EP0091623A1 - Ionisation fire detector - Google Patents

Ionisation fire detector Download PDF

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Publication number
EP0091623A1
EP0091623A1 EP83103225A EP83103225A EP0091623A1 EP 0091623 A1 EP0091623 A1 EP 0091623A1 EP 83103225 A EP83103225 A EP 83103225A EP 83103225 A EP83103225 A EP 83103225A EP 0091623 A1 EP0091623 A1 EP 0091623A1
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Prior art keywords
ionization
insulating
electrodes
electrode
areas
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EP83103225A
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German (de)
French (fr)
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EP0091623B1 (en
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Andreas Dr. Scheidweiler
Bernhard Durrer
Jürg Muggli
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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

  • Ionization fire detector with an ionization chamber containing a radioactive preparation and two electrodes separated by an insulating part, accessible to the outside atmosphere, and an electrical circuit for signaling and alarming.
  • Ionization fire detectors of the type specified above are known, for example from DE-AS 2'130'889. With these ionization fire detectors, the air in the ionization chamber (measuring chamber), which is accessible to the outside atmosphere, is ionized by a radioactive preparation and, due to the direct voltage applied to the two electrodes of the ionization chamber, an ion current flows between the electrodes. If smoke, fire aerosols or other particles enter the ionization chamber through the chamber openings, the electrical current changes. The electrical circuit evaluates this change in current in such a way that an alarm signal is sent to a control center via lines when the conductivity in the ionization chamber is reduced.
  • the ionization chamber is in series with a resistance element, e.g. an almost closed or fire-aerosol-insensitive second reference ionization chamber, and the potential difference between the two chambers is determined using a high-resistance amplifier element, e.g. of a field effect transistor.
  • a resistance element e.g. an almost closed or fire-aerosol-insensitive second reference ionization chamber
  • a high-resistance amplifier element e.g. of a field effect transistor.
  • Another possibility is to periodically scan the charge on the electrodes of the ionization chamber.
  • ionization fire detectors are very sensitive to impurities, which reduce the electrical resistance of the insulating part (insulation gap) between the electrodes of the measuring chamber.
  • insulating part insulation gap
  • plastics are subject to natural aging, which can be accelerated by the influence of atmospheric oxygen (partly also ozone) or aggressive ingredients in the surrounding air and in the cleaning agents used in the detector revision.
  • atmospheric oxygen partly also ozone
  • Such corrosive substances are present in extremely low concentrations in normal ambient air, but can take on considerable values in a special environment.
  • the duration of exposure should not be neglected, nor the fact that the air is ionized by the radioactive source in the detector, which causes ozone and others, the detector material attacking substances are formed inside the detector. Since the atmosphere can penetrate between the labyrinth and the insulation section, the problem of aging of the insulation section remains.
  • the object of the present invention is to provide an ionization fire detector of the type mentioned at the outset which does not have the disadvantages mentioned above and in which in particular the insulation value of the insulating part between the electrodes is retained over a longer period of time.
  • the insulating part has at least two regions consisting of different insulating materials, which are arranged between the electrodes in such a way that the creepage distance between these electrodes leads over all of these regions.
  • the insulating part consisting of three different insulating materials ranges auf.Besonders preferably, the first region for example, is a polycarbonate, the second area, for example, from an epoxy resin and the third area, for example, from a polyester.
  • one electrode is designed as a central electrode, and the other electrode consists of an opening for the entry of the surrounding air, which forms the boundary of the ionization chamber that is accessible to the outside atmosphere from the outside atmosphere.
  • the areas consisting of different materials are arranged around the center electrode, preferably practically concentrically.
  • the detector shown in Figure 1 consists of a metallic hood 1, which has openings 2 and 3 for the entry of the surrounding air.
  • a labyrinth 4 made of highly insulating plastic is arranged in the interior of the hood 1 and has a number of webs 5 arranged in the form of a ring to extend the creepage distances.
  • the stamp-shaped central electrode 6 is located in the middle of the labyrinth 4.
  • the outer electrode is formed by the metallic hood 1.
  • the two electrodes are partially detachable by means of an isolating means, which are not shown Part 7 connected.
  • the insulating part 7 and the labyrinth 4 are made of the same plastic, preferably polycarbonate, for example Makrolon.
  • FIG. 2 shows an embodiment of an ionization fire detector according to the invention in section.
  • the ionization fire detector also consists of a metallic hood 1, which has openings 3 for the entry of the surrounding air.
  • Thermoplastic polyesters ie polycondensation products of carbonic acid with diols, are suitable as the material for the first region 8. These polycarbonates are resistant to water, neutral salt solutions, mineral acids, for example also to hydrofluoric acid, aqueous solutions of oxidizing agents, hydrocarbons, oils, fats etc.
  • this area of the insulation section is made from Makrolon O.
  • the second area 9 is preferably made of a thermoset made of epoxies with polyols.
  • the electronic components of the ionization fire detector can be embedded in this potting compound made of epoxy resin will.
  • the epoxy resins are resistant to atmospheric influences, water, acids, alkalis, oil, petrol, benzene, etc.
  • the third region 10 is preferably produced from a polycondensation product of polyhydric alcohols (diols, polyols) with polybasic carboxylic acids. These polyesters are resistant to all organic solvents, but are less resistant to water and alkalis, as well as to acids above 70 ° C.
  • one or more of the different regions 8, 9, 10 can be equipped with ring-shaped elevations for extending the creepage distance, without the process for producing the insulating part becoming significantly more complicated.
  • An essential advantage of the ionization fire detector according to the invention is that the insulating ability of the insulating part 7 is maintained over substantially longer periods of time than in the known ionization fire detectors. If the surface resistance of one of the plastics forming the insulating part 7 is reduced due to the action of aggressive ingredients from the atmosphere or due to the slightest damage caused by the cleaning or drying agents, the insulating ability remains due to the different chemical composition of the individual areas received at least one of the other areas. When developing the technological procedural rules for cleaning plastic parts, the chemical nature of the plastic parts is largely taken into account. However, since the composition of the dust deposited on the insulation section is not known, it is often necessary to work with very active cleaning agents, for example solutions from RBS.
  • the detector parts In order to enable efficient detector revision, the detector parts must be dried after cleaning, using water displacement agents, such as isopropyl alcohol or freon. The maintenance of the surface quality of the plastic parts can therefore not be guaranteed in the long run. However, if the individual areas of the insulating part 7 are made of plastics of different chemical resistance, the risk that the insulating ability of the entire insulating part 7 will drop below an acceptable limit is considerably lower than in the known ionization fire detectors.

