DE2011340C3 - Fire alarms with at least one measuring chamber - Google Patents

Description

Cu (NHASO ,, Ni (NH ") _r SO" Ag (NH,)., Cl or Fe (NH,) _e CU.

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3. Fire alarm according to claim 1, characterized in that the reactant is ethylenediamine or Dimethylandn is.

4. Fire alarm according to claim 1, characterized in that the reaction medium-releasing Substance releases ammonia under the action of catalysts or moisture.

5. Fire alarm according to claim 1, characterized in that the substance releasing the reactive agent is a metal amide or metal-cyanamide _{4 <J} .

6. Fire alarm according to claim 5, characterized in that the reactive agent-releasing Substance is calcium cyanamide or magnesium cyanamide.

7. Fire alarm according to claim 1, characterized in that the measuring chamber (1) has a light source (S) and at least one photocell (6) which are arranged so that the photocell (6) direct light from the light source (S ) _s "receives.

8. Fire alarm according to claim 1, characterized in that the measuring chamber (10) has a Light source (12) and at least one photocell (13) which are arranged so that the The photocell (13) does not receive any direct light from the light source (12), but only absorbs scattered light can, which is scattered on particles in the measuring chamber (10).

9. Fire alarm according to claim 1, characterized ge βο indicates that the measuring chamber is an ionization chamber (16) which has two electrodes (17, 19) and at least one radioactive preparation (20).

10. The detector according to claim 9, characterized overall e _s denotes that the reaction medium releasing substance (26) is in a porous carrier material (19).

11, fire alarm according to claim 1, characterized in that that in the vicinity of the reoktionsmittelabenden Substance (8, 15, 26) an electrical auxiliary heating for setting a desired Temperature is present.

45 The invention relates to a fire detector having at least one measuring chamber, to which the surrounding atmosphere by convection access has, and which is designed to emit an alarm signal via an electrical circuit when the combustion products in the form of fire aerosols or smoke to penetrate into the measuring chamber.

Fire alarms of the type mentioned have a McB-kamnicr. having openings through which the surrounding atmosphere, e.g. B. by convection into which Mcßkammcr can enter. The products of combustion resulting from a fire or fire. z. B. Rauchpartikcl or Brandaerosolc. may be in the Mcßkannner detected in various ways we ^r the.

A known optical fire alarm contains a light source which throws light onto a photocell. Through smoke particles: the illuminance and photo / .cllcnstrom are changed, the current is changed for example medium ·; a bridge circuit or a reference Sirahlengiinges without Lichi. attenuation / ur alarm gabc exploited.

Another known optical fire alarm makes use of the syndrome effect. Lamp and photocell are arranged so that no direct light falls on the photo cells. If smoke appears in the The measuring chamber receives the photocell scattered light and the photocell current is used to generate an alarm.

Well-known ionization fire alarms work according to a different principle, in which the measuring chamber has two live electrodes and one radioactive Contains radiation source. Flows between the electrodes a stream of ionized gas molecules or atoms. If the gas composition or the content changes on larger particles, such as aerosols or smoke, the ionization current also changes. This change in current is triggered by an amplifier and threshold value detector circuit used.

Instead of convection, the atmosphere can also contain combustion products through suction devices. z. B. be supplied via pipelines to the measuring chamber.

The known devices described are sufficient in most cases to prevent a fire from developing at an early stage Report to. A prerequisite, however, is that the combustion products are in the form of aerosols or Smoke present.

However, the increasing use of plastics has brought with it that with a fire low temperatures or in the case of pyrolytic decomposition as a preliminary stage of a fire, often only to a lesser extent A lot or no aerosols are produced, but a considerable amount of gaseous combustion products. which are difficult to detect with the fire alarms described.

Especially the use of halogen-containing plastics. / .. B. Polyvinyl chloride (PVC), leads to the appearance of gaseous halogen-hydrogen in a fire. /. B. Sahric acid vapor. which is very corrosive. Even small amounts can therefore be

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Meaningful .Schptlcn cause.

