US3728615A - Smoke, gas, or rapid temperature increase detector utilizing a periodic electric field to create a self-sustained avalanche current - Google Patents

Smoke, gas, or rapid temperature increase detector utilizing a periodic electric field to create a self-sustained avalanche current Download PDF

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Publication number
US3728615A
US3728615A US00872210A US3728615DA US3728615A US 3728615 A US3728615 A US 3728615A US 00872210 A US00872210 A US 00872210A US 3728615D A US3728615D A US 3728615DA US 3728615 A US3728615 A US 3728615A
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Prior art keywords
electric field
pulses
current
periodic
atmosphere
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US00872210A
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English (en)
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W Hill
I Gurol
S Dave
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Eaton Corp
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Eaton Yale and Towne Inc
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    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N27/00—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means
    • G01N27/62—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating the ionisation of gases, e.g. aerosols; by investigating electric discharges, e.g. emission of cathode
    • G01N27/68—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating the ionisation of gases, e.g. aerosols; by investigating electric discharges, e.g. emission of cathode using electric discharge to ionise a gas
    • G01N27/70—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating the ionisation of gases, e.g. aerosols; by investigating electric discharges, e.g. emission of cathode using electric discharge to ionise a gas and measuring current or voltage
    • G—PHYSICS
    • G08—SIGNALLING
    • G08B—SIGNALLING OR CALLING SYSTEMS; ORDER TELEGRAPHS; ALARM SYSTEMS
    • G08B17/00—Fire alarms; Alarms responsive to explosion
    • G08B17/10—Actuation by presence of smoke or gases, e.g. automatic alarm devices for analysing flowing fluid materials by the use of optical means
    • G08B17/11—Actuation by presence of smoke or gases, e.g. automatic alarm devices for analysing flowing fluid materials by the use of optical means using an ionisation chamber for detecting smoke or gas