Abstract

Due to aging of the insulating materials arranged between the electrodes in ionization fire alarms or detectors the insulating efficiency of these thus formed so-called insulating paths or spans deteriorates in the course of time despite, or maybe even due to the cleaning operations performed upon such ionization fire alarms. To ensure that the insulating capacity does not fall below a critical value the insulating path or span is formed by at least two different insulating materials. The materials are arranged in such a manner that the creepage path between the electrodes extends across all the different insulating materials. This principle also may be applied to other measuring devices which require a high input resistance of an amplifier stage.

Description

Ionisationsfeuermelder mit einer ein radioaktives Präparat enthaltenden und zwei durch ein isolierendes Teil getrennte Elektroden aufweisenden, der Aussenatmosphäre zugänglichen Ionisationskammer und einer elektrischen Schaltung zur Signal- und Alarmgabe.Ionization fire detector with an ionization chamber containing a radioactive preparation and two electrodes separated by an insulating part, accessible to the outside atmosphere, and an electrical circuit for signaling and alarming.

Ionisationsfeuermelder der oben angegebenen Art sind bekannt, beispielsweise aus der DE-AS 2'130'889. Bei diesen Ionisationsfeuermeldern wird die in der der Aussenatmosphäre zugänglichen Ionisationskammer (Messkammer) befindliche Luft durch ein radioaktives Präparat ionisiert und auf Grund der an die beiden Elektroden der Ionisationskammer angelegte Gleichspannung fliesst ein Ionenstrom zwischen den Elektroden. Treten Rauch, Brandaerosole oder andere Partikeln durch die Kammeröffnungen in die Ionisationskammer ein, so ändert sich der elektrische Strom. Die elektrische Schaltung wertet diese Stromänderung derart aus, dass bei einer bestimmten Herabsetzung der Leitfähigkeit in der Ionisationskammer über Leitungen ein Alarmsignal an eine Zentrale abgegeben wird. Bei bekannten derartigen Schaltungen liegt die Ionisationskammer in Serie mit einem Widerstandselement, z.B. einer nahezu abgeschlossenen oder gegen Brandaerosole unempfindlichen zweiten Referenzionisationskammer, und die Potentialdifferenz zwischen beiden Kammern wird mit Hilfe eines hochohmigen Verstärkerelementes, z.B. eines Feldeffekttransistors, bestimmt. Eine weitere Möglichkeit besteht in der periodischen Abtastung der Aufladung der Elektroden der Ionisationskammer.Ionization fire detectors of the type specified above are known, for example from DE-AS 2'130'889. With these ionization fire detectors, the air in the ionization chamber (measuring chamber), which is accessible to the outside atmosphere, is ionized by a radioactive preparation and, due to the direct voltage applied to the two electrodes of the ionization chamber, an ion current flows between the electrodes. If smoke, fire aerosols or other particles enter the ionization chamber through the chamber openings, the electrical current changes. The electrical circuit evaluates this change in current in such a way that an alarm signal is sent to a control center via lines when the conductivity in the ionization chamber is reduced. In known such circuits, the ionization chamber is in series with a resistance element, e.g. an almost closed or fire-aerosol-insensitive second reference ionization chamber, and the potential difference between the two chambers is determined using a high-resistance amplifier element, e.g. of a field effect transistor. Another possibility is to periodically scan the charge on the electrodes of the ionization chamber.

