I.G. not bad
Department head technical support of the company "System Sensor Fair Detectors", Ph.D.
General provisions
A fire smoke aspiration detector is a detector in which air and smoke samples are transported through a sampling device (usually through pipes with holes) to a smoke-sensitive element (point smoke detector) located in the same unit with an aspirator, for example, a turbine, a fan or pump (Fig. 1).
The main characteristic of an aspiration detector, like any smoke detector, is sensitivity (that is, the minimum value of the specific optical density in one of the samples at which the detector generates a "Fire" signal). It depends on the sensitivity of the point smoke detector used, as well as on the design of the sampling device, on the number, size and location of holes, etc. It is important to ensure approximately the same sensitivity for different samples, that is, a balance in sensitivity. Another important characteristic of an aspiration detector, which is not taken into account for a point smoke detector, is the transport time, the maximum period of time required to deliver an air sample from the sampling point in the protected room to the sensitive element.
test room
To determine the sensitivity of the aspiration detector according to the EN 54-20 standard, tests are carried out on test foci in a room with a size of (9-11) x (6-8) m and a height of 3.8-4.2 m (Fig. 2), as in spot tests smoke detectors according to EN 54-7. A test fire source is installed on the floor in the center of the room, and on the ceiling, three meters from its center in the 60 ° sector, there is an aspiration detector pipe with one air intake hole, as well as a meter for the specific optical density of the medium m (dB / m) and a radioisotope meter concentration of combustion products Y (dimensionless value).
It is allowed to test no more than two samples of aspiration detectors simultaneously, while their air intake openings must be located at a distance of at least 100 mm from each other, as well as from the elements of the measuring equipment. The center of the light beam of the medium optical density meter m must be at least 35 mm from the ceiling.
Test fires for point smoke detectors
Point fire smoke detectors according to the EN54-12 standard are tested on fumes from four test sources: TF-2 - smoldering of wood, TF-3 - smoldering of cotton, TF-4 - burning of polyurethane and TF-5 - burning of n-heptane.
The hearth TF-2 consists of 10 dry beech blocks (moisture ~ 5%) with dimensions of 75x25x20 mm, located on the surface electric stove 220 mm in diameter, having 8 concentric grooves 2 mm deep and 5 mm wide (Fig. 3). Moreover, the outer groove should be located at a distance of 4 mm from the edge of the plate, the distance between adjacent grooves should be 3 mm. The power of the stove is 2 kW, the temperature of 600 ° C is reached in about 11 minutes. All tested detectors must be activated when the specific optical density m is less than 2 dB/m.
The TF-3 hearth consists of approximately 90 cotton wicks 800 mm long and weighing approximately 3 g each, suspended on a wire ring 100 mm in diameter, mounted on a tripod at a height of 1 m above a base of non-combustible material (Fig. 4). Cotton wicks should not have protective coating, if necessary, they can be washed and dried. The lower ends of the wicks are set on fire so that smoldering with a glow appears. All tested detectors must be activated when the specific optical density m is less than 2 dB/m. Fireplace TF-4 consists of three stacked polyurethane foam mats, free of fire retardant additives, with a density of 20 kg/m3 and dimensions of 500x500x20 mm each. The hearth is ignited by a flame of 5 cm3 of alcohol in a container with a diameter of 50 mm, installed under one of the corners of the lower mat. All tested detectors must be activated when the concentration of combustion products Y is less than 6. The TF-5 hearth is 650 g of n-heptane (minimum 99% purity) with the addition of 3% by volume of toluene (minimum 99% purity) in a square tray made of steel measuring 330x330x50 mm. Activation is done by flame, spark, etc. All tested detectors must be activated when the concentration of combustion products Y is less than 6.
Classification of aspiration detectors
Aspiration detectors, unlike point smoke detectors, according to the EN54-20 standard are divided into three classes according to their sensitivity:
- class A - ultrasensitive;
- class B - high sensitivity;
- class C - standard sensitivity.