Definitions

  • the apparatus includes a pulsing circuit to UNITED STATES PATENTS periodically apply a high voltage to a pair of detector tubes having center electrodes, one tube being ex- 2,954,474 9/1960 Lawrance ..324/33 posed to the ambient atmosphere, the other Shielded 3350'703 0/1967 Johnson "340/237
  • a pulsing circuit periodically ap- 3,439,26l 4/1969 Loh et al ..324/33 3,445,757 5/1969 Krucoff ..324 33 Ples to W3 deteFtor tube and a hldmg 3460l25 8/1969 Lieberman at a] 324/33 X and comparison circuit is provided to compare successive- 3,497,805 2/1970 Camnitz ..324/140 sive pairs of voltage pulses created by current flows 2,369,499 2/1945 Truvhaft ..73/359 caused by the periodic application of high voltages to 2,493,54
  • Another class of prior art device has provided an electric field exposed to the ambient atmosphere and an external ionization energy source in said field, usually by means of a radioactive element. Flow of the ions in this field produces a current, which varies with the presence of smoke and gas.
  • This class of device however suffers from the drawback of the necessity to include the radioactive element or other energy source with its attendant disadvantages and also since the resultant current flow is very small, sophisticated amplifier elements and circuitry are necessary for measuring and comparing the current flow.
  • the invention disclosed in Ser. No. 806,190 establishes an electric field of sufficient intensity and of proper configuration so that a Townsend avalanche will occur and in addition the field is of sufficient strength so that substantial numbers of ions are produced by photoionization (corona) and photo-emission and supply enough ions so that the basic Townsend avalanche will be self-sustaining and'a steady current flow result.
  • This current flow for the configuration disclosed therein is on the order of microamperes, greater by a factor of to 10 than that of the prior art device discussed above.
  • the presence of smoke particles or typical gaseous of combustion such as CO and CO affects the current flow and variations in current flow provide an indication of their presence.
  • FIG. 1 shows in a block diagram one form of the invention.
  • FIG. 2 is a block diagram representation of a second form of the invention.
  • a dual tube arrangement 10 is shown.
  • the arrangement includes an input voltage source, the output of which is controlled by a pulsing circuit that switches the voltage source in and out of the rest of the circuit periodically.
  • This circuit of which many types are well known in the art, provides a pulsing output which for this particular design is of the order of 30 milliseconds duration every 10 seconds.
  • This pulse is regulated by means of a voltage regulator as indicated so as to minimize the effects of line variations in voltage, and provide a constant voltage through the duration of the periodic pulse, since variations in voltage during the pulse would lead to current flow variations, and possible false trippings.
  • This regulated output is then applied to a high voltage power supply, which may be of any suitable design, to provide an output voltage of positive polarity and of the order of 3,500 volts. This voltage is selected so as to cause the sustained Townsend avalanche for the par ticular geometry of the detector tubes.
  • This voltage is then applied to the detector tubes l2, 14 via center electrodes 16 and 18.
  • These electrodes are constructed, in this embodiment, of 0.003 inch tungsten wire, while the tubes are approximately 5% inch long and have an ID of 0.302 inch, and each is equipped with slots 20, 22 to allow ambient atmosphcre to pass into the tube.
  • the positive polarity of the center electrodes 16, 18 creates a positive corona, since these are the high intensity electrodes. It has been found that this type of arrangement is much superior to that producing a negative corona, since the ionization process is sustained by the movement of the relatively low mass electrons, rather than the high mass positive ions. Thus much lower voltages are possible while producing the selfsustained Townsend avalanche, and the system is much less sensitive to changes in humidity, etc.
  • Detector tube 14 is partially sealed from the ambient atmosphere by means of a shield enclosure 24.
  • This enclosure is designed so that slow changes in temperature of the surrounding atmosphere are felt within the enclosure, while rapid rises in temperature, as well as the presence of smoke, and gaseous products of combustion are at least temporarily prevented from affecting the air contained within tube 14 in order to provide a reference as will hereinafter be more fully discussed.
  • Detector tubes 12 and 14 are connected with the control circuitry so that the current pulses resulting from the avalanche effect created between the center electrodes l6, l8 and their respective tubes l2, 14 is fed through a pulse forming network which may be any suitable RC circuit as indicated which serves to provide pulses free from hash and transient effects, so that reliable indications of variations in temperature and the presence of smoke and gas are obtained.
  • a potentiometer may be included to equalize current flow through the tubes under no fire conditions, since variations may occur due to normal manufacturing dimensional variations, surface finish, etc.
  • Voltages corresponding to each of the current fiows are then applied to a differential amplifier 26 which provides an amplified voltage signal corresponding to the difference in these voltages.
  • This element 26 is then applied to a pair of comparators 28, 30, which function to provide an output signal if the voltage output of the amplifier indicates a predetermined current flow difference between tubes l2, 14.
  • This predetermined difference is established by applying a reference voltage to each comparator, one for a voltage difference corresponding to a greater current flow in tube 12 than tube 14, indicating a higher ambient temperature of the atmosphere in tube 12 than 14, and another for a voltage difference corresponding to less current flow in tube 12 than 14, indicating the presence of smoke or the gaseous products of combustion in tube 12.
  • This predetermined difference should be set to allow for some variations due to localized effects but still trigger reliably when a condition indicating a fire exists.
  • a current flow difference of plus or minus microamps is a satisfactory level to create an output signal indicating a fire condition.
  • voltage levels produced by the differential amplifier corresponding to this current flow difference would give the indicated signal condition.