Da die verwendeten Ionisationskammern im allgemeinen einen Widerstand von mehr als 1010 2 besitzen und die elektrische Schaltung einen wesentlich höheren Eingangswiderstand haben muss, sind Ionisationsfeuermelder sehr empfindlich auf Verunreinigungen, welche den elektrischen Widerstand des isolierenden Teils (Isolationsstrecke) zwischen den Elektroden der Messkammer herabsetzen. In gleicher Weise wie Brandaerosole werden Partikeln aus der Umgebung des Melders, z.B. Staub, in die Messkammer hineintransportiert und dort abgelagert, wodurch der elektrische Widerstand der Isolationsstrecke abnimmt. Dies macht eine häufige Wartung von Feuermeldeanlagen und eine Reinigung der Ionisationsfeuermelder notwendig.Since the ionization chambers used generally have a resistance of more than 10 10 2 and the electrical circuit has a significantly higher input resistance ionization fire detectors are very sensitive to impurities, which reduce the electrical resistance of the insulating part (insulation gap) between the electrodes of the measuring chamber. In the same way as fire aerosols, particles from the surroundings of the detector, such as dust, are transported into the measuring chamber and deposited there, as a result of which the electrical resistance of the insulation path decreases. This makes frequent maintenance of fire alarm systems and cleaning of ionization fire detectors necessary.

Das Problem der Aufrechterhaltung des elektrischen Widerstands wurde gemäss DE-AS 2'130'889 dadurch gelöst, dass die Isolationsstrecke im Inneren der als Aussenelektrode dienenden, Oeffnungen zum Eintritt der umgebenden Luft aufweisenden Haube durch ein aus dem gleichen hochisolierendem Kunststoff bestehendes Labyrinth abgedeckt wurde. Dadurch wurde die Kriechstrecke zwischen der Mittelelektrode und der Entgegenelektrode vor der Verschmutzung geschützt und der der Verschmutzung ausgesetzte Kriechweg wurde durch die ringförmigen Stege des Labyrinths um mehr als das vierfache verlängert. Es war so möglich den Zeitraum bis zum Unwirksamwerden des Melders erheblich zu verlängern, d.h. die Serviceintervalle konnten vergrössert werden. Kunststoffe unterliegen jedoch der natürlichen Alterung, die durch Einwirkung des Luftsauerstoffs (z.T. auch Ozon) oder agressiver Ingredienzien in der umgebenden Luft und in den bei der Melderrevision verwendeten Reinigungsmitteln beschleunigt werden kann. Solche korrosiven Stoffe sind in der normalen Umgebungsluft zwar in äusserst geringer Konzentration vorhanden, können in spezieller Umgebung jedoch beträchtliche Werte annehmen. Schliesslich ist die Dauer der Einwirkung nicht zu vernachlässigen, sowie die Tatsache, dass durch die im Melder vorhandene radioaktive Quelle die Luft ionisiert wird, wodurch Ozon und andere, das Meldermaterial angreifende Stoffe gerade im Melderinneren gebildet werden. Da die Atmosphäre zwischen das Labyrinth und die Isolierstrecke eindringen kann, bleibt das Problem der Alterung der Isolationsstrecke bestehen.The problem of maintaining the electrical resistance was solved according to DE-AS 2'130'889 in that the insulation path inside the hood serving as the external electrode and having openings for the entry of the surrounding air was covered by a labyrinth made of the same highly insulating plastic. As a result, the creepage distance between the center electrode and the counter electrode was protected from soiling, and the creeping path exposed to soiling was lengthened by more than four times due to the annular ridges of the labyrinth. It was thus possible to extend the period of time until the detector became ineffective, ie the service intervals could be increased. However, plastics are subject to natural aging, which can be accelerated by the influence of atmospheric oxygen (partly also ozone) or aggressive ingredients in the surrounding air and in the cleaning agents used in the detector revision. Such corrosive substances are present in extremely low concentrations in normal ambient air, but can take on considerable values in a special environment. Finally, the duration of exposure should not be neglected, nor the fact that the air is ionized by the radioactive source in the detector, which causes ozone and others, the detector material attacking substances are formed inside the detector. Since the atmosphere can penetrate between the labyrinth and the insulation section, the problem of aging of the insulation section remains.

