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US3767917A - Ionizing-type fire alarm sensor - Google Patents

Ionizing-type fire alarm sensor Download PDF

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Publication number
US3767917A
US3767917A US00162781A US3767917DA US3767917A US 3767917 A US3767917 A US 3767917A US 00162781 A US00162781 A US 00162781A US 3767917D A US3767917D A US 3767917DA US 3767917 A US3767917 A US 3767917A
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United States
Prior art keywords
parts
sensor according
sensor
separable
elements
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Expired - Lifetime
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US00162781A
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English (en)
Inventor
T Lampart
M Kuhn
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Cerberus AG
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Cerberus AG
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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
    • G08B17/10—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

  • ABSTRACT A housing structure made of metal, includes at least three interlocking parts, having interengaging elements which operate in different directions, in space, for example elements I and 2 being connectable by rotation in one direction, elements 2 and 3 being connectable by vertical movement and, if desired, rotation in another direction to permit ready disassembly of selected elements for cleaning and maintenance without, however, accidental dislodgment of the elements of the structure in case of fire or exposure to high temperature.
  • the first part forms a socket; the second part includes an electric circuit and one portion of an ionization chamber with a radioactive substance; and the third part forms the other portion of the ionization chamber, containing no radioactive substances andshielding the second part from dust and 13 Claims, 2 Drawing Figures 1 IbNIZlNG-TYPE FIRE ALARM SENSOR
  • The'present invention relates to ionizing-type fire alarm sensor, and more particularly to a structure in which at least one radioactive substance is included within the sensor located within an ionization chamber accessible to outside atmosphere; and which further includes an electrical circuit to generate and transmit an electrical'alarm signal.
  • Ionizing-type fire alarm sensors for use in fire alarm systems include a measuring-chamber'in which atmosphere is ionized by a radioactive substance localized therein.
  • An ion current will be'obtainablevbetween electrodes located in the ionization chamber. lf smoke, smoke aerosols, or other particles penetrate through openings into the ionization chamber, then the electrical ionization current will change and this change in current can be utilized to provide an'alarm signal, for example to a central fire station.
  • the electrical circuits are as close to the ionization chamber as possible and are in circuit with a resistance element, for example a second reference ionization chamber being completely,
  • the potential difference between two chambers is then determined by means of a high resistance amplifierv element, for example a field effect transistor (FET).
  • FET field effect transistor
  • the charge on the electrodes in the ionization chamber can also be determined, from 1 time to time, for example by scanning in order to detertion, dirt, and other interfering'effects' which decrease i the insulation resista'nce.
  • particles in the immediate. vicinity of the sensor, such as dust are also ionized andtransported within the measuring chamber, to be deposited therein.
  • Smoke aerosols are likewise deposited
  • the fire alarm sensors have 'to be cleaned-frequent ly' and, particularly, the ionization chamberrequires cleaning. Such cleaningand mainte fiance is time-consuming, ⁇ frequently difficult and sometimes dangerous.
  • the increase in temperature can melt plastic particles located within the socket and the ionization sensor.
  • the ionization sensor comprises a housing structure having at least three interlocked parts which are formed with engaging, independently separately interlock means to enable individualseparation of the parts from each other.
  • One of the parts forms a socket and is adapted to be secured to a support surface,;such as a ceiling.-It has electrical contacts and is adapted for connection to an electrical alarm system.
  • a second'part has. separable contacts engaging with the contacts on the first, ceiling-mounted part and is shaped to form one portion of an ionization chamber within which radioactive substances can be maintained.
  • a third part is then provided; comprising the other portion of'the' ionization chamberhaving' no radioactive substances, independently separable from the other parts which surrounds at'least 'the sec- 0nd part and is shaped'to form a'dustand atmosphere
  • the sensors are usually constructed as compact,
  • the interengaging interlocking means ares'o arranged that, between a first pair of adjacent parts, separation can be effected by motion in a predetermined direction, for example clockwise rotation; and the interlocking means between one of the'parts of the first pair and the remaining part is so arranged as to be separable upon motion in a different direction, for example longitudinally,
  • the sensors have to be recuit, for example the field effect transistor at the input,
  • the construction infaccordance with this concept permits separation of the third part, which forms, together with a'portion of the second part, the ionization chamber to be separately removed and-cleaned: the construction is preferably so selected thatall surfaces subject to contamination by dustor dirt'are separated upon removal of the third part, the ionizing element itself being shielded from such contamination.
