US3725011A - Automatic fire alarm with at least one measuring chamber - Google Patents

Automatic fire alarm with at least one measuring chamber Download PDF

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Publication number
US3725011A
US3725011A US00019244A US3725011DA US3725011A US 3725011 A US3725011 A US 3725011A US 00019244 A US00019244 A US 00019244A US 3725011D A US3725011D A US 3725011DA US 3725011 A US3725011 A US 3725011A
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US
United States
Prior art keywords
measuring chamber
fire alarm
automatic fire
reaction agent
smoke
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
US00019244A
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English (en)
Inventor
G Purt
W Bosshard
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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Publication of US3725011A publication Critical patent/US3725011A/en
Anticipated expiration legal-status Critical
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    • G—PHYSICS
    • G08—SIGNALLING
    • G08B—SIGNALLING SYSTEMS, e.g. PERSONAL 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
    • G08—SIGNALLING
    • G08B—SIGNALLING SYSTEMS, e.g. PERSONAL 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
    • G08B17/117—Actuation by presence of smoke or gases, e.g. automatic alarm devices for analysing flowing fluid materials by the use of optical means by using a detection device for specific gases, e.g. combustion products, produced by the fire
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
    • Y10S—TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10S422/00—Chemical apparatus and process disinfecting, deodorizing, preserving, or sterilizing
    • Y10S422/903—Radioactive material apparatus