Die Reinigung der Melder bei der Revision stellte auch bisher kein Problem dar, aber die wiederholte Reinigung unter Aufrechterhaltung der hohen Oberflächenisolationswerte von ca. ρQ 10 Q über längere Zeit war immer noch problematisch. Die Suche nach Materialien mit genügend hoher Widerstandsfähigkeit gegen Umwelteinflüsse (Lösungsmitteldämpfe, Insektizide) führte zu keinem befriedigenden Ergebnis, da es nicht möglich war, einen Kunststoff zu finden, der optimale Eigenschaften im Hinblick auf sämtliche Umwelteinflüsse besitzt.The cleaning of the detectors during the revision has not yet been a problem, but repeated cleaning while maintaining the high surface insulation values of approx. ΡQ 10 Q was still problematic. The search for materials with a sufficiently high resistance to environmental influences (solvent vapors, insecticides) did not lead to a satisfactory result, since it was not possible to find a plastic that had optimal properties with regard to all environmental influences.

Die Aufgabe der vorliegenden Erfindung besteht darin, einen Ionisationsfeuermelder der eingangs genannten Art zu schaffen, der die vorstehend erwähnten Nachteile nicht aufweist und bei dem insbesondere der Isolationswert des isolierenden Teils zwischen den Elektroden über einen längeren Zeitraum erhalten bleibt.The object of the present invention is to provide an ionization fire detector of the type mentioned at the outset which does not have the disadvantages mentioned above and in which in particular the insulation value of the insulating part between the electrodes is retained over a longer period of time.

Diese Aufgabe wird erfindungsgemäss dadurch gelöst, dass das isolierende Teil mindestens zwei aus unterschiedlichen isolierenden Materialien bestehende Bereiche aufweist, die so zwischen den Elektroden angeordnet sind, dass der Kriechweg zwischen diesen Elektroden über sämtliche dieser Bereiche führt.According to the invention, this object is achieved in that the insulating part has at least two regions consisting of different insulating materials, which are arranged between the electrodes in such a way that the creepage distance between these electrodes leads over all of these regions.

Gemäss einer bevorzugten Ausführungsform des erfindungsgemässen Ionisationsmelders weist das isolierende Teil drei aus unterschiedlichen isolierenden Materialien bestehende Bereiche auf.Besonders bevorzugt ist es, den ersten Bereich beispielsweise aus einem Polycarbonat, den zweiten Bereich beispielsweise aus einem Epoxidharz und den dritten Bereich beispielsweise aus einem Polyester herzustellen. G emäss a preferred embodiment of the inventive Ionisationsmelders, the insulating part consisting of three different insulating materials ranges auf.Besonders preferably, the first region for example, is a polycarbonate, the second area, for example, from an epoxy resin and the third area, for example, from a polyester.

Bei einer Ausgestaltung des erfindungsgemässen Ionisationsfeuermelders ist die eine Elektrode als Mittelelektrode ausgebildet, und die andere Elektrode besteht aus einer Oeffnungen zum Eintritt der umgebenden Luft aufweisenden Haube, welche die Begrenzung der der Aussenatmosphäre zugänglichen Ionisationskammer gegen die Aussenatmosphäre bildet. Die aus unterschiedlichen Materialien bestehenden Bereiche sind dabei um die Mittelektrode herum angeordnet und zwar vorzugsweise praktisch konzentrisch.In one configuration of the ionization fire detector according to the invention, one electrode is designed as a central electrode, and the other electrode consists of an opening for the entry of the surrounding air, which forms the boundary of the ionization chamber that is accessible to the outside atmosphere from the outside atmosphere. The areas consisting of different materials are arranged around the center electrode, preferably practically concentrically.

