Unfortunately, not everyone in our country understands the advantages that addressable analogue systems provide, and some even reduce their advantages to “caring for smokers.” Therefore, let’s also take a look at what addressable analogue systems give us.
It is important not only to detect in time, but also to warn in time
Let me remind you that there are three classes of systems fire alarm: non-addressable, addressable, addressable-analog.
In non-addressable and addressable systems, the “fire decision” is made directly by the detector itself and then transmitted to the control panel.
Analog addressable systems are essentially telemetry systems. The value of the parameter controlled by the detector (temperature, smoke in the room) is transmitted to the control panel. The control panel constantly monitors the status environment in all rooms of the building and, based on this data, makes a decision not only on the generation of a “Fire” signal, but also a “Warning” signal. We especially emphasize that the “decision” is made not by the detector, but by the control panel. The theory states that if you plot the intensity of a fire versus time, it will look like a parabola (Fig. 1). On initial stage During the development of a fire, its intensity is low, then it increases and then an avalanche-like cycle begins. If you throw an unextinguished cigarette butt into a basket of papers, they will first be observed to smolder with the release of smoke, then a flame will appear, it will spread to the furniture and then the intensive development of the fire will begin, which is no longer easy to cope with.
It turns out that if a fire is detected at an early stage, it can be easily extinguished with a glass of water or a regular fire extinguisher and the damage from it will be minimal. This is exactly what analog addressable systems allow you to do. If, for example, a non-addressable (or addressable) heat detector provides the formation of a “Fire” signal at a temperature of 60 ° C, then until this value is reached, the duty officer does not see any information on the control panel about what is happening in the room. Still, this presupposes a significant fire. A similar situation is observed with smoke detectors, where the required level of smoke must be achieved.
Addressable does not mean analog addressable
Addressable analogue systems, constantly monitoring the state of the environment in the room, immediately detect the beginning of a change in temperature or smoke and issue a warning signal to the duty officer. Therefore, analogue addressable systems provide early fire detection. This means that the fire can be easily extinguished with minimal damage to the building.
Let us emphasize that the “watershed” is not between non-addressable systems, on the one hand, and addressable and addressable-analog systems, on the other, but between addressable-analog and other systems.
In real analog addressable devices there is a principle. the ability to individually set not only the levels of formation of the "Fire" and "Warning" signals for each detector, but also to determine the logic of their joint operation. In other words, we get our hands on a tool that allows us to optimally create an early fire detection system for each object, taking into account its individual characteristics, i.e. we have a principle. the ability to optimally build a fire safety system for a facility.
At the same time, a number of important tasks are also solved, for example, monitoring the performance of detectors. Thus, in an addressable analogue system, in principle, there cannot be a faulty detector that is not detected by the control panel, since the detector must transmit a certain signal all the time. If we add to this the powerful self-diagnosis of the detectors themselves, automatic dust compensation and detection of dusty smoke detectors, it becomes obvious that these factors only increase the efficiency of analogue addressable systems.
Key Features
An important component of addressable analog devices is the construction of alarm loops. The loop operation protocol is the company's know-how and constitutes a trade secret. At the same time, it is he who largely determines the characteristics of the system. Let's study the most characteristic features of addressable analog systems.
Number of detectors in the loop
Typically it ranges from 99 to 128 and is limited by the energy capabilities of the detectors' power supply. In early models, detectors were addressed using mechanical switches; in later models, there are no switches, and the address is stored in the non-volatile memory of the sensor.
Ring alarm loop
In principle, most addressable analog devices are capable of working with a radial loop. but there is a possibility of “losing” a large number of detectors due to a cable break. That's why ring loop– a means of increasing system survivability. If it breaks, the device generates a corresponding notification, but ensures operation with each half-ring, thereby maintaining the functionality of all detectors.
Short circuit localization devices
This is also a means of increasing the “survivability” of the system. Typically, these devices are installed through 20–30 detectors. When there is a short circuit in the loop, the current in it increases, which is detected by two localization devices, and the faulty section is switched off. Only a segment of the loop with two short-circuit localization devices fails, and the rest of it remains operational due to the ring organization of the connection.
In modern systems, each detector or module is equipped with a built-in short-circuit localization device. At the same time, due to a significant reduction in prices for electronic components, the cost of sensors has not actually increased. Such systems practically do not suffer from short circuits of loops.
Standard set of detectors
It includes smoke optoelectronic, thermal maximum temperature, thermal maximum differential, combined (smoke plus thermal) and manual call points. These detectors are usually sufficient to protect the main areas of the building. Some manufacturers additionally offer quite exotic types of sensors, for example, an addressable analogue linear detector, an optical smoke detector for premises with high levels of pollution, an optical smoke detector for explosive premises, etc. All this expands the scope of application of analogue addressable systems.
Non-addressable sub-loop control modules
They allow the use of non-addressable detectors. This reduces the cost of the system, but at the same time, naturally, the properties inherent in addressable analog equipment are lost. In some cases, such modules can be successfully used to connect conventional linear smoke detectors or create explosion-proof loops.
Control and monitoring modules
They are included directly in alarm loops. Typically, the number of modules corresponds to the number of detectors in the loop, and their address field is additional and does not overlap with the addresses of the detectors. In some systems, the address field of detectors and modules is common.
The total number of connected modules can be several hundred. It is this property that allows, on the basis of the addressable analogue fire alarm system SPS, to integrate automatic fire protection buildings (Fig. 2).
