GB2042191A - Air or gas-flow detecting device - Google Patents

Air or gas-flow detecting device Download PDF

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Publication number
GB2042191A
GB2042191A GB7901886A GB7901886A GB2042191A GB 2042191 A GB2042191 A GB 2042191A GB 7901886 A GB7901886 A GB 7901886A GB 7901886 A GB7901886 A GB 7901886A GB 2042191 A GB2042191 A GB 2042191A
Authority
GB
United Kingdom
Prior art keywords
gas
cut
air
air flow
light
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Withdrawn
Application number
GB7901886A
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
United Gas Industries Ltd
Original Assignee
United Gas Industries Ltd
Priority date (The priority date 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 date listed.)
Filing date
Publication date
Application filed by United Gas Industries Ltd filed Critical United Gas Industries Ltd
Priority to GB7901886A priority Critical patent/GB2042191A/en
Publication of GB2042191A publication Critical patent/GB2042191A/en
Withdrawn legal-status Critical Current

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Classifications

    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
    • F23N—REGULATING OR CONTROLLING COMBUSTION
    • F23N5/00—Systems for controlling combustion
    • F23N5/18—Systems for controlling combustion using detectors sensitive to rate of flow of air or fuel
    • F23N5/187—Systems for controlling combustion using detectors sensitive to rate of flow of air or fuel using electrical or electromechanical means
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01P—MEASURING LINEAR OR ANGULAR SPEED, ACCELERATION, DECELERATION, OR SHOCK; INDICATING PRESENCE, ABSENCE, OR DIRECTION, OF MOVEMENT
    • G01P13/00—Indicating or recording presence, absence, or direction, of movement
    • G01P13/0006—Indicating or recording presence, absence, or direction, of movement of fluids or of granulous or powder-like substances
    • G01P13/0026—Indicating or recording presence, absence, or direction, of movement of fluids or of granulous or powder-like substances by using deflection of baffle-plates
    • G01P13/0033—Indicating or recording presence, absence, or direction, of movement of fluids or of granulous or powder-like substances by using deflection of baffle-plates with electrical coupling to the indicating device
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01P—MEASURING LINEAR OR ANGULAR SPEED, ACCELERATION, DECELERATION, OR SHOCK; INDICATING PRESENCE, ABSENCE, OR DIRECTION, OF MOVEMENT
    • G01P13/00—Indicating or recording presence, absence, or direction, of movement
    • G01P13/0006—Indicating or recording presence, absence, or direction, of movement of fluids or of granulous or powder-like substances
    • G01P13/006—Indicating or recording presence, absence, or direction, of movement of fluids or of granulous or powder-like substances by using thermal variables
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
    • F23N—REGULATING OR CONTROLLING COMBUSTION
    • F23N5/00—Systems for controlling combustion
    • F23N5/18—Systems for controlling combustion using detectors sensitive to rate of flow of air or fuel
    • F23N2005/181—Systems for controlling combustion using detectors sensitive to rate of flow of air or fuel using detectors sensitive to rate of flow of air
    • F23N2005/182—Air flow switch
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
    • F23N—REGULATING OR CONTROLLING COMBUSTION
    • F23N5/00—Systems for controlling combustion
    • F23N5/18—Systems for controlling combustion using detectors sensitive to rate of flow of air or fuel
    • F23N2005/185—Systems for controlling combustion using detectors sensitive to rate of flow of air or fuel using detectors sensitive to rate of flow of fuel

Abstract

A gas-fired appliance having a fan-assisted airflow to its burners has a cut-out switch 18 for shutting down the appliance when the air flow is deficient. A pivoted vane 15 is moved by the flowing air to clear the switch 18 at normal air flows, the switch being operated when the air flow drops too low. Another embodiment described has a thermistor heated by a coil in the air flow, the resistance of the thermistor operating the cut-out when the air flow is reduced and the temperature of the thermistor consequently rises. <IMAGE>