  • the sec 0nd part, together with the radioactive substance and the electrical circuit which is sensitive to touch can remain in the socket. If desired, the second and third 'part can'be removed together, or the second part can beremoved separately after removal of the third. Screw connections, for example by set screws can be provided to prevent separation of the second part containing the ionizable substance so that this portion can be removed only by trained personnel under appropriate safety regulations.
  • Separable, independent interlocking interconnections are arrangements in which one or both parts have spring elements which are pressed from their rest or normal position and which then can snap into holes, notches, grooves or recesses in order to retain the parts together, if and only if they are in the proper locking position.
  • the spring elements at least in part, are accessible from the outside, with orwithout any separate tools, so that they can be pressed from their rest position in order to release the interconnecting parts. Snap springs, spring rings, bayonet connections or other arrangements with similar function are suitable.
  • the interlocking connections are so made that they can be reached from ground level directly, or by means of a simple separating tool which can be raised to the ceiling. If the springy elements are movable in different directions, then, by selecting the direction of movement, only the third part or the second and third part together can be, selectively, removed.
  • FIG. 1 is a vertical sectional view of the three portions of the ionization sensing device, in exploded, removed form;
  • FIG. 2 is a generally perspective view of a similar ionization-type sensor, partly cut open, with the second and third part connected and the second part removed from the first; and illustrating further a removal tool, in schematic form, aligned in engagement with the sensor.
  • the socket which forms one part of the separable ionization sensor is a cylindrical housing 1 having a base 2 which can be secured to a support surface, for example a ceiling.
  • This housing preferably, is of metal.
  • the housing is formed at various portions of its circumference with slits 3; the material punched out from the slits is bent inwardly as an inwardly projecting angle 4.
  • a part 5, for example of plastic or ceramic, is secured to the bottom shell 2 of the housing.
  • Part 5 carries at its bottom side a plurality of contact springs 6 which are readily movable in vertical direction.
  • the contact springs 6 are connected with electric connection wires 7 which interconnect the various sensors among each other, and with a fire alarm central station.
  • the contact springs 6 additionally form the connection between these lines and matching suitably arranged contact surfaces 8 on the second part of the sensor.
  • An outer shell 9 which may consist, for example, of plastic can be used to adapt the sensor to various types of attachments, for example to fire alarm outlet boxes or the like.
  • the second portion of the fire alarm sensor includes a ring 10 of insulating material, for example plastic, and having suitably shaped grooves and projections.
  • a plate 11 of insulating material is secured to ring 10.
  • the upper part of plate 11 has a printed circuit placed thereon.
  • the circumference of plate 11 is formed with various slits 12 through which the inwardly extending angles 4 can pass.
  • the angle 4 will slide over camming element 13, formed, for example, as a projecting punchmark, and lock in position by means of pressure of spring 6 on the insulating plate 11.
  • the extent of rotation is limited by the extent of slits 14 in the plastic ring 10.
  • the lower side of the insulating plate 11 has a metallic ring 15 secured thereto which is formed at various points of its circumference with pinching or friction holding springs 16 to secure the third part of the sensor thereto.
  • metallic ring 15 is formed into projections 17 which extend to the upper side of insulating plate 11. If, for example, due to excessive heating, for example due to a fire, insulating plate 11 deforms, metallic ring 15 will still secure the sensing element together by catching on, and bearing against the angles 4 of the socket part.
  • the upper side of insulating plate 11 has a metallic hood 18 secured thereto, defining therein a reference ionization chamber.
  • Hood 18 has one or more cam projections 19 which fit into slits 20 of part 5 and provide a guide for the proper fitting together of the first and second portion of the sensor.
  • a doubled electrode 21 is located centrally of the plastic ring 10.
  • Double electrode 21 is formed with double-sided end faces, like a double mushroom, and radioactive substances 22, 23 are located at the flat faces of the double-sided electrode 21.
  • the various components of the electrical circuit 24 are located in the space between ring 10 and insulating plate 11.
  • the connecting wires are connected to appropriate points of the printed circuit on the upper side of the insulating plate 11.
  • the embodiment illustrated utilizes two ionization chambers, connected to a field effect transistor (FET) having highly insulated input.
  • FET field effect transistor
  • the field effect transistor is encapsulated within a suitable insulating mass, and located in the space between plate 10 and plate 11.
  • a control lamp 26, visible from the outside, indicates the state of sensing of the ionization sensor.
  • the third portion of the sensor comprises a metallic shroud 27, having openings 28, 29 for surrounding atmosphere.
  • the upper edge 30 of shroud 2 7 is bent over outwardly, so that, upon attaching together the second and the third portion, it will catch over holding springs 16. Removal of this interengagement is possible only when springs 16 are pressed outwardly, so that shroud 27 can be removed.
