PS detector Smoke photovotta radioisotope light. Types of fire detectors. Linear smoke detectors
Description
In ionization flue detectors, 1151E uses isotope americium-241, the radiation of which ionizes air molecules in the sensitive chamber. Under the action of the electric field, the resulting positive and negative ions create a current, the value of which is constantly monitored. Upon admission to a sensitive smoke chamber, a current decreases due to the combining of part of the ions on the surface of smoke particles. When the current is reduced to the threshold, the detector is activated.
The "fire" mode is preserved and after scattering smoke. Return to the duty mode is made short-term outage voltage. The specialized chip provides repeatability of the parameters in the production and stability of the detector during the entire service life. The ionization source of isotope americium-241 is in a hermetically case, and its activity is so low that does not increase the level of natural background and is not fixed by household dosimeters. Used in 1151eis detectors ionization sources are exempt from radiation accounting and control.
For visual indication of the detector status, two red LEDs are installed, providing an indication of a detector mode with an angle of view of 360 °. It is possible to incorporate the remote optical alarm (BR). The Bord LED connects to the first contact of the base, through a resistor 100 ohms. Due to the used circuitry solutions, the detectors 1151e remain completely operational in the event of non-compliance with the polarity of the connection, it ceases to function only the output optical indicator. The ability to connect detectors to different base bases is expanding the list of compatible PCP and makes the application of 1151E detectors more flexible. In addition, specifically for the PCP with a four-wire inclusion scheme, System Sensor has developed M412RL, M412NL modules, M424RL, to the outputs of which can be connected to conventional two-wire loops with 40 detectors 2151E with B401 bases. M412RL modules, M412NL are calculated on the nominal voltage of 12 volts, the M424RL module is on the nominal 24 volt voltage.
Easy signal testing is provided - by exposure to the magnet field, the detector is translated into the "Fire" mode. In addition, when connecting to an external detector of the MOD400R module manufactured by System Sensor, it is possible without disconnecting and disassembly to control the level of its sensitivity and the need for maintenance during operation. The XP-4 device with XP-4 bars allows you to install, remove and test 1151e detectors at an altitude of up to 6 meters without using stairs.
Detector 1151E is installed in the base bases B401, B401R, B401RM, B401RU, B412NL, B412RL, B424RL. All types of databases allow you to protect the detectors 1151e from unauthorized extraction and ensure reliable mounting in the conditions of transport shaking when installed on moving objects. After activating the protection function, the detector can be removed only using the instrument in accordance with the instructions.
To protect the flue chambers of dust, the detectors 1151e are supplied with plastic technological covers on them yellow color. When commissioning the fire alarm, these covers must be removed from the detectors.
Technical characteristics of the detector 1151
| Average area controlled by one detector | up to 110 m 2 |
| Noise immunity (on NPB 57-97) | 2 The degree of rigidity |
| Seismic resistance | up to 8 points |
| Work voltage | from 8.5 V to 35 V |
| Current in standby mode | less than 30 μA |
| Maximum allowable current in "Fire" mode | 100 mA |
| Duration of power supply sufficient sufficient to reset the "Fire" mode | 0.3 seconds, min. |
| Activity of the ionization source american-241 | less than 0.5 microcures |
| Basome height B401 | 43 mm |
| Diameter | 102 mm |
| Basome weight B401 | 108 gr. |
| Operating temperature range | -10 ° C + 60 ° C |
| Permissible relative humidity | up to 95% |
| Degree of protection of the detector shell | IP43. |
Examples of selecting databases for connecting detectors 1151E to various types PKP
Bases B401 without a resistor are used when connected to the PCP with a short-circuit current of the loop of less than 100 mA.
Bases B401R, B401RM with a current reduction resistor are used when connecting to the PCP with signal formation. Attention, fire or with a short circuit current of the loop of more than 100 mA.
The B401RU bases are used when connected to the PCP with a sign-changed voltage in the loop.
Bases B412NL, B412RL, B424RL are used when connected to the PCP on a 4-wired circuit, with separate signaling circuits and power. Relay module type A77-716.
Description
In ionization flue detectors, 1151E uses isotope americium-241, the radiation of which ionizes air molecules in the sensitive chamber. Under the action of the electric field, the resulting positive and negative ions create a current, the value of which is constantly monitored. Upon admission to a sensitive smoke chamber, a current decreases due to the combining of part of the ions on the surface of smoke particles. When the current is reduced to the threshold, the detector is activated.
The "fire" mode is preserved and after scattering smoke. Return to the duty mode is made short-term outage voltage. The specialized chip provides repeatability of the parameters in the production and stability of the detector during the entire service life. The ionization source of isotope americium-241 is in a hermetically case, and its activity is so low that does not increase the level of natural background and is not fixed by household dosimeters. Used in 1151eis detectors ionization sources are exempt from radiation accounting and control.