Sensitivity limits for detectors of different classes for various types of test sources are given in Table. 1. Class C aspirating detectors are equivalent in sensitivity to point detectors, and the same test sources are used for their testing. The only difference is that the end of the test is determined 60 seconds after reaching boundary conditions. Obviously, this time is required to take into account the time of transportation of the sample through the pipe. Aspiration detectors of classes A and B have a significantly higher sensitivity compared to a class C detector. For example, for test fires TF2 and TF3, the sensitivity indicators of a class B aspiration detector are 13.33 times higher, and class A - 40 times higher than those of class C detectors and point smoke detectors. Such high performance is achieved through the use of laser point smoke detectors with a sensitivity of 0.02% / Ft (0.0028 dB / m) and higher as a smoke-sensitive element. In addition, taking air samples from a controlled room and creating a constant flow of air in one direction through the smoke chamber with an aspirator puts even a conventional optical detector in a more advantageous position than when it is installed on the floor, where the efficiency is significantly reduced due to the significant aerodynamic resistance of the protective mesh and smoke chamber at low air velocities. Under conditions of constant air flow, the sensitivity of the smoke detector is more stable, and its value practically does not differ from the results of measurements in a wind tunnel according to NPB 65-97, which simplifies the design of fire alarm systems using aspiration fire detectors. Analog addressable aspiration detectors with programmable sensitivity can belong to several classes (A/B/C). In accordance with their range of measurement of the specific optical density of the medium, they can generate, in addition to the "Fire" signal, one or more preliminary signals, for example, "Attention" and "Warning", for more early stages development of a fire situation. The laser aspiration detector, in fact, is a high-precision meter of the optical density of the medium entering the central unit in a wide range. To adapt to different conditions operation and for programming several thresholds, about 10 samples are usually sufficient (Table 2).
Test foci for aspirating detectors of classes A and B
To measure the sensitivity of aspiration detectors of classes A and B, test foci are used that are several times smaller. In the test hearths TF2A and TF2B, instead of 10 beech bars, only 4 or 5 bars are used (Fig. 5), in the hearths TF3A and TF3B, instead of 90 wicks, approximately 30-40 are used.
It is physically difficult to ensure a slower development of a polyurethane foam lesion compared to the TF4 test foci, therefore TF4A, TF4B foci are absent in the EN54-20 standard. Test foci TF5A, TF5B with n-heptane are formed much easier: the dimensions of the tray and the volume of n-heptane used are reduced. Compared with the area of the test TF5 lesion, the area of the TF5B lesion is 3.56 times smaller, and the area of the TF5A lesion is 10.89 times smaller (Table 3). One reduction in the size of the test foci for testing highly sensitive class B and ultra-highly sensitive class A aspiration detectors was not enough. To create minimal smoke concentrations under the ceiling in the test room, a ventilation system is installed (Fig. 6) at the level of half the height of the room and at a distance of 1 m from the source in the horizontal projection. When the ventilation system is operating, the smoke from the test hearth does not accumulate under the ceiling, but is evenly distributed throughout the entire volume of the room. Thus, a decrease in the size of the test source and the distribution of smoke throughout the room made it possible to ensure a slow increase in the optical density of the medium, which made it possible to measure the sensitivity of the aspiration detector with high accuracy at a level of less than 0.01 dB/m. As an example, in fig. Figure 7 shows the dependences of the specific optical density for the TF3A test focus. It should be noted that the optical density when using test sources when measured in dB/m increases linearly, which makes it possible to estimate the gain in time for determining a fire situation with an increase in the sensitivity of the smoke detector.