Definitions

  • the present invention relates to an improved automatic fire alarm of the type possessing at least one measuring chamber freely accessible to the surrounding air and constructed such that it can deliver via an electric circuit an alarm signal when combustion products in the form of combustion aerosols or smoke penetrate into the measuring chamber.
  • Automatic fire alarms of the above-mentioned type possess a measuring chamber equipped with openings through which the surrounding atmosphere can enter such measuring chamber, for instance by convection.
  • the products of combustion appearing during a fire for instance smoke particles or combustion aerosols, can be detected in the measuring chamber in different ways.
  • a known optical fire alarm incorporates a light source which directs light upon a photocell. Smoke particles cause a variation of the illumination intensity and the photocell current, this current variation being used for sounding an alarm, for instance by means of a bridge circuit or a reference ray path without weakening the light.
  • Ionization fire alarms operate according to another principle in which the measuring chamber is equipped with two voltage-carrying electrodes and a source of radioactive radiation. A current of ionized gas molecules or atoms flows between the electrodes. If the gas composition changes or the content of larger particles, such as for instance aerosols or smoke, then the ionization current will also change. This change in current is employed for sounding an alarm through the agency of an amplifierand threshold value detector circuit.
  • such atmosphere can also be delivered thereto by suitable suction devices, for instance via pipe conduits.
  • halogen-containing plastics for instance polyvinylchloride (PVC)
  • gaseous hydrogen halides for instance hydrogen chloride or hydrochloric acid vapors
  • PVC polyvinylchloride
  • Even small quantities can cause considerable damage.
  • an automatic fire alarm is required to work faultlessly free of wear over a long period of time, and additionally, that it respond to all possibly encountered products of combustion.
  • Another, more specific object of the present invention is the provision of an automatic fire alarm which responds both to combustion products in the form of combustion aerosols or smoke and to hydrogen halides and which can work effectively for long periods of time without maintenance.
  • the inventive automatic fire alarm is of the type incorporating a measuring chamber which contains a solid or liquid substance which, during the course of time, delivers a gaseous reaction agent suitable for forming, with hydrogen halide vapors, condensation products in the form of aerosols.
  • a particular characteristic of such substances is that their vapors, either because of the partial pressure in the temperature range of 25 C. to +100 C., or because of their chemical nature, do not appreciably influence the detection sensitivity of combustion aerosols.
  • FIG. 1 is a sectional schematic view of a fire alarm utilizing light absorption for its operation
  • FIG. 2 schematically illustrates in sectional view a fire alarm utilizing dispersed or stray light for its operation
  • FIG. 3 schematically illustrates in sectional view an ionization fire alarm.
  • the optical fire alarm shown in FIG. 1 comprises a measuring chamber 1 having at its wall 2 openings 3 allowing the entry of external air to the interior of this measuring chamber 1. The incidence of direct light is prevented through the use of the diaphragms or light stops 4.
  • a lamp 5 and a photocell 6 are located in the measuring chamber 1. Lamps 5 and photocell 6 are arranged such that direct light from the lamp 5 impinges upon the photocell 6. Now if smoke enters into the measuring chamber 1, then a portion of the light is absorbed by the smoke and the illumination intensity at the photocell and, thus, the photocell current changes.
  • This photocell current is evaluated via the leads or conductors 7 by means of a non-illustrated electric circuit suitable for this purpose, and well known to the art, and, if desired, that is to say, when the light absorption in the measuring chamber 1 has reached a certain degree, can be employed for sounding an alarm.
  • the invention contemplates providing a substance 8 in the measuring chamber 1 which has the properties of slow- 1y delivering reaction agent vapors during the course of time. If the air entering through the opening 3 by natural convection only has traces of a hydrogen halide, for instance gaseous hydrochloric acid, then upon wiping contact with the substance 8 there is formed a fine-suspended particle mist which will be detected by the fire alarm in the same manner as smoke.
  • a hydrogen halide for instance gaseous hydrochloric acid
  • the described fine alarm thus responds equally sensitively to smoke as such occurs normally during a fire as well as to hydrochloric acid vapors resulting from combustion of PVC.
  • FIG. 2 illustrates an optical fire alarm utilizing the Tyndall effect for its operation.
  • the wall 9 of the measuring chamber 10 has openings 11 for the entry of air. These openings are covered by parts of the wall in such a way that it is impossible for light to directly enter from the outside.
  • the lamp 12 and photocell 13 are arranged such that no direct light impinges from the lamp 12 upon the photocell 13. This photocell 13 is thus without current in its rest condition. If smoke enters the measuring chamber 10, then, a portion of the light transmitted by the lamp 12 is dispersed to the photocell 13, and a photocell current can be observed at the conductors 14 which can be used by an elec tric circuit to sound an alarm.
  • reaction agent delivery substance 15 which communicates with the interior of the measuring chamber 10 by openings in the wall. Accordingly, a certain partial pressure of reaction agent prevails in the measuring chamber 10. If the air entering the measuring chamber 10 contains traces of hydrogen halide, then, once again, there is formed a suspended-substance mist which, in the same manner as smoke causes light to disperse, therefore results in the presence of a photocell current as previously explained. Also, in this instance, the construction of a fire alarm and the application of the reaction agent-delivering substance in the measuring chamber can be optionally selected and according to the desired purposes.
  • FIG. 3 depicts an ionization fire alarm wherein its measuring chamber 16 is surrounded by an external or outer electrode 17 having a number of small openings 18 rendering possible the entry of external air.
  • a punch-shaped inner electrode 19 Internally of the measuring chamber 16 there is located a punch-shaped inner electrode 19 which carries a suitable radioactive preparation 20.
  • a partition wall 21 separates the measuring chamber 16 from a second ionization chamber 22 serving as a reference chamber and connected in series with the measuring chamber 16.
  • a hood member 23 serving as an outer electrode, this reference chamber 22 is almost sealed from the external air so that smoke particles cannot penetrate into such chamber, but a pressure equalization is possible.
  • Serving as the inner electrode for the reference chamber 22 is the same punchshape member 19 as in the measuring chamber 16. It carries at the side of the reference chamber 22 a further radioactive preparation 24.
  • the plate member 25 supports electronic components and a printed circuit which evaluates a change in the ionization current in the measuring chamber for sounding an alarm.
  • a reaction agent-delivering substance 26 is housed in the measuring chamber 16, and specifically, internally of the punch-shaped inner electrode 19. It communicates with the interior of the measuring chamber 16 via openings provided at the wall of the punch-1ike member and is capable of maintaining in the measuring chamber 16 a certain reaction agent-partial pressure.
  • the re action agent-delivering substance 26 can be located at a different place in the measuring chamber, for instance upon the closure plate 21 or preferably in the region of the openings for the entry of the gas.
  • the radioactive substances 20 or 24 be located upon the common electrode 19. They can equally well be situated at a different location of the measuring chamber, for instance upon the plate member 21, and instead the ammonia-delivering substance can then be placed at the location of the preparation 20 upon the punch-like member 19 of the inner electrode of the measuring chamber 16.
  • the vapor pressure at room temperature is high enough to detect early enough the first traces of hydrochloric acid vapors which occur during a PVC-fire.
  • the vapor pressure should not be so high that there oc-' curs an adverse effect upon the surroundings.
  • reaction agent cannot have any appreciable influence upon the normal combustion aerosolsensitivity of the fire alarm. In the case of the optical fire alarm, this means that the reaction agent must be optically neutral, that is to say that it behaves like air.
  • the mobility of the ions of the reaction agent in the electric field of the ionization chamber must be in the same order of magnitude as that of the air ions. With larger deviations with respect to the mobility of air ions such must be compensated by a lower partial pressure of the reaction agent.
  • the reaction agent can be ammonia gas which is produced from an aqueous ammonia solution by its normal ammonia vapor pressure.
  • an ionization chamber in which there is located aqueous ammonia solution is thus primarily filled with ammonia gas and its cur-" rent-voltage characteristic deviates considerably from that which is only filled with air which, in turn, strongly impairs the smoke aerosol-detection sensitivity. Therefore, aqueous ammonia solutions are unsuitable.
  • the substance can contain ammonia and possess a certain ammonia vapor pressure.
  • Such substances are, for instance, inorganic heavy metal-complex amine salts.
  • tetraaminecopper sulfate [Cu(NH SO- hexaaminenickel sulfate [Ni(NH SO diaminesilver chloride [Ag(NH Cl], hexaamineiron chloride and so forth.
  • Particularly suitable are salts of nickel and copper.
  • ammonia gas can be produced from certain substances through chemical reactions, whereby there results a slight air moisture or catalytically influencable decomposition.
  • small quantities of ammonia gas are slowly formed from calcium cyanamide or appropriate magnesium salts through small quantities of Water vapor in a chemical reaction.
  • Magnesium cyanamide is particularly suitable for the described process.
  • a completely different group of substances are those which can indeed be chemically derived from ammonia, but themselves do not deliver any ammonia.
  • organic nitrogen compounds more or less, depending upon their chemical composition, possess basic properties and tend to form salts with hydrogen halide materials.
  • such compounds when they possess a certain vapor pressure in the air space, together with hydrogen halides in a chemical reaction deliver aerosols which leads to increased detection sensitivity of hydrogen halides.
  • Very suitable substances are tertiary organic amines, or, for instance, ethylenediamine or dimethylamine.
  • the substance is liquidous at room temperature or at the maximum operating temperature which is to be expected, then it is advantageous to embed such in porous supporting material in the measuring chamber.
  • Such additional electrical heating means 50 has been schematically shown in FIG. 2 for example.
  • Such a device can also serve for regulating a predetermined desired sensitivity for hydrogen halides under certain conditions.
  • An automatic fire alarm having at least one measuring chamber accessible to the surrounding atmosphere and sensitive both to combustion products such as smoke, and to hydrogen halide vapors and constructed to deliver an alarm signal through the agency of an electric circuit when either combustion products or hydrogen halide vapors or both enter the measuring chamber, said measuring chamber comprising means for detecting combustion products such as smoke, and a substance which over prolonged periods of time continually delivers a reaction agent with a vapor pressure of less than torr at 20 C. and forming with hydrogen halide vapors products having properties similar to and detectable in the same manner as combustion products.
  • reaction agent is ammonia
  • reaction agent is dimethylamine
  • reaction agent delivering substance is a member selected from the group comprising calcium cyanamide and magnesium cyanamide.
  • reaction agent-delivering substance is located in a porous support material.
  • reaction agent-delivering substance is a metal cyanamide.
  • reaction agent-delivering substance gives off ammonia in the presence of moisture.
  • reaction agent-delivering substance is a metal cyanamide.
  • reaction agent-delivering substance is a member selected from the group comprising inorganic amines, ammonia and organic amines.
  • reaction agent-delivering substance is an inorganic heavy metal-complex amine salt.
  • said inorganic heavy metal-complex amine salt is a member selected from the group comprising tetraaminecopper sulfate, hexaaminenickel sulfate, diaminesilver chloride and hexaamineiron chloride.