For visual indication of the detector status, two red LEDs are installed, providing an indication of a detector mode with an angle of view of 360 °. It is possible to incorporate the remote optical alarm (BR). The Bord LED connects to the first contact of the base, through a resistor 100 ohms. Due to the used circuitry solutions, the detectors 1151e remain completely operational in the event of non-compliance with the polarity of the connection, it ceases to function only the output optical indicator. The ability to connect detectors to different base bases is expanding the list of compatible PCP and makes the application of 1151E detectors more flexible. In addition, specifically for the PCP with a four-wire inclusion scheme, System Sensor has developed M412RL, M412NL modules, M424RL, to the outputs of which can be connected to conventional two-wire loops with 40 detectors 2151E with B401 bases. M412RL modules, M412NL are calculated on the nominal voltage of 12 volts, the M424RL module is on the nominal 24 volt voltage.
Easy signal testing is provided - by exposure to the magnet field, the detector is translated into the "Fire" mode. In addition, when connecting to an external detector of the MOD400R module manufactured by System Sensor, it is possible without disconnecting and disassembly to control the level of its sensitivity and the need for maintenance during operation. The XP-4 device with XP-4 bars allows you to install, remove and test 1151e detectors at an altitude of up to 6 meters without using stairs.
Detector 1151E is installed in the base bases B401, B401R, B401RM, B401RU, B412NL, B412RL, B424RL. All types of databases allow you to protect the detectors 1151e from unauthorized extraction and ensure reliable mounting in the conditions of transport shaking when installed on moving objects. After activating the protection function, the detector can be removed only using the instrument in accordance with the instructions.
To protect smoke cameras from dust, the detectors 1151e are supplied with plastic technological covers of yellow. When commissioning the fire alarm, these covers must be removed from the detectors.
Technical characteristics of the detector 1151
| Average area controlled by one detector | up to 110 m 2 |
| Noise immunity (on NPB 57-97) | 2 The degree of rigidity |
| Seismic resistance | up to 8 points |
| Work voltage | from 8.5 V to 35 V |
| Current in standby mode | less than 30 μA |
| Maximum allowable current in "Fire" mode | 100 mA |
| Duration of power supply sufficient sufficient to reset the "Fire" mode | 0.3 seconds, min. |
| Activity of the ionization source american-241 | less than 0.5 microcures |
| Basome height B401 | 43 mm |
| Diameter | 102 mm |
| Basome weight B401 | 108 gr. |
| Operating temperature range | -10 ° C + 60 ° C |
| Permissible relative humidity | up to 95% |
| Degree of protection of the detector shell | IP43. |
Examples of selecting databases for connecting detectors 1151E to various types of PCP
Bases B401 without a resistor are used when connected to the PCP with a short-circuit current of the loop of less than 100 mA.
Bases B401R, B401RM with a current reduction resistor are used when connecting to the PCP with signal formation. Attention, fire or with a short circuit current of the loop of more than 100 mA.
The B401RU bases are used when connected to the PCP with a sign-changed voltage in the loop.
Bases B412NL, B412RL, B424RL are used when connected to the PCP on a 4-wired circuit, with separate signaling circuits and power. Relay module type A77-716.
Fire detector - A device for generating a fire signal. Using the term "sensor" is incorrect, since the sensor is part of the detector. Despite this, the term "sensor" is used in many sectoral standards, in the meaning "detector".
Legend
The conditional designation of fire detectors should consist of the following elements: IP x1x2x3-x4-x5.
The abbreviation of IP defines the name "Fire detector". Element X1 - denotes a controlled sign of a fire; Instead of x1, one of the following digital designations are given:
1 - thermal;
2 - smoke;
3 - flames;
4 - gas;
5 - manual;
6 ... 8 - reserve;
9 - under the control of other signs of fire.
Element x2x3 denotes the principle of action of pi; Instead of x2x3, one of the following digital designations are given:
01 - using the dependence of the electrical resistance of elements on temperature;
02 - with the use of thermo-emf;
03 - Using linear expansion;
04 - Using fuse or combustible inserts;
05 - using the dependence of magnetic induction on temperature;
06 - using Hall effect;
07 - using bulk expansion (liquid, gas);
08 - Using ferroelectrics;
09 - using the dependence of the modulus of elasticity from temperature;
10 - using resonant-acoustic temperature control methods;
11 - radioisotope;
12 - optical;
13 - electric induction;
14 - using the "memory memory" effect;
15 ... 28 - reserve;
29 - ultraviolet;
30 - infrared;
31 - thermobarometric;
32 - using materials that change optical conductivity depending on temperature;
33 - Aeroimion;
34 - thermoshumy;
35 - When using other principles of action.
The X4 element indicates the sequence number of the development of a detector of this type.
The element x5 denotes the detector class.
Classification for the possibility of re-inclusion
Automatic fire detectors depending on the possibility of their re-inclusion after triggering are divided into the following types:
- return detectors with the possibility of re-inclusion are detectors that can be back from the fire alarm status without replacing any nodes to return to the control state, unless the factors have disappeared that led to their response. They are divided into types:
- detectors with automatic re-inclusion - detectors that after the triggering are independently switched to the control state;
- detectors with remote re-inclusion - detectors that using the remotely submitted command can be translated into the control state;
- detectors with manual inclusion - detectors that with manual switching on the detector itself can be translated into the control state;
- detectors with interchangeable elements - detectors that, after the triggering, can be translated into the control state only by replacing some elements;
- detectors without the possibility of re-inclusion (without replaceable elements) - detectors that, after the operation, can no longer be translated into the control state.
