US3500368A - Automatic ionic fire alarm system - Google Patents

Automatic ionic fire alarm system Download PDF

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Publication number
US3500368A
US3500368A US573284A US3500368DA US3500368A US 3500368 A US3500368 A US 3500368A US 573284 A US573284 A US 573284A US 3500368D A US3500368D A US 3500368DA US 3500368 A US3500368 A US 3500368A
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United States
Prior art keywords
ion chamber
ion
electrode
voltage
automatic
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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 - Lifetime
Application number
US573284A
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English (en)
Inventor
Nagao Abe
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Nittan Co Ltd
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Nittan Co Ltd
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Publication of US3500368A publication Critical patent/US3500368A/en
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    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01T—MEASUREMENT OF NUCLEAR OR X-RADIATION
    • G01T7/00—Details of radiation-measuring instruments
    • G01T7/12—Provision for actuation of an alarm
    • G01T7/125—Alarm- or controlling circuits using ionisation chambers, proportional counters or Geiger-Mueller tubes, also functioning as UV detectors
    • 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
    • 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
    • G08B17/113—Constructional details

Definitions

  • An automatic fire detecting device comprising a housing with openings communicating with the atmosphere, a dividing means within the housing for dividing the housing into an atmospheric isolated inner ion chamber and an outer ion chamber, the latter communicating with the atmosphere and isolated from the inner chamber, the dividing means including an electrode cover having an inner and outer surface communicating with the inner and outer ion chambers, respectively, an inner radioactive source disposed on the inner surface and an outer radioactive source disposed on the outer surface, an inner electrode means disposed in the inner ion chamber in spaced relationship from the inner radioactive source, and an outer electrode means disposed in the outer ion chamber spaced from the outer radioactive source, the inner and outer radioactive ources emitting radioactive rays toward the inner and outer electrode means, respectively, and circuit means for comparing the ionization conditions of the inner and outer chambers and detecting any difference therebetween caused by smoke entering the outer ion chamber, including
  • the present invention relates to a fire alarm device using an ion system which operates in response to smoke, containing inflammable particles, generated in the initial period of a fire.
  • the production procedure and expenses for manufacture thereof becomes very expensive. Also, precise measuring and detecting of the smoke cannot be expected.
  • the glass body of the relay tube which is built into the ion chamber is aflixed by an adhesive material. Further, the glass of the tube is fixed to the disc by the use of a special metal alloy.
  • a constant voltage diode which allows operation of a regulating rectifier for passing current to actuate an alarm and a comparator means compares ionization conditions in the inner and outer chambers and includes a field effect transistor which become conductive upon a change of voltage due to a change of conditions in the outer chamber and which allow operation of the constant voltage diode after detection of changes of the ions appearing in the ion chambers.
  • FIGURE 1 is a perspective view of one embodiment of the present invention.
  • FIG. 2 is an axial section of the present invention
  • FIG. 3 is a circuit diagram of the present invention.
  • FIG. 4 is a characteristic graph showing the voltage and current of the ion chambers.
  • FIG. 5 is a graph illustrating the voltage and current of both ion chambers.
  • a fire detecting device A which detects smoke comprises a housing h and a base 11.
  • the housing h is divided into an inner ion chamber 5 and an outer ion chamber 8, respectively, by an electrode cover 1 having radioactive sources 2 and 3, for instance, such as radium, etc., on both the outer and inner surfaces thereof, contained in the housing h fixed to the base b.
  • the radioactive source 2 located on the inside surface of the electrode cover is covered by the electrode cover 1 and a base plate 4 closes an open end of the cover 1 so that the outer atmosphere is practically isolated from the inner ion chamber 5.
  • an electrode tube 7, having a metal net 6 is disposed, and the electrode tube 7 encloses the outer ion chamber 8 with the radioactive source 3.disposed on the outer surface of the electrode cover 1. Accordingly, the ion chamber 8 is in communication with the outer atmosphere through the metal net 6.
  • the base plate 4 is maintained by a support 5 of a base plate 7' and is substantially made of an insulating material such as, acrylic resin, or any other suitable material, for supporting an inner electrode plate 9 disposed within the inner ion chamber 5.
  • the electrical circuit is carefully constructed so that the high impedance is not damaged by fixing a field-effect transistor F-ET of high impedance (10 9).
  • a gate electrode of the transistor FET applied as a circuit element in the present device is connected to the electrode cover 1 forming the ion chambers, while drain and source electrodes are respectively operatively connected with the inner electrode plate 9 of the inner ion chamber 5 and a circuit C extending to a receiver R through a potentiometer R Both a resistor R and a condenser ,u. act as circuit protection elements.
  • a circuit C constitutes a testing circuit of a receiver and is connected with the electrode tube 7 of the outer ion chamber 8.