During integration, actuators are controlled and their operation is monitored. The number of monitoring and control points is precisely several hundred.
Branched logic for generating control signals
This indispensable attribute addressable analogue control and control devices. It is the powerful logical functions that ensure the construction of a unified automatic fire protection system for the building. These functions include the logic for generating a “Fire” signal (for example, for two triggered detectors in a group), and the logic for turning on the control module (for example, for each “Fire” signal in the system or for a “Fire” signal in a given group), and the principle . the ability to set time parameters (for example, when there is a “Fire” signal, turn on the control module M after time T1 for time T2). All this allows you to effectively build even powerful gas fire extinguishing systems based on standard elements.
And not just early detection
The very principle of constructing addressable analog systems allows, in addition to early fire detection, to obtain a number of unique qualities, for example, increasing the noise immunity of the system. Let's explain this with an example.
In Fig. Figure 3 shows several consecutive polling cycles (n) by a thermal addressable analogue detector device. For ease of understanding, on the ordinate axis we will plot not the duration of the signal from the detector, but the temperature value immediately corresponding to it. Suppose that during polling cycle 4 there was a false signal from the detector or a distortion in the duration of the detector response under the influence of electromagnetic interference, that the value perceived by the device corresponds to a temperature of 80 °C. If a false signal arrives, the device must generate a “Fire” signal, i.e. false alarms will occur.
In analog addressable systems, this can be avoided by introducing an averaging algorithm. For example, let's introduce averaging over three consecutive samples. the value of the parameter for “making a decision” about a fire will be the sum of the values for three cycles, divided by 3:
- for cycles 1, 2, 3 T=60:3=20 °C – below the threshold;
- for cycles 2, 3, 4 T=120:3=40 °C – below the threshold;
- for cycles 3, 4, 5 T=120:3=40 °C – below the threshold.
That is, when a false count arrives, the “Fire” signal is not generated. At the same time, I would like to draw special attention to the fact that since the “decision” is made by the control panel, no resets or re-requests of the detectors are needed.
Note that if the received signal is not false, it means that in cycles 4 and 5 the parameter value corresponds to 80 °C, then with this averaging the signal will be generated, since T = 180:3 = 60 °C, which means it corresponds to the threshold for generating the "Fire" signal ".
What's the result?
So, we are convinced that, thanks to their unique properties, analogue addressable systems are an effective means of ensuring fire safety of objects. The number of detectors in such systems can be several tens of thousands, which is enough for the most ambitious projects.
The market for analogue addressable systems abroad has shown a steady upward trend over the past few years. The share of addressable analogue systems in the total production volume confidently exceeded 60%. The mass production of addressable analogue detectors led to a reduction in their cost, which was an additional incentive to expand the market.
Unfortunately, in our country the share of addressable analog systems is, according to various estimates, from 5 to 10%. The lack of an insurance system and current regulations do not contribute to the introduction of high-quality equipment and the cheapest equipment is often used. Nevertheless, certain shifts have already emerged, and it seems that we are on the verge of a fundamental change in the market. Only in recent years, the cost of optical smoke detectors and analogue detectors in Russia has decreased by approximately 2 times, which makes them more affordable. Without addressable analogue systems, it is unthinkable to ensure the security of high-rise buildings, multifunctional complexes and a number of other categories of objects.
Smoke protection systems for buildings: design problemsIt’s too early to write off
In the Russian Federation, about 700 fires occur every day, in which more than 50 people die. Therefore, preserving human life remains one of the most important tasks of all security systems. Recently, the topic of early fire detection has been increasingly discussed.
Developers of modern fire-fighting equipment compete to increase the sensitivity of fire detectors to the main signs of a fire: heat, optical radiation from the flame and smoke concentration. A lot of work is being done in this direction, but all fire detectors are triggered when at least a small fire has already broken out. And few people discuss the topic of detecting possible signs of a fire. However, devices that can record not a fire, but only the threat or probability of a fire, have already been developed. These are gas fire detectors.
Comparative analysis
It is known that a fire can occur either from a sudden emergency situation(explosion, short circuit), and with gradual accumulation hazardous factors: accumulation of flammable gases, vapors, overheating of the substance above the ignition point, smoldering insulation of electrical cables from overload, rotting and heating of grain, etc.
In Fig. Figure 1 shows a graph of the typical response of a gas smoke detector to a fire starting with a burning cigarette dropped on a mattress. The graph shows that the gas detector responds to carbon monoxide after 60 minutes. after a burning cigarette hits the mattress, in the same case the photoelectric smoke detector reacts after 190 minutes, the ionization smoke detector - after 210 minutes, which significantly increases the time for making a decision to evacuate people and eliminate the fire.
If you record a set of parameters that can lead to the start of a fire, then you can (without waiting for flames or smoke to appear) change the situation and avoid a fire (accident). When receiving an early signal from a gas fire detector service staff will have time to take measures to weaken or eliminate the threat factor. For example, this can be ventilating the room from flammable vapors and gases; if the insulation overheats, turn off the cable power and switch to using a backup line; if there is a short circuit on the electronic board of computers and controlled machines, extinguish a local fire and remove the faulty unit. Thus, it is the person who makes the final decision: to call fire department or eliminate the accident on your own.
Types of gas detectors
All gas fire detectors differ in sensor type:
- metal oxide,
- thermochemical,
- semiconductor.