Signal transmission classification
Automatic fire detectors by type of signal transmission divide:
- double-mode detectors with one output for the transmission of the signal as the absence and availability of signs of fire;
- multi-mode detectors with one output for transferring a limited number (more than two) types of signals about the state of rest, fire alarm or other possible states;
- analog detectors that are intended to transmit a signal to the value of the sign controlled by them a fire, or analog / digital signal, and which is not a direct fire alarm signal.
Application
Thermal fire detector design XIX century. It consists of two wires a and b that are connected by the CC with a material that does not conduct electricity. On the side of the device, the tube D is arranged with a capsule E filled with mercury and closed with a plate from wax. With increasing temperature, the wax melts, mercury is poured into the device and the contact between the two wires is installed, as a result of which the signal appears
It is used if a significant amount of heat is distinguished at the initial stages of the fire, for example, in warehouses of fuel and lubricants. Either in cases where the use of other detectors is impossible. Application in administrative and household premises is prohibited.
The field of the greatest temperature is located at a distance of 10 ... 23 cm from the ceiling. Therefore, it is precisely in this area that it is desirable to have a heat-sensitive element of the detector. The thermal detector located under the ceiling at an altitude of six meters above the firefight will work with a heat dissipation of a 420 kW fire.
Cotton
The detector reacting to fire factors in the compact zone.
Multipoint
Thermal multipoint detectors are automatic detectorsThe sensitive elements of which are the work of point sensors discretely located over the line. The step of their installation is determined by the requirements. regulatory documents and technical specifications specified in the technical documentation for a specific product.
Linear (thermocabel)
There are several types of linear thermal fire detectors, constructively different from each other:
- semiconductor - linear thermal fire detector, in which the coating of wires with a substance having a negative temperature coefficient is used as a temperature sensor. This type of thermocabel works only in a set with an electronic control unit. When exposed to temperature on any section of the thermocabel, resistance changes at the point of exposure. With the help of the control unit, you can set different thresholds of temperature response;
- mechanical - the quality of the sensor temperature of this detector uses a sealed metal tube filled with gas, as well as a pressure sensor connected to the electronic control unit. When exposed to a temperature on any section of the sensor tube, the internal pressure of the gas changes, the value of which is recorded by an electronic unit. This type of linear thermal fire detector reusable. The length of the working part of the metallic sensor tube has a limit to a length of up to 300 meters;
- electromechanical - linear thermal fire detector, in which the temperature sensor is used as a temperature sensor, applied to two mechanically stress wires ( twisted para), Under the influence of temperature, the heat-sensitive layer softens, and the two conductors are shorted.
Smoke detectors - detectors that react to combustion products capable of influencing the absorbing or dispersion capacity of radiation in infrared, ultraviolet or visible spectrum bands. Smoke detectors can be point, linear, aspiration and autonomous.
Application
The sign that the smoke detectors react - smoke. The most common type of detector. When protecting the fire alarm system of administrative and domestic premises, only smoke detectors should be used. The use of other types of detectors in administrative and household premises is prohibited. The number of detectors protecting the room depends on the size of the room, the type of detector, the presence of systems (fire extinguishing, smoke removal, equipment lock) which controls the fire alarm.
Up to 70% of fires occurs from thermal microchways developing in conditions with insufficient access to them oxygen. Such a development of the focus accompanied by the release of combustion products and flowing within a few hours is characteristic of cellulose-containing materials. To detect similar foci to the most efficiently registering combustion products in small concentrations. This allows you to do smoke or gas detectors.
Optical
Smoke detectors using optical detection tools react differently on smoke different colors. Currently, manufacturers provide limited information on the reaction of smoke detectors in specifications. Information on the detector reaction includes only the nominal values \u200b\u200bof the reaction (sensitivity) on the gray smoke, and not black. Often indicates the sensitivity range instead of the exact value.
Cotton
Worked the smoke fire detector (the red LED is continuously lit)
Smoke detectors at the time of repair in the room should be closed to avoid dust.
The spot detector reacts to fire factors in the compact zone. The principle of operation of point optical detectors is based on the scattering of infrared radiation with gray smoke. It is well reacting to the gray smoke that is released when the early stages of the fire. Poor reacts to the black smoke absorbing infrared radiation.
For periodic detector maintenance, a detachable connection is necessary, the so-called "socket" with four contacts to which the smoke detector is connected. To control the disconnection of the sensor from the loop, there are two negative contacts that closes when the detector is set to the outlet.
Chimney and electronics of a point chimney detector
In all point chimney optical fire detectors, IP 212-xx according to the classification of NPB 76-98, the effect of diffuse dispersion of the LED radiation on smoke particles is used. The LED is located in such a way as to exclude the direct hit of its radiation to the photodiode. With the appearance of smoke particles, part of the radiation is reflected from them and enters the photodiode. To protect against the outer light of the optocoupler - the LED and the photodiode, are placed in a black-colored chimney.
