The statistics of a large number of fires is confirmed by the daily response of fire brigades. The causes of a fire can be varied - from smoking in the wrong place and careless handling of fire to electrical short circuits and arson. An automatic fire alarm warns of a fire and allows you to eliminate the source in time.
What is a fire alarm
Primary recording devices - sensors - are designed to timely and quickly detect the first signs of fire and smoke. The sensor can either independently activate the alarm, or activate the warning system, turn on fire extinguishing and transmit data to the emergency department of the Ministry of Emergency Situations. The fire alarm is the set of technical means of primary detection and information described above.
Proper setup and timely testing of fire detection systems play an important role. Sensors for a long timeoperation can get dirty, fail, which affects their performance and, as a result, the safety of life and property of people. Rapid detection of a fire source and decoding information about its location can solve various problems:
- Activation of the fire extinguishing system and informing the fire brigade of the Ministry of Emergency Situations.
- Evacuation of people.
- Localization of the source of fire.
- Reducing financial spending.
- Minimize human injury and death.
Types of fire alarms
Components of modern fire systems may vary. The principle of operation and the type of alarm determine the choice of the necessary equipment - cables, sensors, power supplies, etc. According to the structural diagram, fire alarms are:
- Threshold with radiant train.
- Threshold with modular construction.
- Addressable analog.
- Address polling.
- Combined.
Address-analogue systems
To collect and analyze information received from humidity, temperature, smoke and other sensors, analogue addressable fire systems are being created. The control panel reads in real time the readings of the sensors, each of which is assigned a specific location address. The information received from different sensors is analyzed, after which, by means of an address signaling, the location of the ignition source is determined and a signal is given on fire. The structure of the address loops is ring,up to 200 sensors and devices are connected to each of them:
- Manual and automatic call points.
- Relay.
- Control modules.
- Sirens.
Advantages of analogue addressable fire alarms:
- Almost no false alarms.
- Quick fire detection.
- Ability to adjust the sensitivity of the sensors.
- Minimum costs for connection of the fire alarm circuit and its subsequent maintenance.
Address polling
In addressable and threshold systems, the fire signal is generated by the sensor itself. The information exchange protocol is implemented in the loop in order to determine the triggered sensor. Unlike the address-analogue system, the algorithm of the address-interrogation is simpler. Signals are sent from the sensors to the control panel, then the detectors are cyclically polled to find out their status. The disadvantage of such systems is the increase in the time of detection of the ignition source.
Benefits of alarms:
- Best value for money.
- Informativeness of received signals.
- Control of settings and functionality of detectors.
Threshold
Fire alarm system with a circuit in which each detector has a certain sensitivity threshold. The alarm signal in it is triggered by the number of one of the sensors. Such fire systems are installed on small objects- in kindergartens and shops. Their disadvantage is the minimum information content - only the sensor is triggered - and the lack of indication of the location of the source of ignition. The advantages include the low cost of the alarm itself and the process of its installation.
Design of fire systems
The fire and security alarm system is represented by sensors that signal the appearance of smoke, a system for collecting, controlling and transmitting data. Each of the elements of the fire system is responsible for specific tasks:
- Security and fire panel - activates the system.
- Sensors - detect smoke and give an appropriate signal.
- Reception and control panels - collect and process incoming information, transmit signals to the appropriate services.
- Peripheral equipment - provides communication lines, power supply, activation of the fire extinguishing system, information methods.
- Equipment for the central control of the fire and security alarm system - receives alarms from various objects and collects information for the departments of the Ministry of Emergency Situations.
Working principle
The fire alarm system operates on the basis of a sequential poll of all sensors and the detection of the fact that one of them is triggered in the case of threshold systems or changes in environmental parameters in the case of addressable analog systems. Threshold systems, when the sensor is triggered, cut off the entire loop, which indicates the presence of a fire in the area where this loop is located. Irrigation activation in the smoke zoneoccurs in automatic fire extinguishing systems after receiving the appropriate signal, which also gives an alarm and sends a call to the central console.
