US3154773A - Fire alarm with an aerosol indicator for detecting combustion products suspended in the air - Google Patents

Fire alarm with an aerosol indicator for detecting combustion products suspended in the air Download PDF

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Publication number
US3154773A
US3154773A US90989A US9098961A US3154773A US 3154773 A US3154773 A US 3154773A US 90989 A US90989 A US 90989A US 9098961 A US9098961 A US 9098961A US 3154773 A US3154773 A US 3154773A
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United States
Prior art keywords
fire alarm
filter
particles
air
housing
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Lifetime
Application number
US90989A
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English (en)
Inventor
Meili Ernst
Lampart Thomas
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Cerberus AG
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Cerberus AG
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Filing date
Publication date
Application filed by Cerberus AG filed Critical 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
    • 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
    • G01N27/64—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 wave or particle radiation to ionise a gas, e.g. in an ionisation chamber
    • G01N27/66—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 wave or particle radiation to ionise a gas, e.g. in an ionisation chamber 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
    • 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
    • G08B17/103—Actuation by presence of smoke or gases, e.g. automatic alarm devices for analysing flowing fluid materials by the use of optical means using a light emitting and receiving device

Definitions

  • the present invention relates to a novel fire alarm system of the type provided with an aerosol indicator for detecting combustion products suspended in the air.
  • combustion products relates to particles of microscopic and submicroscopic sizes which are produced by combustion and which float or are suspended in the A number of fire alarm systems are known which respond to these particles and, more specifically, aerosols in order to actuate, for example, a fire alarm.
  • ionization fire alarms which respond to visible and invisible combustion products.
  • alarms which operate with a light source and a photosensitive cell which respond either to a decrease in the intensity of the light received by the photosentive cell from the light source in the event that aerosols are present between them, or to the refiection of light by the aerosols.
  • the heretofore mentioned indicators of aerosols provided in fire alarm systems operate prefectly if the air does not contain substantial portions of other suspended contaminants, such as dust, soot, vapors and the like. If such contaminants are present, the operation of the fire alarm systems is adversely affected, or rendered impossible, since the contaminants cause the same efiect as the combustion products which are to be detected.
  • the contaminants may have the same effect on the transparency or reflective power or" a gas at the aerosols, and they may alter the current flowing through an ionization chamber in the same manner as the aerosols stemming from combustion. In rooms and surroundings in which dust or other impurities are present, the sensitivity or" the indicators must be considerably reduced if continual false alarms are to be avoided. Obviously, such an alteration in the system always involves a loss of sensitivity in detection of actual fires.
  • a further detrimental efiect experienced with the operation of fire alarm systems provided with aerosol indicators is due to the soiling of these indicators by dust. if a breakdown after a short period of operation is to be prevented, costly cleaning processes are required.
  • the present invention has for one of its primary objects to provide a fire alarm system of the type mentioned which obviates the disadvantages mentioned hereinabove, which operates reliably even in rooms containing heavily contaminated air, and which responds most sensitively to the aerosols formed by combustion, even if such aerosols are present in very low concentrations.
  • Another important object of the present invention is to provide means preventing contaminants, other than those generally resulting from a combustion process, for actuating a fire alarm system.
  • Still a further object of the present invention is to provide means for filtering out foreign particles within a predetermined size range prior to entry into a fire alarm system in order to preserve the integrity of said system.
  • FIGURE 4 shows several fire alarms connected to a common fan which produces the pressure difference at the filters.
  • the normal dust particles are retained by the filter 1 so that they cannot impede the light passing from the light source 3 to the photoelectric cell
  • aerosol particles of which the diameter is less than about one ,u. will be present in the indicating area of the housing 6. These particles will pass through the filter l and cause the light energy passing to the photoelectric cell 4- to be reduced. This results in a reduction of the voltage which will be indicated by the microvoltrneter 5.
  • Such reduction of voltage is an indication of the presence of a combustion process.
