The early warning system of forest fires. Early Fire Detection Systems Early Fire Prevention System Scanning Surface Temperature

The cost of damage from the fire even in a separate room can reach impressive sums. For example, when equipment is in the premises, the price of which significantly exceeds the cost of fire protection. The traditional ways of extinguishing fire in this case are not suitable, since their use threatens no less damage than the fire itself.

That is why the need for the early detection of fire is growing, which will be able to identify signs of fire in the infarder stage and take operational measures to prevent it. Early fire detection equipment performs its functions due to super-sensitive sensors. These are temperature sensors, smoke, as well as chemical, spectral (flame reactive) and optical. All of them are part of a single system aimed at early detection and superoperative location of fire.

The most important role here plays the property of devices for early detection of a fire on continuous monitoring of the chemical composition of air. When burning plastics, plexiglas, polymeric materials, the composition of the air changes dramatically, which should fix the electronics. Semiconductor gas-sensitive sensors are widely used for such purposes, the material of which is capable of changing electrical resistance from chemical impact.

Systems using semiconductors are improved all the time, the semiconductor market is constantly growing, as evidenced by the indicators of financial markets. Modern semiconductor sensors are able to catch the minimum concentrations of substances allocated during combustion. First of all, it is hydrogen, carbon monoxide, and carbon dioxide, aromatic hydrocarbons.

On the discovery of the first signs of fire, the operation of fire extinguishing systems is only beginning. The detection instrument acts clearly and quickly, replacing several people and excluding the human factor when heating fire. These devices are ideally related to all building engineering systems that can speed up or slow down the spread of fire. An early detection system, if necessary, will completely disable the ventilation of the room, in the required quantity - elements of power supply, will include anxiety, will ensure the timely evacuation of people. And most importantly, it will launch a fire extinguishing complex.

In the earliest stages, smear the fire is much easier than on the subsequent, and it can take just a few minutes. Fire extinguishing at the ridiculous stages can be made with the help of methods that exclude the physical destruction of facilities in the room. This method is, for example, extinguishing by replacing oxygen on non-combustible gas. In this case, the liquefied gas during the transition to a bat lowers the temperature in the room or on a particular area, and also suppresses the combustion reaction.

Fire doors - an integral part of any fire safety system. This is a design element that prevents the spread of a fire into neighboring rooms for a certain time.

Early ignition detection devices are required primarily to ensure the safety of people. The need for them is proven by numerous and bitter experience. Fire is one of the most unpredictable natural disasters, as the entire history of human civilization says. Nowadays, this factor has not been less relevant. On the contrary, today even local ignition can cause catastrophic losses associated with the failure of expensive equipment and equipment. That is why it is advantageous to invest in such an early detection system.

UDC 614.842.4.

Modern fire detection systems

M. V. Savin, V. L. Health

All-Russian Research Institute of Fire Defense Emergencies Ministry of Russia

A brief description of various types of fire detectors, their positive qualities and disadvantages is given. The device and advantages of aspi-rational fire detectors are considered in detail.

One of the most important elements of the fire alarm system are firefighters from broadcasters. They are divided depending on the type of physical fire factor, which react, and, accordingly, are classified for thermal, smoke, gas, flame detectors combined. In addition, depending on the configuration of the measuring zone, fire detectors are distinguished, multipoint and linear. The spot fire detector reacts to a fire factor controlled near its compact sensitive element. The multipoint fire detector characterizes the discrete arrangement of point sensitive elements in the measuring line. Linear fire detector is a detector, the geometric form of the control zone of which has a long section, that is, environmental control is carried out throughout a certain line. Each type of fire detectors has its advantages and disadvantages. The combination of these properties and determines the scope of their application. But still, for all these detectors, one common drawback is characterized - this is the so-called "passive" scan of the protected area. After all, they are actually waiting for the factors accompanying the fire (smoke, elevated temperature) themselves in the detector detection field. In particular, the smoke fire detector only then give an alarming notice when smoke falls into the detector chamber, which significantly depends on the presence of air flows in the protective room.

Currently, the aspiration firefighters are actively implemented in our market. They are actually a letter, consisting of a sensing element and signal processing scheme, which can be located both inside and outside the protected room, and a system of intake pipelines, for which air samples are transported from

flashing room to a sensitive element of aspiration fire detector.

Aspiration fire detectors have several basic advantages over traditional smoke detection systems. First of all, ensuring the delivery of air samples to a sensitive element, regardless of the presence of forced and natural air flows in the protective room.

Aspiration fire detectors provide the so-called cumulative detection. When smoke spreads and dissipates throughout the room, its concentration decreases and becomes more difficult to detect it with traditional means. Cumulative detection refers to the ability to take air from many points within the protected zone in one is the rank. Aspiration fire detectors continuously select small amounts of air samples throughout the entire protected area and transfer them to a sensitive element of the aspiration fire detector.

One of the service functions of modern as-pirate fire detectors is the ability to continuously monitor the overall dust of air dusting, predicting and adjusting its work in accordance with the realities of the protected object. This is another possible application of this product - monitoring air purity. In addition, most of the detectors constantly analyze possible malfunctions in their work (pollution in tubes, clogging of smoke-sinking holes, etc.).

Essentially, aspiration firefighters were noticeable, these are intelligent fire microstatons. They are the same as conventional fire alarm systems, in their composition stationary and peripheral equipment. As peripheral equipment, both a system of intake pipelines with smoke-mixing capillary tubes and various

Fire-security 6 "2003

modules (Fig. 1), designed to perform such functions as providing visual indication of the state of the aspiration detector in separate zones, setting, checking and service, as well as programming a separate detector and the entire network as a whole.

As a sensitive element of aspiral fire detectors, both ordinary fire detectors (chimneys or gas) (Fig. 2) and intelligent smoke detection systems according to the method of scanning laser technology (Fig. 3) can be used as a sensitive element.

We will analyze the principle of action of aspiration fire detectors on the example of the Vesion Fire & Security VESDA series detectors. The air from the protected room is continuously absorbed into the detector using a highly efficient fan (aspirator) through the system of intake pipelines (Fig. 4). The sample of this air is passed through the filters. First, dust and contamination is removed before the sample enters the optical smoke detection chamber. Then, on the second stage of cleaning (if it is available), an additional serving of a portion of pure

air to prevent pollution of optical surfaces and ensuring the stability of calibration and long service life of the aspiration detector. After the filter, the air sample enters the measuring chamber, which recognizes the availability of smoke. Then the signal is processed and is indicated by means of a linear scale indicator, threshold indicators of alarm signal or graphic display (depending on the modification of the detector). Next, aspiration detectors through a relay or interface can transmit this information to the instruments receiving and control fire, fire control, on the centralized observation console or other external devices.

The emerging sunbathings are usually four stages: the depression, visible smoke, flame and fire. In fig. 5 shows how the development of lighting in time proceeds. Please note that the duration of the first stage - provides more time to detect a potential fire and, accordingly, to combat its distribution before it causes significant damage and destruction. Traditional flue fire detectors often detect smoke when the fire has already begun, which leads to

t-I Stage: 2nd stage:

Glowing fire visible

1 traditional

3rd stage Flame

4th stage! Fire I.

Vesda Fire 2 (Fire extinguishing system included)

considerable material damage. A number of aspiral fire detectors thanks to their peculiarities make it possible to detect a fire at stage and recognize the process of propagation.

The scope of aspiration fire detectors is quite wide:

In warehouses;

In the widespread profile supermarkets, which contain various volumes of inventories: from raw material materials and wholesale goods to retail items of consumption and finished products;

In the data e-processing nodes, such as Internet data processing centers, network management and similar systems that represent a significant hazard of fire due to their high electricity and electronic density density;

On sites with clean industrial premises, such as plants for the production of semiconductors, research and development organizations, pharmaceutical production facilities representing a significant danger of fire due to the permanent supply of flammable materials;

In the energy industry, which uses various types of fuel to generate electricity.

Aspiration fire detectors with air filtration system have a low probability

the supply of false alarms is allowed to reduce significant material damage that could occur with a false start of fire extinguishing systems, stopping the technological process, etc.

At the same time, aspiration fire detectors can be used in buildings and rooms with high demands for aesthetics - these are modern offices, visual, rehearsal, lectures, reading and conference rooms, meeting rooms, sorrow, lobby, halls, corridors, dressing rooms, and also Historic buildings, cathedrals, museums, exhibitions, art galleries, book storage, archives.

Aspiration fire detectors can be used:

In extreme conditions: at low temperatures, mechanical overloads and harsh operating conditions, since the intake pipeline system and directly sensitive element of the detector can be installed in different rooms;

They can work both independently as individual funds and as part of automatic system for collecting and processing information about the situation and transmit signals to external devices in a different way (by wires, radio channel, etc.);

As effective means of forming a starting signal to start fire extinguishing systems due to the presence of several levels of alarms and a customizable sensitivity range. At the same time, for the implementation of the fire extinguishing and fire extinguishing algorithm, it is assumed to have two separate detection points, which are necessary for the operation of the system, that is, the presence of two separate aspiration fire detectors. Thus, smoke fire detectors

aspiration type is a serious addition in the complex of measures to ensure the safety of premises, along with traditional fire detectors, in no case reducing the significance and capabilities of the latter.

PodpobsisBeCOCHOCT 6 "2003

Manufacturer "Vision Fire & Security" "Securiton-Hekatron" "Esser"

Characteristic Name of aspiration fire detector

Vesda Laser Vesda Laser Plus Scanner Vesda Laser Compact Ras ASD 515-1 Ras ASD XL ARS 70 LRS-S 700

Nutrition, at 18 ... 30 18.30 18.30 20.28 18.38 24.30 18.30

Operating temperature, ° C -20 ... + 60 -20 ... + 60 -20 ... + 60 0 ... + 60 0 ... + 52 0 ... + 50 -10. + 60

Sensitivity,% 0.005.20 0.005.20 0.005.20 is determined by the fire detector 0.005.1 is determined by the fire detector 0.005.20

Smoke Definition Technology Laser Laser Laser Optical Smoke Firefighter Shot Spare Laser Optical Fire Fire Fire Fighting Spare Laser

Maximum pipe length in the beam, M 200 200 50 60 60 80 200

Pipe diameter, mm 25 25 25 25/40 25/40 25 25

Hole diameter, mm 2.6 2.6 2.6 3.4 3.4 2.6 2.6

Maximum protected area, m2 2000 2000 500 800 800 1200 1600

Number of filters, pcs. 2 2 2 no no 1 2

Number of fire hazard levels, pcs. 4 4 2 1 4 1 4

Dimensions, mm 350 x 225 x 125 350 x 225 x 125 x 360 x 126 317 x 225 x 105 285 x 360 x 126 225 x 225 x 95

Weight, kg 4.0 4.0 1.9 2.7 3,4 2.7 3.5

Work on the VESDANET network (99 devices) Vesdanet (99 devices) Vesdanet (99 devices) No LaserNet (127 devices) No vesdanet (99 devices)

AutoMLAARNTM AUTOLEARNTM MODE PROGRAMMED AUTOLEARNTM Programming AutoLearnt programmable No Is no programmable

On the Russian market now certified aspiration firemen notify whether the following leading Western companies:

"Vision Fire & Security" (Australia) - notice-teli Fire smoke aspiration series VESDA Laser Plus (Fig. 6), VESDA Laser Scanner (Fig. 7), VESDA Laser Compact (Fig. 8);

"SCHRACK SECONET AG" (Austria) - Detectors Fire Fire Smoke Aspiration RAS ASD

515-1 (FG030140), production "SECURITON-HEKATRON", Germany (Fig. 9);

"Fittich AG" (Switzerland) - detectors Fire smoke aspiration RAS ASD 515-1, production "Securiton-Hekatron", Germany;

"Minimax GmbH" (Germany) is the detectors of fire aspiration AMX 4002.

The table presents the comparative characteristics of some types of aspiration fire detectors.

Our organization in the territory of the Voronezh region has carried out the installation of equipment and software systems of the early detection of forest fires. In the territories of Voronezh, Tambov and Lipetsk regions, technical support is carried out by the functioning of these software and hardware complexes in the interests of the territorial bodies of the Ministry of Emergency Situations of Russia and the Forest Management Bodies.

Description of the complex

The Forest Watch Information System is a software and hardware complex for forest monitoring and early detection of forest fires.

Architecture of the forest monitoring system and early detection of forest fires "Forest Watch"

System " Forest Watch"Consists of two parts: hardware and software. The hardware is a network of controlled observation sensors (video cameras, thermal imaging sensors, infrared chambers). The software part is a special software (software) with which the customer monitors forests in real time and determines the coordinates of fire. The latter assumes that the system can detect fire at the prejudice stage - the stages of fire, which in practice allows you to prevent emergencies.

There is already an existing infrastructure of mobile operators (cellular tower, communication equipment and serving commands). Because The system is easily scaled and expanded, it is suitable for detecting forest fires both in small territories and in large areas.

System Characteristics

• A possible error in determining the coordinates of the fireplace is up to 250 meters.
• The radius of the view of one monitoring point is up to 30 kilometers.
• The accuracy of determining the direction to the focus of ignition - 0.5 °
• Time for viewing one point - up to 10 minutes. Depends on the performance of the customer's server.
• Integration and accounting of meteorological data.
• Integration and accounting of satellite data.
• Integration of data from third-party information systems.
• The ability to promptly scaling and expanding the system to increase the monitoring area.
• Unlimited number of users with access to the system.
• The ability to promptly obtain information on mobile devices.
• Automatic detection of potentially dangerous objects: smoke and flame.

SCTEA works on the basis of modern technologies:

• computer vision;
• IP video surveillance;
• wireless broadband;
• geographic information systems (GIS);
• client-server Internet applications.

The system of distributed video monitoring "Forest Watch" consists of the following elements:

• Distributed video camera system
• Communication channels connecting video cameras with the Internet
• System server " Forest Watch»Connected to the Internet
• System System Software Forest Watch»
• Equipment of the automated operator's workplace
• Software " Forest Watch»Automated workplace

Robotic server

The robotic server is the system server " Forest Watch", Which has a number of key functions, namely:

• controls the network of camcorders (sensors) and performs with their help video surveillance of the territory, including on the basis of specified pathrol routes;
• manages computer vision subsystem to search for smoke and fire;
• provides recommendations to the user, informing it about the presence of potentially dangerous focus of fire.

Smart monitoring point

When installing the system, sometimes situations occur when the Internet connection speed is extremely small (less than 512 kbps) and the transfer of video data into the control center is difficult. To solve this problem, our specialists use the concept of a "smart monitoring point".

The meaning of the concept is that the main part of the data from the camcorder is processed before it turns out on the network and is transmitted to the control center. This is done through special mini-servers, "attached" to each specific monitoring point. It is on mini-servers a preliminary analysis of media information is carried out and "information noise" is made.

As a result, even through a weak Internet, the operator receives the same archive of potentially hazardous objects (VET) as a standard data media transmission scheme.

This allows the customer to avoid expensive communication channels or in cases where access to high-quality Internet connection is extremely difficult to access.

Fieldworker system functionality

The possibilities of the system ensure the conduct of forest video monitoring near the settlements in real time.

Functional system " Forest Watch»Allows you to carry out the following:

• Access to the system from any control center, if you have an internet connection at the required speed with a sufficient number of traffic.
• The ability to select any available camera to receive video from it.
• Change the orientation of the camera, both in azimuth and height, change the approximation of the camera.
• Set the parameters of the video obtained from the camera, such as permission and image quality (compression value).
• Change the parameters used by the infrared filter chamber to achieve acceptable visibility conditions in different conditions.
• The ability to obtain information on the current orientation of the chamber relative to the north (azimuth) in the form of the number and direction indication.
• Receive information about the current approximation of the chamber in the form of the number and sector of the review.
• The ability to submit information about the location of the camcorders and their current orientation.
• The ability to control the camera using software algorithms.
• The ability to save and access the saved orientation of the camera (bindings) to predetermined objects, such as fire facilities, natural benchmarks, etc.
• To form patrol routes intended for automatic scanning of a given territory.
• Launch patrol routes separately for selectable cameras, as well as sequentially multiple routes on different cameras by forming a list of routes to view.
• To start simultaneously to four patrol routes in one window, intended for overview monitoring several cameras at once (a high bandwidth of communication channels is required).
• Ability to dwell view one route or group of routes.
• The ability to automatically disable the application with the long-term absence of user activity.
• Save the current image from the camera in the form of a picture and in the form of a video file for further viewing and analysis.
• The ability to automatically update with minimal user participation to add new functionality and eliminate program errors anywhere.
• The ability to work multiple users with one chamber in time separation mode using the control lock and viewing mechanism.
• The possibility of marking various objects intended to perform procedures for forest monitoring (settlements, landmarks, etc.).
• The ability to display on the video entering from the camera, objects entering the area of \u200b\u200bthe review with the object type.
• Determine the direction to the visible fire when visible from one chamber with an accuracy of 0.5 degrees and marking this object.
• To determine the exact geographical coordinates of the visible at least with 2 fire chambers with an accuracy of 250m and display it in the information base.
• The ability to determine the quarter by geographic coordinates.
• The possibility of presenting information on the current fire situation on a mobile phone.
• To determine the coordinates of the fire based on the information coming from the ground-based monitoring system - from fire and observation steps. Marking fire.
• The ability to adjust the camera orientation when it is physically displaced, to save all camera orientation bindings.
• The possibility of presenting in a single information block of information from various information sources (meteorological data, data from satellite monitoring system, etc.).
• The ability to automatically detect fire foci by the system and signaling to the operator when viewing patrol routes (high processor performance required).
• The ability to automatically detect the foci of the system and alarm to the operator when performing monitoring in manual mode (high performance of the processor is required).
• Automatic detection of foci of ignition and the preservation of photo information and information about the direction to a potentially dangerous object in the archive.
• Providing access to the archive of potentially hazardous objects detected by the automatic system, with the possibility of clarification.
• The ability to exchange operational messages about the current situation with other operators and groups of operators as part of the tasks to detect and eliminate fires.
• Receive notifications, instructions, recommendations from the administrators of the system on the functioning of the components of the product.

Software complex

The software part is written on platform .NET using MS SQL Express and is a micro-service architecture. The software and hardware has a system of distributed servers plus a server for storing parent databases. The system has an early fire detection unit written in C ++ and built into the so-called camera controller. The system represents a friendly interface and has a wide functionality, namely

• 24-hour patrolling of the chamber of the territory of the forest massif by the laid routes;
• Automatic definition of fire hazard;
• Determination of the distance to the fire hazardous object, the route to it;
• The ability to assign various categories of fire hazardous object;
• Storage of rollers in accordance with the fire facility;
• Storage of the archive of all objects present in the program;
• Visualization of forces and means of extinguishing fires;
• Support for quarterly cards;
• Many service functions
• The Forest Watch Complex is currently shipped both dexte and web version.

Alarm Transmission Channels

• the Internet
• Mobile networks
• Built-in alert system

Informing all necessary services

• Departments of the Forest Watch
• Administration of cities and towns
• District administrations
• Environmental Services

LLC DSK© 2017, Nizhny Novgorod

As you know, the day of downtime of the data center costs dozens, and even hundreds of millions of dollars. For continuous operation, the data center must be protected from many hazards, including fires. In major American and European codes, aspiration systems of early detection of fires are actively used.

Specificity of fires in the Codes

The data center is a high-tech building that consumes more electricity than a regular office. An important requirement for data centers is to maintain a certain room temperature in the room. This goal is a special air conditioning system, with the help of which the internal air flows are created between the racks and inside them, which ensure the removal heat removal and the comfortable temperature for the equipment.

Such a complex air conditioning system requires a special approach to fire-based. The fact is that in the presence of strong air flows, ordinary fire detectors for detecting smoke or thermal radiation are ineffective. Smoke adjusted by air flows may not get into the smoke chamber of the detector. And if he still gets into the chamber, then by this time the limiting concentration of smoke has been achieved in the room, so when the detector works, the spread of fire is already inevitable. Therefore, in modern data centers use active aspiration systems of fire alarm.

Currently, aspiration fire alarm systems are released only abroad; Their main manufacturers are Bosch, Safe Fire Detection, Securiton, System Sensor and Xtralis (it belongs to the brand of equipment VESDA and ICAM, the latter was recently purchased by it).

Systems of this class, for example, VESDA and ICAM from Xtralis, Titanus Bosch Security or aspiration detectors System Sensor of the company of the same name, are already used in many countries of the world at objects of this type, including in Russia.

Historical reference In 1967, American researchers Alquist and Charlson (Ahlquist & Charlson) for the first time creating an oil meter for measuring the transparency of air and the degree of its contamination, which allows to control carbon dioxide content on city streets. This device was improved and issued to the US market. In 1970, the Australian Commonwealth CSIRO used the oil meter in forest fire research. Few later in Csiro addressed the chief Department of Apo Post, with the order for studying the problem of preventing fires in postal services. The purpose of the study was to find the most appropriate technology to protect against fire stations, computer rooms and cable tunnels. Sources of risk on these objects were cables that were heated from electric current or hot plates. In this study, CSIRO used oil meters, with which they controlled the degree of smoke in the ventilation channels. Subsequently, this study gave impetus to the development of a highly sensitive device capable of detecting a smoke at an early stage of the fire. The exit of the improved version of this device to the market has become a huge jump in the development of early detection systems of smoke.

It should be noted that in the requirements of some international insurance companies, the use of early detection systems of the fire, including both the means of reducing insurance payments, is already prescribed. And in the regulations of the largest international IT companies, the early detection system of the fire is part of the fire safety system.

Principle of operation

Aspiration systems are the early detection systems of the fire. As a rule, they have a modular architecture that allows you to adapt the system to specific operating conditions and layout of the building. The main components of such a system are the pipeline for airborne air from the controlled area and the detector itself, which can be placed anywhere inside the protected room or outside it.

PVC pipes are usually used as a pipeline. With the help of adapters, corners, tees and other accessories, you can create flexible networks of pipelines for air intake, taking into account the characteristics of each individual premises. At the same time, the aspiration detector itself creates a vacuum in the pipeline system to ensure continuous air intake from the controlled area through specially made holes. These actively obtained air samples pass through a detection chamber, in which the smoke particles in them are checked. In addition, for example, in the VESDA system, dust and contamination are first removed from the air sample using the built-in filter, and then the sample is supplied to the aspiration detector chamber. This prevents pollution of the optical surfaces of the camera.

Air sample enters the calibrated chamber of the detector in which the laser beam passes through it. If there are smoke particles in the air, light dispersion inside the chamber is observed, and this is immediately detected by a highly sensitive receiving system (Fig. 1). The signal is then processed and displayed on a histogram display, threshold indicators of signaling alarm and / or graphic display. The sensitivity of the detector can be adjusted, and the air flow is continuously monitored for damage detection of the pipeline.

Aspiration detectors are conditionally divided into two categories. The first POB detectors (POINT IN THE BOX), in which conventional smoke sensors of increased sensitivity are used as a detection camera, for example, ASD-Pro or LASD company System Sensor with a sensitivity of 0.03 to 3.33% / m. The second group is aspirational detectors of type VESDA, ICAM or TITANUS, which have its own built-in smoke detection chambers with a sensitivity range from 0.005 to 20% / m in VESDA, from 0.001 to 20% / m at ICAM and from 0.05 to 10% / m at Titanus. We will consider only the detectors of the second group, since it is they who have the largest range of sensitivity compared to PIB, which allows to detect the fire even at the melting stage of the wire and install the highest threshold for running the gas fire extinguishing system of the premises of data centers.

Features and advantages

Classic fire alarm systems are not triggered until the drainage is started or the fire will not appear. At this stage of fire, the fight against the fire is already becoming a difficult matter. The most important advantage of aspiration systems is that they detect the emerging fire and provide early fire alert. The intelligent processor of the smoke detection camera analyzes the data obtained and decides whether they correspond to any typical fire models. In this case, external factors that can cause false positives are suppressed.

So, what are the main advantages of aspiration systems?

1. Reliable ignition detection for wound warning. Highly sensitive sensors determine the fire on its earliest stage - in the pyrolysis phase, even before the propagation of visible smoke particles (for example, when a wire or other electronic equipment element begins to be melted). In most cases, such systems prevent significant material damage, since it is quickly detected by a failed element that can be de-energized, without giving an emerging fire to switch to the active phase. In addition, aspiration systems do not allow the system of active (usually gas) fire extinguishing and save the means necessary to recharge gas cylinders.

2. Reducing the number of false positives. Thanks to the intellectual processing of the signal from the sensors in aspiration systems, external factors are suppressed, for example, dust, drafts or electrical interference, which often become the cause of false alarms. This ensures higher sensitivity and reliability of the system, even in rooms with high ceilings or extreme temperatures, as well as under conditions of pollution or high humidity.

3. Quick installation and easy maintenance. Detectors can be installed anywhere both outside and indoors so that it is more convenient to get access to them. Aspiration systems are invisible in the room, and their maintenance does not require high qualifications. Information about all faults, such as pipeline damage, filter contamination, etc., displayed on the display screen. Thus, the staff does not have to spend a lot of time to identify the system malfunction, it can be serviced as information is received.

The main and fundamental difference between aspiration systems from conventional systems with passive smoke sensors is an active air suspension from the communication and server cabinets of the data center, through a built-in fan operating on the principle of a vacuum cleaner. Another important difference is the higher sensitivity of the detectors, which allows to detect particles of smoke, invisible to the human eye, with a concentration of 0.005% / m in the VESDA system, from 0.001% at ICAM or from 0.05% at Titanus.

An important feature is the presence of a built-in (like the VESDA system) and / or an external filter, where the intake air is cleared. Such filters allow to operate aspiration systems in highly contaminated rooms without constant cleaning or replacing laser cameras, which, in turn, increases the service life of the system and reduces the cost of maintenance.

Areas of use

In some cases, the use of aspiration systems brings a tangible result compared to conventional passive detectors. First of all, these are enterprises and companies, where the continuity of production or business processes is of paramount importance, and the downtime is unacceptable. Such, for example, telecommunication systems and server financial organizations, utilities and medical sterile premises (operational), energy and transport systems. Aspiration systems are useful and when it is necessary to eliminate the false response of the active fire extinguishing system, leading to high time and means for restoring the object.

Aspiration systems are preferred in rooms where smoke detection is difficult, for example, with intensive air flows or in high atrium spaces (shopping centers, sports halls, theaters, museums, etc.). They are used in premises where access for maintenance is impossible or difficult; They are optimal to protect the space behind the suspended ceiling and under the raised floor, elevator mines, industrial zones, air ducts, as well as prisons and other detention facilities. Another scope of application is in extreme environmental conditions: with strong dusting, gas supply, humidity, very high or very low temperatures (for example, in power plants, paper or furniture factories, in auto repair shops, mines). Finally, aspiration systems are used if it is important to save the design of the room and the slotting tools are required to be hidden.

Building an aspiration system in the data center

As a rule, the equipment of data centers is in closed cabinets, therefore, the most effective solution for protecting these zones is sampling from cabinets. In the case of aspiration systems in the data centers, the tube with suction holes are carried out on top of the racks with installed equipment. The flexible tube system allows you to select the samples both above the cabinets and inside them with the help of capillaries, ensuring the maximum reliable detection of smoke in fully closed cabinets, as well as in the cabinets with top ventilation (Fig. 2).

How much does it cost from fire The cost of a solution for fire protection of a particular data center depends on the volume and area of \u200b\u200bthe room, as well as on the number of separately protected system components. In any case, this cost does not exceed 1% of the cost of equipment installed in the data center. For example, the price of the 15-channel ICAM detector capable of protecting 15 racks with equipment is 10-11 thousand euros, deviceVESDA VLP, which can protect up to 2000 sq.m., costs 4-5 thousand euros, and Titanus protects up to 400 sq.m. And costs 2000-4000 euros.

Active air absorption and its subsequent analysis on the content of smoke particles in an aspiration chamber makes it possible to build a system so that air flows in the room do not affect the detection of smoke. For example, using an ICAM sensor, you can protect up to 15 racks, paving each of them a separate tube-capillary, as well as to provide targeting, determining the place of ignition with an accuracy of a separate cabinet. The principle of operation of the ICAM sensor is an alternate fence of air from each tube and its further analysis on the content of smoke particles in the detection chamber.

The Titanus system has a room-identification that provides early detection of fire and determination of their location. One detector can control up to five rooms or five racks when laying only one tube. The process of determining the ignition source by the ROOM-Ident system includes four stages, and the result is displayed on the detector.

Stage 1. (normal mode): The pipeline is used for the fence and evaluation of air samples in several rooms.

Stage 2. (Early ignition detection): suction and air analysis. If you have smoke, an alarm signal immediately is turned on for early response.

Stage 3. (Reverse Circulation): When the alarm is turned on, the suction fan turns off and turns onto the second, the injection fan that blows all the smoke particles from the pipeline in the opposite direction.

Stage 4. (Determination of the location): After purging the pipeline, the direction of the air movement changes again. Based on the time measurements that needed smoke particles in order to reach a detection module, the system determines the location of the ignition.

Using a flexible piping system, using one VESDA sensor, you can, for example, control the space not only above the racks, but also for the false-brake and counterpart, as well as cable trays that are in any data center and are often a source of fire. In addition, the VESDA system detectors are embedded in the Rack rack, which saves the place and ensures the design of the entire equipment in the data center.

Another key moment of organizing a reliable fire system is a fence of the air directly at the adjusting and exhaust ventilation lattice. The smoke appeared inevitably falls into the airflow, so the installation of the pipe system with intake holes on the air return grid of the circulation system ensures the instant detection of a nascent fire at the earliest stage.

Air suspension directly next to the grill of exhaust ventilation allows you to catch the smoke particles in the air even if the currently created air flows passed all the other intamine openings in the room. This is due to the fact that all air contained in the room circulates through the exhaust ventilation, and therefore, no particle of smoke contained in the air will not pass by the intake opening (Fig. 3).

The ability to install different levels of fire hazard allows you to program the system to appropriate reactions at different stages of fire development, for example, to disable air conditioning systems or the launch of active fire extinguishing systems. For example, you can install multiple thresholds of the prereversions or the highest sensitivity - to determine the moment of melting the equipment elements. If this sensitivity threshold is exceeded, the paths will be transmitted to the fire post so that the staff identifies the melting place and turn off the power supply of the equipment, preventing the spread of the fire.

You can also install the average sensitivity, and at the same time the system will determine the moment of strong smoke of the room, when it is difficult to find a place or equipment that is the reason for smoke. If this sensitivity threshold is exceeded, you can program the system for shutdown air conditioners. The lowest sensitivity is set for the smoke level of the room, when it is impossible to prevent further fire distribution without active fire extinguishing systems. When this sensitivity threshold is reached, the inclusion of the gas fire extinguishing system is programmed (Fig. 4).

The inclusion of fire extinguishing systems is the second stage of preventing the spread of the fire in the data center, when the fire development is no longer possible using simple actions: disabled the smoking server, air conditioning systems, etc. As a rule, gas systems of fire extinguishing are used to actively extinguishing the fire, using two principles of fire extinguishing in the data center. The first is a common gas fire extinguishing, when the total area of \u200b\u200bthe Central Square is being extinguished. The second is a rack gas fire extinguishing, when it is extinguished separately taken by the rack. The latter principle is used for racks with special purpose equipment, when the data loss will cost more installation and operation of the fire extinguishing system. But this is the topic of a separate article.

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Timely detection of fire in the data center can prevent the loss of equipment and the most important data, as well as forced downtime, conjugate with financial and material costs for the company. The investment in a reliable fire alarm system of data centers guarantees the organization to protect against future expenditures on the restoration of electronic equipment and lost in the free information. Sometimes these financial losses are incomparably more than the cost of the fire detection system at an early stage.

In the Russian Federation, about 700 fires occur daily, in which more than 50 people die. Therefore, the preservation of people's life remains one of the most important tasks of all security systems. Recently, the theme of early fire detection is increasingly discussed.

The developers of modern fire fighting equipment compete in increasing the sensitivity of fire detectors to the main signs of the fire: heat, optical radiation from flame and smoke concentration. In this direction, a huge work is carried out, but all fire detectors work when at least a small fire has already arisen. And few discusses the topic of detecting possible signs of fire. However, devices that can not register fire, but only the threat or the likelihood of fire appear, have already been developed. These are gas fire detectors.

Comparative analysis

It is known that the fire may occur both from a sudden emergency (explosion, short circuit) and with a gradual accumulation of hazardous factors: the accumulation of combustible gases, vapors, overheating of the substance above the point of ignition, the insulation of the insulation of the electrocabolic wires from overload, rotting and heating grain and grain and T.P.

In fig. 1 shows a graph of a typical reaction of the gas fire detector for a fire, starting with a burning cigarette that fell on the mattress. From the graph, it can be seen that the gas detector reacts to carbon monoxide after 60 minutes. After entering the burning cigarette on the mattress, in the same case, the photovoltaic smoke detector reacts after 190 minutes, ionization smoke - after 210 minutes, which significantly increases the time to make a decision on the evacuation of people and the elimination of the fire focus.

If you fix the set of parameters, which can lead to the beginning of the fire, then it is possible (without waiting for the appearance of flame, smoke) to change the situation and avoid a fire (accident). In the early receipt of the signal from the gas fire detector, the service personnel will have time to take measures to weaken or eliminate the threat factor. For example, it can be airing the room from combustible vapors and gases, when the insulation is overheated, the power supply of the cable and the transition to the use of a backup line, with a short circuit on the electronic board of computing and controlled machines - extinguishing the local fire and deleting a faulty block. Thus, it is a person who takes the final decision: to cause fire protection or eliminate an accident on its own.

Types of gas detectors

All gas fire detectors differ in the type of sensor:
- metal oxide,
- thermochemical,
- semiconductor.

Metallooxide sensors

Metalloxide sensors based on thick-film microelectronic technology are manufactured. A polycrystalline aluminum oxide is used as a substrate, on which the heater and the metal oxide gas-sensitive layer are applied on both sides (Fig. 2). The sensitive element is placed in a housing, protected by a gas-permeable shell, satisfying all the requirements of the explosion-resumption.

Metalloxide sensors are designed to determine the concentrations of combustible gases (methane, propane, butane, hydrogen, etc.) in the air in the interval of concentrations from thousandth to units of percent and toxic gases (CO, ARSIN, phosphine, hydrogen sulfide, etc.) on The level of maximum permissible concentrations, as well as for the simultaneous and selective determination of oxygen concentrations and hydrogen in inert gases, for example in rocket technology. In addition, they have a record low-class electrical power required for heating (less than 150 MW), and can be used in gases leaks and fire alarm systems of both stationary and wearable.

Thermochemical gas alarm

Among the methods used to determine the concentration in the atmospheric air of combustible gases or vapors of combustible liquids, the thermochemical method is used. Its essence is to measure the thermal effect (additional increase in temperature) from the reaction of oxidation of combustible gases and vapors on the catalytically active element of the sensor and the further conversion of the resulting signal. The signaling sensor using this thermal effect, generates an electrical signal, a proportional concentration of combustible gases and vapors with different proportionality coefficients for various substances.

When combustion of various gases and vapors, the thermochemical sensor produces signals, different in magnitude. The same levels (in% NKRR) of various gases and vapors in air mixtures correspond to unequal output signals of the sensor.

The thermochemical sensor is not elected. Its signal characterizes the level of explosion hazard, determined by the total content of combustible gases and vapors in the air mixture.

In the case of monitoring the combination of components in which the content of individual, in advance known combustible components ranges from zero to some concentration can lead to control error. Such an error exists under normal conditions. This factor must be taken into account to set the boundaries of the range of signal concentrations and the admission to change them - the limit of the allowed basic absolute response error. The measurement limits of the alarm is the smallest and largest concentration value of the component of the component, within which the alarm is measured with an error that does not exceed the specified one.

Description of the measuring circuit

The measuring circuit of the thermochemical converter is a bridge circuit (see Fig. 2). Sensitive B1 and compensating B2 elements located in the sensor are included in the bridge circuit. The second branch of the bridge - R3-R5 resistors are in the signaling unit of the corresponding channel. The bridge is balanced by the R5 resistor.

With catalytic combustion of the air mixture of combustible gases and vapors on a sensitive element B1, heat is released, an increase in temperature and, therefore, an increase in the resistance of the sensing element. At the compensating element B2 burning does not occur. The resistance of the compensating element changes when it is aging, changing the power current, temperature, speed of the controlled mixture, and the like. These same factors also act on a sensitive element, which significantly reduces the bridge (dreuff of zero) caused by them (zero drift) and control error.

With stable power of the bridge, the stable temperature and the speed of the controlled mixture, the bridge is notable with a significant degree of accuracy is the result of changing the resistance of the sensing element.

In each channel, the sensor bridge power supply device provides the current control of the optimal temperature of the elements. As a temperature sensor, the same sensitive element B1 is used as a temperature sensor. The bridge unbalance signal is removed from the AB bridge diagonal.

Semiconductor gas sensors

The principle of action of semiconductor gas sensors is based on the change in the electrical conductivity of the semiconductor gas-sensitive layer in the chemical adsorption of gases on its surface. This principle allows you to effectively use them in fire alarm devices as alternative devices with traditional optical, thermal and smoke alarms (detectors), including radioactive plutonium containing. A high sensitivity (for hydrogen from 0.00001% voluminous), selectivity, speed and low cost of semiconductor gas sensors should be considered as the main advantage over other types of fire detectors. The physicochemical principles of detection of signals used in them are combined with modern microelectronic technologies, which causes low cost of products with mass production and high technical specifications.

Semiconductor gas-sensitive sensors are high-tech elements with low power consumption (from 20 to 200 MW), high sensitivity and increased speed up to a fraction of seconds. Metalloxide and thermochemical sensors are too expensive for such use. The introduction of gas fire detectors based on semiconductor chemical sensors manufactured by group technology allows us to significantly reduce the cost of gas detectors, which is important for mass applications.

Regulatory requirements

Regulatory documents on gas fire detectors have not yet been fully developed. The existing departmental requirements of the RD BT 39-0147171-003-88 are applied to the facilities of the oil and gas industry. In the NPB 88-01 on the placement of gas fire detectors it is said that they should be installed in the premises on the ceiling, walls and other building structures of buildings and structures in accordance with the instruction manual and recommendations of specialized organizations.

However, in any case, in order to accurately calculate the number of gas detectors and correctly make them install on the facility, you must first know:
- the parameter according to which security is monitored (type of gas, which is allocated and indicates a hazard, for example CO, CH4, H2, etc.);
- the size of the room;
- appointment of the room;
- availability of ventilation systems, air support, etc.

Summary

Gas fire detectors are the following generation devices, and therefore they still require domestic and foreign companies engaged in fire-fighting systems, new research surveys to develop the theory of gas dividing and distribution of gases in the premises of various purposes and operation, as well as carrying out practical experiments for Development of recommendations on the rational placement of such detectors.