Smoke reduction (dilution)
If there are several holes for sampling, the concentration of smoke in the air sample decreases in proportion to the volume of clean air entering the pipe through the remaining holes (Fig. 8). Consider the case with 10 air sampling holes. To simplify the calculation, let's assume that the same volume of air passes through each hole. Assume that smoke with a specific optical density of 2% / m enters the pipe through one air intake hole, and clean air enters through the remaining 9 holes. The smoke in the chimney is diluted clean air 10 times, and its density upon entering the central unit is already 0.2%/m. Thus, if the threshold of the smoke detector in the central unit is set at 0.2%/m, then the signal from the detector will appear when the smoke optical density exceeds 2%/m in one of the holes. In table. 4 shows data to evaluate the effect of smoke dilution for different number air intake holes in the pipe. How more number air intake openings in the pipe, the more pronounced the effect of reducing the sensitivity of the aspiration detector. In reality, calculating the dilution of smoke with clean air is more complicated than described above. It is necessary to take into account the size, number and location of air sampling openings, the presence of corner connections, tees and capillaries in 
pipe system, diameter, etc. In addition, to equalize the air flows through the holes, and, accordingly, the sensitivity, a plug with a hole is installed at the end of the pipe, the area of \u200b\u200bwhich is several times larger than the air intake holes, which should also be taken into account in the calculation. When designing a fire alarm system using aspiration fire detectors, it is necessary to use computer program calculation for a specific type of equipment. In practice, smoke usually enters simultaneously through several adjacent openings. This is the so-called cumulative effect, which is most pronounced in high rooms. Therefore, when increasing the height of the room, it is not necessary to reduce the distance between the pipes and between the holes in the pipes. According to the British standard BS 5839-1:2001, class C standard sensitivity aspiration detectors are allowed to protect rooms up to 15 m high, class B high sensitivity detectors up to 17 m, class A ultra-high sensitivity detectors up to 21 m. horizontal projection in the form of a circle with a radius of 7.5 m.
Airflow control
It is essential to control the air flow through the smoke detector in the aspirating detector unit. A decrease in air flow indicates clogging of the holes in the pipes, an increase indicates a leak in the pipe connection or mechanical damage to the pipeline. In these cases, there is a violation of performance - a decrease in sensitivity.
Monitoring the change in the level of air flow in the aspiration detector is equivalent to monitoring the state of the loop (for open and short circuits) when using point fire detectors. In addition, there is a need to store the value of the "normal" air flow in non-volatile memory in case of power failure. To be able to measure the deviation of the air flow from the norm, it is necessary to ensure high stability of the performance of the aspirator during the entire service life of the aspirating detector, i.e. at least 10 years. Thus, despite the seeming simplicity of constructing an aspiration detector, its practical implementation impossible without knowledge of the laws of aerodynamics, the use high technology and special computer programs.
According to the requirements of the EN54-20 standard, the aspiration detector must signal "Fault" when the air flow changes by ± 20%. In the course of testing, the amount of air flow in the pipe is initially measured using an anemometer, when air is supplied through the pipe in the normal mode. After that, only an anemometer and two valves are installed in front of the block (Fig. 9). Valve 2 is set to the middle position, and valve 1 is used to set the initial air flow with an accuracy of ±10%. After that, the valve 2 increases the air flow by 20%, and then reduces it by 20%. In both cases, the formation of the "Fault" signal is monitored.
Requirements for the installation of aspiration detectors
The requirements for the installation of aspiration detectors are given in the Recommendations of the Federal State Institution VNIIPO EMERCOM of Russia. One zone protected by one channel of an aspiration fire detector may include up to ten isolated and adjacent rooms with a total area of not more than 1600 m2 located on one floor of the building, while, in accordance with the requirements of NPB 88-2001 *, isolated rooms must have access to common corridor, hall, vestibule, etc.
The maximum height of the protected room, as well as the maximum distances in horizontal projection between the air intake opening, the wall and between adjacent openings are given in Table. 5. When protecting rooms of arbitrary shape, the maximum distances between air inlets and walls are determined based on the fact that the area protected by each air inlet has the shape of a circle 6, 36. (Fig. 10)
conclusions
Aspiration detectors of class B provide an increase in system sensitivity by more than 10 times, and class A - by 40 times compared to point smoke detectors. Recommendations for the design of fire alarm systems using aspiration smoke fire detectors, developed by FGUVNIIPO EMERCOM of Russia, determine wide opportunities on protection by aspiration detectors of objects of various types.