Im folgenden werden anhand der Figur 1 ein Ionisationsfeuermelder des Standes der Technik und anhand der Figur 2 eine beispielsweise gewählte Ausführungsform eines erfindungsgemässen Ionisationsfeuermelders beschrieben. Es zeigen

  • Fig. 1 einen Ionisationsfeuermelder nach dem Stand der Technik im Schnitt
  • Fig. 2 einen IonisationsfeuermeldPr nach der Erfindung im Schnitt.
An ionization fire detector of the prior art is described below with reference to FIG. 1, and an embodiment of an ionization fire detector according to the invention, selected by way of example, is described with reference to FIG. Show it
  • Fig. 1 shows an ionization fire detector according to the prior art in section
  • Fig. 2 shows an ionization fire alarm P r according to the invention in section.

Der in Figur 1 dargestellte Melder besteht aus einer metallischen Haube 1, welche Oeffnungen 2 und 3 zum Eintritt der umgebenden Luft aufweist. Im Inneren der Haube 1 ist ein Labyrinth 4 aus hochisolierendem Kunststoff angeordnet, welches im Inneren eine Anzahl kreisringförmig angeordneter Stege 5 zur Verlängerung der Kriechwege aufweist. In der Mitte des Labyrinths 4 befindet sich die stempelförmige Mittelelektrode 6. Die Aussenelektrode wird von der metallischen Haube 1 gebildet. Die beiden Elektroden sind durch nichtdargestellte Verbindungsmittel - zum Teil lösbar - mit einem isolierenden Teil 7 verbunden. Das isolierende Teil 7 und das Labyrinth 4 sind aus dem gleichen Kunststoff, vorzugsweise Polycarbonat, z.B. Makrolon, hergestellt.The detector shown in Figure 1 consists of a metallic hood 1, which has openings 2 and 3 for the entry of the surrounding air. A labyrinth 4 made of highly insulating plastic is arranged in the interior of the hood 1 and has a number of webs 5 arranged in the form of a ring to extend the creepage distances. The stamp-shaped central electrode 6 is located in the middle of the labyrinth 4. The outer electrode is formed by the metallic hood 1. The two electrodes are partially detachable by means of an isolating means, which are not shown Part 7 connected. The insulating part 7 and the labyrinth 4 are made of the same plastic, preferably polycarbonate, for example Makrolon.

In Figur 2 ist eine Ausführungsform eines erfindungsgemässen Ionisationsfeuermelders im Schnitt dargestellt. Der Ionisationsfeuermelder besteht ebenfalls aus einer metallischen Haube 1, welche Oeffnungen 3 zum Eintritt der umgebenden Luft aufweist. Die Gegenelektrode 6, die in der Mitte der der Aussenatmosphäre zugänglichen Ionisationskammer 11 angeordnet ist, befindet sich auf einer zentralen Erhöhung 8 des isolierenden Teils 7. Zwischen der Mittelelektrode 6 und der die andere Elektrode bildenden metallischen Haube 1 ist das isolierende Teil in einen ersten Bereich 8 aus einem Polycarbonat, einen zweiten Bereich 9, welcher aus einem Epoxidharz besteht und einen dritten Bereich 10, welcher aus einem Polyester besteht, unterteilt.FIG. 2 shows an embodiment of an ionization fire detector according to the invention in section. The ionization fire detector also consists of a metallic hood 1, which has openings 3 for the entry of the surrounding air. The counterelectrode 6, which is arranged in the middle of the ionization chamber 11 accessible to the outside atmosphere, is located on a central elevation 8 of the insulating part 7. Between the center electrode 6 and the metallic hood 1 forming the other electrode, the insulating part is in a first region 8 made of a polycarbonate, a second area 9, which consists of an epoxy resin and a third area 10, which consists of a polyester, divided.