  • the microvoltrneter 5 may also be replaced by relay members or the like, which are suitable to trigger the alarm if the voltage supplied by the photoelectric cell 4 drops below a predetermined value.
  • the filter 1 may be formed of a nylon or cotton fabric, much in the same manner as presently employed as a filtering material in commercial vacuum cleaners.
  • filters formed of non-swelling fibers may be advantageous, since the filtering properties will then be independent of humidity.
  • filters formed of spun-glass fabrics may be found to be suitable.
  • the filters are designed so that, for example, particles having a diameter or greatest di- 'rnension preferably less than one ,u. are passed, While particles of a dimension exceeding five U. are retained.
  • the fiber grade employed in each particular case will also depend on the degree of contamination of the air.
  • FIGURE 2 there is shown an ionization fire alarm system in which the gas to be tested is capable of passing through the filter 11 in both directions.
  • the indicator of the fire alarm contains two electrodes 14 and 15 connected to an indicating or measuring instrument 17 provided with a direct voltage source 18.
  • a radioactive material 16 Provided for one electrode, such as electrode 15, is a radioactive material 16, which at least partly ionizes the space between the two electrodes 14 and 15. If aerosols reach the space between the electrodes, the ions, as is generally known, will adhere to the aerosols, thus reducing the effective mobility of the oins. This will result in a certain decrease in the ionization current.
  • the current decrease may be detected by the sensitive current indicator 17 or be employed to initiate an alarm by means of a relay member.
  • the filter 11 cannot become soiled since the dirt particles which are deposited on the outside surface of the filter during the suction stroke are blown away during the pressure stroke.
  • the filter will, therefore, remain operative for considerable periods without necessitating servicing.
  • FIGURE 3 shows a further embodiment of an ionization fire alarm.
  • the electrical members are arranged in a manner similar to FIGURE 2, so that for clarity in comprehension the same reference numerals have been employed.
  • the two electrodes of the indicator are arranged within a tubular housing 23 which may be arranged, for example, in a duct or conduit.
  • the gas to be tested for combustion products flows through the duct in the direction indicated by the arrows.
  • a filter 21 which retains the aerosol particles having a diameter of, for example, over five ,u. while the particles having a smaller diameter are allowed to pass.
  • the filter 21, furthermore, performs the function of reducing the flow within the tube 23. This is desirable because excessive flow may change the relationship between the electrodes 14 and 15 so as to reduce indicator sensitivity.
  • FIGURE 4 Such an arrangement is shown in FIGURE 4.
  • Three fire alarms A, B and C, each comprising an aerosol indicator 32 and a filter 31, are connected, via lines 34, with a fan 33 which maintains constant negative pressure in the line 34. This negative pressure will regularly cause air to be drawn through the filters 31 and tested in the indicator 32. Soiling of the filters 31 may be avoided by forcing air through the lines 34 in the op posite direction at regular intervals for the purpose of cleaning the filters 31.
  • the indicators 34 are connected with a central station which may actuate an alarm if the content of floating particles or aerosols having a diameter of, for example, one t exceeds a predetermined critical value.
  • the pressure difierence in the embodiments shown may influence the response threshold of the alarm.
  • the pressure difference in the alarm is relatively great, a larger number of floating particles will pass through the filter than if the pressure ditlerence is smaller.
  • Reliable monitoring and communication, respectively, may therefore require control of the pressure difference at the filters for the reason just mentioned.
  • the combination with a fire alarm for detecting the presence of products of combustion contained in a fluid medium, of the type comprising circuit means for operating said fire alarm, housing means having an inlet opening and internally provided with an ionization chamber communicating with said inlet opening and including spaced electrode means and radioactive material provided in said ionization chamber for at least partially ionizing the space therebetween, filter means operatively associated with said inlet opening of said housing for preventing particles entering said ionization chamber which substantially result from other than a combustion process, said filter means being constructed to pass particles having a diameter smaller than 1 micron while retaining the majority of particles having a diameter greater than 5 microns.
  • said pressure diiference creating means being a pump, said pump drawing, via said filter means, fluid medium into said housing during its suction stroke and forcing at least a portion of said fluid medium, via said filter means, from said housing during 5 6 its exhaust stroke, to carry out a cleaning action on said said duct member such that a pressure difierence is crefilter means. ated across said filter means.