Can you help me with the IPA aspiration detector?Certificate of conformity С-Ru.ПБ01.В.00242
Aspiration fire detector IPA TU 4371-086-00226827-2006
Operation manual DAE 100.359.100-01 RE p. 2.9 The detector detects the occurrence of a fire with the formation of notices and ranking according to the degree of danger in accordance with paragraphs 2.12.2, 2.12.3 (at the inlet of the connection to the suction pipe detector) with standard sensitivity class A according to GOST R 53325-2012.
Note - Upon detection of a fire and the issuance of danger signals "Alarm"
ha 1", "Alarm 2", "Start" simultaneously take into account the data of all measurement channels
of fire factors and their sensitivity is adjusted in an interconnected manner.
paragraph 4.1 The detector is made in a sealed housing, consisting of five
separate compartments (discharge, injection and coarse cleaning, fine cleaning, change
rhenium and terminal connections). Inside the case under the top panel is located
compartment of the electronic module with channels for measuring fire factors:
- "Temperature" - responds to changes in the temperature of the controlled environment;
- "Smoke" - reacts to changes in the optical density of the gas-air medium;
- "Gas" - responds to changes in the concentration of installed gases;
- "Flow" - responds to changes in the gas-air flow and filter contamination.
I am citing an excerpt from SP5 p14.2 ... when one fire detector is triggered that meets the recommendations set out in Appendix P. In this case, at least two detectors are installed in the room (part of the room), switched on according to the "OR" logic circuit. The placement of the detectors is carried out at a distance of no more than the normative one.
APPENDIX R:
P.1 Use of analysis equipment physical characteristics fire factors and (or) the dynamics of their change and issuing information about its technical condition (for example, dust content).
P.2 Use of equipment and its modes of operation, excluding the impact on detectors or loops of short-term factors not related to fire.
It follows from this that the aspiration detector complies with Appendix P, and therefore we do not reduce the distance between the detectors and make two air intake holes in each room, but there is one more point in the manual:
Operation manual DAE 100.359.100-01 RE point 6.10 The location of intake openings in the protected room must be carried out in accordance with the requirements of clause 13.3 of SP 5.13130.2009
Reading SP:
13.3.2 At least two fire detectors connected according to the "OR" logical scheme should be installed in each protected room.
Note - In the case of using an aspiration detector, unless specifically specified, it is necessary to proceed from the following provision: one air intake hole should be considered as one point (non-address) fire detector. In this case, the detector must generate a fault signal in the event of a deviation in the air flow rate in the air intake pipe by 20% from its initial value set as an operating parameter.
1. That is, by connecting the device to the S2000-KDL, we prescribe the address of the device, and the IPA detector becomes addressable and paragraph 13.3.2 is already in effect?
2. But the question arises then why point 6.10 of the instruction manual, which means that it is possible to connect the IPA to Signal 20, but at the same time we reduce the distance and put three detectors per room?
3. The manual states that plastic pipes can be used as an air duct, but will metal-plastic be suitable?
4. Are all generated commands displayed on the S2000 control panel?
5. For example, there is a warehouse wooden planks, height 12.8 m, length 60 m, width 25, stacks of boards do not exceed a height of 4 m, the boards are loaded directly inside, that is, transport drives directly to the warehouse. Naturally, it is not heated, dust, the wind is walking, but consider the street, do you think it is advisable to use this type of fire detectors?
The principle of forced air intake (aspiration) from various parts of the room for constant monitoring has become the basis for the creation of a whole line of highly sensitive smoke detectors of the LASD (Laser Aspirating Smoke Detector) series. Effective indoors up to 2 thousand square meters, with a ceiling height of up to 21m, with a length of air ducts - from 50 to 120m.