Durch diese Anordnung wird erreicht, dass ein Kriechstrom, der sich zwischen der Mittelelektrode 6 und der die Aussenelektrode bildenden metallischen Haube 1 ausbildet, über drei Isolierstrecken aus unterschiedlichem Kunststoffmaterial führt. Als Material für den ersten Bereich 8 kommen thermoplastische Polyester, d.h. Polykondensationsprodukte der Kohlensäure mit Diolen, in Frage. Diese Polycarbonate sind beständig gegen Wasser, Neutralsalzlösungen, Mineralsäuren, beispielsweise auch gegen Flussäure, wässrige Lösungen von Oxidationsmitteln, Kohlenwasserstoffe, Oele, Fette usw. Insbesondere wird dieser Bereich der Isolationsstrecke aus Makrolon O hergestellt. Der zweite Bereich 9 wird vorzugsweise aus einem Duroplast aus Epoxiden mit Polyolen hergestellt. In diese aus Epoxidharz gebildete Vergussmasse können die elektronischen Bauteile des Ionisationsfeuermelders eingebettet werden. Die Epoxidharze sind widerstandsfähig gegen atmosphärische Einflüsse, gegen Wasser, Säuren, Laugen, Oel, Benzin, Benzol usw. Der dritte Bereich 10 wird vorzugsweise aus einem Polykondensationsprodukt von mehrwertigen Alkoholen (Diolen, Polyolen) mit mehrbasischen Carbonsäuren hergestellt. Diese Polyester sind gegen alle organischen Lösungsmittel beständig, sind jedoch gegen Wasser und Alkalien, sowie gegen Säuren oberhalb von 70°C, weniger beständig. Zur Verbesserung der Isolationsfähigkeit des isolierenden Teils 7 können ein oder mehrere der verschiedenen Bereich 8, 9, 10 mit ringförmigen Erhebungen zur Verlängerung des Kriechwegs ausgestattet werden, ohne dass dadurch das Verfahren zur Herstellung des isolierenden Teils wesentlich komplizierter wird.This arrangement ensures that a leakage current which forms between the center electrode 6 and the metallic hood 1 forming the outer electrode leads over three insulating sections made of different plastic material. Thermoplastic polyesters, ie polycondensation products of carbonic acid with diols, are suitable as the material for the first region 8. These polycarbonates are resistant to water, neutral salt solutions, mineral acids, for example also to hydrofluoric acid, aqueous solutions of oxidizing agents, hydrocarbons, oils, fats etc. In particular, this area of the insulation section is made from Makrolon O. The second area 9 is preferably made of a thermoset made of epoxies with polyols. The electronic components of the ionization fire detector can be embedded in this potting compound made of epoxy resin will. The epoxy resins are resistant to atmospheric influences, water, acids, alkalis, oil, petrol, benzene, etc. The third region 10 is preferably produced from a polycondensation product of polyhydric alcohols (diols, polyols) with polybasic carboxylic acids. These polyesters are resistant to all organic solvents, but are less resistant to water and alkalis, as well as to acids above 70 ° C. In order to improve the insulating ability of the insulating part 7, one or more of the different regions 8, 9, 10 can be equipped with ring-shaped elevations for extending the creepage distance, without the process for producing the insulating part becoming significantly more complicated.

Ein wesentlicher Vorteil des erfindungsgemässen Ionisationsfeuermelders besteht darin, dass die Isolationsfähigkeit des isolierenden Teils 7 über wesentlich längere Zeiträume erhalten bleibt als bei den bekannten Ionisationsfeuermeldern. Wird nämlich der Oberflächenwiderstand eines der das isolierende Teil 7 bildenden Kunststoffe durch die Einwirkung agressiver Ingredienzien aus der Atmosphäre oder durch wenn auch noch so geringe Schädigung durch die Reinigungs- oder Trocknungsmittel veringert, so bleibt aufgrund der unterschiedlichen chemischen Zusammensetzung der einzelnen Bereiche immer noch die Isolationsfähigkeit mindestens eines der anderen Bereiche erhalten. Es wird zwar bei der Ausarbeitung der technologischen Verfahrensvorschriften für das Reinigen von Kunststoffteilen weitgehend auf die chemische Beschaffenheit der Kunststoffteile Rücksicht genommen. Da jedoch die Zusammensetzung des auf der Isolationsstrecke abgeschiedenen Staubs nicht bekannt ist, muss häufig mit sehr aktiven Reinigungsmitteln, z.B. Lösungen von RBS, gearbeitet werden. Um eine rationelle Melderrevision zu ermöglichen, müssen die Melderteile im Anschluss an die Reinigung getrocknet werden, wobei Wasserverdrängungsmittel, wie Isopropylalkohol oder Freon, angewendet werden. Die Aufrechterhaltung der Oberflächenbeschaffenheit der Kunststoffteile kann daher auf die Dauer nicht garantiert werden. Werden jedoch die einzelnen Bereiche des isolierenden Teils 7 aus Kunststoffen unterschiedlicher chemischer Widerstandsfähigkeit hergestellt, so ist die Gefahr, dass die Isolationsfähigkeit des gesamten isolierenden Teils 7 unter eine noch akzeptable Grenze sinkt, erheblich geringer als bei den bekannten Ionisationsfeuermeldern.An essential advantage of the ionization fire detector according to the invention is that the insulating ability of the insulating part 7 is maintained over substantially longer periods of time than in the known ionization fire detectors. If the surface resistance of one of the plastics forming the insulating part 7 is reduced due to the action of aggressive ingredients from the atmosphere or due to the slightest damage caused by the cleaning or drying agents, the insulating ability remains due to the different chemical composition of the individual areas received at least one of the other areas. When developing the technological procedural rules for cleaning plastic parts, the chemical nature of the plastic parts is largely taken into account. However, since the composition of the dust deposited on the insulation section is not known, it is often necessary to work with very active cleaning agents, for example solutions from RBS. In order to enable efficient detector revision, the detector parts must be dried after cleaning, using water displacement agents, such as isopropyl alcohol or freon. The maintenance of the surface quality of the plastic parts can therefore not be guaranteed in the long run. However, if the individual areas of the insulating part 7 are made of plastics of different chemical resistance, the risk that the insulating ability of the entire insulating part 7 will drop below an acceptable limit is considerably lower than in the known ionization fire detectors.

