formed in said mixing chamber for allowing combustion air to be drawn into said mixing chamber; and an exit nozzle through which said gaseous fuel and said combustion air exit said mixing chamber.
3. The oxygen depletion sensor of claim 1, wherein said flame serves as a pilot flame for igniting a main burner of said appliance.
4. The oxygen depletion sensor of claim 3, further comprising: a thermopile operative to generate a voltage when subjected to said flame sufficient to allow said valve to regulate the flow of gaseous fuel to said main burner. 20 WO 00/50815 PCT/US00/04851
5. The oxygen depletion sensor of claim 4, wherein said thermopile is positioned directly above said flame.
6. An oxygen depletion sensor, comprising: a flame forming component for causing combustion of a mixture of a gaseous fuel and combustion air to form a flame which shifts in position as a function of the oxygen content of said combustion air; and 5 a thermocouple operative to generate a voltage as a function of temperature, positioned so as to be located within said flame when said combustion air has an acceptable oxygen content and outside said flame when said combustion air has an unacceptable oxygen content.
7. The oxygen depletion sensor of claim 6, further comprising: a valve for controlling the flow of said gaseous fuel therethrough, responsive to the voltage generated by said thermocouple and configured to shut off said flow of gaseous fuel at voltages below those generated when said thermocouple is located within said flame. 21 WO 00/50815 PCT/US00/04851
8. The oxygen depletion sensor of claim 7, wherein said valve controls the flow of said gaseous fuel to said flame forming component and to a main burner of a fuel-burning appliance and wherein said flame serves as a pilot flame for igniting said main burner.
9. An oxygen depletion sensor, comprising: a thermocouple operative to generate a voltage as a function of temperature; and a flame forming component for causing combustion of a mixture of a gaseous fuel and combustion air to form a flame, wherein such flame envelops said thermocouple only 5 when said oxygen content of said combustion air is above a preselected level while said flame is positioned adjacent said thermocouple when said oxygen level of said combustion air is below a preselected level.
10. The oxygen depletion sensor of claim 9, further comprising a valve for controlling a flow of said gaseous fuel therethrough, responsive to the voltage generated by said thermocouple and configured to shut off said flow of gaseous fuel at voltages below those generated when said thermocouple is enveloped by said flame. 22 WO 00/50815 PCT/US00/04851
11. The oxygen depletion sensor of claim 10, wherein said valve controls the flow of said gaseous fuel to said flame forming component and to a main burner of a fuel-burning appliance and wherein said flame serves as a pilot flame for igniting said main burner. 23
Applications Claiming Priority (3)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
US12190999P | 1999-02-26 | 1999-02-26 | |
US60121909 | 1999-02-26 | ||
PCT/US2000/004851 WO2000050815A1 (en) | 1999-02-26 | 2000-02-24 | Oxygen depletion sensor |
Publications (1)
Publication Number | Publication Date |
---|---|
AU3007500A true AU3007500A (en) | 2000-09-14 |
Family
ID=22399484
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
AU30075/00A Abandoned AU3007500A (en) | 1999-02-26 | 2000-02-24 | Oxygen depletion sensor |
Country Status (4)
Country | Link |
---|---|
JP (1) | JP2002538402A (en) |
AU (1) | AU3007500A (en) |
CA (1) | CA2362615A1 (en) |
WO (1) | WO2000050815A1 (en) |
Families Citing this family (7)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
ES2287436T3 (en) * | 2002-11-13 | 2007-12-16 | Coprecitec, S.L. | THERMOELECTRIC GENERATOR GROUP WITH A PILOT BURNER. |
US7766006B1 (en) | 2007-03-09 | 2010-08-03 | Coprecitec, S.L. | Dual fuel vent free gas heater |
US8403661B2 (en) | 2007-03-09 | 2013-03-26 | Coprecitec, S.L. | Dual fuel heater |
US8057219B1 (en) | 2007-03-09 | 2011-11-15 | Coprecitec, S.L. | Dual fuel vent free gas heater |
US8118590B1 (en) | 2007-03-09 | 2012-02-21 | Coprecitec, S.L. | Dual fuel vent free gas heater |
ES1067938Y (en) | 2008-05-12 | 2008-10-16 | Coprecitec Sl | PILOT FLAME BURNER WITH OXYGEN EMPOBRECIMIENTO DETECTOR |
US8899971B2 (en) | 2010-08-20 | 2014-12-02 | Coprecitec, S.L. | Dual fuel gas heater |
Family Cites Families (5)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JPS57101227A (en) * | 1980-12-16 | 1982-06-23 | Matsushita Electric Ind Co Ltd | Instantaneous gas water heater with prevention device against incomplete combustion |
ES8405127A1 (en) * | 1982-08-03 | 1984-06-01 | Stefani & C G Pernumia | A safety device for gas heating apparatus. |
JPS60218526A (en) * | 1984-04-14 | 1985-11-01 | Rinnai Corp | Safety device for combustion of gas instrument |
JPS61105023A (en) * | 1984-10-26 | 1986-05-23 | Rinnai Corp | Safety device of gas burning equipment |
US5674065A (en) | 1996-01-22 | 1997-10-07 | Op S.R.L. | Apparatus for controlling the supply of gas to and heat from unvented gas heating appliances |
-
2000
- 2000-02-24 CA CA002362615A patent/CA2362615A1/en not_active Abandoned
- 2000-02-24 AU AU30075/00A patent/AU3007500A/en not_active Abandoned
- 2000-02-24 WO PCT/US2000/004851 patent/WO2000050815A1/en active Application Filing
- 2000-02-24 JP JP2000601371A patent/JP2002538402A/en active Pending
Also Published As
Publication number | Publication date |
---|---|
WO2000050815A1 (en) | 2000-08-31 |
CA2362615A1 (en) | 2000-08-31 |
JP2002538402A (en) | 2002-11-12 |
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Date | Code | Title | Description |
---|---|---|---|
MK1 | Application lapsed section 142(2)(a) - no request for examination in relevant period |