  • the circuit C is for performing an operative test by adjusting the electric voltage of both the inner and outer ion chambers which is effected from the changes in the electric voltage between the circuits N and C through the use of the testing resistor R
  • the two radioactive sources provided one in each of the outer ion chamber and the inner ion chamber, respectively, always discharge X-rays (alpha rays) in particular directions to- Ward the opposite electrodes.
  • the X-rays ionize the atrnospheric air in chamber 8 and very weak electric current flow between the electrodes 7 and 1, and 9 and 1, the currents being efiected by an electric voltage supplied to the ion chambers.
  • the current-voltage curve (a) in FIG. 4 shows that an electric current becomes saturated by a certain voltage value.
  • the current i which flows to the outer ion chamher will decrease to current i, while the voltage v of the outer ion chamber will increase to voltage v
  • the drain electric current of the transistor FET consequently increases as the voltage between circuits B and C increases as shown in FIG. 3. Therefore, if the electric voltage between circuits C and E becomes larger than the breakdown voltage of the Zener diode D, the rectifier SCR operates as the electric current flows into the gate electrode of the rectifier SCR. In such a state, the signal imparted to the rectifier may accordingly effect operation of an alarm signal by an alarm 10 or lamp 11 connected with the receiver R through a relay device 12, the latter being connected to a battery 13.
  • a fire detecting device in accordance with the present invention was 114 mm. x 90 mm., and had a total weight of 690 g. (base: 190 g., head 500 g.) and 15 volts D.C. constant circuit voltage.
  • the device was installed at the central portion of a ceiling of 3 meters height and had a fire proof construction.
  • the fire detecting device operated within 30 seconds when a sheet of newspaper of a size of 55 cm. X 82 cm. burned at the corner of the room.
  • the detecting device when the same fire detecting device was installed in one corner of the room and the same newspaper was burned at another corner, the detecting device operated within 40 seconds.
  • the room temperature and the humidity at that time were 18 C. and 55%, respectively.
  • the energy of the X-rays, discharged by Ra was 4.77 mega-electron-volt and the distance traveled up to 32 mm. That is, the outer ion chamber is entirely covered with an effective radiation of X-rays and the space thereof is filled with a uniform disperion of both ion and ion.
  • the smoke generated in anticipation of a fire is detected by an ionic phenomenon of radio-active rays and the circuit construction is designed to be operated with a considerably small amount of smoke.
  • the fire detection accordingly, can be quickly achieved and, in addition, the radioactive soprces which are harmful to the human body are .4 as small as one percent of those of conventional fire detecting devices.
  • the present device also is remarkably durable due to its simple construction in which a very low constant voltage is applied.
  • An automatic fire detecting device comprising a housing havin openings communicating with the atmosphere
  • dividing means within said housing for dividing said housing into an atmospheric isolated inner ion chamber and an outer ion chamber, said outer ion chamber communicating with the atmosphere and isolated from said inner ion chamber by said dividing means,
  • said dividing means including an electrode cover having an inner and outer surface communicating with the inner and outer ion chambers, respectively,
  • an inner electrode plate disposed in said inner ion chamber in spaced relationship from said inner radioactive source
  • said inner and outer radio-active sources emitting radioactive rays toward said inner electrode plate and said outer electrode means, respectively,
  • circuit means for comparing the ionization conditions of the inner and outer chambers and detecting any diiference therebetween caused by smoke entering the outer ion chamber
  • circuit means comprising,
  • a field effect transistor means operative in response to differences in electrical potential across said inner and outer ion chambers caused by changes in the ionization condition of said outer ion chamber upon entrance of smoke therein,
  • a controlling rectifier means responsive to the output from said constant voltage diode means.
  • said field eflect transistor means comprises a field effect transistor including a gate end connected to said electrode cover, a drain end connected to said inner electrode plate, and a source end,
  • a potentiometer having fixed terminals and a variable wiper terminal and said fixed terminals connected between said source end and the negative side of a voltage source
  • said constant voltage diode means comprises a Zener diode one terminal of which is connected to said variable wiper terminal of said potentiometer, and
  • said controlling rectifier means comprises a positive terminal connected to the positive side of said voltage source, and :a negative terminal connected to the negative side of the voltage source, and a gate connected to the other terminal of said Zener diode.
  • said electrode cover is closed at one end
  • a housing base plate enclosing one end of said housing, said housing thereby constituting a cylinder closed at one end
  • said housing and said electrode cover are coaxially disposed in inverted position such that the open end of one faces the closed end of the other.
  • a cover base plate covering said open end of said electrode cover and substantially isolating said inner ion chamber from said outer ion chamber.
  • the automatic fire detecting device as set forth in claim 3, further comprising a cylindrical base releasably connected to said housing base plate.
  • the automatic fire detecting device as set forth in claim 4, further comprising a support rod extending coaxially within said housing and secured at one end to said housing base plate and adjacent to the other end supporting said cover base plate.

