US3582646A - Ionization fire detection device - Google Patents

Ionization fire detection device Download PDF

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Publication number
US3582646A
US3582646A US703348A US3582646DA US3582646A US 3582646 A US3582646 A US 3582646A US 703348 A US703348 A US 703348A US 3582646D A US3582646D A US 3582646DA US 3582646 A US3582646 A US 3582646A
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United States
Prior art keywords
detection device
chamber
unsaturated
enclosure
fire detection
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Expired - Lifetime
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US703348A
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English (en)
Inventor
Christian Marie Maurice Ponsar
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Vigifeu Aubervilliers
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Vigifeu Aubervilliers
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    • G—PHYSICS
    • G08—SIGNALLING
    • G08B—SIGNALLING OR CALLING SYSTEMS; ORDER TELEGRAPHS; ALARM SYSTEMS
    • G08B17/00—Fire alarms; Alarms responsive to explosion
    • G08B17/12—Actuation by presence of radiation or particles, e.g. of infrared radiation or of ions
    • 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
    • G08B17/113—Constructional details

Definitions

  • a fire detection device comprising an enclosure enclosing a reference ionization chamber and an unsaturated measuring ionization chamber interconnected in series and each containing a source of radioactive radiations, at least one alarm and/0r automatic intervention device, a grid permeable to gases defining one end of the enclosure, the enclosure having apertures communicating with passages at one end of the unsaturated chamber so that gas can flow through the unsaturated chamber, from outside the device, a common electrode extending into both chambers and a printed circuit controlling the alarm and/or intervention device.
  • the present invention relates to devices ascertaining the start ofa fire by the detection of variations in the composition of a gas, and in particular the presence of smoke in the atmosphere.
  • detectors proper which are disposed in suitable chosen places in a building or an installation and which, when excited by a sufficiently large modification in the surrounding conditions, actuate an alarm device and/or an automatic intervention device.
  • the radioactivity of this source must be high, for example of the order ofa few tens of microcuries. Further, the voltages which must be applied between the wall of the ionization chambers and their electrode are rather high, exceeding 200 v. in most cases.
  • the object of the invention is to provide a detection device which is devoid of the drawbacks of known devices, simple and particularly reliable in operation.
  • the invention provides a fire detection device comprising a reference ionization chamber and an unsaturated measuring ionization chamber interconnected in series and each containing a source of radioactive radiation, at least one alarm and/or automatic intervention device, an enclosure defined at one end by a grid which is permeable to the gases and encloses said ionization chambers, said unsaturated chamber communicating through one end with the space defined by said grid and having at its other end passages which communicate with the vicinity of apertures formed in said enclosure, whereby the gas surrounding the detector passes in said unsaturated chamber, a common electrode extending into both of said chambers, said enclosure also enclosing a printed circuit plate which carries a circuit controlling the alarm device.
  • control circuit comprises the electrode common to the two ionization chambers connected through an amplifying device to the gate electrode of a triggering or actuating switch inserted in the feed circuit of the alarm device.
  • the amplifying device comprises a transistor the base of which is connected to the common electrode and the switch can be a thyristor whose gate electrode is connected to the emitter of the transistor.
  • Another object of the invention is to provide a fire detection installation comprising a plurality of detection devices defined hereinbefore which are connected in parallel to a line having three conductors one of which has a positive potential. the second a zero potential and the third a negative potential, a first alarmdevice responsive to the triggering of the switch of any one of the detection devices, and a second alarm device which is actuated when a break occurs in the line.
  • FIG. 1 is a longitudinal sectional view of a preferred embodiment of a fire detection device according to the invention.
  • FIG. 2 is a circuit diagram of an installation comprising detection devices of the type shown in FIG. 1, with a more detailed circuit diagram of one of said detection devices, and
  • FIG. 3 is a view similar to FIG. 1 of said a detection device in a slightly simplified form.
  • FIG. 1 shows a detection device D which is defined externally by a cylindrical enclosure 1 and a grid 2 of metal fabric or plastics material in the shape of a spherical dome.