  • plastic ring 10 is sealed by the presence of labyrinth 31, so that smoke and dust will precipitate in those portions of the measuring chamber which form part of the third element of the fire alarm sensor.
  • the sensor can thus be effectively cleaned by mere removal of the third part without removing the sensitive portions of the electrical circuit or the radioactive substances therein. This completely prevents damage of the fire alarm sensor during maintenance, and any danger to personnel during cleaning or repair.
  • the second portion may, additionally, be secured against undesired and unauthorized removal by means of a set screw 35 located in ring which presses the insulating plate ii to angle 4 to such an extent that angle 4 can no longer pass over cam 13.
  • the third portion that is the third element of the sensor, can be removed without difficulty, whereas the second portion can be removed only by additional loosening of the safety set screw.
  • the upper side of the labyrinth 31 is formed with an annular projection 6 which, when the parts are assembled together, fits into a corresponding groove 37 of ring lit). This presses pin 38 upwardly, thus opening a short circuit switch.
  • Field effect transistor 25 is thus protected from damage by accidental contact of the electrodes when shroud 27 is removed (see Swiss Pat. No. 460,594 for a full disclosure, which is hereby incorporated by reference).
  • shroud 27 may have a second shroud 39 applied'thereover (see Swiss Pat. No. 475,614, hereby incorporated by reference) which has atmospheric inlet openings 40 offset with respect to openings 28, 29 of shroud 27. This substantially decreases the sensitivity of the ionization fire alarm sensor to air currents.
  • FIG. 2 additionally shows a suitable removal tool, adapted for the removal of the components of the sensor of the present invention. It essentially comprises a cylindrical shell 41 which fits exactly in the space between shroud 27 and ring 10. Placing shell 41 in this space compresses springs 16, by pressing them radially 30 outwardly,-thus removing the third element of the sensor from the second and permitting its longitudinal removal.
  • the arrangement in accordance with the present invention is so made that, if the sensor is subjected to a temperature high enough that all plastic parts therein will melt, constructional integrity of the sensor itself is not impaired. All three portions of the sensor will not separate and particularly the radioactive substance will not fall out of the sensor but remain therein. This effectively inhibits radioactive contamination of the location of a tire.
  • the essential feature is to form the sensor of single parts so that one element, that is one component includes all the sensitive and potentially hazardous parts, another one provides a shield or shroud protecting the sensitive and potentially hazardous parts against dust, dirt or other contamination and the third secures the assembly to a support, such as a ceiling; whereas all parts are so constructed that they are independently separable and connected by independently operable interlocking arrangements.
  • the specific type and arrangement of the interlocks themselves can be selected depending on the specific form and shape of the sensing elements.
  • the third part ,of the sensor which is particularly subject to dirt and dust is so constructed that all sensitive elements of the second part, and particularly the insulation path; between the electrodes of the ionization chamber are so covered, when the third part is attached to the second, thatcontamination by deposit of dust, or the like, is avoided.
  • Ionizing-type fire alarm sensor comprising a housing structure having at least three interlocked parts formed with engaging, self-locking, independently separate interlock means to hold the three parts together and permit individual separation of the parts from each other;
  • a first part forminga socket adapted to be secured to a support and being formed with electrical contacts and adapted for connection to a fire alarm system;
  • a second part comprising separable contacts engaging the contacts of said first part, means defining one position of an ionization chamber, radioactive ionizing substances being located on the second part and comprising all radioactive substances of the sensor, part of the ionizing substance being located in said chamber, and an electrical circuit means responsive to changes in electrical characteristics of the atmosphere in the chamber;
  • said third part separable from said second part independent of separation or nonseparation of the second and first parts, said third part comprising the other non-radioactive portion of the ionization chamber and including shield elements fitting against the second part to form a dust and dirt shield for the second part when the second and third part are connected together.
  • interlock means comprises spring elements secured to at least one engaging part and having an overcenter position to positively seat and position the engaging parts.
  • said removal means being adapted for transferring removal motion in both rotary and longitudinal direction.
  • interlock means interconnecting the first pair comprises a bayonet-type interlock requiring both rotary and longitudinal movement, the longitudinal movement being spring-loaded.
  • interlock means comprises metallic interengaging elements remaining engaged even upon melting of non-metallic elements of the sensor.
  • the second part comprises an electrode terminal connected to the electrical circuit means
  • the third part comprises a metallic housing and the shield elements include an insulating labyrinth separating said electrode terminal from said metallic housing, said labyrinth being shaped to extend the surface creep path between the electrode terminal and the housing by at least four times the minimum distance therebetween.
  • the electrical circuit means comprises a printed circuit on said insulating plate.