Each model is equipped with a system for detecting malfunctions in the functioning of the hardware and the air sampling pipe system. With a simple connection to a PC or PPC, standard settings can be changed using the PipeIQ® software, which also handles the design of ductwork and installation of basic equipment.
Functional features of LASD detectors
The air flow from the protected room passes through a chamber with a laser emitter capable of detecting the presence of smoke particles. The laser beam is not reflected from the walls of the chamber, which eliminates background noise and erroneous operation, and the presence of programmable states "ATTENTION", "WARNING", "FIRE" guarantees very early information about changes in the composition of air masses, which in turn prevents the development of critical situations ( stoppage of production, evacuation, material damage).
The highest level of protection for objects, especially those that do not allow the installation of classic point detectors, can be achieved due to the design and principle of operation of the LASD series detectors:
Sensitivity - maximum 0.03% / m;
Log of fixing critical situations - up to 18,000 events;
The influence of the movement of air flows on the reliability of the data is minimized;
Two levels of filtration, FLU2;
Intuitive indication on the front panel;
Maintenance and installation - simple, comfortable and fast;
Minimum costs for the modernization of substation systems.
The LASD System Sensor series is represented by 4 basic models with structural differences.
One laser detector in one channel, up to 1000 sq.m. controlled area;
Two laser detectors in one channel, up to 1000 sq.m. controlled area;
One laser detector in each of two channels, up to 2000 sq.m. controlled area;
Smoke aspiration fire detectors (IPDA) are detectors of a new generation that can provide fire protection of objects at the highest possible level and under almost any operating conditions.
Unlike point and linear aspiration smoke detectors, there are no regulatory restrictions on the maximum sensitivity level, and their principle of operation and design features allow you to effectively protect the most complex objects. For example, areas with high airflow rates, overhead and underfloor spaces with extremely high or low temperatures, dusty and explosive areas, rooms with limited access, rooms with high ceilings, domes, beams, etc. Concealed installation of pipes in overhead space, in building structures or in decorative elements rooms with transparent capillary tubes for the formation of remote air sampling points.
Aspirating smoke detectors were invented by Xtralis over 30 years ago and have been featured on the market for over 20 years. Russian market. Until 2009, aspiration detectors were used according to the recommendations of VNIIPO, which were developed for aspiration detectors of each specific type. In 2009, the requirements for the installation of smoke aspiration detectors were defined in the “Code of Rules SP 5.13130.2009 of the System fire protection. Fire alarm and fire extinguishing installations are automatic. Norms and rules of design». In the same year, GOST R 53325-2009 “Fire fighting equipment. Technical means fire automatics. Are common technical requirements. Test Methods”, which for the first time defined the technical requirements and methodology for testing IPDA. These norms and requirements were further developed in subsequent versions of these documents: in GOST R 53325-2012 and in SP 5.13130.2009 with Amendments No. 1.
Of greatest practical interest are class A laser smoke detectors, which have now achieved a fantastic sensitivity of 0.0002%/m (0.00001 dB/m). High-sensitivity laser aspiration detectors provide the highest level of fire protection in cleanrooms, containment areas, operating rooms, computer magnetic resonance, positron emission tomography, pressure chambers, high rooms and areas with air currents: atriums, data centers , in MCC, industrial shops, in high-rise warehouses, etc. Highly sensitive laser IPDA provide ultra-early detection of fire danger, which determines the minimum material losses, no need for evacuation and interruption of the enterprise. To ensure the possibility of prompt response of personnel, several pre-alarm and alarm signals are generated at various levels of smoke. Aspiration detectors with increased sensitivity of class B and class C with standard sensitivity, i.e. with the sensitivity of a point smoke detector, have a narrower scope.
Operating principle
According to GOST R 53325-2012, an aspiration fire detector is an “automatic fire detector that provides sampling through a system of pipes with air sampling holes and delivery of air samples (aspiration) from the protected room (zone) to a device for detecting a sign of fire (smoke, changes chemical composition environment)" (Fig. 1). This principle of construction of the detector, unusual at first glance, with pipes with air intakes and an aspirator, determines a lot of advantages compared to smoke point and linear detectors. Air samples from the controlled room enter the pipes due to the discharge created by the aspirator, which, together with the optical density meter, is located in the processing unit.