  • an ionization chamber 3 whose cylindrical wall 3 constitutes an electrode spaced from the enclosure by an insulating ring 4. One end 3 of this chamber freely communicates with the space defined by the grid 2. At its other end 3 the chamber 3 is provided with an end wall having apertures 3 which communicate with the volume of the enclosure 1 in the vicinity of apertures 1 formed in the latter so as to ensure a flow of the surrounding air in the chamber 3.
  • the chamber 3 contains, fixed to its lateral wall, a radioactive source 5 having a radioactivity of the order of a few microcuries.
  • a second chamber 6 is connected to the first chamber through insulating spacer members 7.
  • This chamber 6 has a wall 6 which is substantially closed and nonresponsive to surrounding conditions and also contains at least one radioactive source 6', 6
  • the wall 6" of this chamber constitutes an electrode in the same way as the wall 3" ofthe first chamber 3.
  • An electrode 8 is located between the two chambers 3 and 6 and extends into each of them.
  • this electrode is fixed to the wall of the chamber 6 through an insulating support 9 and carries a disc 10 in the part thereof extending into the chamber 3 for deforming the field lines within the chamber 3.
  • a plate 11 of a printed circuit is mounted on the chamber 6 by means of spacer members 12 near the inner end of the chamber 1, this plate carrying various electric and electronic components of the control circuit shown at D in FIG. 2.
  • the chamber 1 is closed at its rear or inner end by an insulating disc 13.
  • FIG. 2 shows the diagram of an installation which comprises in particular n detection devices D D D similar to the detection device D shown in FIG. 1.
  • the measuring electrode 8 is connected to the base of a transistor 14 whose collector is brought to a positive potential and whose emitter is connected through a resistor 15 connected in series with the gate electrode of a thyristor 16.
  • a filter capacitor 17 is connected between the gate electrode and the cathode of the thyristor.
  • a lamp 118 interposed between the anode of this thyristor and a conductor L ofa line L, brought to a positive potential, is a lamp 118 to which is connected in parallel a Zener diode 19.
  • the line L comprises three conductors L of positive potential, L of negative potential-to which the wall 3 of the chamber 3 is connected through a potentiometer 20 the latter being connected to the conductor L through a resistor 21- -and a neutral conductor L
  • the lamp 18, the diode 19, the collector of the transistor 14, the wall 6 of the chamber 6 and the resistor 21 are connected to the conductor L,.
  • the cathode of the thyristor l6 and the grid 2 are connected to the conductor L the grid being consequently at zero potential.
  • Each detector D,, 0,, D is connected to the conductors L,, L L, of the line L through three conductors C,, C C
  • An end-of-line resistor 22 and a coil 23 in the conductor L are also provided.
  • the coil 23 serves to excite the two contacts 24, 25 having different characteristics which are preferably relays of the reed" or double-position type. These contacts 24, 25 actuate alarm devices 26, 27 respectively.
  • the detection device and the installation operate in the following manner:
  • the walls 3 and 6 of the chambers 3 and 6 are respectively brought to negative and positive potentials, the electrode 8 being at an intermediate potential which is insufficient to excite the base of the transistor 14 and render it conductive.
  • the potentiometer assembly 20, 21 permits bringing the wall 3 to a predetermined potential as a function of the characteristics required of this detection device, and thus setting the detection threshold of each detection device.
  • the ionization conditions change in this chamber and the potential of the electrode 8 reaches a magnitude sufficient to render the transistor 14 conductive.
  • the latter performs the function of an amplifier, which is necessary owing to the very small current values, namely of the order of I A, employed in the ionization chambers.
  • the current supplied by the emitter of the transistor 14 actuates the thyristor l6, and causes the passage of the current in the signal lamp l8 and the increase in the current which passes through the coil 23.
  • the lamp 18 lights up and this supplies a first alarm signal by the illumination of the detector since this lamp is within the enclosure 1 (FIG. 1).
  • the current increase in the coil 23 actuates the contact 24 and feeds the alarm device 26 which is located at a certain distance from the points of detection.
  • the Zener diode 19 is adapted to permit the passage of a current to the coil 23 in the event that there is a break in the lamp 18.
  • a transistor having a field effect and whose input impedance decreases with the temperature is employed as transistor 14, the leakage current doubling for example for an increase in temperature of about C. For a predetermined temperature of the order of 60 C. for example, this leakage current becomes sufficient to actuate the thyristor 16.
  • the device operates therefore also as a temperature limiter in case the presence ofsmoke had not be detected.
  • the other safety device consists of the relay and the alarm device 27 which operates in response to a break in the line. The latter is consequently completely supervised.
  • the special arrangement of the detection device shown in FIG. I affords a number of advantages.