Metal oxide sensors
Metal oxide sensors are manufactured based on thick film microelectronic technology. Polycrystalline aluminum oxide is used as a substrate, onto which a heater and a 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 that meets all explosion and fire safety requirements.
Metal oxide sensors are designed to determine the concentrations of flammable gases (methane, propane, butane, hydrogen, etc.) in the air in the concentration range from thousandths to units of percent and toxic gases (CO, arsine, phosphine, hydrogen sulfide, etc.) at level of maximum permissible concentrations, as well as for the simultaneous and selective determination of oxygen and hydrogen concentrations in inert gases, for example in rocket technology. In addition, they have class-leading electrical power required for heating (less than 150 mW) and can be used in gas detectors and systems fire alarm both stationary and portable.
Thermochemical gas detectors
Among the methods used to determine the concentration of flammable gases or vapors of flammable liquids in the atmospheric air, the thermochemical method is used. Its essence lies in measurement thermal effect(additional increase in temperature) from the oxidation reaction of flammable gases and vapors on the catalytically active element of the sensor and further conversion of the received signal. The alarm sensor, using this thermal effect, generates an electrical signal proportional to the concentration of flammable gases and vapors with different proportionality coefficients for different substances.
When various gases and vapors burn, the thermochemical sensor produces signals of different sizes. The same levels (in % LEL) of various gases and vapors in air mixtures correspond to unequal output signals from the sensor.
The thermochemical sensor is not selective. Its signal characterizes the level of explosion hazard determined by the total content of flammable gases and vapors in the air mixture.
In the case of monitoring a set of components, in which the content of individual, previously known flammable components varies from zero to some concentration, this can lead to a control error. This error also exists under normal conditions. This factor must be taken into account to set the limits of the range of signal concentrations and the tolerance for their change - the limit of the permissible basic absolute response error. The measurement limits of the detector are the lowest and highest concentration values of the component being determined, within which the detector carries out measurements with an error not exceeding 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 a bridge circuit. The second branch of the bridge - resistors R3–R5 are located in the signaling unit of the corresponding channel. The bridge is balanced by resistor R5.
During catalytic combustion of an air mixture of flammable gases and vapors on the sensitive element B1, heat is released, the temperature increases and, consequently, the resistance of the sensitive element increases. There is no combustion at compensating element B2. The resistance of the compensating element changes with its aging, changes in supply current, temperature, speed of movement of the controlled mixture, etc. The same factors also act on the sensitive element, which significantly reduces the bridge imbalance (zero drift) caused by them and the control error.
With stable power to the bridge, stable temperature and speed of the controlled mixture, the imbalance of the bridge with a significant degree of accuracy is the result of changes in the resistance of the sensing element.
In each channel, the sensor bridge power supply provides constant current regulation optimal temperature elements. As a rule, the sensitive element B1 itself is used as a temperature sensor. The bridge imbalance signal is taken from the bridge diagonal ab.
Semiconductor gas sensors
The operating principle of semiconductor gas sensors is based on a change in the electrical conductivity of the semiconductor gas-sensitive layer during chemical adsorption of gases on its surface. This principle allows them to be effectively used in fire alarm devices as alternative devices to traditional optical, thermal and smoke alarms (detectors), including those containing radioactive plutonium. And the high sensitivity (for hydrogen from 0.00001% volume), selectivity, speed and low cost of semiconductor gas sensors should be considered as their main advantage over other types of fire detectors. The physical and chemical principles of signal detection used in them are combined with modern microelectronic technologies, which leads to low cost of products in mass production and high technical characteristics.
Semiconductor gas-sensitive sensors are high-tech elements with low power consumption (from 20 to 200 mW), high sensitivity and increased speed up to fractions of seconds. Metal oxide and thermochemical sensors are too expensive for this use. The introduction into production of gas fire detectors based on semiconductor chemical sensors, manufactured using group technology, can significantly reduce the cost gas detectors, which is important for mass use.
Regulatory Requirements
Regulatory documents for gas fire detectors have not yet been fully developed. The existing departmental requirements of RD BT 39-0147171-003-88 apply to oil and gas industry facilities. NPB 88-01 on the placement of gas fire detectors states that they should be installed indoors on the ceiling, walls and other building structures buildings and structures in accordance with the operating instructions and recommendations of specialized organizations.
However, in any case, in order to accurately calculate the number of gas detectors and correctly install them at the site, you must first know:
- the parameter by which safety is monitored (the type of gas that is released and indicates danger, for example CO, CH4, H2, etc.);
- volume of the room;
- purpose of the premises;
- availability of ventilation systems, air pressure, etc.
Summary
Gas fire detectors are next-generation devices, and therefore they still require domestic and foreign companies involved in fire protection systems, new research studies to develop the theory of gas emission and distribution of gases in rooms of different purposes and operation, as well as conducting practical experiments to develop recommendations for the rational placement of such detectors.
This system is designed to detect the initial stage of a fire, transmit notification of the place and time of its occurrence and, if necessary, turn on automatic fire extinguishing and smoke removal systems.
An efficient system alerts fire danger is the use of alarm systems.
The fire alarm system must:
Quickly identify the location of the fire;
Reliably transmit a fire signal to the receiving and control device;
Convert the fire signal into a form convenient for perception by the personnel of the protected facility;
Remain immune to influence external factors, different from fire factors;
Quickly identify and report faults that impede the normal functioning of the system.
Means against fire automatics equip industrial buildings of categories A, B and C, as well as objects of national importance.