Experimental studies have shown that the detection time of a test focus of a fire when the smoke detectors are located at a distance of 0.3 m from the ceiling increases 2..5 times. And when installing a detector at a distance of 1 m from the overlap, you can predict an increase in the fire definition time already at 10..15 times.
When the first Soviet optical smoke detectors were developed, there was no specialized element base, standard LEDs and photodiodes. In the smoke photovoltaic detector of IDF-1M, the incandescent lamp of type SG24-1.2 and a FC-G1 photoresistor were used as the optocoupler. It determined low specifications Idf-1m detector and weak protection against external influences: the inertia of the operation at an optical density of 15-20% / m was 30 seconds, the supply voltage is 27 ± 0.5 V, the current consumption current is more than 50 mA, weight of 0.6 kg, background illumination to 500 LCs, air flow speed up to 6 m / s.
In the combined smoke-thermal detector Dip-1, a LED and photodiode were used, and located in the vertical plane. No continuous radiation was used, and pulse: Duration 30 μs, frequency of 300 Hz. To protect against interference, synchronous detection was applied, i.e. The inlet of the amplifier was opened only during the radiation of the LED. This provided a higher interference protection than in the detector IDF-1M and significantly improved the characteristics of the detector: inertia decreased to 5 seconds with an optical density of 10% / m, i.e. 2 times smaller, the mass decreased by 2 times, the allowable background illumination increased 20 times to 10,000 LCs, the permissible air flow rate increased to 10 m / s. In the "Fire" mode, the Red LED indicator turned on. To transmit alarm signal in DIP-1 detectors and IDF-1M, a relay was used, which determined significant consumption currents: more than 40 mA in standby mode and more than 80 mA in alarm, at a supply voltage of 24 ± 2.4 V and the need to use separate signal circuits and power circuits. The limit work on the failure of the dip-1 V is 1.31 · 104 hours.
Linear detectors
Linear - a two-component detector consisting of a receiver unit and a radiator block (or one block of the emitter and reflector receiver) responds to the appearance of smoke between the receiver unit and the emitter.
The device of linear flue fire detectors is based on the principle of weakening the electromagnetic flow between the radiation source separated in space and the photodetector under the influence of smoke particles. The device of this type consists of two blocks, one of which contains a source of optical radiation, and the other is a photodetector. Both blocks are placed on one geometric axis in the area of \u200b\u200bthe line of sight.
A feature of all linear flue detectors is the self-test function with the transmission of a "malfunction" signal receiving-control device. Because of this feature, one-time with other detectors is correct is the use of only in alternating loops. Turning on linear detectors In the alternate loops, it leads to the signal "Fault" signal "Fire" signal, which contradicts NPB 75. In the alpopulated loop, you can include only one linear detector.
One of the first Soviet line detectors was the name of the additional 1 and used as a light bulb of the incandescent Lamp of SG-24-1.2. A germanium photodiode was used as a photodetector. The detector consisted of a receiving-transmission unit serving for radiation and reception of the light beam, and a reflector installed perpendicular to the directional light beam at the desired distance. The nominal distance between the receiving-transmission unit and the reflector 2.5 ± 0.1 m.
The device of the photolum FEUP-M of Soviet production consisted of emitter and photodetector of the infrared beam.
Aspiration detectors
Aspiration detector uses forced selection of air from a protected volume with monitoring ultra-sensitive laser smoke detectors provides ultra-abnormal detection of a critical situation. Aspiration flue fire detectors allow you to protect objects in which it is impossible to directly place the fire detector.
The firefighter aspiration detector is applicable in the premises of archives, museums, warehouses, server, switching premises of electronic communication sites, control centers, "clean" production zones, hospital premises With high-tech diagnostic equipment, television centers and broadcasting stations, computer rooms and other premises with expensive equipment. That is, for the most important premises, where material values \u200b\u200bare stored or where the means embedded in the equipment are huge, or where is the damage to stopping the production or interruption of functioning, or a lot of missed benefit from the loss of information. At such objects, it is extremely important to reliably detect and eliminate the hearth at the earliest stage of development, during the decline stage - long before the appearance open fireOr in the event of overheating of individual components electronic device. At the same time, given that such zones are usually equipped with a temperature control system and humidity, air filtering is performed in them, it is possible to significantly increase the sensitivity of the fire detector, avoiding false positives.
Disadvantage aspiration detectors is their high cost.
Autonomous detectors
Autonomous - a fire detector reacting to a certain level of the concentration of aerosol products of combustion (pyrolysis) of substances and materials and, possibly, other fire factors, in which the autonomous power supply and all components needed to detect fire and direct alerts are constructively combined. The autonomous detector is also point.
Ionization detectors
The principle of operation of ionization detectors is based on the registration of changes in ionization current resulting from the impact on it combustion products. Ionization detectors are divided into radioisotope and electric induction.