Selbstverständlich ist es möglich, anstelle der vorstehend genannten Kunststoffe andere Kunststoffe einzusetzen, wenn darauf geachtet wird, dass die Resistenz gegen äussere Einwirkungen bei den verwendeten Kunststoffen möglichst unterschiedlich ist. Der Erfindungsgedanke, nämlich Isolationsstrecken dadurch widerstandsfähiger zu machen, dass sie in Bereiche unterschiedlicher chemischer Zusammensetzung aufgeteilt werden, ist vorstehend für Ionisationsbrandmelder beschrieben. Aber auch die Isolationsstrecken anderer Brandmelder, bei denen es auf einen hohen Eingangswiderstand einer Verstärkungsstufe ankommt, können dadurch erheblich verbessert werden, dass man bei der Herstellung der Isolationsstrecken Bereiche unterschiedlicher Kunststoffe in Serie anordnet.Of course, it is possible to use other plastics instead of the plastics mentioned above, if care is taken to ensure that the resistance to external influences is as different as possible in the plastics used. The idea of the invention, namely to make insulation sections more resistant by dividing them into areas of different chemical compositions, has been described above for ionization fire detectors. But also the insulation distances of other fire detectors, where a high input resistance of a gain stage is important, can be considerably improved by arranging areas of different plastics in series during the production of the insulation distances.

Claims (4)

1. Ionisationsfeuermelder mit einer ein radioaktives Präparat enthaltenden und zwei durch ein isolierendes Teil (7) getrennte Elektroden (1, 6) aufweisenden, der Aussenatmosphäre zugänglichen Ionisationskammer und einer elektrischen Schaltung zur Signal- und Alarmgabe, dadurch gekennzeichnet, dass das isolierende Teil (7) mindestens zwei aus unterschiedlichen isolierenden Materialien bestehende Bereiche (8, 9, 10) aufweist, die so zwischen den Elektroden (1, 6) angeordnet sind, dass der Kriechweg zwischen diesen Elektroden über sämtliche dieser Bereiche (8, 9, 10) führt.1. Ionization fire alarm with an ionization chamber containing a radioactive preparation and two electrodes (1, 6) separated by an insulating part (7), which is accessible to the outside atmosphere and an electrical circuit for signaling and alarming, characterized in that the insulating part (7 ) has at least two areas (8, 9, 10) made of different insulating materials, which are arranged between the electrodes (1, 6) in such a way that the creepage distance between these electrodes leads over all of these areas (8, 9, 10). 2. Ionisationsmelder gemäss Patentanspruch 1, dadurch gekennzeichnet, dass das isolierende Teil (7) drei aus unterschiedlichen isolierenden Materialien bestehende Bereiche (8, 9, 10) aufweist.2. Ionization detector according to claim 1, characterized in that the insulating part (7) has three areas consisting of different insulating materials (8, 9, 10). 3. Ionisationsmelder gemäss Patentanspruch 2, dadurch gekennzeichnet, dass der erste Bereich (8) aus einem Polycarbonat, der zweite Bereich (9) aus einem Epoxidharz und der dritte Bereich (10) aus einem Polyester besteht.3. Ionization detector according to claim 2, characterized in that the first region (8) consists of a polycarbonate, the second region (9) consists of an epoxy resin and the third region (10) consists of a polyester. 4. Ionisationsmelder gemäss einem der Patentansprüche 1 bis 3, dadurch gekennzeichnet, dass die eine Elektrode (6) als Mittelelektrode ausgebildet ist und die andere Elektrode (1) aus einer Oeffnungen (3) zum Eintritt der umgebenden Luft aufweisenden Haube besteht, welche die Begrenzung der der Aussenatmosphäre zugänglichen Ionisationskammer (11) gegen die Aussenatmosphäre bildet und dass die aus unterschiedlichen isolierenden Materialien bestehenden Bereiche (8, 9, 10), vorzugsweise praktisch konzentrisch, um die Mittelektrode (6) herum angeordnet sind.4. Ionization detector according to one of claims 1 to 3, characterized in that one electrode (6) is designed as a central electrode and the other electrode (1) consists of an opening (3) for the entry of the surrounding air hood, which has the limitation which forms the ionization chamber (11) accessible to the outside atmosphere against the outside atmosphere and that the areas (8, 9, 10) made of different insulating materials are arranged, preferably practically concentrically, around the center electrode (6).
EP83103225A 1982-04-08 1983-03-31 Ionisation fire detector Expired EP0091623B1 (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
AT83103225T ATE17409T1 (en) 1982-04-08 1983-03-31 IONIZATION FIRE DETECTOR.