The fire alarm system consists of fire detectors and converters that convert fire factors (heat, light, smoke) into an electrical signal; a monitoring and control station that transmits a signal and turns on a light and sound alarm; and automatic installations fire extinguishing and smoke removal.
Detecting fires at an early stage makes them easier to extinguish, which largely depends on the sensitivity of the sensors.
Detectors, or sensors, can be of various types:
- heat fire detector– an automatic detector that responds to a certain temperature value and (or) the rate of its increase;
- smoke detector– automatic fire detector that responds to aerosol combustion products;
- radioisotope fire detector – a smoke fire detector, which is triggered due to the influence of combustion products on the ionized flow of the detector’s working chamber;
- optical fire detector– a smoke fire detector that is triggered due to the influence of combustion products on the absorption or propagation of electromagnetic radiation from the detector;
- fire flame detector– reacts to electromagnetic radiation flame;
- combined fire detector– reacts to two (or more) fire factors.
Heat detectors are divided into maximum, which are triggered when the temperature of the air or the protected object rises to the value by which they are adjusted, and by differential, which are triggered at a certain rate of temperature increase. Differential thermal detectors can usually also operate in maximum mode.
Maximum thermal detectors are characterized by good stability, do not give false alarms and have a relatively low cost. However, they are insensitive and even when placed at a short distance from places of possible fires, they operate with a significant delay. Differential type heat detectors are more sensitive, but their cost is high. All heat detectors must be placed directly in work areas, so they are subject to frequent mechanical damage.
Rice. 4.4.6. Schematic diagram detector PTIM-1: 1 – sensor; 2 – variable resistance; 3 – thyratron; 4 – additional resistance.
Optical detectors are divided into two groups : IR – direct vision indicators who must “see” the fire, and photovoltaic flue. Sensitive elements do not have direct vision indicators practical significance, since they, like heat detectors, should be located in close proximity to potential sources of fire.
Photovoltaic smoke detectors are triggered when the luminous flux in the illuminated photocell weakens as a result of smoke in the air. Detectors of this type can be installed at a distance of several tens of meters from a possible fire source. Dust particles suspended in the air can cause false alarms. In addition, the sensitivity of the device noticeably decreases as fine dust settles, so the detectors must be inspected and cleaned regularly.
Ionization smoke detectors For reliable operation It is necessary to thoroughly inspect and check it at least once every two weeks, remove dust deposits in a timely manner and adjust sensitivity. Gas detectors are triggered when gas appears or its concentration increases.
Smoke detectors designed to detect combustion products in the air. The device has an ionization chamber. And when smoke from a fire enters it, the ionization current decreases and the detector turns on. The response time of a smoke detector when smoke enters it does not exceed 5 seconds. Light detectors are designed according to the operating principle ultraviolet radiation flame.
The choice of the type of automatic fire alarm detector and installation location depends on the specifics of the technological process, the type of flammable materials, methods of their storage, room area, etc.
Heat detectors can be used to monitor premises at the rate of one detector per 10 - 25 m 2 of floor. A smoke detector with an ionization chamber is capable (depending on the installation location) of serving an area of 30 - 100 m 2. Light detectors can control an area of about 400 - 600m2. Automatic detectors are mainly installed on the stream or suspended at a height of 6 - 10 m from the floor level. The development of the algorithm and functions of the fire alarm system is carried out taking into account the fire danger of the facility and architectural and planning features. Currently used following settings fire alarm: TOL-10/100, APST-1, STPU-1, SDPU-1, SKPU-1, etc.
Rice. 4.5.7. Diagram of automatic smoke detector ADI-1: 1.3 – resistance; 2 – electric lamp; 4 – ionization chamber; 5 – diagram of connection to the electrical network
18.03.2017, 12:18
Zaitsev Alexander Vadimovich, scientific editor of the journal “Security Algorithm”
About “ultra-early fire detection” here and there you can find the most different materials: from individual articles to teaching aids. In one case, the authors are trying to prove that some “philosopher’s stone” has been found that solves all the problems of detecting a fire at the earliest stage, even when it does not exist yet. In another case, other specialists are beginning to figure out how to organize organizational measures for fire safety at facilities, taking into account this possibility.
But after some time, it turns out every time that one or another proposed technical means is far from an ideal solution. And even if they have some additional capabilities, they are not universal, or the use of these technical means is not economically justified.
A comparative analysis of the use of certain means for fire detection should, to some extent, help get rid of myths that arise from time to time.
I would like to immediately note that this analysis cannot be objective and final for a long period of time. Everything flows, everything changes. New technologies appear, new problems appear and, accordingly, ways to solve them. The task of specialists will be to try to get to the bottom of the matter every time they make another statement about the possibility of “ultra-early detection” of a fire, because we all know very well that miracles do not happen in the world.
“SUPER EARLY DETECTION” WHAT AND WHY
As usual, I would like to start with some existing definitions or terms related to “ultra-early detection” or even just “early detection”. But no definitions have yet been invented on this topic.
It must be understood that the occurrence of a fire is characterized by several, sometimes unrelated, environmental parameters by which it can be detected:
■ flames and sparks;
■ heat flow and elevated ambient temperature;
■ increased concentration of toxic combustion and thermal decomposition products;
■ reduced visibility in smoke.
As a result, it is through these indirect environmental parameters that the fact of a fire can be detected using technical means. Unfortunately, any of the indirect parameters is not a fully absolute criterion.
Heat comes from both heating objects and heat treatment products that we cannot do without in life.