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  • Chemical & Material Sciences (AREA)
  • Analytical Chemistry (AREA)
  • Business, Economics & Management (AREA)
  • Emergency Management (AREA)
  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Fire-Detection Mechanisms (AREA)
  • Other Investigation Or Analysis Of Materials By Electrical Means (AREA)
  • Conveying And Assembling Of Building Elements In Situ (AREA)
US00162781A 1970-07-23 1971-07-15 Ionizing-type fire alarm sensor Expired - Lifetime US3767917A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
CH1120370A CH508251A (de) 1970-07-23 1970-07-23 Ionisationsfeuermelder

Publications (1)

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US3767917A true US3767917A (en) 1973-10-23

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US00162781A Expired - Lifetime US3767917A (en) 1970-07-23 1971-07-15 Ionizing-type fire alarm sensor

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US (1) US3767917A (xx)
JP (3) JPS526080B1 (xx)
AU (1) AU463927B2 (xx)
CH (1) CH508251A (xx)
DE (1) DE2130889B2 (xx)
DK (1) DK130857B (xx)
FI (1) FI56287C (xx)
FR (1) FR2103672A5 (xx)
GB (1) GB1324286A (xx)
HK (1) HK70078A (xx)
NL (1) NL7108647A (xx)
NO (1) NO126976B (xx)
SE (2) SE375871B (xx)
YU (1) YU35684B (xx)
ZA (1) ZA714783B (xx)