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  • General Physics & Mathematics (AREA)
  • Physics & Mathematics (AREA)
  • Business, Economics & Management (AREA)
  • Chemical & Material Sciences (AREA)
  • Analytical Chemistry (AREA)
  • Emergency Management (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • High Energy & Nuclear Physics (AREA)
  • Molecular Biology (AREA)
  • Spectroscopy & Molecular Physics (AREA)
  • Health & Medical Sciences (AREA)
  • Fire-Detection Mechanisms (AREA)
  • Alarm Systems (AREA)
  • Other Investigation Or Analysis Of Materials By Electrical Means (AREA)
US573284A 1966-03-30 1966-08-18 Automatic ionic fire alarm system Expired - Lifetime US3500368A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
JP1966028133U JPS446089Y1 (pl) 1966-03-30 1966-03-30

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US (1) US3500368A (pl)
JP (1) JPS446089Y1 (pl)
BE (1) BE686726A (pl)
GB (1) GB1163121A (pl)

Cited By (31)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3573777A (en) * 1968-12-09 1971-04-06 Honeywell Inc Combustion products detector control apparatus
US3657713A (en) * 1969-06-02 1972-04-18 Nittan Co Ltd Device for testing ionization smoke detector
US3657737A (en) * 1969-12-29 1972-04-18 Jeffrey E Hamm Method of and device for smoke detection and circuits therefor
US3662177A (en) * 1968-07-11 1972-05-09 Nittan Co Ltd Ionization type smoke detectors with fet protected against open circuit input
US3666954A (en) * 1969-06-21 1972-05-30 Nittan Co Ltd Ionization smoke detector and leakage sensing means therefor
US3676680A (en) * 1969-06-24 1972-07-11 Cerberus Ag Ionization fire alarm with insulation monitoring system
US3676681A (en) * 1969-07-22 1972-07-11 Nittan Co Ltd Ionization smoke detector
US3688119A (en) * 1969-07-24 1972-08-29 Nittan Co Ltd Ionization smoke detector
US3717862A (en) * 1969-10-16 1973-02-20 Nittan Co Ltd Fire detecting system and testing means therefor
US3736445A (en) * 1970-01-12 1973-05-29 Medar Inc Proximity detector
FR2169898A1 (pl) * 1971-12-29 1973-09-14 Hochiki Co
US3767917A (en) * 1970-07-23 1973-10-23 Cerberus Ag Ionizing-type fire alarm sensor
US3775616A (en) * 1970-06-08 1973-11-27 Nittan Co Ltd Ionization smoke detector
US3792254A (en) * 1971-07-15 1974-02-12 Vigifeu Ionization chamber in particular for a fire detection device
US3838283A (en) * 1971-10-20 1974-09-24 Securitas Ab Bevaknings Ionization smoke detector
US3866195A (en) * 1973-05-07 1975-02-11 Fire Alert Company Combustion product detector and method of calibrating
US3909815A (en) * 1973-06-01 1975-09-30 Gamma Electronic Detector for fumes and combustion gases
US3935466A (en) * 1968-09-26 1976-01-27 Hochiki Kabushiki Kaisha Smoke detector adapted to a smoke sensing apparatus
US4082952A (en) * 1975-07-11 1978-04-04 Institut National des Radio-elements - Nationaal Instituut voor Radio-elementen, en abrege: "I.R.E." Ion detector