Powerful lights, welding, and direct sunlight can simulate flames.
Toxic products in a gaseous state are one of the signs of civilization and human presence.
Smoke, being one of the types of aerosols, is sometimes not much different from other aerosols (steam, dust, etc.).
As soon as the developers of fire detection tools begin to talk about the high sensitivity of their fire detectors (FD), the question immediately arises about the likelihood of false alarms due to the presence of background values not related to the fire. And immediately work begins to protect fire detectors from false alarms, down to reducing sensitivity to reasonable values. This is the basis of the spiral of development of fire detection equipment.
The strangest thing here is that this is happening in a country in which only a couple of years ago they began to evaluate the real sensitivity of broadcasters to fire. During this time, our domestic manufacturers and a very small part of users in best case scenario They just began to understand what kind of detectors they had to deal with until recently.
Not a single trendsetter from foreign countries associated with the production of fire detectors has any thoughts of prohibiting anyone from producing or using something. It meets the requirements of the standards - that’s it, it is a full-fledged market participant. And here we must not forget that our standards for detectors are almost 90% consistent with European ones, and there is no concept of “extra-early” detectors in either one or the other. There will be a definition, requirements and assessment methods will be developed, and then there will be something specific to talk about. In the meantime, it makes sense to deal with what we have.
In the last few years, when fire tests for fire detectors were finally included in GOST R 53325-2012 “Fire automatic equipment”, it seems that it became possible to evaluate or at least compare certain fire detectors by response time when conducting standardized test fires (TF). To some extent, the results of these tests can be correlated with the time of detection of an actual fire.
A fire detector cannot be included in the honorable caste of “super-early ones” only on the basis that it was ahead of the rest in some type of test fires.
Of course, someone may suggest that if a fire detector responds to all these test fires in all cases without exception, for example, ten times faster than others, then it can and should be classified as “extra early”. But this will only be an excuse. But as a consequence, there will certainly immediately follow a proposal to ban the use of all other types and types of fire detectors, or at least to obtain some preferences in use. Then, however, it turns out that the manufacturers got a little carried away and did not take into account side effects, did not evaluate the economic efficiency, etc.
"ULTRA-EARLY" OR TIMELY DETECTION
Today there is no such task as organizing “ultra-early fire detection.” There is a requirement for timely detection, and in each specific case it may have different numerical indicators.
In particular, it is precisely the timely detection of a fire that is discussed in Article 83 of the “Technical Regulations on Fire Safety Requirements.”
How is timeliness determined? And this question has an answer in the same Technical regulations in Article 54. The goal is to detect a fire in the time required to activate the warning systems for the organization safe evacuation of people.
To implement the requirements for timely detection, there are existing standards and rules in the field of fire safety, in which all these issues are strictly linked into a single system of fire protection of the facility, starting from architectural and planning solutions and ending with smoke ventilation and internal fire water supply.
The economic indicators of “ultra-early detection” also cannot be discounted; everyone knows how to count money.
So tell me why the term “timely fire detection” is bad. Why does it not suit someone and why use non-existent and undefined terms. Why constantly confuse technical capabilities with marketing delights.
COMPARISON OF SOME FIRE DETECTION METHODS
As has already been written here, several years ago in our country there was a real opportunity to compare fire detection methods within the framework of fire tests using our domestic fire detectors. And this, of course, had to be taken advantage of.
I don’t want to reveal all the secrets in this article: who, where and when. What specific detectors there were and from which manufacturers is not in my competence, but I can say with full responsibility that the source data on which I will rely exists, and not in one copy. Maybe when the time comes, this data will be available to everyone, but not now. In this article, I really don’t want to either praise or scold anyone. Moreover, not all manufacturers of the samples used were even aware of these tests. The only thing I can note is that there were no random participants, only the best.
Before we begin to consider any results, it should be noted that they were not obtained during certification tests of specific samples in accordance with standard methods, but as part of certain research work. Therefore, in particular, instead of the required 4 samples of point optoelectronic smoke detectors from one manufacturer, several similar detectors from different manufacturers were used. They did roughly the same thing with gas fire alarms.
Moreover, to obtain additional information for subsequent analysis, in addition to standard test fires, approximately the same tests were carried out with modified characteristics of the test fire load, but I do not consider it necessary to present their results.
And yet, during test fires, in addition to the response time, other parameters should be monitored, but since all the detectors were simultaneously in similar conditions during the tests, I am omitting this question with a clear conscience, the main thing is that the parameters do not go beyond the limits provided for by the standard .
Table 1 shows the ratio of the time required for the activation of fire detectors during test fires TP2 - TP5 to the standardized one. If you try to translate this into more accessible language, then the percentage of time that was needed to detect a fire for one or another type of detector, in relation to the standardized time. For example, the maximum response time for TP3 is 750 seconds, and the detector was triggered after 190 seconds. It turns out to be only 25% of the time from the limit value. It worked four times faster than required - now we can put him in the “super early” caste, but let’s not rush.
Table 1. The ratio of the time required for the activation of fire detectors at TP2 - TP5, in relation to the standardized
|
according to TP2-TP5 |
|||||
|
Maximum operating time of MP, s |
|||||
|
IPDOT standard nephelometric |
|||||
|
IPDOT experimental absorption |
|||||
|
IPDOT tubeless |
no data |
||||
|
IPDA (sensitivity class A) imported with the maximum possible length of the air pipeline |
|||||
|
no data |
|||||
|
IPG semiconductor |
|||||
|
IPG electrochemical |
Since the article is not of a scientific nature, but is only informational, for greater clarity, the values presented in the table under consideration are very rounded in nature without any probabilistic dependencies.