However, such Halogenwiisserstoffdimipfi- ¹ can only be poorly recorded by the described fire alarms. -So is /. B, in the case of ionization fire clusters, the sensitivity to proximity is low because the molecular weight of hydrogen chloride is only slightly greater than that of air molecules. Hydrochloric acid droplets only form in sufficient quantities if the air has a sufficiently high moisture content. Only in this case are ionization fire alarms sufficiently sensitive to hydrochloric acid vapors.

A method is known from German patent specification I 08b 460 to detect the presence of interfering gases in an atmosphere by adding a reagent to the atmosphere which forms a fine mist with the gas to be detected. Thus, for example, from German patent specification 133170 a device for detecting the presence of ammonia gases known to give a hydrochloric acid-containing container upstream is seen ^ao, flow out of which hydrochloric acid vapors, which with any existing ammonia gases / u visible Combine ammonium chloride mist. Because of the high vapor pressure and the rapid exhaustion of such a device is not ^a 5 operable for extended periods. An application in fire alarm technology was therefore not possible.

Further z. B. has become known under the name "Billion Aire trace gas analyzer" devices in which the atmosphere to be examined is sucked in 3 ", with ammonia being added to the gas stream, which is produced chemically or from an ammonia solution Any mist that arises is observed or detected in the usual way.These devices, e.g. leak detectors, however, usually only react specifically to a certain substance to be detected and can therefore only be used as warning devices when processing or detecting certain chemicals . in addition, they require a continuous operation of an air circulation system and the continuous generation and supply suitable gaseous reagents. These must * ⁵ be present for a good detection sensitivity always in excess, as they are consumed in the airflow to a considerable extent. Such devices are therefore hardly for suitable for continuous operation net.

A fire alarm, on the other hand, is required to be free of wear and tear over a long period of time works and also responds to all possible combustion products that may occur.

The invention is based on the object of providing a fire alarm of the type specified in the introduction create, which affects both combustion products in the form of fire aerosols or smoke and hydrogen halides responds and works for long periods without maintenance.

This object is achieved in that according to the invention, soft, the measuring chamber a solid or liquid sub- ^6p substance from the group of inorganic or organic amines, of ammoniates, heavy metal-amine complex salts containing or amides proposed gaseous ammonia over time which is adapted to form with halogen-hydrogen ^e 5 vapors condensation products in the form of aerosols wherein the substance at 20 ° C an ammonia vapor dirt exceeding 100 Torr.

There is a special characteristic of these substances. that their Piimpfe either green! ues pure tial pressure in the temperature range from -25 to + 100 "C, or the detection sensitivity due to their chemical nature not noticeable of Bninda aerosols influence.

In order to maintain the gas discharge for as long as possible and in order not to cause disruptive nuisance to the environment, it is particularly useful to have a To choose a substance which has a Rcaktionsmiiteldampf-partial pressure below 100 Torr at room temperature.

Exemplary embodiments of the invention are explained with reference to the figures. It shows

F i g. I a fire alarm that works with light absorption,

F i g. 2 a fire alarm working with scattered light,

F i g. 3 -jnien ionization fire alarms.

The in F i g. 1 shown optical fire alarm consists from a measuring chamber 1, in the wall 2 of which there are openings 3, which allow access to the outside air allow inside the measuring chamber 1. The fall of direct light is prevented by front panels 4. % i of measuring chamber I is a lamp

5 and a photocell 6. Lamp 5 and photocell 6 are arranged so that direct light from the lamp 5 hits the photocell 6. Now smoke enters the measuring chamber I a. so part of the light is absorbed by the smoke, and the illuminance on the photocell

6 and thus the photocell current change. The photocell current is via lines 7 by means of a electrical circuit (not shown) evaluated and, if necessary, d. h .. when the light absorption in the measuring chamber 1 has reached a certain level. used for Alnrmgabe. In addition, is in the measuring chamber 1 a substance 8 attached, which has the property. Slow reaction agent vapor over time submit. Contains the air entering through the openings 3 by natural convection now traces of a halogen-hydrogen, e.g. B. of hydrochloric acid gas, it forms when you pass by of substance 8 is a fine aerosol mist, which registers in the same way as smoke from the fire alarm will. The described fire alarm responds as sensitive to smoke as it normally does when it is burned, as well as the hydrochloric acid vapors produced when PVC is burned.