  • the reception of the surrounding air and smoke occurs through the grid 2 and in the the space the latter defines, and this air and smoke pass through the chamber 3 and thereafter issue by way of the apertures 1.
  • the opposite path could be taken, but in both cases the fact that the air is not directly received or collected by the measuring chamber is important. Indeed, this permits reducing the dimensions of this chamber and consequently decreasing the radioactivity of the source 5 and the voltage applied.
  • the diameter of the chamber can even be less than the free mean path of the ionizing particles.
  • the voltage applied to each of the chambers is around 50 v. and the radioactivity of the source 5 is generally less than 5 microcuries.
  • the result of this arrangement is that the detection device according to the invention is little responsive to variations in density and variations in the rate of flow of the gases within the ionization chamber.
  • the measuring ionization chamber is not in direct contact with the atmosphere and is thus protected.
  • Another advantage of this detection device is that the outer part of the device, namely the enclosure and grid, are at zero potential and this satisfies safety regulation requirements.
  • FIG. 3 shows a simplified modification of the detection device proper in which the saturated ionization chamber 6 of the first embodiment is eliminated.
  • This saturated chamber is here defined by the grid 2 and a disc 28 carried by the electrode 8 and on which is placed a radioactive source 29.
  • the electric circuit diagram is somewhat modified, the grid no longer being at zero potential but at the potential to which the wall of the chamber 6 of the first embodiment was brought. This is a slight drawback compared to the first embodiment described. Apart from this, the wiring and the operation are the same as described hcreinbefore.
  • a fire detection device comprising an enclosure, a grid at one end of the enclosure, which is permeable to gases and defines a gas collection space, a reference ionization chamber and an unsaturated measuring ionization chamber, said chambers being connected in series and each containing a source of radioactive radiation for ionizing the gas therein, said enclosure having apertures in its lateral wall, said unsaturated measuring chamber being located in said enclosure and opening at one end in the gas collection space defined by said grid and having at its other end passages which communicate with said apertures, whereby the gas surrounding the detection device can flow through said unsaturated measuring chamber, a common electrode extending into both of said chambers, and having an intermediate point thereof connected in an electric control circuit including alarm means and being responsive to changes in the ionization in said unsaturated chamber and reacting to said changes.
  • a fire detection device as claimed in claim 1, wherein said circuit comprises said electrode which is common to said two ionization chambers, a transistor whose base is connected to said intermediate point of the common electrode and a gate controlled switch connected in the feed circuit of said alarm means, the gate of said switch being connected to the emitter of said transistor.
  • a fire detection device as claimed in claim 1 comprising, on a part of said common electrode located in said unsaturated chamber, a disc which deforms the field lines inside said unsaturated measuring chamber.
  • a fire detection device as claimed in claim I wherein current is supplied to the unsaturated measuring chamber through a potentiometer circuit for setting the detection threshold of the detector.
  • a fire detection device as claimed in claim I wherein said common electrode carries a disc which defines a chamber with said grid, a passage being provided around said disc for communication with the measuring chamber, said disc carrying a radioactive source on the face thereof facing said grid so that said chamber constitutes the reference chamber and the gas collection space.
  • a fire detection device comprising an enclosure, a grid at one end of the enclosure, which is permeable to gases and defines a gas collection space, a reference ionization chamber and an unsaturated measuring ionization chamber, said chambers being connected in series and each containing a source of radioactive radiation for ionizing the gas therein, said enclosure having apertures in its lateral wall, said unsaturated measuring chamber being located in said enclosure and opening at one end in the gas collection space defined by said grid and having at its other end passages which communicate with said apertures, whereby the gas surrounding the detection device can flow through said unsaturated measuring chamber, a common electrode extending into both of said chambers, and having an intermediate point thereof connected in a control cirionization cuit, said control comprising in each detection device, a transistor and a gate controlled switch, the transistor having its base connected to said intermediate point of the corresponding common electrode, and its emitter connected to the gate of said switch; a first alarm device responsive to actuation of said switch of any of said detection devices and a second
  • each of said detection devices includes a signal lamp and a Zener diode connected in parallel with the signal lamp between said switch and said line.