Cited By (40)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3900795A (en) * 1973-08-15 1975-08-19 Honeywell Inc Installation and test tool for ionization smoke detector
US3908957A (en) * 1973-04-17 1975-09-30 Cerberus Ag Ionization-type fire sensor
US3909815A (en) * 1973-06-01 1975-09-30 Gamma Electronic Detector for fumes and combustion gases
US3934145A (en) * 1973-10-25 1976-01-20 Emhart Corporation Ionization smoke detector and alarm system
US3961195A (en) * 1974-08-26 1976-06-01 Timothy John Newington Fire detector having means for heating the support member of an electrode to prevent formation of moisture thereon
US3963929A (en) * 1973-04-24 1976-06-15 Geba-Gesellschaft Fur Elektronische Brandmeldeanlagen Mbh & Co. Ionization analyzing air pollution, smoke and fire alarm device
US4017733A (en) * 1974-04-18 1977-04-12 Hochiki Corporation Ionization type smoke sensor
US4053777A (en) * 1976-07-07 1977-10-11 Geba, Gesellschaft Fuer Elektronische Brandmeldeanlagen Mbh & Co. Accident- and tampering-proof attachment means of an object to a stationary support
US4056727A (en) * 1975-09-05 1977-11-01 Geba, Gesellschaft Fuer Brandmeldeanlagen Mbh & Co. Attachment means of an object to a support
US4074341A (en) * 1973-12-07 1978-02-14 Cerberus Ag Interlocked separable fire sensor construction
US4075487A (en) * 1976-05-14 1978-02-21 Patent Development & Management Company Ionization chamber assembly
US4081684A (en) * 1974-07-02 1978-03-28 Wieder Horst K Combustion product detector
US4194120A (en) * 1976-11-29 1980-03-18 Cerberus Ag Adjustable ionization chamber
US4238679A (en) * 1978-12-07 1980-12-09 Conrac Corporation Dual-chamber ionization smoke detector assembly
US4258261A (en) * 1979-05-07 1981-03-24 Pittway Corporation Electrode assembly for combustion products detector
US4286159A (en) * 1979-04-10 1981-08-25 Hochiki Corporation Detector coupling mechanism
DE3100022A1 (de) * 1980-01-02 1981-12-17 Société Gamma Electronic, 75800 Paris Ionisierungsrauchmelder
US4396840A (en) * 1980-10-01 1983-08-02 Matsushita Electric Works, Ltd. Ionization type smoke sensing device
EP0233754A2 (en) * 1986-02-13 1987-08-26 Nohmi Bosai Ltd. A fire detector
FR2625352A1 (fr) * 1987-12-26 1989-06-30 Hochiki Co Detecteur de fumee par ionisation
US4864141A (en) * 1986-02-25 1989-09-05 Jacques Lewiner Smoke detector with ionization chamber
EP0399244A2 (en) * 1989-05-02 1990-11-28 Nohmi Bosai Kabushiki Kaisha A light-scattering-type smoke detector
US5399864A (en) * 1992-04-25 1995-03-21 Nohmi Bosai Ltd. Ionization type smoke detector
US5403198A (en) * 1992-04-25 1995-04-04 Nohmi Bosai Ltd. Detector base
US5486816A (en) * 1992-04-25 1996-01-23 Nohmi Bosai Ltd. Fire detector having optic base clamping optic elements to a circuit board
WO1996021208A1 (en) * 1995-01-04 1996-07-11 Caradon Gent Limited Improvements in and relating to smoke detectors
US5565852A (en) * 1992-11-30 1996-10-15 Sentrol, Inc. Smoke detector with digital display
EP0836164A1 (en) * 1996-10-11 1998-04-15 Nittan Company, Limited Ionization smoke detector
US6292105B1 (en) * 1998-12-23 2001-09-18 The Johns Hopkins University Thermal ionization detector
US6976883B2 (en) * 2003-05-20 2005-12-20 Walter Kidde Portable Equipment, Inc. Adaptor apparatus and method for interchanging smoke alarms
US20060158327A1 (en) * 2005-01-18 2006-07-20 Fuchs Andrew M Retrofitting detectors into legacy detector systems
US20120326741A1 (en) * 2011-06-21 2012-12-27 Adc Communications (Australia) Pty Limited Apparatus for transmission testing of a telecommunications jack
US9055664B1 (en) * 2013-03-12 2015-06-09 Larry J. Huff Tool for removing a smoke detector cover
US20160305874A1 (en) * 2014-07-14 2016-10-20 Fenwal Controls Of Japan, Ltd. Photoelectric Smoke Detector
US10151693B2 (en) 2015-08-25 2018-12-11 Fenwal Controls Of Japan, Ltd. Photoelectric smoke sensor
US20190013658A1 (en) * 2017-07-05 2019-01-10 Hubbell Incorporated Weatherproof electrical enclosure with reinforcement
US20190173227A1 (en) * 2016-05-03 2019-06-06 Autronica Fire & Security As Fire detector mounting assembly and method
US10878682B1 (en) * 2019-08-13 2020-12-29 Ronald Tucker Smoke detector
US20230009165A1 (en) * 2021-07-07 2023-01-12 Sidewalk Labs LLC Wireless occupancy sensors and methods for using the same
US11887450B2 (en) 2018-05-09 2024-01-30 Carrier Corporation Smoke chamber for multiwave multiangle smoke detector