US4091364A (en) * 1974-09-09 1978-05-23 Unitec, Inc. Combustion detection device
US4097850A (en) * 1976-11-01 1978-06-27 Pittway Corporation Means for adjusting and for testing a detecting device
US4138664A (en) * 1976-12-14 1979-02-06 Pittway Corporation Warning device
US4142219A (en) * 1976-02-20 1979-02-27 Hochiki Corporation Two-wire system including signal receiving section and detection section with protected relay
US4148023A (en) * 1977-05-02 1979-04-03 E.D.I. Safety Devices, Inc. Emergency exit indicator
US4187432A (en) * 1978-03-16 1980-02-05 NRD, Division of Mark IV Industries, Inc. Source holder for mounting radioactive foil and holder-foil assembly
USRE30323E (en) * 1968-09-26 1980-07-01 Hochiki Kabushiki Kaisha Smoke detector adapted to a smoke sensing apparatus
US4364031A (en) * 1979-12-14 1982-12-14 Cerberus Ag Ionization smoke detector with increased operational reliability
US4396840A (en) * 1980-10-01 1983-08-02 Matsushita Electric Works, Ltd. Ionization type smoke sensing device
US4471346A (en) * 1981-06-02 1984-09-11 Eberhard Faber, Inc. Smoke detector
US10605790B2 (en) * 2016-08-08 2020-03-31 Tsinghua University Device and method for detecting defect in main shaft of wind turbine
CN111149136A (zh) * 2017-09-28 2020-05-12 三星电子株式会社 电子装置及控制电子装置的方法

Families Citing this family (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS583195Y2 (ja) * 1977-10-20 1983-01-20 ツエルベルス・アクチェン・ゲゼルシャフト イオン式火災感知器
GB2138570B (en) * 1983-04-19 1987-10-28 Emi Ltd Smoke detector
JP2006011540A (ja) * 2004-06-22 2006-01-12 Nittan Co Ltd イオン化式煙感知器

Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2646556A (en) * 1950-06-17 1953-07-21 C O Two Fire Equipment Co Supervised alarm system
US2702898A (en) * 1953-10-06 1955-02-22 Electro Watt Electrical And In Gas-responsive control apparatus
US3078450A (en) * 1961-08-03 1963-02-19 Martin J Mcginn Pressure compensated ionization chamber fire detector system
US3271756A (en) * 1960-03-22 1966-09-06 Harold J Burke Method and apparatus for detecting a hazardous condition
US3301307A (en) * 1963-11-12 1967-01-31 Ngk Insulators Ltd Device for detecting the configuration of a burning flame
US3310724A (en) * 1964-04-27 1967-03-21 Gen Electric Battery charging regulators

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2646556A (en) * 1950-06-17 1953-07-21 C O Two Fire Equipment Co Supervised alarm system
US2702898A (en) * 1953-10-06 1955-02-22 Electro Watt Electrical And In Gas-responsive control apparatus
US3271756A (en) * 1960-03-22 1966-09-06 Harold J Burke Method and apparatus for detecting a hazardous condition
US3078450A (en) * 1961-08-03 1963-02-19 Martin J Mcginn Pressure compensated ionization chamber fire detector system
US3301307A (en) * 1963-11-12 1967-01-31 Ngk Insulators Ltd Device for detecting the configuration of a burning flame
US3310724A (en) * 1964-04-27 1967-03-21 Gen Electric Battery charging regulators