Radioisotope detectors
The radioisotope detector is a smoke fire detector, which is triggered due to the impact of combustion products on the ionization current of the detector's internal working chamber. The principle of operation of the radioisotope detector is based on the ionization of the air of the chamber when irradiation with its radioactive substance. When introduced into such a chamber oppositely charged electrodes, ionization current occurs. The charged particles "stick" to heavier smoke particles, reducing their mobility - ionization current decreases. Its reduction to a certain value detector perceives as alarm signal. A similar detector is effective in the smokes of any nature. However, along with the advantages described above, radioisotope detectors have a significant disadvantage that should not be forgotten. We are talking On the use of radioactive radiation source detectors in the design. In this regard, there are problems of compliance with safety measures during operation, storage and transportation, as well as disposal of detectors after the expiration date. Effective for detecting fires, accompanied by the appearance of so-called "black" types of smoke characterized by high levels Absorption of light.
In Soviet radioisotope detectors (RID-1, KI), the source of ionization was the radioactive isotope of Plutonium-239. Detectors are included in the first group of potential radiation danger.
Radiisotope Smoke Detector Reed-1
The main element of the RID-1 radioisotope detector is two ionization chambers included in series. The connection point is connected to the tiratron control electrode. One of the chambers is open, the other is closed and performs the role of a compensating element. Air ionization in both chambers is created by plutonium isotope. Under the action of the applied voltage in the chambers flows ionization current. When smoke hit open Camera Its conductivity decreases, the voltage on both chambers is redistributed, resulting in a voltage on the control electrode of the thiratron. When the ignition stress is reached, the thiratron begins to carry out the current. An increase in current consumption leads to alarm trigger. Embedded radiation sources are not dangerous, as the radiation is completely absorbed in the volume of ionization chambers. Danger may occur only in disruption of the integrity of the radiation source. Also, the detector uses Tiratron TX11G with a slight amount of radioactive nickel, the radiation is absorbed by the volume of the thiratron and its walls. Danger may occur when breaking a thiratron.
The designated service life of radioactive sources of detectors was:
Reed-1; Ki-1; Di-1 - 6 years;
Reed-6; RID-6M and the like - 10 years.
RED-6M Radiisotope Fire Fire Fire Fire Fire Detector More than 15 years has been produced at the Signal Plant (Obninsk, Kaluga region) with a total release of up to 100 thousand hp. in year. The RID-6M detector has a limited appointed service life of AIP-REID-type alpha sources - 10 years from the date of their release. There is a technology for installing new AIP-RID alpha sources in fire detectors of past years of release, which allows to continue the exploitation of detectors for another 10 years, instead of their forced dismantling and burial.
High sensitivity allows the use of radioisotope detectors as an integral component of aspiration detectors. When pumping through the air detector of the protected premises, it can supply the signal when even an insignificant amount of smoke appears - from 0.1 mg / m³. In this case, the length of the tubes for air intake is practically not limited. For example, almost always registers the fact of ignition of the match head at the inlet of the air intake tube with a length of 100 m.
Electrical adduction detectors
The principle of operation of the detector: aerosol particles are sucked from the environment in a cylindrical tube (gas duct) with a small-sized electric pump And fall into the charging chamber. Here, under the influence of unipolar corona discharge, the particles acquire a bulk electric charge and, moving further on the gas duct, enter the measuring chamber, where the electrical signal, proportional to the volume charge of particles and, therefore, their concentrations are added to its measuring electrode. The signal from the measuring chamber enters the pre-amplifier and then to the processing unit and signal comparison. The sensor selection of a signal in speed, amplitude and duration and issues information when the specified thresholds are exceeded as a contact relay closure.
Electrophy-adduction detectors are used in fire alarm systems "Zarya" and "Pier" modules.
Flame detectors
The flame detector is a detector reacting to electromagnetic radiation Flame or glowing hearth.
Flame detectors apply as a rule to protect zones where necessary high efficiency Detection, since the detection of the fire flame detectors occurs in the initial phase of the fire, when the temperature in the room is still far from the values \u200b\u200bin which thermal fire detectors are triggered. Flame detectors provide the ability to protect zones with significant heat exchange and open areaswhere the use of thermal and smoke detectors is impossible. Flame detectors are applied to organize control of the presence of superheated surfaces of aggregates during accidents, for example, to detect a fire in the car, under the cover of the unit, control the presence of solid fragments of superheated fuel on the conveyor.
Gas detectors
The gas detector is a detector reacting to gases that are distinguished by damage or burning materials. Gas detectors can react to carbon monoxide (carbonate or carbon monoxide), hydrocarbon compounds.
Flowing fire detectors
Flowing fire detectors are used to detect fire factors as a result of the analysis of the medium propagating ventilation canals exhaust ventilation. Detectors should be installed in accordance with the instructions for the operation of these detectors and the manufacturer's recommendations agreed with authorized organizations (having permission to type activities).
Manual detectors
Fire manual detector - a device designed to manually turn on the fire alarm signal in fire alarm systems and fire extinguishing. Manual fire detectors should be installed at an altitude of 1.5 m from the ground or floor level. The illumination at the installation site of the manual fire detector should be at least 50 LCs.