STANDARD FIRE DETECTORS SMOKE OPTICAL-ELECTRONIC SPOINT DETECTORS (IPDOT)
The one who has always raised doubts is the IPDOT. And here the first and very unexpected conclusion appears. Our domestic IPDOTs, which no one takes seriously in terms of the capabilities of timely fire detection and are used only in accordance with their cost, have, it turns out, a very decent margin in detection time in relation to the normalized one. And this should only make you happy. Unfortunately, in our country not all of them are like that, especially serial ones. But all the same, they can do it whenever they want.
Now imagine what they would be like if they still applied the developments that have long been used in modern foreign EITIs.
EXPERIMENTAL ABSORPTION TYPE IDPOT
This is a very interesting way to detect smoke. This IP does not use the principle of light scattering of the emitter from smoke particles in the measuring chamber, which is called the nephelometric method, but the principle of light absorption (absorption method), like linear fire detectors, only with a very short control section. Two entire articles in the journal “Security Algorithm” were devoted to both the detection method and the detector itself used in this analysis, so I will not consider here the details of the design of this IP.
Oddly enough, but it is he who most claims to be the “ultra-early” fire with a four-fold generalized margin for all test fires. Of course, how else could he be if he has aerodynamic drag air flows are reduced to zero, there are no problems with the statics of the case and it is not afraid of flying dust. But what does the second journal article show us?
of the two already mentioned. It turns out that work on increasing sensitivity, and with it reducing the time to detect a fire, is just beginning. During the comparative tests that I am writing about here, very interesting patterns were discovered. Their implementation can bring a lot of new and interesting things, and then again there will be a reason to hold comparative analysis. And now these are only experimental single copies, and it is still very difficult to say how much the technical and economic indicators of these detectors will justify our hopes.
IPDOT CHAMBERLESS
This type does not have an EITI closed by a housing and labyrinths of the measuring zone. Sometimes this type of IPDOT is classified as a detector with a virtual detection zone, since it is located outside the detector housing. Naturally, this type of detector, just like the absorption type IPDOT, has no aerodynamic resistance to air flows. Consequently, no time is required to overcome the static potential of the body, and no additional energy is required to overcome the labyrinth to the measuring zone. This is the well-deserved result - a three-fold generalized reserve for all test fires. If desired, he can also be classified as a “super-early” caste.
This is a very promising direction in the development of fire detectors, especially if we take into account the results achieved in imported detectors with a similar method of detecting smoke. It is a pity that in our country practically no attention is paid to this area; abroad this is no longer a special case (Fig. 1).
Rice. 1. Options for tubeless IPDOT
THE ASPIRATION MAN, HE IS THE ASPIRATION MAN
Almost everyone knows about the features and exceptional capabilities of aspirating fire detectors (AFDA). Here a detector from a foreign manufacturer was used, and then only as a kind of standard. He is one of the leaders in our table. You just need to understand that not everything is so simple.
Somewhere, in some grocery store within walking distance, you have seen IPDA with your own eyes. I personally don't. Why? And it’s like climbing into a tractor with a tool for laparoscopic operations. Somehow it happened historically that when this type of detector appeared on the market, few people understood that this was not a universal detector for all occasions. And, despite its popularity among specialists, it was used to a very limited extent.
But when manufacturers realized that this type of detector needed to be positioned completely differently, the cart moved. And it really turned out that in some areas of fire protection there are no analogues to it. In the last two or three years, a sufficient number of articles have appeared on this topic, and everything has fallen into place. “Render unto Caesar the things that are Caesar’s, and the things that belong to God that are God’s.”
WHAT IS THE AMBIGUITY OF JUDGMENT ABOUT IPDA?
The IPDA processing unit itself has unsurpassed sensitivity. No one will even argue with this. If you use it to control a small volume, then the IPDA may end up in the mode “if you sniff very closely, the wire has not yet overheated, but is already warm and even smells a little, and something may happen to it someday, but not now, but a little later." The only question that immediately arises is how much it will cost. A lot, but in some cases this is justified.
The same IPDA can be used to control large areas of several thousand square meters, just as stated in the documentation for it. But here you will need to immediately understand that in this case you will have to forget about the crazy sensitivity to fire in each individual room. The gain will only be due to the delivery time of the smoke-air mixture, and even then it will not be that big. But in the same deep-frozen warehouses or in elevator shafts, you can’t put anything else. And in this case, does it make sense to once again mention its possibility of “ultra-early detection” of a fire? Hardly.
SMOKE IONIZATION FIRE DETECTOR (IPDI)
Now we can move on to the sad stuff.
IPDI is what older specialists are constantly nostalgic for. This is their favorite “radioisotope nickname”. It was argued that if IPDOTs can detect only “light smoke,” then the “radioisotope” detector can detect any kind, be it light or dark, and very quickly. And the problem is only with the “green” ones, because of which they have tightened the disposal of these detectors as much as possible.
This myth arose back when the threshold for triggering the IPDOT in the Smoke Channel installation was within 0.5 dB/m (GOST 26342-84), and not as it is now 0.05-0.2 dB/m. Moreover, now IPDOT is obliged to detect not only “light” smoke, but also all others.
Over the past 30 years, a lot has changed, only IPDI has remained the same. And now the opportunity has arisen to compare them with the new generation of fire detectors. And not just based on the response threshold in the smoke duct, which is the least of our interests, but during fire tests.
And what turned out to be - average and even very good. Few people need to use a fairly average detector given today's difficulties in handling radioisotope materials.
It is also necessary to take into account the weak point of IPDI - for them it makes no difference what aerosol particles to detect: smoke, steam, dust. So they still don’t have a way to combat this.
Maybe we have all been nostalgic for so many years in vain and will forgive these “greens” for their “meanness”; without them, it is unlikely that we would have begun to seriously engage in alternative directions.
FEATURES OF APPLICATION OF FIRE GAS DETECTORS (IGD)
A little over ten years ago, there was a wave of using IPG for early fire detection abroad.
The basis was the postulate that every fire is preceded by smoke from smoldering and carbon monoxide (carbon monoxide). This carbon monoxide, due to diffusion, instantly spreads throughout the premises, much faster than the smoke reaches ceiling smoke detectors; this diffusion is not particularly affected by convection air currents. This distribution method allows you to install fire detectors almost anywhere in the controlled premises.
And based on these postulates, we immediately started talking about the possibility of “ultra-early fire detection” using IPG (CO). A holy place is never empty, manufacturers of sensors for IPG (CO) immediately appeared, fortunately they already had similar tasks in industrial automation.
But in the process of developing standards for IPG (SO), we were faced with the fact that they cannot be sensitive to all the main test fires. Well, we left only TP2 (smoldering wood) and TP3 (smoldering cotton with glow) in the requirements and came up with one additional TP9 (smoldering cotton without glow). But left behind are all synthetics and flammable liquids, which can also emit smoke. The producers of IPG (SO) stubbornly hid this from everyone, but you can’t wear an awl in your pants for a long time.
It turned out that when synthetics smolder, it is not carbon monoxide that is released, but hydrogen chloride, which all these IPGs (CO) cannot detect. So, if synthetics surround us everywhere, then with cotton, which must smolder for the IPG (CO) to work, it is much more difficult in our everyday life; it still needs to be found. And then can IPG (SO), which has the ability to detect fire from a limited list of combustible materials, be used as a self-sufficient and universal fire detector?
As a result, a couple of years ago the wave of IPG (SO) abroad completely died out, and people began to forget about it.
And when in our country we had the opportunity to compare everything together, it turned out that the idea of “ultra-early fire detection” using IPG (SO) collapsed at the same time, just as it had done abroad several years earlier. And we had to forget about deep diffusion as a fact that had not been confirmed in practice, and as a consequence, it was impossible to arbitrarily install IPG (CO) in rooms, even behind a cabinet, even under a cabinet.
But what about there, abroad? They didn’t worry too much about it and didn’t break their spears. They very smoothly moved from IPG (SO) to multi-criteria fire detectors. And this is where all the developments in IPG (SO) came in very handy. We in Russia still have to comprehend all this first, especially since we do not yet have such a class of fire detectors as multi-criteria.
SOME FEATURES OF IPG TECHNOLOGIES
It should be noted right away that the sensors carbon monoxide(CO) come in two types: electrolytic-type electrochemical sensors and metal-oxide semiconductor sensors. The former consume practically no electricity, but have a limited service life due to the use of electrolyte, the latter have a fairly long service life, but also have high energy consumption.
For electrolytic type sensors, the service life begins to count from the moment they are removed from a special container in which they are stored in warehouse conditions for their subsequent installation in the IPG. Specifications and the price of the carbon monoxide sensor itself, about 1-2 thousand rubles, are decisive for IPG (CO).
Today, only one manufacturer of these sensors in the world (Nemoto Sensor Engineering Co) can provide a 10-year service life guarantee. All the rest so far guarantee no more than five years, and a couple of years ago there was no more than three years of work.
The limited service life of carbon monoxide sensors does not allow the widespread use of both IPGs themselves and their combinations with thermal or smoke channels detection. Almost all manufacturers of fire automatic equipment, with the exception of IPG, indicate in their documentation the period
service for at least 10 years. In practice, the service life is rarely less than 15 years; after all, this is not the cheapest pleasure. Not a single foreign manufacturer allows you to independently replace carbon monoxide sensors in detectors, while honestly stating their service life of 5 years.
This is “ultra-early detection” using IPG, and the opportunities are still illusory, and the difficulties are objective.
SO TO BE OR NOT TO BE “SUPER EARLY FIRE DETECTION”
This issue should be resolved by the direct customers of fire safety services. If all requirements are met regulatory documents, if the manufacturer does not produce products that do not meet the declared characteristics, then nothing extra may be needed.
If someone wants to distinguish himself, he can put an IPDOT in his electrical panel next to the electricity meter, hide the same one behind the refrigerator and behind the TV, and go to bed with a calm soul. Similar method“ultra-early detection” of fire may even be the most economically effective compared to others. But who can force it to be used and on what basis?
If you particularly wish, you can install an aspiration detector in the office of the head of a particular organization, at his request and for his money, which will be triggered every time during heated disputes with subordinates. Well, the customer’s desire is the law.
In this article I have never mentioned linear smoke detectors (LSD). Also a very good thing, it just so happens that they did not take part in the research trials. If IPDL is used with maximum sensitivity at short distances, then the fire detection time is reduced several times. What is not “ultra-early detection”. It’s very simple, and you don’t need to invent anything new, I tested it myself. It's just low economic efficiency does not allow making such decisions.
No one, either abroad or in our country, will agree to additional requirements to ensure “ultra-early detection” of fire. As a result, this term should be excluded from everyday practice; it should not be used on occasion or not and mislead others with it. We don't need these myths.
LITERATURE
1. GOSTR 53325-2012 “Fire fighting equipment. Fire automatic equipment. Are common technical requirements and test methods."
-
For buildings and structures that store priceless collections and at the same time are objects with large numbers of people, timely and reliable fire detection is key. But there are objective reasons why traditional fire alarm systems remain either unacceptable or not reliable enough for cultural heritage sites. The best decision aspiration detector. That is why a whole list of cultural sites around the world are equipped with WAGNER products.
Modern development of microprocessor electronics and information technologies allowed us to approach the problem of fire detection in a fundamentally new way: from the analysis of a set of individual sensor elements that continuously measure atmospheric parameters in the vicinity of the detector (concentration of solid particles and carbon monoxide, air temperature), to the ability to recognize in the measured values the “sufficiency” of conditions corresponding to a fire , in a minimum amount of time. Bosch's technology for continuous analysis of seven environmental parameters helps improve the reliability of fire alarm system detection and significantly reduce the likelihood of false alarms, even in difficult operating conditions.
For reliable fire detection in facilities with special conditions environments such as corrosive gases, high humidity, high temperatures and air pollution, Securiton offers a system based on the MHD635 LIST temperature sensitive cable. This is the system high level safety, easy to install and install and does not require maintenance. Thermal sensitive cable Securiton MHD635 is used in the following objects: automobile and railway tunnels; tunnels and metro stations, track facilities; conveyor systems and automatic lines; cable tunnels and trays; warehousing and racking; industrial furnaces; freezers deep frozen; cooling and heating devices; food industry facilities; parking lots, walking excavators, ship mechanisms.
The SecuriSens ADW 535 thermal differential linear detector from Securiton combines a proven operating principle with the latest advances in sensor and processor technologies. Thanks to the extremely resistant sensor tube, SecuriSens ADW 535 can be used where traditional fire detectors cannot be used. Durability and maintenance-free design make the ADW 535 the ideal solution. SecuriSens ADW 535 fully meets the requirements for modern linear thermal detectors, such as: full automatic monitoring of large spaces, resistance to aggressive environments, extreme humidity and high temperatures, the ability to distinguish real dangers from false ones. SecuriSens ADW 535 is a smart device that works great even in the most difficult conditions.
-
For 2019, it is planned to develop a new national standard “Fire Alarm Systems. Manual for design, installation, maintenance and repair. Performance test methods." The article discusses issues related to maintenance and repair. It is important that, due to incomplete or incorrect formulations, service organizations do not end up in the extreme and are not forced to eliminate shortcomings they made at the design stage. It is imperative to test all systems as a whole at sites during scheduled maintenance to check their functioning according to the algorithms specified by the project.
-
Target of this material– consider the main aspects of legislative regulation of the implementation of federal state control (supervision) over the activities of legal entities and individual entrepreneurs, and especially the activities of legal entities with special statutory tasks and departmental security units.
Work on the project began in January 2017 interstate standard“Fire control and control devices. Fire control devices. General technical requirements. Test methods". The next stage was the draft set of rules “Fire alarm systems and automation of fire protection systems. Design norms and rules." In the drafts of new documents, the tasks at hand are identified, and the necessary requirements aimed at their implementation are attached to them. Each requirement is a consequence or cause of other requirements. Together they form a completely interconnected system.
Currently, most detection methods forest fires are associated with the personal presence of rescuers: patrolling, observation from towers and helicopters, as well as the use of space data. All measures taken are certainly effective in the absence of abnormal heat. But, during a drought, when fires simultaneously cover vast territories in the most different corners country, the question of more advanced monitoring and early warning systems for forest fires is acute.
Forest fire detection system
Innovative developments in this direction have made it possible to create a completely unique “Forest fire detection” system. Unlike all currently existing methods of fighting fires, this system works automatically, with virtually no human intervention, alerting the operator at the earliest stages of fire detection.
“Forest fire detection” is a large-scale system of sensors that allows:
- Conduct continuous video surveillance.
- Detect smoke early.
- Automatically notify rescue services.
- Predict the scale of development of the fire source.
- Calculate the amount of forces aimed at extinguishing the fire.
The equipment is equipped autonomous system food and has high degree protection from various weather conditions and force majeure circumstances. This means that the system will not fail during a thunderstorm and will allow detection of areas affected by lightning.
How to purchase a system
Company "Xorex-Service", representing technology "Forest fire detection" on the Belarusian market, has established itself as a reliable partner in the field of IT technologies. All equipment promoted by the company undergoes mandatory certification and is of excellent quality.
Each order is processed individually:
- At the initial stage, highly qualified specialists will assess the area, taking into account all the features of the relief, the availability of infrastructure, and even the weather conditions of the provided territory.
- At the second stage, all work on installing and configuring the equipment will be carried out, taking into account all the individual characteristics identified earlier.
- After preparation, the company’s specialists will train your organization’s personnel to use the system and provide ongoing support from their side. These are the guarantees of service!
What’s also attractive is that you can see for yourself the effectiveness "Forest fire detection" having tried our system. You will definitely be pleased with the team of professionals and the cost of system maintenance. And timely forecasting of a terrible natural disaster will help to avoid many irreversible consequences of forest fires.