  • the output signal may then be fed to a relay driver which amplifies the signal current before being applied to a relay.
  • the relay is used to activate an indicator device such as an alarm or to operate fire control devices.
  • the signal could of course be fed to a high sensitivity relay, eliminating the need for amplification of the signal.
  • the pulsing circuit periodically will apply a pulse of high positive voltage to the detector tubes l2, 14, which for the geometry given at atmospheric pressure and normal temperature will be sufficient to create a Townsend avalanche, and also will produce sufficient incidence of photoionization and photoemission via the positive corona established so that this avalanche will be self-sustaining.
  • a second embodiment of the invention is shown in schematic form in FIG. 2.
  • currents created by voltage pulses applied at different points in time to a single detector tube 12 are compared and differences therein are utilized to trigger the indicator device in a manner similar to the above described embodiment. Since the spacing of the pulses is of relatively short duration, (approximately 20 seconds) slow changes in ambient temperature conditions such as created by normal temperature swings will not produce significant current differences, hence eliminating one cause of false tripping, and also providing the advantage of the pulsed electric field in eliminating electrostatic coating of the electrodes of the detector.
  • This arrangement is comprised of an input voltage source, pulsing circuit, voltage regulator and detector tube similar to the embodiment described above.
  • the pulsing circuit turns on both the monostable and bistable multivibrators which then provide a signal through the AND gate No. 1 to turn on analog gate No. 1 and allow the pulse which passes through the tube 12 and a pulse forming network similar to that in the embodiment described above to pass into the Hold circuit.
  • the next pulse then turns off the bistable multivibrator, turns on the monostable multivibrator, which results in a signal from AND gate No. 2, in turn causing analog gate No. 2 and No. 3 to be turned on.
  • This allows the pulse from the detector tube 12 and the pulse from the Hold circuit to be transmitted simultaneously to the differential amplifier 26, which functions to produce an amplified output corresponding to the difference in the pulses.
  • the output of the amplifier 26 is then fed to comparators 28 and 30 which provide an output signal to drive a relay when the voltage difference exceeds that of the reference voltages, which are set, in a similar manner to that in the above-described embodiment, to provide an output signal when a voltage difference ofa magnitude indicating the presence of smoke or gas, or when a fire indicative rapid rise in ambient temperature occurs.
  • a detector of smoke, gaseous products of combustion, or rapid temperature rise has been provided that is simple, reliable, provides a strong output signal eliminating the need for extensive amplifier components and circuitry, requires no radioactive material or other external ionization energy source, is relatively unaffected by electrostatic precipitation of dust, and is not subject to false tripping as a result of normal ambient temperature changes.
  • An apparatus for detecting an abnormal condition in an atmosphere such as the existence of smoke, gaseous products of combustion, or increases in ambient temperature in said atmosphere comprising:
  • A. means producing periodic voltage pulses having a substantially constant voltage throughout the duration of each of said pulses
  • first electric field means responsive to said pulses for establishing a first periodic electric field in said atmosphere in which a self-sustained avalanche current will occur for the duration of each of said pulses;
  • C. means providing a periodic reference current representative of a self-sustained avalanche current which would occur in an electric field in the absence of said abnormal conditions in said atmosphere;
  • comparing means producing an output signal in response to a predetermined difference between said first electric field current and said reference current.
  • said means providing said periodic reference current includes:
  • E. second electric field means partially sealed from said atmosphere and responsive to said pulses for establishing a second periodic electric field in which said self-sustained avalanche reference current will occur.
  • said means providing said periodic reference current includes:
  • E. hold means for holding a current occurring in said first periodic electric field during said duration of one of said pulses
  • F. means transmitting the held current to said com- 5 paring means for comparison with a subsequent current occurring in said first periodic electric field.
  • a method of detecting an abnormal condition such as the presence of smoke, gaseous products of combustion, or increases in ambient temperature in an atmosphere, comprising the steps of:
  • step providing said periodic reference current includes the steps of:
  • step providing said periodic reference current includes the steps of:
  • a method of detecting an abnormal condition such as the presence of smoke, gaseous products of combustion, or increases in ambient temperature in an atmosphere, comprising the steps of:
  • An apparatus for detecting changes in the condition of an atmosphere such as smoke, gaseous products of combustion, or temperature comprising:
  • first electric field means responsive to said positive pulses for establishing a first electric field in said atmosphere in which a first positive corona current will occur during each of said pulses;
  • second electric field means partially sealed from said atmosphere and responsive to said positive pulses for establishing a second electric field in which a second positive corona current will occur during each of said pulses;
  • comparing means producing an output signal in response to a predetermined difference between said first and second positive corona currents.
  • An apparatus for detecting changes in the condition of an atmosphere such as smoke, gaseous products of combustion, and temperature comprising:
  • A. means producing positive periodic voltage pulses having a substantially constant voltage throughout the duration of each of said pulses
  • C. hold means for holding a current occurring in said periodic electric field during the duration of one of said pulses
  • comparing means producing an output signal in response to a predetermined difference between the held current and a current occurring in said electric field in response to a subsequent one of said pulses.