Manual fire detectors should be installed on evacuation paths in places available for their inclusion when a fire occurs.
In facilities for ground storage of freeware and combustible liquids, manual detectors are set on the embankment.
By 1900, 675 manual detectors with the output of the signal in the fire service were installed in London. By 1936, the number increased to 1732.
In 1925, in Leningrad, manual detectors were 565 points, they passed about 13% of all fires about fires in the city. At the beginning of the 20th century, there were manual detectors included in the ring cable of the registering device. When the detector is turned on, the detector made an individual number of closures and opening and thus transmitted a signal to the Morce apparatus installed on the registering device. Manual design detectors of that time consisted of a clock mechanism with a pendulum descent consisting of two main gear wheels and a signal wheel with three driving contacts. The mechanism is activated using a belt spiral spring, and the mechanism of the detector powered by repeats the signal number four times. One plant plant is enough for the flow of six signals. Contact parts of the mechanism, to avoid oxidation, are covered with silver. This type of signaling was proposed in 1924 by the head of the workshops of the Fire Telegraph Rulman A.F., the devices of which were established for experience in the 7th points of the city's central part with the receiving station in part. t. Lenin. The alarm action was open on March 6, 1924. After a ten-month experienced operation, which showed that there was no incompleteness of the signal and that the alarm was noted a complete trouble-free and accurate effect, the system was recommended for widespread use.
Application in explosive zones
When protecting the fire alarm systems of explosive objects, it is necessary to apply detectors with explosion protection tools. For point flue detectors, the type of explosion protection "intrinsically safe electrical circuit (I)" is used. For thermal, manual, gas and flame detectors, explosion protection types "intrinsically safe electrical circuit (I)" or "Blastingproof shell (D)" are used. Also possible in one detector, a combination of protection I and D.
Are mandatory engineering system Any building. Not only the safety of property depends on their unmistakable work, but also, most importantly, the health and life of people. Timely and reliable ignition detection gives people the opportunity to evacuate into a safe zone, and fire teams - promptly proceed to steam fire, not allowing its distribution.
Types of detectors
Fire detectors in the composition are designed to detect fire. Depending on the principle of operation, they are divided into species. It:
- - reacts to the appearance of smoke indoors;
- the thermal sensor is triggered when a given temperature is exceeded;
- the flame detector - fixes the visible either infrared radiation of the flame;
- gas analyzer - registers such as damp gas.
The correct selection of the detector allows you to detect a fire source in a timely manner.
Fire load and detector type
Premises of various purposes have their own specifics in the development of fire and the manifestation of its factors. The fire load is crucial - all objects and materials located in the room. For example, the ignition of paints or fuels is accompanied by a bright flame, which can be fixed by the flame detector. But the same will not be effective in the premises with the storage of materials, prone to degeneration, smoke detector will react on smoke from glowing materials.
Smoke detectors
The most common I. effective tool Fire detection is an automatic smoke detector. After all, the allocation of smoke is characterized by the process of burning many substances, such as paper, wood, textiles, cable products, electronic equipment And so on. These sensors are designed to detect fires accompanied by the release of smoke in the early stages of the fire. Detectors of this type are effective when installing in residential buildings, public buildings, industrial and warehouses with a turnover of materials inclined to highlight the smoke during combustion.
The principle of action of flue detectors
The effect of smoke sensors is based on the dispersion of light on smoke microparticles. The sensor emitter is usually a LED operating in a light or infrared band. It irradiates the air in the smoke chamber, when smoking, part of the light stream is reflected from smoke particles and dissipates. This scattered radiation is fixed on the photodetector. The microprocessor based on the photodetector translates the detector to the alarm state. Depending on the concentration of the emitter and receiver, the detectors can be point and linear. The names of this type begin with "IP 212", then there is a digital designation of the model. In the designation, the letters are decrypted as "Fire detector", the first figure 2 - "smoke", the number 12 is "optical". Thus, the whole marking "IP 212" denotes: "Fire Fire Fire Detector".
Spot smoke sensors
In the instruments of this type, the emitter and receiver are installed in one case along different sides from the smoke chamber. Perforation of the sensor housing ensures unimpeded smoke penetration into the smoke chamber. Thus, the detector fire smoke optical-electronic controls the degree of smoke of the room is only at one point. Sensors of this type are characterized by compactness, simplicity of installation and efficiency. Their main drawback is a limited controlled area, not exceeding 80 sq.m. In most cases, point detectors are installed on the ceiling, with a step depending on the height of the room. But they can be installed on the walls, under the overlap.
Linear smoke detectors
In these sensors, the emitter and receiver are made in the form of separate devices installed on different sides of the room. Thus, the beam of the emitter passes through the entire room and controls his smoke. As a rule, the range of detectors of this type does not exceed 150 m. There are variants of devices in which the emitter and receiver are installed in one case, and their optical axes are directed in one direction. To work such a detector, an additional reflector is used (cataphoth), installed on the opposite wall and returning the transmitter ray to the receiver. The linear smoke detector is primarily used to protect extended and high rooms, such as halls, indoor arena, galleries. They are installed on the walls under the overlap, the emitter on the same wall, the receiver on the opposite. In high rooms, such as atrium, sensors are installed in several tiers.