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
CH218482 1982-04-08
CH2184/82 1982-04-08

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EP0091623A1 true EP0091623A1 (en) 1983-10-19
EP0091623B1 EP0091623B1 (en) 1986-01-08

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EP83103225A Expired EP0091623B1 (en) 1982-04-08 1983-03-31 Ionisation fire detector

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US (1) US4582996A (en)
EP (1) EP0091623B1 (en)
JP (1) JPS58186896A (en)
AT (1) ATE17409T1 (en)
AU (1) AU554415B2 (en)
BR (1) BR8301799A (en)
CA (1) CA1217284A (en)
DE (1) DE3361760D1 (en)
ES (1) ES8404079A1 (en)
NO (1) NO831246L (en)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5298223A (en) * 1990-09-05 1994-03-29 Esser Sicherheitstechnik Gmbh Ionization fire detector

Families Citing this family (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS6044194U (en) * 1983-09-05 1985-03-28 能美防災工業株式会社 Heat-resistant case for ionization smoke detector
US5485144A (en) * 1993-05-07 1996-01-16 Pittway Corporation Compensated ionization sensor

Citations (3)

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Publication number Priority date Publication date Assignee Title
CH506148A (en) * 1969-02-28 1971-04-15 Mefina Sa Smoke detector device
CH508251A (en) * 1970-07-23 1971-05-31 Cerberus Ag Ionization fire alarms
US3676681A (en) * 1969-07-22 1972-07-11 Nittan Co Ltd Ionization smoke detector

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BE731052A (en) * 1969-04-04 1969-10-06 Acec PROCESSES FOR THE MANUFACTURING OF INSULATING LAMINATES
DE2143365B2 (en) * 1971-08-30 1977-09-08 Siemens AG, 1000 Berlin und 8000 München ARRANGEMENT FOR INSULATING ELECTRODES
JPS5823705B2 (en) * 1977-08-24 1983-05-17 株式会社東芝 radiation detector
JPS57135977A (en) * 1981-02-16 1982-08-21 Canon Kk Photoelectrical indicator

Patent Citations (3)

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Publication number Priority date Publication date Assignee Title
CH506148A (en) * 1969-02-28 1971-04-15 Mefina Sa Smoke detector device
US3676681A (en) * 1969-07-22 1972-07-11 Nittan Co Ltd Ionization smoke detector
CH508251A (en) * 1970-07-23 1971-05-31 Cerberus Ag Ionization fire alarms

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5298223A (en) * 1990-09-05 1994-03-29 Esser Sicherheitstechnik Gmbh Ionization fire detector

Also Published As

Publication number Publication date
AU554415B2 (en) 1986-08-21
EP0091623B1 (en) 1986-01-08
CA1217284A (en) 1987-01-27
ES521785A0 (en) 1984-04-01
BR8301799A (en) 1983-12-20
NO831246L (en) 1983-10-10
ES8404079A1 (en) 1984-04-01
US4582996A (en) 1986-04-15
DE3361760D1 (en) 1986-02-20
AU1295883A (en) 1983-10-13
JPS58186896A (en) 1983-10-31
ATE17409T1 (en) 1986-01-15

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