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DE2314567B2 (de) * 1973-03-23 1978-10-12 Siemens Ag, 1000 Berlin Und 8000 Muenchen Feuermelder
SE7609408L (sv) * 1975-09-05 1977-03-06 Elektornische Brandmeldeanlage Anordning for fastsettning av ett foremal pa ett underlag
JPS53100295A (en) * 1977-02-14 1978-09-01 Omron Tateisi Electronics Co Ionization type smoke detector
CH639859A5 (de) * 1979-10-05 1983-12-15 Cerberus Ag Vorrichtung zur entnahme eines brandmelders aus einem sockel.
JPS6234399Y2 (xx) * 1980-03-31 1987-09-02
FR2523309A1 (fr) * 1982-03-09 1983-09-16 Hugon Emile Nouveau detecteur de fumees capacitif a modules interchangeables
US4582996A (en) * 1982-04-08 1986-04-15 Cerberus Ag Electrode insulating member for ionization fire alarm
DE3341781A1 (de) * 1983-11-18 1985-05-30 Siemens AG, 1000 Berlin und 8000 München Automatischer brandmelder und verfahren zur fertigung automatischer brandmelder
JPH0390693U (xx) * 1989-12-26 1991-09-17
ES2070748B1 (es) * 1993-05-17 1996-05-16 Kilsen Sa Detector ionico de humos.
DE9416314U1 (de) 1994-10-10 1994-12-01 Fritz Fuss Gmbh & Co, 72458 Albstadt Rauchmelder
DE102014019773B4 (de) 2014-12-17 2023-12-07 Elmos Semiconductor Se Vorrichtung und Verfahren zur Unterscheidung von festen Objekten, Kochdunst und Rauch mittels des Displays eines Mobiltelefons
DE102014019172B4 (de) 2014-12-17 2023-12-07 Elmos Semiconductor Se Vorrichtung und Verfahren zur Unterscheidung von festen Objekten, Kochdunst und Rauch mit einem kompensierenden optischen Messsystem

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US3560737A (en) * 1967-08-02 1971-02-02 Honeywell Inc Combustion products detector using a radioactive source and detector

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US3271756A (en) * 1960-03-22 1966-09-06 Harold J Burke Method and apparatus for detecting a hazardous condition
US3500368A (en) * 1966-03-30 1970-03-10 Nittan Co Ltd Automatic ionic fire alarm system
US3560737A (en) * 1967-08-02 1971-02-02 Honeywell Inc Combustion products detector using a radioactive source and detector