Sensor sensitivity
The most important parameter of the flue detectors is their sensitivity. It characterizes the ability of the sensor to catch the minimum concentration of smoke particles in the analyzed air. This value is measured in dB and is in the range of 0.05-0.2 dB. The difference of high-quality sensors is the ability to maintain its sensitivity when changing the orientation, supply voltage, illumination, temperature and other external factors. To check the photodetector use special laser pointers or aerosols, allowing to remotely monitor the performance of the detector.
Analog and Address Systems
The detectors are connected by the loop to the receiving-control device, which analyzes their status and in case of triggering it gives an alarm. Depending on the method of transmitting your state, detectors are analog or address.
The detector fire smoke analog connection is connected to the loop in parallel and when triggered sharply reduces its resistance, simply speaking, the train shoes. This is a loop and fixed by the receiving-control device. As a rule, the connection of analog detectors is performed by a two-wire loop, which also serves power. But there are options for connecting on a four-wire diagram. The disadvantage of such a system is the impossibility of continuously controlling the performance of the detector, in addition, sometimes the brake work is fixed without specifying the sensor.
The address detector Fire Fire Opto-Electronic is equipped with a microprocessor that controls the status of the sensor and adjusts its settings if necessary. Such sensors are connected to a digital loop in which each detector is assigned its number. In such a system, the receiving and control unit receives not only data on the triggering of the detector and its number, but also a service information about working capacity, dust, etc.
In the buildings of most modern detectors, LEDs are built on, their migration determining their condition.
Autonomous fire detectors
Often there is no need to install automatic installation Fire alarm, it is enough to just notify the emergence of a fire of people in the same room. For these purposes, the detector smoke autonomous. These devices combine smoke sensor and (siren). When smoking the room, the detector determines the presence of smoke and his sound signal notifies people about the presence of a dangerous concentration of smoke. Such sensors have autonomous food - built-in batteries, the capacitances of which are enough to work for three years.
These detectors are ideal for installation in an apartment or a small house. Some models allow you to combine sensors into a small network, for example within the apartment. On the case of such a sensor, there is a LED indicator, the color and frequency of the flashing of which are talking about its condition.
Ionization fire detector - This is a high-tech automatic device for registration of a fire focus on the appearance of a protected premises of volatile products of the combustion process - the smallest particles of soot, Gary. This method of detection is based on the property of ionized air to attract particles of the flue stream, which served as the appearance of such a name.
In its effectiveness, this is one of the last steps of technical development, comparable by sensitivity, speed / inertia detection characteristic signs combustion process with the formation of smoke, only with gas, aspiration, flow sensors; Performance of optical electronic devices intended for the same purposes.
Ionization fire detectors are able to detect the focus of fire not only at the earliest stage on the appearance of volatile burning particles, but also react to any of their size; as well as color, depending on the physicochemical parameters of the fire load in the protected areas, the so-called gray and black smoke; What is not available to most other automatic devices that fix the formation of a flue stream.
Due to the complexity of production, technical control when creating such devices; The need to dispose / deactivation, which served their term of ionization fire detectors only on specialized enterprises of the atomic industry, created prerequisites for the high cost of products.
Due to the presence in them, albeit in the permissible state norms, a small number of radioactive substances inside miniature radioisotope emitters, which are an integral element of the design in most product models; In part, because of the biased public opinion formed in our country, they are not serially produced.
However, abroad their manufacture continues, and the product certified in the prescribed manner can be purchased on russian market Fire and technical products.
Fire detector smoke-ionization
According to the definition given in, this is an automatic fire detection device, the method of action of which is based on the change in the values \u200b\u200bof the electric current passing through artificially ionized air, when smoke particles appeared in them formed during the combustion of solid, liquid materials.
According to the controlled sign of the fire, the design of products, technical device Sensitive elements of sensors, the method of detecting flue particles to ionization fire detectors include two types:
- Radioisotope.
This is a smoke fire detector, which is triggered due to the effects of burning products on the ionization current of the detector's internal working chamber. The principle of operation of the radioisotope detector is based on the ionization of the air of the chamber when irradiation with its radioactive substance. The principle of operation of the radioisotope detector is based on the ionization of the air of the chamber when irradiation with its radioactive substance. When introduced into such a chamber oppositely charged electrodes, ionization current occurs. The charged particles "stick" to more severe smoke particles, reducing their mobility - the ionization current decreases. Its reduction to a certain value of the detector perceives as alarm signal.
A similar detector is effective in the smokes of any nature. However, along with the advantages described above, radioisotope detectors have a significant disadvantage that should not be forgotten. We are talking about the use of radioactive radiation source detectors. In this regard, there are problems of compliance with safety measures during operation, storage and transportation, as well as disposal of detectors after the expiration date. Effective for detecting fires, accompanied by the appearance of so-called "black" types of smoke, characterized by a high level of light absorption.
- Electro-induction.