Cited By (31)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3662177A (en) * 1968-07-11 1972-05-09 Nittan Co Ltd Ionization type smoke detectors with fet protected against open circuit input
USRE30323E (en) * 1968-09-26 1980-07-01 Hochiki Kabushiki Kaisha Smoke detector adapted to a smoke sensing apparatus
US3935466A (en) * 1968-09-26 1976-01-27 Hochiki Kabushiki Kaisha Smoke detector adapted to a smoke sensing apparatus
US3573777A (en) * 1968-12-09 1971-04-06 Honeywell Inc Combustion products detector control apparatus
US3657713A (en) * 1969-06-02 1972-04-18 Nittan Co Ltd Device for testing ionization smoke detector
US3666954A (en) * 1969-06-21 1972-05-30 Nittan Co Ltd Ionization smoke detector and leakage sensing means therefor
US3676680A (en) * 1969-06-24 1972-07-11 Cerberus Ag Ionization fire alarm with insulation monitoring system
US3676681A (en) * 1969-07-22 1972-07-11 Nittan Co Ltd Ionization smoke detector
US3688119A (en) * 1969-07-24 1972-08-29 Nittan Co Ltd Ionization smoke detector
US3717862A (en) * 1969-10-16 1973-02-20 Nittan Co Ltd Fire detecting system and testing means therefor
US3657737A (en) * 1969-12-29 1972-04-18 Jeffrey E Hamm Method of and device for smoke detection and circuits therefor
US3736445A (en) * 1970-01-12 1973-05-29 Medar Inc Proximity detector
US3775616A (en) * 1970-06-08 1973-11-27 Nittan Co Ltd Ionization smoke detector
US3767917A (en) * 1970-07-23 1973-10-23 Cerberus Ag Ionizing-type fire alarm sensor
US3792254A (en) * 1971-07-15 1974-02-12 Vigifeu Ionization chamber in particular for a fire detection device
US3838283A (en) * 1971-10-20 1974-09-24 Securitas Ab Bevaknings Ionization smoke detector
FR2169898A1 (pl) * 1971-12-29 1973-09-14 Hochiki Co
US3866195A (en) * 1973-05-07 1975-02-11 Fire Alert Company Combustion product detector and method of calibrating
US3909815A (en) * 1973-06-01 1975-09-30 Gamma Electronic Detector for fumes and combustion gases
US4091364A (en) * 1974-09-09 1978-05-23 Unitec, Inc. Combustion detection device
US4082952A (en) * 1975-07-11 1978-04-04 Institut National des Radio-elements - Nationaal Instituut voor Radio-elementen, en abrege: "I.R.E." Ion detector
US4142219A (en) * 1976-02-20 1979-02-27 Hochiki Corporation Two-wire system including signal receiving section and detection section with protected relay
US4097850A (en) * 1976-11-01 1978-06-27 Pittway Corporation Means for adjusting and for testing a detecting device
US4138664A (en) * 1976-12-14 1979-02-06 Pittway Corporation Warning device
US4148023A (en) * 1977-05-02 1979-04-03 E.D.I. Safety Devices, Inc. Emergency exit indicator
US4187432A (en) * 1978-03-16 1980-02-05 NRD, Division of Mark IV Industries, Inc. Source holder for mounting radioactive foil and holder-foil assembly
US4364031A (en) * 1979-12-14 1982-12-14 Cerberus Ag Ionization smoke detector with increased operational reliability
US4396840A (en) * 1980-10-01 1983-08-02 Matsushita Electric Works, Ltd. Ionization type smoke sensing device
US4471346A (en) * 1981-06-02 1984-09-11 Eberhard Faber, Inc. Smoke detector
US10605790B2 (en) * 2016-08-08 2020-03-31 Tsinghua University Device and method for detecting defect in main shaft of wind turbine
CN111149136A (zh) * 2017-09-28 2020-05-12 三星电子株式会社 电子装置及控制电子装置的方法

Also Published As

Publication number Publication date
GB1163121A (en) 1969-09-04
DE1516529B1 (de) 1970-06-25
JPS446089Y1 (pl) 1969-03-05
BE686726A (pl) 1967-02-15

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