Aspiration smoke detectors are sophisticated active fire detection devices that provide a reliable warning or alarm signal at the earliest stages of the appearance of signs of a fire. Aspiration fire smoke detectors consist of a detector unit with an aspirator and a piping system with air sampling holes through which air samples from the controlled space are delivered to the detection device (Fig. 1). This design of the detector allows you to isolate the measuring chamber from external influences as much as possible. High sensitivity, which in some models reaches 0.0015% / m (0.000065 dB / m), is many times higher than the parameters of point detectors and is achieved through the use of ultra-sensitive optical density meters. Aspiration detectors are used to control not only premises, but also equipment, air conditioning installations and air ducts. The use of aspiration detectors provides the highest level fire protection of any object, and the specifics of the design and accessories allow them to be used even where the use of other types of detectors would be ineffective or simply impossible.
On this moment technical requirements for aspiration detectors are established in GOST R 53325-2009 “Fire fighting equipment. Technical means of fire automatics. General technical requirements. Test Methods". In this article, we will not focus on technical specifications, and consider the possible applications and advantages of installing aspiration detectors on various types objects.
In Russia, the basic requirements for the design and installation of aspirating fire detectors are defined by the Code of Rules SP 5.13130.2009 “Fire protection systems. Fire alarm and fire extinguishing installations are automatic. Norms and rules of design». And here the first point is the recommendation to install aspiration detectors to protect large open spaces. These areas include atriums, production shops, warehouses, trading floors, passenger terminals, sports halls, stadiums, etc. According to clause 13.9.1, class A aspiration detectors can be installed in rooms up to 21 m high, class B - up to 15 m, class C - up to 8 m In the case of using aspiration detectors in a room with a height of more than 12 m, unlike linear smoke detectors, installation of a second tier of detectors is not required. Building structures usually impose certain restrictions on the installation sites of linear smoke detectors in such premises, forcing them to be mounted at a certain distance from the ceiling, which in turn seriously reduces the level of fire protection of the premises and the facility as a whole. Aspiration detectors do not have these disadvantages. Piping with air sampling holes can pass directly under the ceiling, avoid obstacles, while expanding the controlled area and reducing the likelihood of false alarms.
Moreover, in accordance with SP 5, it is allowed to embed air sampling pipes in building construction and finishing elements. This application option allows you to protect rooms with high design requirements, such as historical buildings, museums, rooms with a large glass area, etc. Moreover, the elements of the fire alarm system in this case are really invisible, and the level of fire protection remains at the highest level.
Air sampling pipes can be laid both horizontally and vertically. vertical plane, which makes it possible to determine at the system design stage best option access to the detector for maintenance and repair and locate it in the most convenient place for this. Suppose you want to control limited hard-to-reach spaces, such as the space behind false ceiling and under the raised floor, cable duct, the interior of units and mechanisms, such as escalators or conveyor lines. And here, according to SP 5, the use of aspiration fire detectors is allowed. It is allowed to control both the main and allocated space of the room, i.e. in the case of monitoring the overhead space, the pipes of the aspiration detector are located behind the false ceiling, and additional capillary tubes lead the air sampling holes into the main space. Special attention should be given to the issue of protection of expensive equipment and material assets. The use of highly sensitive aspiration detectors when protecting, for example, servers or data arrays, makes it possible to detect even overheating of individual components of an electronic device. The advantage of aspirating detectors is that the pipe or capillary outlet with an air intake is led directly to the object to be protected. Figure 3 shows an example of equipment cabinet protection. Server rooms, data processing centers, warehouses with rack storage and other facilities where it is extremely important to detect and eliminate the source of ignition at the earliest stage in order to prevent major damage are equipped in the same way.