Fire system sensors
The main function of fire alarm sensors is a quick response to changes in environmental parameters. Sensors differ from each other in terms of the principle of operation, the type of controlled parameter, and the method of transmitting information. The principle of functioning can be of two types - passive and active: the first implies only operation, the second - operation and monitoring of environmental parameters. Depending on the threat level, active detectors send different signals to the automatic control post.
Aspiration detectors take air samples, deliver them and analyze them. Sensors differ from each other in controlled physical parameters, according to which they are divided into several categories:
- Thermal.
- Smoke.
- Flames.
- Natural/carbon monoxide leaks.
- Water leaks.
How a smoke detector works
The smoke detector, part of the fire alarm circuit, is designed to determine the source of ignition by detecting smoke in the part of the building where it is located. Sensors of this type are optical - the generation of an electrical signal occurs by fixing the light from the LED by the photocell of the air chamber. When it smokes, a smaller amount of light enters the photocell, whichtriggers the sensor. The operating temperature range of the sensors is from -30 to +40 degrees.
Installation standards
Installation of the fire alarm circuit is carried out in accordance with official documentation - fire safety standards NPB 88-2001, which specify the rules for the design, installation and operation of such systems. The process of creating various fire extinguishing complexes is regulated by these rules. For example, the area and height of the ceilings in a room determine the number of point smoke detectors and their location relative to each other.
Fire alarm sensors connection diagram
Sensors are combined into a single system by means of wires. Some types of detectors can transmit signals to the control unit without wiring.
The fire alarm circuit is connected after determining the required number of sensors. Immediately before installation, the locations of the control unit, manual fire detectors and the warning system are marked. Places with open access are suitable for this: in case of fire, nothing should prevent getting to the detectors and other elements of the system.
Most fire alarm systems involve mounting detectors to the ceiling. Their disguise with finishing materials is possible, provided that their work efficiency is maintained.
Sensors are connected to the control unit.
Installation of firealarms
The first stage of installation includes the selection of a fire alarm circuit, basic and additional equipment and a security system. The combination of fire and security systems creates a security and fire complex. Installation and connection of a fire alarm at the object chosen by the customer is carried out in several stages:
- Designing a fire alarm circuit.
- Laying cables and loops.
- Installation of sensors.
- Commissioning.
Installation recommendations
Before placing fire alarm sensors, the area of the room in which the installation will be carried out is estimated. For this, the range of the detectors is determined. It is best to do this together with specialists.
The work of installed detectors should not be interfered with by third-party irritants: for example, smells from the kitchen can provoke a reaction of smoke sensors. Heat sensors should be placed away from sources of artificial heat.
Multi-sensor sensors increase the efficiency of fire alarms, especially if installed in a multi-storey building. A variant is possible in which a combined scheme of fire alarm sensors is provided, communicating with each other via radio control.
The alarm system is installed so that the alarm can be heard by all people in the room or building.
The main recommendation is the timely maintenance of the alarm. To do this, the systems are periodically checked andreconfigure. Some models are equipped with protection against insects, dust, moisture and other irritants.
The complete set of fire-fighting systems includes instructions for installation and operation. If the manufacturer's recommendations are followed, the devices can last a long time.
Fire alarm system "Bolid"
A wide range of security systems is presented on the Russian market, but the Bolid fire and security alarm system is considered the most popular and widespread.
The Bolid security and fire system is a set of technical means, the action of which is aimed at collecting data from various annunciators and sensors and converting them into information transmitted to operators in the event of a fire or penetration of third parties into the protected area.
The Bolid alarm functionality allows:
- Perform constant surveillance of the facility using CCTV cameras.
- Give an alarm in case of equipment failure.
- Determination of the place of violation of the protected perimeter.
- Automatic activation of the fire extinguishing system in the event of a fire.
- Quick detection of temperature increase, room smoke or fire.