Cited By (52)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3908957A (en) * 1973-04-17 1975-09-30 Cerberus Ag Ionization-type fire sensor
US3963929A (en) * 1973-04-24 1976-06-15 Geba-Gesellschaft Fur Elektronische Brandmeldeanlagen Mbh & Co. Ionization analyzing air pollution, smoke and fire alarm device
US3909815A (en) * 1973-06-01 1975-09-30 Gamma Electronic Detector for fumes and combustion gases
US3900795A (en) * 1973-08-15 1975-08-19 Honeywell Inc Installation and test tool for ionization smoke detector
US3934145A (en) * 1973-10-25 1976-01-20 Emhart Corporation Ionization smoke detector and alarm system
US4074341A (en) * 1973-12-07 1978-02-14 Cerberus Ag Interlocked separable fire sensor construction
US4017733A (en) * 1974-04-18 1977-04-12 Hochiki Corporation Ionization type smoke sensor
US4081684A (en) * 1974-07-02 1978-03-28 Wieder Horst K Combustion product detector
US3961195A (en) * 1974-08-26 1976-06-01 Timothy John Newington Fire detector having means for heating the support member of an electrode to prevent formation of moisture thereon
US4056727A (en) * 1975-09-05 1977-11-01 Geba, Gesellschaft Fuer Brandmeldeanlagen Mbh & Co. Attachment means of an object to a support
US4075487A (en) * 1976-05-14 1978-02-21 Patent Development & Management Company Ionization chamber assembly
US4053777A (en) * 1976-07-07 1977-10-11 Geba, Gesellschaft Fuer Elektronische Brandmeldeanlagen Mbh & Co. Accident- and tampering-proof attachment means of an object to a stationary support
US4194120A (en) * 1976-11-29 1980-03-18 Cerberus Ag Adjustable ionization chamber
US4238679A (en) * 1978-12-07 1980-12-09 Conrac Corporation Dual-chamber ionization smoke detector assembly
US4286159A (en) * 1979-04-10 1981-08-25 Hochiki Corporation Detector coupling mechanism
US4258261A (en) * 1979-05-07 1981-03-24 Pittway Corporation Electrode assembly for combustion products detector
DE3100022A1 (de) * 1980-01-02 1981-12-17 Société Gamma Electronic, 75800 Paris Ionisierungsrauchmelder
US4396840A (en) * 1980-10-01 1983-08-02 Matsushita Electric Works, Ltd. Ionization type smoke sensing device
EP0233754A2 (en) * 1986-02-13 1987-08-26 Nohmi Bosai Ltd. A fire detector
US4724430A (en) * 1986-02-13 1988-02-09 Nohmi Bosai Kogyo Co., Ltd. Fire detector
EP0233754A3 (en) * 1986-02-13 1989-02-08 Nohmi Bosai Kogyo Co., Ltd. A fire detector
US4864141A (en) * 1986-02-25 1989-09-05 Jacques Lewiner Smoke detector with ionization chamber
FR2625352A1 (fr) * 1987-12-26 1989-06-30 Hochiki Co Detecteur de fumee par ionisation
EP0399244A2 (en) * 1989-05-02 1990-11-28 Nohmi Bosai Kabushiki Kaisha A light-scattering-type smoke detector
EP0399244A3 (en) * 1989-05-02 1991-05-02 Nohmi Bosai Kabushiki Kaisha A light-scattering-type smoke detector
US5403198A (en) * 1992-04-25 1995-04-04 Nohmi Bosai Ltd. Detector base
US5399864A (en) * 1992-04-25 1995-03-21 Nohmi Bosai Ltd. Ionization type smoke detector
US5478256A (en) * 1992-04-25 1995-12-26 Nohmi Bosai Ltd. Fire detector having bayonet coupling and locking mechanism for base and detector unit
US5486816A (en) * 1992-04-25 1996-01-23 Nohmi Bosai Ltd. Fire detector having optic base clamping optic elements to a circuit board
US5565852A (en) * 1992-11-30 1996-10-15 Sentrol, Inc. Smoke detector with digital display
WO1996021208A1 (en) * 1995-01-04 1996-07-11 Caradon Gent Limited Improvements in and relating to smoke detectors
US6057775A (en) * 1996-10-11 2000-05-02 Nittan Company, Limited Ionization smoke detector
EP0836164A1 (en) * 1996-10-11 1998-04-15 Nittan Company, Limited Ionization smoke detector
US6292105B1 (en) * 1998-12-23 2001-09-18 The Johns Hopkins University Thermal ionization detector
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Also Published As

Publication number Publication date
CH508251A (de) 1971-05-31
FI56287C (fi) 1979-12-10
SE369794B (xx) 1974-09-16
ZA714783B (en) 1972-04-26
JPS5082998A (xx) 1975-07-04
JPS5543545B2 (xx) 1980-11-06
FI56287B (fi) 1979-08-31
YU35684B (en) 1981-04-30
AU463927B2 (en) 1975-08-07
JPS5082999A (xx) 1975-07-04
DK130857C (xx) 1975-09-22
DE2130889B2 (de) 1973-04-19
YU180271A (en) 1980-09-25
HK70078A (en) 1978-12-08
NL7108647A (xx) 1972-01-25
JPS526080B1 (xx) 1977-02-18
AU3152871A (en) 1973-01-25
DK130857B (da) 1975-04-21
SE375871B (xx) 1975-04-28
DE2130889A1 (de) 1972-02-03
GB1324286A (en) 1973-07-25
FR2103672A5 (xx) 1972-04-14
NO126976B (xx) 1973-04-16

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