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  • Chemical & Material Sciences (AREA)
  • Analytical Chemistry (AREA)
  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Business, Economics & Management (AREA)
  • Emergency Management (AREA)
  • Health & Medical Sciences (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Toxicology (AREA)
  • Electrochemistry (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Biochemistry (AREA)
  • General Health & Medical Sciences (AREA)
  • Immunology (AREA)
  • Pathology (AREA)
  • Fire-Detection Mechanisms (AREA)
  • Investigating Or Analysing Materials By Optical Means (AREA)
US90989A 1960-02-26 1961-02-23 Fire alarm with an aerosol indicator for detecting combustion products suspended in the air Expired - Lifetime US3154773A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
CH220860A CH379974A (de) 1960-02-26 1960-02-26 Feuermeldeanlage mit mindestens einem Aerosol-Indikator zur Feststellung von in Luft schwebenden Verbrennungsprodukten

Publications (1)

Publication Number Publication Date
US3154773A true US3154773A (en) 1964-10-27

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US90989A Expired - Lifetime US3154773A (en) 1960-02-26 1961-02-23 Fire alarm with an aerosol indicator for detecting combustion products suspended in the air

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US (1) US3154773A (de)
CH (1) CH379974A (de)
GB (1) GB954578A (de)

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4035788A (en) * 1976-01-15 1977-07-12 Celesco Industries Inc. Incipient fire detector
DE2724510A1 (de) * 1977-05-31 1978-12-14 Brunswick Corp Fruehwarnfeuermelder
DE3139582A1 (de) * 1981-10-05 1983-04-21 Preussag AG Bauwesen, 3005 Hemmingen Brandmeldeeinrichtung
US4897549A (en) * 1988-12-19 1990-01-30 Zerda Tadeusz W Method of measuring pore diameters by positronium decay

Families Citing this family (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4543815A (en) * 1983-07-15 1985-10-01 Cerberus Ag Device for the detection of foreign components in a gas and an application of the device
FR2583878A1 (fr) * 1985-06-21 1986-12-26 Icare Sa Dispositif analyseur d'ambiance a chambre d'ionisation a reactif gazeux avec aspirateur collecteur
US5926098A (en) * 1996-10-24 1999-07-20 Pittway Corporation Aspirated detector
US7656302B2 (en) 2006-11-20 2010-02-02 Honeywell International Inc. Sensing chamber with enhanced ambient atmospheric flow

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2079474A (en) * 1935-12-11 1937-05-04 Thomas A Walsh Dust and fume sampler
US2228216A (en) * 1939-01-06 1941-01-07 Power Patents Co Apparatus for testing cigarettes and the like
US2572008A (en) * 1946-06-05 1951-10-23 C O Two Fire Equipment Co Smoke detector and signal for diesel locomotives

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2079474A (en) * 1935-12-11 1937-05-04 Thomas A Walsh Dust and fume sampler
US2228216A (en) * 1939-01-06 1941-01-07 Power Patents Co Apparatus for testing cigarettes and the like
US2572008A (en) * 1946-06-05 1951-10-23 C O Two Fire Equipment Co Smoke detector and signal for diesel locomotives

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4035788A (en) * 1976-01-15 1977-07-12 Celesco Industries Inc. Incipient fire detector
DE2724510A1 (de) * 1977-05-31 1978-12-14 Brunswick Corp Fruehwarnfeuermelder
DE3139582A1 (de) * 1981-10-05 1983-04-21 Preussag AG Bauwesen, 3005 Hemmingen Brandmeldeeinrichtung
US4897549A (en) * 1988-12-19 1990-01-30 Zerda Tadeusz W Method of measuring pore diameters by positronium decay

Also Published As

Publication number Publication date
CH379974A (de) 1964-07-15
GB954578A (en) 1964-04-08

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