Aerosol particles are sucked from the environment into a cylindrical tube (gas duct) with the help of a small-sized electric pump and fall into the charging chamber. Under the influence of a unimpolar corona discharge, the particles acquire a volume electric charge and, moving further on the gas duct, fall into the measuring chamber, where the electrical signal is proportional to its measuring electrode, proportional to the volumeting of the particles and, consequently, their concentration. The signal from the measuring chamber enters the pre-amplifier and then to the processing unit and signal comparison. The sensor selection of the signal in speed, amplitude and duration and issues information when the specified thresholds are exceeded as a contact relay closure.
- High voltage modulator.
- Voltage regulator.
- Power Supply.
- Amplifier.
- Information processing unit.
- Charger, electrode ring.
- Charger, electrode needle.
- Capacitor.
- Resistor.
- Resistor.
- Stabitron
- Induction electrode.
- Light-emitting diode.
- Aerosol flow rate.
- F - output.
Structurally, the measuring line is a cylindrical gas duct, at the input of which is a charging chamber of the needle-cylinder type, and at the output of the measuring electrode ring and the air mixture consumption.
The main parameter of the electroinduction fire detector, which allows you to apply a floating threshold, is its sensitivity, which allows for a steady level of electrical signal proportional to the weight concentration of the aerosol, in its entire possible change range.
In, on the requirements for designing APS, AUPT systems, the selection of point flue fire detectors is recommended to perform in accordance with their sensitivity to various types of smoke. In this characteristic indicator, ionization fire detectors are out of competition among such devices, incl. Effectively detect "black" smoke.
Principle of operation of ionization fire detectors
An amazing history of the invention of the smoke radioisotope detector. In the late 1930s. Physicist Walter Yegen engaged in the development of the ionizing sensor to detect the poison gas. He believed that the ions of air molecules, formed under the action of a radioactive element (scheme A, b), will be born gas molecules and due to this will decrease electricity In the device chain. However, small concentrations of poisonous gas did not affect the conductivity in the measuring ionization chamber of the sensor. Walter from the disorder was lit and soon noted with surprise that the microammeter connected to the sensor fixed the current drop. It turned out that particles of smoke from cigarette reproduced that effect that could not provide poisoning gas (scheme B). This experiment Walter Yeger paved the way to create the first smoke detector.
Based on fixation, registration of changes in the indicators of electric fiber passing through ionized air molecules in a sensitive sensor element, when exposed to small particles of volatile combustion reaction products.
When such particles hit in the chamber of the ionization smoke detector, they are due to the difference electric potentials join the ions, which reduces the speed of their movement and, as a result, current strength; With a decrease in their number, removing from a sensitive element of the device - the current of the current begins to grow.
Reducing the power of electrotock passing through ionized air to the threshold / critical value set by the product settings is perceived by the device as a feature of the detection of the fire focus in the controlled zone, the protected room; With the formation, transmission of alarm message to the APS installation and control equipment or automatic fire extinguishing system.
The principle of operation of radioisotope flue detectors is based on the ionization of the air in the control chamber of the sensing element, placed inside the body of the product, with the intensive radiation of its low-powerly narrow-controlled source of radioactive radiation; In the electro-induction fire sensors, air ionization is carried out by a unipolar corona discharge of an electric current.
The design of the ionization detector
The greatest distribution compared to the electro-induction device, the ionization radioisotope smoke detector consists of the following elements:
- Housings made of high-quality plastic, for example, non-combustible polycarbonate with holes for the entrance and release of air, flue gases, protected as a shallow metal mesh from the penetration of insects and the form of the body around them, their location on it to protect against direct air flows.
- Mounting base with electronic pCBwhich installed two, successively included in the electrical chain ionization chambers - control and measuring; a control unit with a microcontroller designed to process data, signal transmission, device addressing; Input / output sliding clamping contacts / terminals for connecting to the CPS installation loop.
- Structurally, the control chamber is placed inside the measuring, being a closed volume protected from the penetration of smoke particles; While the measuring chamber is open, intended for free penetration, filtering the gas-air medium to fix the changes occurring in it.
- A compact source of radioactive radiation, which more often containing a negligible amount of the isotope of America-241, applied to the metal foil installed inside the control chamber. Its radiation penetrates through both chambers, forming positively and negatively charged particles in the air - air ions; In this case, the radioisotope radiation source is positive, and the outer measuring chamber is a negative charge. When the power supply is submitted to the input contacts of the ionization fire detector inside it, an electric field occurs.
- When accumulated on a signal electrode installed on the boundary of the connection of the control and measuring smoke chambers, a positive charge of sufficient force set by the microcontroller settings; It is through an analog-to-digital converter, which is part of the electronic integrated circuit, is formed into an alarm signal transmitted to the device / installation unit of the APS.
The strength of the current in the ionized space inside such a fire detector remains stable only while maintaining normal conditions in the control zone.
With the slightest changes in the air, ionization fire detectors persistently react, leading the entire complex automatic fire protectionwhat makes it possible if the focus of fire is not immediately eliminated; It is possible to give it to localize it, give time prior to the arrival of fire units, minimize material damage.
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