Description

SPECIFICATION Air or gas-flow detecting devices This invention relates to air or gas flow detecting devices.
The invention provides a device having means for mounting in a gas or air flow path, which means is sensitive to gas or air movement and operates on a warning or cut-out circuit so that a warning is made or a cut-out operated when the gas or air flow falls below a predetermined level.
The sensitive means may comprise a thermister and a coil located to heat said thermister, the thermister being connected to a circuit which produces a warning or cut-out operation when the resistance of the thermister indicates gas or air flow below said predetermined level.
Alternatively, the sensitive means may comprise a pivoted vane, located to be pivoted by said gas or air flow. Said vane may interrupt a light beam, which light beam operates said warning or cut-out.
According to another aspect, the invention provides a gas-fired appliance having a fan-assisted air supply to its burners, and an air flow detecting device as described above in a path from the fan to the burners. Said cut-out may operate to shut off the appliance. In such appliances the airflow may not be very great and a particularly sensitive detecting device is required to determine the difference between a normal level of airflow and a dangerously low level.
Specific embodiments of the invention are shown in the accompanying drawings, in which: Figure lisa diagrammatic section through a first embodiment.
Figure2 is a diagrammatic section through a second embodiment, and Figure 3 is a detail of a variation of the embodiment of Figure 2.
Referring first to Figure 1, a fan 11 is arranged to blow air or other gas in the direction of arrows A along a pathway 12. In the gas stream is positioned a thermister 13, the resistance of which varies with temperature. A heater coil (not shown) is located to heat the thermister for example to a temperature of 1 600C when there is no gas flow. The thermister is connected into a cut-out circuit 14 outside the gas stream, which circuit is sensitive to the resistance of the thermister. When the gas stream is moving at a speed in a normal range, indicating that the fan is operating correctly, the thermister is cooled below 160"C to a temperature at which the resistance does not trigger the cut-out circuit.If the gas stream is moving at a speed below the normal range, or not at all, the temperature of the thermister rises and the cut-out circuit is triggered. The cut-out circuit operates to stop operation of a heating appliance of which the fan forms part, but alternatively may operate a warning device.
Figure 2 operates on another principle, and has a light-weight vane 15 in the gas stream. The vane is pivoted at or outside the periphery of the gas path so that one end of it is moved in the direction of arrow B by the gas movement. The other, shorter end of the vane carries a small weight 16 which balances the weight of the longer end, so that the lever is easily moved, but when free of pressures due to gas movement returns to a vertical position. In the verticai position the upper end of the lever operates a microswitch 18 or similar switching mechanism.
This microswitch operates like the cut-out circuit of the embodiment of Figure 1, to stop the operation of an appliance the safety of which is dependent on a proper supply of gas or air.
Figure 3 shows a detail of a vane 15' similar to that of Figure 2, the vane being formed of thin aluminium foil so as to present little resistance to movement.
The pivot may be a line contact bearing to produce low frictional resistance. In place of the microswitch of Figure 2, the upper end of the lever is located in a light path between a light source 20 (e.g. a neon bulb) and a light detector 21. When no gas or air flow is present, or a flow below a predetermined speed, the upper end of the lever interrupts the light path and the light detector sees no light. When the gas or airflow is in a normal range the lever is pivoted in the direction of arrow C out of the light path. The light detector then sees the light. When no light is detected the detector acts like the cut-out circuit of Figure 1 or in conjunction with such a circuit to stop the operation of an appliance.
Should the light source fail to operate or the light path be interrupted by a contaminant carried in the gas or air, the cut-out will operate, drawing attenion to the failure or contamination.
The devices described above are preferably used in gas-fired appliances in which fans supply air to gas burners. When the fans are not working or, due for instance to bearing failure, are rotating slowly and delivering only a fraction of their normal air flow, the gas burners may be starved of oxygen, and be dangerous. The devices described detect the failure of the fans and turn the appliances off, for instance by closing gas valves.
However, although of preferred use in gas-fired appliances, the devices may be used in any context where the failure of a gas or air supply needs to be detected.
1. A gas or air flow detecting device having means for mounting in a gas or air flow path, which means is sensitive to gas or air movement and operates on a warning or cut-out circuit so that a warning is made or a cut-out operated when the gas or air-flow falls below a predetermined level.
2. A device as claimed in claim 1, wherein said sensitive means comprises a thermistor and a coil located to heat said thermistor, the thermistor being electrically connected into a circuit which produces the warning or cut-out operation when the resistance of the thermistor indicates gas or air flow below said predetermined level.
3. A device as claimed in claim 1, wherein said sensitive means comprises a pivoted vane located to be pivoted by said gas or airflow.
4. A device as claimed in claim 3, wherein said pivoted vane operates an electrical switch in said
**WARNING** end of DESC field may overlap start of CLMS **.

Claims (9)

**WARNING** start of CLMS field may overlap end of DESC **. SPECIFICATION Air or gas-flow detecting devices This invention relates to air or gas flow detecting devices. The invention provides a device having means for mounting in a gas or air flow path, which means is sensitive to gas or air movement and operates on a warning or cut-out circuit so that a warning is made or a cut-out operated when the gas or air flow falls below a predetermined level. The sensitive means may comprise a thermister and a coil located to heat said thermister, the thermister being connected to a circuit which produces a warning or cut-out operation when the resistance of the thermister indicates gas or air flow below said predetermined level. Alternatively, the sensitive means may comprise a pivoted vane, located to be pivoted by said gas or air flow. Said vane may interrupt a light beam, which light beam operates said warning or cut-out. According to another aspect, the invention provides a gas-fired appliance having a fan-assisted air supply to its burners, and an air flow detecting device as described above in a path from the fan to the burners. Said cut-out may operate to shut off the appliance. In such appliances the airflow may not be very great and a particularly sensitive detecting device is required to determine the difference between a normal level of airflow and a dangerously low level. Specific embodiments of the invention are shown in the accompanying drawings, in which: Figure lisa diagrammatic section through a first embodiment. Figure2 is a diagrammatic section through a second embodiment, and Figure 3 is a detail of a variation of the embodiment of Figure 2. Referring first to Figure 1, a fan 11 is arranged to blow air or other gas in the direction of arrows A along a pathway 12. In the gas stream is positioned a thermister 13, the resistance of which varies with temperature. A heater coil (not shown) is located to heat the thermister for example to a temperature of 1 600C when there is no gas flow. The thermister is connected into a cut-out circuit 14 outside the gas stream, which circuit is sensitive to the resistance of the thermister. When the gas stream is moving at a speed in a normal range, indicating that the fan is operating correctly, the thermister is cooled below 160"C to a temperature at which the resistance does not trigger the cut-out circuit.If the gas stream is moving at a speed below the normal range, or not at all, the temperature of the thermister rises and the cut-out circuit is triggered. The cut-out circuit operates to stop operation of a heating appliance of which the fan forms part, but alternatively may operate a warning device. Figure 2 operates on another principle, and has a light-weight vane 15 in the gas stream. The vane is pivoted at or outside the periphery of the gas path so that one end of it is moved in the direction of arrow B by the gas movement. The other, shorter end of the vane carries a small weight 16 which balances the weight of the longer end, so that the lever is easily moved, but when free of pressures due to gas movement returns to a vertical position. In the verticai position the upper end of the lever operates a microswitch 18 or similar switching mechanism. This microswitch operates like the cut-out circuit of the embodiment of Figure 1, to stop the operation of an appliance the safety of which is dependent on a proper supply of gas or air. Figure 3 shows a detail of a vane 15' similar to that of Figure 2, the vane being formed of thin aluminium foil so as to present little resistance to movement. The pivot may be a line contact bearing to produce low frictional resistance. In place of the microswitch of Figure 2, the upper end of the lever is located in a light path between a light source 20 (e.g. a neon bulb) and a light detector 21. When no gas or air flow is present, or a flow below a predetermined speed, the upper end of the lever interrupts the light path and the light detector sees no light. When the gas or airflow is in a normal range the lever is pivoted in the direction of arrow C out of the light path. The light detector then sees the light. When no light is detected the detector acts like the cut-out circuit of Figure 1 or in conjunction with such a circuit to stop the operation of an appliance. Should the light source fail to operate or the light path be interrupted by a contaminant carried in the gas or air, the cut-out will operate, drawing attenion to the failure or contamination. The devices described above are preferably used in gas-fired appliances in which fans supply air to gas burners. When the fans are not working or, due for instance to bearing failure, are rotating slowly and delivering only a fraction of their normal air flow, the gas burners may be starved of oxygen, and be dangerous. The devices described detect the failure of the fans and turn the appliances off, for instance by closing gas valves. However, although of preferred use in gas-fired appliances, the devices may be used in any context where the failure of a gas or air supply needs to be detected. CLAIMS
1. A gas or air flow detecting device having means for mounting in a gas or air flow path, which means is sensitive to gas or air movement and operates on a warning or cut-out circuit so that a warning is made or a cut-out operated when the gas or air-flow falls below a predetermined level.
2. A device as claimed in claim 1, wherein said sensitive means comprises a thermistor and a coil located to heat said thermistor, the thermistor being electrically connected into a circuit which produces the warning or cut-out operation when the resistance of the thermistor indicates gas or air flow below said predetermined level.
3. A device as claimed in claim 1, wherein said sensitive means comprises a pivoted vane located to be pivoted by said gas or airflow.
4. A device as claimed in claim 3, wherein said pivoted vane operates an electrical switch in said circuit.
5. A device as claimed in claim 3, wherein said pivoted vane in located to pivot into or out of the path of a light beam directed toward a light detector, which detector is connected in said circuit.
6. A device as claimed in any of claims 3 to 5, wherein said pivoted vane is formed of thin metal foil.
7. A gas or air flow detecting device substantially as described hereinbefore with reference to any of the accompanying-drawings.
8. A gas-fired appliance having a fan-assisted air supply to its burners and an air flow detecting device as claimed in any of claims 1 to 7 in the path of air flowing from the fan to the burners.
9. A gas-fired appliance as claimed in claim 8, wherein said cut-out is connected to shut off the appliance.
GB7901886A 1979-01-18 1979-01-18 Air or gas-flow detecting device Withdrawn GB2042191A (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
GB7901886A GB2042191A (en) 1979-01-18 1979-01-18 Air or gas-flow detecting device

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
GB7901886A GB2042191A (en) 1979-01-18 1979-01-18 Air or gas-flow detecting device

Publications (1)

Publication Number Publication Date
GB2042191A true GB2042191A (en) 1980-09-17

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Application Number Title Priority Date Filing Date
GB7901886A Withdrawn GB2042191A (en) 1979-01-18 1979-01-18 Air or gas-flow detecting device

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Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2512853A1 (en) * 1981-09-16 1983-03-18 Bosch Siemens Hausgeraete HOUSEHOLD APPLIANCE OPERATING WITH WATER AND EQUIPPED WITH MEANS SIGNALING THE PROPER FUNCTIONING OF THE CIRCULATION PUMP
GB2116726A (en) * 1982-03-03 1983-09-28 Herbert Nicholson Device for indicating gas flow in flue of heating appliance
FR2545585A1 (en) * 1983-05-05 1984-11-09 Laurent Francois Improvements to gas-operated heat generators which are capable of being connected to a controlled induction
US4513233A (en) * 1983-12-22 1985-04-23 Gte Automatic Electric Incorporated Pulse monitor circuit for use as a fan speed monitor
EP0351042A1 (en) * 1988-05-19 1990-01-17 Varian Associates, Inc. Fluid flow sensor
EP0863367A1 (en) * 1997-03-05 1998-09-09 Electrowatt Technology Innovation AG Control device for a gas burner

Cited By (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2512853A1 (en) * 1981-09-16 1983-03-18 Bosch Siemens Hausgeraete HOUSEHOLD APPLIANCE OPERATING WITH WATER AND EQUIPPED WITH MEANS SIGNALING THE PROPER FUNCTIONING OF THE CIRCULATION PUMP
GB2116726A (en) * 1982-03-03 1983-09-28 Herbert Nicholson Device for indicating gas flow in flue of heating appliance
FR2545585A1 (en) * 1983-05-05 1984-11-09 Laurent Francois Improvements to gas-operated heat generators which are capable of being connected to a controlled induction
US4513233A (en) * 1983-12-22 1985-04-23 Gte Automatic Electric Incorporated Pulse monitor circuit for use as a fan speed monitor
EP0351042A1 (en) * 1988-05-19 1990-01-17 Varian Associates, Inc. Fluid flow sensor
US4931776A (en) * 1988-05-19 1990-06-05 Varian Associates, Inc. Fluid flow sensor with flexible vane
EP0863367A1 (en) * 1997-03-05 1998-09-09 Electrowatt Technology Innovation AG Control device for a gas burner

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WAP Application withdrawn, taken to be withdrawn or refused ** after publication under section 16(1)