Often there are objects, the control of which by traditional methods is complicated by difficult conditions, such as dust, dirt, extreme temperatures, high humidity, electromagnetic interference, high air flow speeds, etc. The use of aspiration detectors here is also effective way protection. Since air sampling from controlled volumes is carried out through small holes, air flows from ventilation and air conditioning systems do not affect the detection ability. That is why it is possible to place the air intake pipes of the aspiration detector directly in the air ducts and on the air intake grilles. If the operating conditions are associated with significant contamination or dustiness, then additionally installed in the pipeline system external filters(Fig. 4).
Protecting the measuring chamber of the instrument from foreign particles entering it reduces the likelihood of false alarms and prolongs the life of the system. In the most difficult conditions, such as in waste treatment plants or industrial productions, additionally provide for purging the pipeline in the opposite direction. To do this, a valve is installed, which, when blowing, cuts off part of the pipe to the detector unit, after which the contaminants are blown out of the pipeline. And in some cases, when blockages in pipes can happen too often, it may be advisable to implement automatic cleaning of the pipe system.
| Rice. 3. Location of pipes when protecting cabinets with equipment |
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Rice. 4. Three-level replaceable filter for air purification |
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Rice. 5. Condensate extraction device (FAS*ASD*WS) |
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Rice. 6. Example of a pipeline with a condensation protection device |
In the case of monitoring areas with changing temperature or incoming fresh air, condensation may form in the aspiration system, which may impair the operation of the detector unit. However, there is a solution for this case as well. Piping in areas with high humidity
equipped with an additional device for collecting condensate (Fig. 5).
In addition to protecting the detector unit from moisture, such devices may have a filter for additional protection from solid particles. It is installed at the lowest point of the pipeline (Fig. 6). And additional pipe turns at an angle of 45 ° allow you to provide access to it during maintenance.
The solution described above is used in areas with temperatures from 0° to 50° C. But the range of operating temperatures during the operation of aspiration detectors is much wider and allows them to be used even at negative values in deep-freeze warehouses. The detector unit itself, depending on the optical density meter used, can operate at temperatures from *20° C to +60° C.
When installing suction systems, halogen-free plastic pipes are usually used. PVC pipes allow them to be used at temperatures from 0° to 60° C. ABS plastic pipes can be used in the range from *40° to +80° C. Nevertheless, the detector unit is most often taken out of the area with difficult conditions. This further expands the scope of this type of detectors. Let's consider one more example. Agree, it is quite difficult to find a suitable detector to protect the sauna. Some models of aspiration detectors allow you to perform their detection functions at air sample temperatures up to 110 ° C. Of course, for this example, plastic pipes are no longer suitable, but to exclude false positives, it is essential to use a condensate extractor.
There are several other areas of application related to the possibility of moving the detector unit outside the controlled area. plastic pipes are not conductors and are not subject to
the influence of electromagnetic interference. Such a system can be operated even in conditions of high radiation. In turn, the remote block of the aspiration detector does not create interference in the controlled area, which is very important for diagnostic and testing laboratories.
Many mistakenly believe that the absence of loop conductors in the controlled area will allow the use of aspiration detectors in explosive objects in a similar way. Such a solution does exist, but the situation is somewhat more complicated. Indeed, in this case, it is not air that enters the measuring chamber, but an explosive gaseous mixture, but the detector unit itself when certain values its composition, concentration, temperature and pressure may become a source of ignition. To prevent the spread of flame through the pipeline and detonation in the explosive zone, special explosion-proof barriers are used in the system (Fig. 7).
As we can see, the possibilities of aspiration detectors are wide and varied. The properties of aspirating smoke detectors, compared to traditional point and other types of detectors, are unique: high sensitivity for early detection, and the ability to install in large spaces, and the ability to work in difficult conditions, and ease of maintenance even in hard-to-reach places. Undoubtedly, the regulatory framework created in 2009 will allow aspiration systems to occupy their niche in the Russian market of fire detectors and increase the level of fire safety many objects.