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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)
  • Investigating Or Analysing Materials By Optical Means (AREA)
  • Other Investigation Or Analysis Of Materials By Electrical Means (AREA)
  • Investigating Or Analyzing Non-Biological Materials By The Use Of Chemical Means (AREA)
US00019244A 1969-03-28 1970-03-13 Automatic fire alarm with at least one measuring chamber Expired - Lifetime US3725011A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
CH474769A CH483682A (de) 1969-03-28 1969-03-28 Automatischer Feuermelder mit mindestens einer Messkammer

Publications (1)

Publication Number Publication Date
US3725011A true US3725011A (en) 1973-04-03

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US00019244A Expired - Lifetime US3725011A (en) 1969-03-28 1970-03-13 Automatic fire alarm with at least one measuring chamber

Country Status (6)

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US (1) US3725011A (fr)
BE (1) BE747708A (fr)
CH (1) CH483682A (fr)
DE (1) DE2011340C3 (fr)
FR (1) FR2039878A5 (fr)
GB (1) GB1243769A (fr)

Cited By (4)

* 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
US3849685A (en) * 1973-06-22 1974-11-19 Honeywell Inc Ionization chamber with recessed radioactive body
JPS5178390A (ja) * 1974-12-28 1976-07-07 Nittan Co Ltd Kemurikanchiki
US4044262A (en) * 1975-02-10 1977-08-23 Hochiki Corporation Ionization smoke sensor

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE2434178C2 (de) * 1974-07-16 1983-12-08 Matsushita Electric Works, Ltd., Kadoma, Osaka Rauchmeldegerät nach dem Lichtstreuprinzip

Cited By (4)

* 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
US3849685A (en) * 1973-06-22 1974-11-19 Honeywell Inc Ionization chamber with recessed radioactive body
JPS5178390A (ja) * 1974-12-28 1976-07-07 Nittan Co Ltd Kemurikanchiki
US4044262A (en) * 1975-02-10 1977-08-23 Hochiki Corporation Ionization smoke sensor

Also Published As

Publication number Publication date
BE747708A (fr) 1970-08-31
DE2011340B2 (de) 1974-07-11
FR2039878A5 (fr) 1971-01-15
GB1243769A (en) 1971-08-25
DE2011340C3 (de) 1978-04-20
CH483682A (de) 1969-12-31
DE2011340A1 (de) 1970-10-08

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