Of course, all known embodiments of optical fire alarms, which with Light absorption work, with such additional ammonia! .Releasing Substances are provided. All known photoelectric elements can also be used such as photo cells, photo resistors, solar cells, etc. to be used. As electrical circuits all known circuits for alarm systems can also be used.

In Fig. 2 is an optical one that makes use of the Tyndalle effect fire alarm shown. The wall 9 of the measuring chamber 10 in turn has openings 11, which allow air access .. The openings 11 are covered by wall parts so that no direct Entry of light from outside is possible. Lamp 12 and photocell 13 are arranged here so that no direct Light from lamp 12 falls on photocell 13. The photo cell 13 is thus de-energized in the idle state. Kick Smoke into the MesskajnrnerilO, then part of the

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from the lamp 12 emitted light on the photocellc H scattered, and it isl to observe a photocell current over the lines 14, which from a electrical circuit can be used to generate an alarm. In an Exkc of the measuring chamber IO isl again a reaction agent-releasing substance 15 attached, which looks through openings in the wall with the interior of the measuring chamber 10 in connection. In the Measuring chamber 10 is thus a certain partial pressure from Rcaktionsmilleln. Contains those in the measuring chamber 10 incoming air traces of halogen-hydrogen, then again a floating-off fog forms, which, in the same way as smoke, gives rise to scattered light and thus to a photocell current. Here too Of course, the construction of the fire alarm and the attachment of the reactive substance-emitting substance can be used in the measuring chamber can be selected as desired and appropriately.

F i g. 3 shows an ionization fire alarm, the measuring chamber 16 of which is surrounded by an outer electrode 17. which has many small openings 18, which allow the entry of the outside air. In the interior of the measuring chamber 16 there is a slam-shaped inner tube 19 which carries a radioactive preparation 20. The partition wall 21 names the measuring chamber 16 from ^{a5 of} a second ionization chamber 22, which is connected in series with the measuring chamber 16 as a reference chamber. With a hood 23 serving as an external electrode, this reference chamber 22 is almost closed off from the outside air, so that smoke particles cannot penetrate into the room 22, but pressure compensation is possible. The same stamp 19 as in the measuring chamber 16 serves as the inner electrode of the reference chamber 22. It carries a further radioactive preparation 24 on the reference chamber side . Again in the measuring chamber 16 a reacionminelabgcbcnde substance 26 is attached, namely in the interior of the stamp 19 so that it is in communication with the interior of the measuring chamber 16 through openings in the stamp wall and is able to do so. to maintain a certain reaction medium parial pressure in the measuring chamber 16. B. on the Abschlussplattc 21 or preferably in the vicinity of the openings for the gas inlet. be attached. Furthermore, it is not necessary for the radioactive substances 20 or 24 to be on the common electrode 19. You can just as easily at another point of the Meßkammcr 16. z. B. be applied to the plate 21, instead the ammonia-releasing substance can then come to the Si part of the preparation 20 on the punch 19 of the Innenclcktrode of the measuring chamber 16.

The ionization fire alarm described has, in the same way as the optical alarm described, the Property that it reacts to both smoke and halogen-hydrogen appeals to the atmosphere. Since he also has brandacrosole. which no more than smoke visible and therefore no longer perceptible with optical detectors are registered, an ionization fire detector provides of the type described is a particularly suitable embodiment of the invention. It is also on which are in the reaction: Reagent + Ialogen-Wasscrstolf = Particularly sensitive to aerosol-forming reactive aerosols.

55 When selecting the substance that releases the reaction agent, it is important to ensure that the Vapor pressure at room temperature is high enough. in order to see the first traces of salt steam as early as possible. which was caused by a PVC fire. On the other hand, the In turn, the vapor pressure should not be so high that the environment is nuisance.