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  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Business, Economics & Management (AREA)
  • Emergency Management (AREA)
  • High Energy & Nuclear Physics (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Health & Medical Sciences (AREA)
  • Molecular Biology (AREA)
  • Spectroscopy & Molecular Physics (AREA)
  • Chemical & Material Sciences (AREA)
  • Analytical Chemistry (AREA)
  • Fire-Detection Mechanisms (AREA)
  • Other Investigation Or Analysis Of Materials By Electrical Means (AREA)
US703348A 1967-02-09 1968-02-06 Ionization fire detection device Expired - Lifetime US3582646A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
FR94266A FR1540305A (fr) 1967-02-09 1967-02-09 Dispositif perfectionné de détection d'incendie

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US3582646A true US3582646A (en) 1971-06-01

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US (1) US3582646A (nl)
AT (1) AT292510B (nl)
BE (1) BE710468A (nl)
DE (1) DE1616020B2 (nl)
ES (1) ES350324A1 (nl)
FR (1) FR1540305A (nl)
GB (1) GB1144624A (nl)
NL (1) NL161280C (nl)

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3832552A (en) * 1973-06-22 1974-08-27 Honeywell Inc Dual chamber ionization smoke detector
US3935492A (en) * 1970-11-13 1976-01-27 Nittan Company, Ltd. Ionization smoke detector
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

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN107219548B (zh) * 2017-07-31 2023-10-27 四川省核地质调查研究所 一种便携式反康普顿探测仪

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2963600A (en) * 1957-10-30 1960-12-06 Cerberus G M B H Device for the determination of changes in the composition of gas
US2994768A (en) * 1957-01-25 1961-08-01 Cerberus G M B H Method and system for the electric determination of aerosols in a gas
US3382364A (en) * 1962-10-12 1968-05-07 Cie Centrale Sicli Apparatus comprising a signal output circuit responsive to a variable d-c voltage input

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2994768A (en) * 1957-01-25 1961-08-01 Cerberus G M B H Method and system for the electric determination of aerosols in a gas
US2963600A (en) * 1957-10-30 1960-12-06 Cerberus G M B H Device for the determination of changes in the composition of gas
US3382364A (en) * 1962-10-12 1968-05-07 Cie Centrale Sicli Apparatus comprising a signal output circuit responsive to a variable d-c voltage input

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3935492A (en) * 1970-11-13 1976-01-27 Nittan Company, Ltd. Ionization smoke detector
US3832552A (en) * 1973-06-22 1974-08-27 Honeywell Inc Dual chamber ionization smoke detector
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

Also Published As

Publication number Publication date
GB1144624A (en) 1969-03-05
NL161280B (nl) 1979-08-15
DE1616020B2 (de) 1976-02-12
AT292510B (de) 1971-08-25
NL6801899A (nl) 1968-08-12
FR1540305A (fr) 1968-09-27
ES350324A1 (es) 1969-04-16
BE710468A (nl) 1968-06-17
NL161280C (nl) 1980-01-15
DE1616020A1 (de) 1971-03-04

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