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  • Chemical & Material Sciences (AREA)
  • Physics & Mathematics (AREA)
  • Analytical Chemistry (AREA)
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  • Life Sciences & Earth Sciences (AREA)
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US00872210A 1969-10-29 1969-10-29 Smoke, gas, or rapid temperature increase detector utilizing a periodic electric field to create a self-sustained avalanche current Expired - Lifetime US3728615A (en)

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JP (1) JPS4812680B1 (enrdf_load_stackoverflow)
CH (1) CH529400A (enrdf_load_stackoverflow)
DE (1) DE2048817A1 (enrdf_load_stackoverflow)
GB (1) GB1295498A (enrdf_load_stackoverflow)

Cited By (21)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3949390A (en) * 1974-06-05 1976-04-06 Rca Corporation High voltage aerosol detector
US4011507A (en) * 1975-11-10 1977-03-08 Burroughs Corporation Full cycle current detector
FR2408837A1 (fr) * 1977-11-15 1979-06-08 Collard Jean Claude Detecteur de gaz de combustion a ionisation par haute tension
US4254414A (en) * 1979-03-22 1981-03-03 The United States Of America As Represented By The Secretary Of The Navy Processor-aided fire detector
US4306230A (en) * 1979-12-10 1981-12-15 Honeywell Inc. Self-checking photoelectric smoke detector
US4387369A (en) * 1978-10-11 1983-06-07 Johnson Controls, Inc. Broad spectrum charged electric field polar gas sensing and detection system
US4404516A (en) * 1980-10-29 1983-09-13 Johnson Jr Victor R System for detecting leaks from liquid-containing reservoirs and conduits
FR2528980A1 (fr) * 1982-06-17 1983-12-23 Pgep Detecteur de niveau d'ionisation d'un milieu gazeux controle par arc electrique
US4543570A (en) * 1982-05-29 1985-09-24 Robert Bosch Gmbh Detecting a rapid change of a critical physical condition
US4698586A (en) * 1984-03-26 1987-10-06 Pgep Professional General Electric Corp. Electric particle detector for the detection of fire
USRE32552E (en) * 1971-03-16 1987-12-01 Tif Instr Inc Gaseous impurity detector employing corona discharge phenomenon
US4774472A (en) * 1986-03-24 1988-09-27 The Simco Company, Inc. Apparatus for method to test efficiency of air ionizers and method for determining ability of an air ionizer to sustain a potential difference between an isolated object and a reference potential
US4884222A (en) * 1984-07-31 1989-11-28 Tetsuya Nagashima Fire alarm system
US4910463A (en) * 1987-12-17 1990-03-20 Sentech Corporation Halogen monitoring apparatus
US5198774A (en) * 1987-12-17 1993-03-30 Williams Ii William J Gas monitoring apparatus
US5347223A (en) * 1993-01-22 1994-09-13 J And N Associates, Inc. Gas leak detector sensing tip with interior concentric bores and corona current generation
US5475311A (en) * 1994-05-03 1995-12-12 Motorola, Inc. Ionization gas analyzer and method
US5539381A (en) * 1994-11-14 1996-07-23 Sentrol, Inc. Fixed threshold and rate of rise heat detector with dynamic thermal reference
US5574434A (en) * 1995-08-11 1996-11-12 Liu; Hung-Chang Alarm for heat multistaged detecting
US6642838B1 (en) 2002-10-31 2003-11-04 Charles A. Barnas Safety system for automobiles
US20050224240A1 (en) * 2002-03-01 2005-10-13 Cosgrove John J Fire detection and suppression apparatus

Families Citing this family (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE4402518C2 (de) * 1994-01-28 1997-10-23 Preussag Ag Minimax Ionisationsrauchmelder
EP0820045A3 (de) * 1996-07-18 1999-10-13 Siemens Aktiengesellschaft Isonisationsrauchmelder
CN106362506B (zh) * 2016-11-29 2018-06-15 中国烟草总公司郑州烟草研究院 一种全烟气暴露实验烟气废气排放装置及排放方法

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US2369499A (en) * 1945-02-13 Apparatus fob measuring rate of
US2493543A (en) * 1947-09-08 1950-01-03 Brush Dev Co Monitoring system of comparator type
US2755999A (en) * 1952-05-17 1956-07-24 Gen Motors Corp Temperature measuring and control apparatus
US2954474A (en) * 1955-04-01 1960-09-27 Nat Res Corp Measuring
US3350703A (en) * 1964-07-17 1967-10-31 Johnson Williams Inc Gas concentration detection apparatus
US3439261A (en) * 1966-09-30 1969-04-15 Gen Electric Combustible gas detector using a corona discharge
US3445757A (en) * 1965-10-14 1969-05-20 Mc Donnell Douglas Corp Capillary ionization gas detector and analyzer using timed interval current fluctuations
US3460125A (en) * 1964-12-10 1969-08-05 Thermal Ind Of Florida Inc Method and apparatus for detecting gaseous impurities
US3497805A (en) * 1960-02-18 1970-02-24 Bausch & Lomb Circuit including a constant amplitude pulse generator for adjusting the amplitude of pulses produced by a transducer

Patent Citations (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2369499A (en) * 1945-02-13 Apparatus fob measuring rate of
US2493543A (en) * 1947-09-08 1950-01-03 Brush Dev Co Monitoring system of comparator type
US2755999A (en) * 1952-05-17 1956-07-24 Gen Motors Corp Temperature measuring and control apparatus
US2954474A (en) * 1955-04-01 1960-09-27 Nat Res Corp Measuring
US3497805A (en) * 1960-02-18 1970-02-24 Bausch & Lomb Circuit including a constant amplitude pulse generator for adjusting the amplitude of pulses produced by a transducer
US3350703A (en) * 1964-07-17 1967-10-31 Johnson Williams Inc Gas concentration detection apparatus
US3460125A (en) * 1964-12-10 1969-08-05 Thermal Ind Of Florida Inc Method and apparatus for detecting gaseous impurities
US3445757A (en) * 1965-10-14 1969-05-20 Mc Donnell Douglas Corp Capillary ionization gas detector and analyzer using timed interval current fluctuations
US3439261A (en) * 1966-09-30 1969-04-15 Gen Electric Combustible gas detector using a corona discharge

Cited By (25)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
USRE32552E (en) * 1971-03-16 1987-12-01 Tif Instr Inc Gaseous impurity detector employing corona discharge phenomenon
US3949390A (en) * 1974-06-05 1976-04-06 Rca Corporation High voltage aerosol detector
US4011507A (en) * 1975-11-10 1977-03-08 Burroughs Corporation Full cycle current detector
FR2408837A1 (fr) * 1977-11-15 1979-06-08 Collard Jean Claude Detecteur de gaz de combustion a ionisation par haute tension
US4387369A (en) * 1978-10-11 1983-06-07 Johnson Controls, Inc. Broad spectrum charged electric field polar gas sensing and detection system
US4254414A (en) * 1979-03-22 1981-03-03 The United States Of America As Represented By The Secretary Of The Navy Processor-aided fire detector
US4306230A (en) * 1979-12-10 1981-12-15 Honeywell Inc. Self-checking photoelectric smoke detector
US4404516A (en) * 1980-10-29 1983-09-13 Johnson Jr Victor R System for detecting leaks from liquid-containing reservoirs and conduits
US4543570A (en) * 1982-05-29 1985-09-24 Robert Bosch Gmbh Detecting a rapid change of a critical physical condition
WO1984000074A1 (fr) * 1982-06-17 1984-01-05 Professional General Elect Detecteur de niveau d'ionisation d'un milieu gazeux controle par arc electrique
EP0099776A1 (fr) * 1982-06-17 1984-02-01 P.G.E.P. PROFESSIONAL GENERAL ELECTRONIC PRODUCTS Société Anonyme Détecteur de niveau d'ionisation d'un milieu gazeux contrôlé par arc électrique
US4629992A (en) * 1982-06-17 1986-12-16 P.G.E.P. Professional General Electronic Products Device for detecting the ionization level of a gas mixture controlled by electric arc
FR2528980A1 (fr) * 1982-06-17 1983-12-23 Pgep Detecteur de niveau d'ionisation d'un milieu gazeux controle par arc electrique
AU571838B2 (en) * 1982-06-17 1988-04-28 P.G.E.P. Professional General Electronic Products Device for detecting the ionisation level of a gas mixture controlled by electric arc
US4698586A (en) * 1984-03-26 1987-10-06 Pgep Professional General Electric Corp. Electric particle detector for the detection of fire
US4884222A (en) * 1984-07-31 1989-11-28 Tetsuya Nagashima Fire alarm system
US4774472A (en) * 1986-03-24 1988-09-27 The Simco Company, Inc. Apparatus for method to test efficiency of air ionizers and method for determining ability of an air ionizer to sustain a potential difference between an isolated object and a reference potential
US4910463A (en) * 1987-12-17 1990-03-20 Sentech Corporation Halogen monitoring apparatus
US5198774A (en) * 1987-12-17 1993-03-30 Williams Ii William J Gas monitoring apparatus
US5347223A (en) * 1993-01-22 1994-09-13 J And N Associates, Inc. Gas leak detector sensing tip with interior concentric bores and corona current generation
US5475311A (en) * 1994-05-03 1995-12-12 Motorola, Inc. Ionization gas analyzer and method
US5539381A (en) * 1994-11-14 1996-07-23 Sentrol, Inc. Fixed threshold and rate of rise heat detector with dynamic thermal reference
US5574434A (en) * 1995-08-11 1996-11-12 Liu; Hung-Chang Alarm for heat multistaged detecting
US20050224240A1 (en) * 2002-03-01 2005-10-13 Cosgrove John J Fire detection and suppression apparatus
US6642838B1 (en) 2002-10-31 2003-11-04 Charles A. Barnas Safety system for automobiles

Also Published As

Publication number Publication date
GB1295498A (enrdf_load_stackoverflow) 1972-11-08
JPS4812680B1 (enrdf_load_stackoverflow) 1973-04-21
CH529400A (de) 1972-10-15
DE2048817A1 (de) 1971-05-06

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