Substances have therefore proven to be particularly useful which are at one temperature of 20 C "a Keaklionsmitiel steam pressure of be 100 torr or less.

In addition, the reaction mixture must not be noticeable Influence on the normal Brandacrosol Enipfind · have the fire alarm wedge. For the optical alarm, this means that the reaction medium is optical must be neutral. d. H. dissolves like air.

With lonisalionsfeuermck the movable wedge must be used Tier ions of the reaction agent in the electric field of the ionization chamber are of the same order of magnitude as that of the l.uflions. For larger deviations compared to the mobility of air ions, this must be achieved by a lower partial pressure of the reactant be compensated.

For example, the reagent can be ammonia gas, which is obtained from an aqueous ammonia solution is generated by their normal ammonia vapor pressure. But this is already at room temperature very considerable. An ionization chamber, in which there is aqueous ammonia solution, is thus be predominantly filled with ammonia gas, and their sirom tension charakic risk differs very strongly from the one only filled with air. what the Kauchacrosol detection sensitivity severely impaired. Aqueous ammonia solutions are therefore unsuitable.

You can get very good results if you choose a substance that has ammonia gas only in relative releases small amounts into the environment. There are two ways of doing this. Once the substance can Comply with ammonia and have a certain ammonia vapor pressure. Such substances are for example inorganic heavy metal complex salts. Well-known representatives of this class are copper tetramine sulfate Cu (NHi) jSOi. Nickel hexamir sulfate Ni (NHiKSOj Silver diamine chloride Ag (NHj) -Cl. Iron hexainir chloride Fe (NHiJhCI: etc. Salts of nickel and copper in particular are very suitable.

Ammonia gas can also be generated from certain substances in a chemical reaction, whereby low humidity or catalytically controllable decomposition takes place. This is how, for example, from calcium cyanamide or the corresponding magnesium salt through small amounts of water vapor in a chemical reaction slowly over them small amounts of ammonia gas. Especially magncsium cyanamide is well suited for the procedure described.

A completely different group of substances are those that can be chemically derived from ammonia but do not give off any ammonia by themselves. So it is known that organic nitrogen compounds are more or less basic, depending on their chemical constitution Have properties and are able to form salts with hydrogen halide. Such connections too when they set up a certain vapor pressure in the air space, with hydrogen halides in a chemical reaction aerosols, which increase the detection sensitivity of water halides to lead.

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Very suitable Suhsimi / cii are (erniirc organic Amine oiler for example Aih> lciidimnin or yours ι h \ L) IHMi.

lsi die Siibstiiii / at R; iiimlemper; iUir or the / u er-Miülcndcn m; i \ im; ilcn lictnebstempeniliir llüssig. is it / awake. them in porous trays in eggs, always vin / iibcllen.

To use an egg crimper under extreme

Temperature-related conditions or, in the case of cold, tenipeiilur swings kiiiin / ur minification of the ammonia diimplilriickcs a useful electrical heating of the iimmoniiikiibenden Substiin / should be provided. Line such a direction can make me / ur lünstelliing one certain desired fidelity for illogical know-how serve under special conditions.

For this purpose I sheet drawings

Claims (2)

2 Oil claims: 1. Fire alarm with at least one measuring chamber, to which the surrounding atmosphere has access by convection, and -'eiche is set up to emit an alarm signal via an electrical circuit when combustion products in the form of fire aerosols or smoke penetrate the measuring chamber, characterized in that the measuring chamber (1, 10, 16) contains a solid or liquid substance (8, 15, 26) from the group of inorganic or organic amines, ammoniacates, heavy metal amine complex salts or amides, which over time contain gaseous ammonia release, which is suitable to form condensation products in the form of aerosols with halogen-hydrogen vapors, the sub- ao punch at 20 ⁰ C has an ammonia vapor pressure of at most 100 Torr 2. Fire alarm according to claim 1, characterized in that the heavy metal-amine complex salt one of the following compositions »5 Has: