The statistics of a large number of fires is confirmed by the daily response of fire crews. The causes of the fire can be varied - from smoking in the wrong place and careless handling of fire to short circuit wiring and arson. An automatic fire alarm warns of a fire and allows you to eliminate the source in time.
What is a fire alarm
The primary recording devices - sensors - are designed for timely and quick detection of the first signs of fire and smoke. The sensor can either independently activate an alarm, or activate a warning system, turn on a fire extinguishing system and transmit data to the emergency rescue unit of the Ministry of Emergencies. Fire alarm is a set of technical means of primary detection and information described above.
Proper configuration and timely verification of fire detection systems play an important role. Sensors during long-term operation can get dirty, fail, which affects their performance and, as a result, the safety of life and property of people. Rapid detection of the source of ignition and decryption of information about its location can solve various problems:
- Activating the fire extinguishing system and informing the fire department of the Ministry of Emergencies.
- Carrying out evacuation of people.
- Localization of the source of fire.
- Lower financial spending.
- Minimizing injuries and deaths among people.
Types of Fire Alarm
Components of modern fire systems may vary. The principle of operation and the type of alarm determine the selection of the necessary equipment - cables, sensors, power supplies, etc. According to the structural diagram, fire alarms are:
- Thresholds with a radial loop.
- Threshold with modular construction.
- Address analog.
- Address-polling.
- Combined.
Analog Addressable Systems
To collect and analyze information received from humidity, temperature, smoke and other sensors, address-analog fire systems are created. The control panel reads in real time the readings of sensors, each of which is assigned a specific location address. The information received from different sensors is analyzed, after which the location of the source of ignition is determined by means of an address signal and a signal is given in case of fire. The structure of the address loops is ring, up to 200 sensors and devices are connected to each of them:
- Manual and automatic detectors.
- Relay.
- Control Modules
- Annunciators.
Advantages of the address-analog fire alarm:
- The almost complete absence of false alarms.
- Fast detection of a fire source.
- Ability to adjust the sensitivity of the sensors.
- Minimum costs for connecting a fire alarm circuit and its subsequent maintenance.
Address polling
In address and threshold systems, a fire signal is generated by the sensor itself. The information exchange protocol is implemented in a loop in order to determine the triggered sensor. Unlike the address-analog system, the algorithm of the address-polling is simpler. From the sensors, signals are sent to the control panel, then the detectors are cycled to determine their status. The disadvantage of such systems is the increase in the detection time of the ignition source.
The advantages of alarms:
- The optimum ratio of price and quality.
- The information content of the received signals.
- Monitoring settings and functionality of detectors.
Threshold
Fire alarm system with a circuit in which each detector detector has a certain sensitivity threshold. An alarm in it is triggered by the number of one of the sensors. Such fire systems are installed in small facilities - in kindergartens and shops. Their minus is the minimum information content - only the sensor is triggered - and the lack of an indication of the location of the fire source. The advantages include the low cost of the alarm itself and the process of installing it.
Fire system design
The fire alarm system is represented by smoke alarms, a data acquisition, control and transmission system. 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 the appropriate signal.
- Reception and control panels - collect and process incoming information, transmit signals to the relevant services.
- Peripheral equipment - provides communication lines, power supply, fire extinguishing system activation, information methods.
- The equipment of the central control panel of the fire alarm system - security and fire alarms - receives alarms from various objects and collects information for the emergency departments.
Principle of operation
The fire alarm system operates on the basis of interrogating all the sensors and detecting the fact of the operation of one of them in the case of threshold systems or changing environmental parameters in the case of address-analog systems. Threshold systems when the sensor is triggered break off the entire loop, which signals the presence of a fire in the zone where this loop is located. Activation of irrigation in the smoke zone occurs in automatic fire extinguishing systems after receiving the appropriate signal, which also gives an alarm and sends a call to the central console.
Fire sensors
The main function of fire alarm sensors is to quickly respond to changing environmental parameters. Sensors differ from each other by the principle of operation, the type of parameter being monitored, and the method of transmitting information. The principle of functioning can be of two types - passive and active: the first implies only actuation, the second - actuation and monitoring of environmental parameters. Depending on the threat level, active detectors send various signals to the automatic control station.
Aspiration detectors carry out air sampling, delivery and analysis. Sensors differ from each other in controlled physical parameters, according to which they are divided into several categories:
- Thermal.
- Smoke
- Flame.
- Leaks of natural / carbon monoxide.
- Water leaks.
The principle of operation of the smoke sensor
The smoke detector included in 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 with the photocell of the air chamber. When it is smoked, a smaller amount of light enters the photocell, which leads to the operation of the sensor. The operating temperature range of the sensors is from -30 to +40 degrees.
Installation Standards
Installation of a 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 a variety of fire fighting systems is regulated by these rules. For example, the area and ceiling height of a room determine the number of point smoke detectors and their location relative to each other.
Connection diagram for fire alarm sensors
The sensors are combined into a single system through wires. Some types of detectors can transmit signals to the control unit without connecting wiring.
The fire alarm circuit is connected after determining the required number of sensors. Immediately before installation, the locations of the control unit, hand-held fire detectors and warning systems are marked. Places with open access are suitable for this: in case of fire, nothing should interfere with getting to the detectors and other elements of the system.
Most fire alarm systems involve mounting detectors to the ceiling. Their masking with finishing materials is possible provided that their work efficiency is maintained.
Sensors are connected to the control unit.
Fire Alarm Installation
The first stage of installation includes the choice of a fire alarm scheme, the main and additional equipment and a security system. Combination of fire and security systems creates a security and fire complex. Installation and connection of a fire alarm at a site selected by the customer is carried out in several stages:
- Designing a fire alarm circuit.
- Laying cables and loops.
- Installation of sensors.
- Carrying out commissioning works.
Installation Recommendations
Before placing the fire alarm sensors, the area of the room in which the installation will be carried out is estimated. For this, the radius of action of the detectors is determined. This is best done in conjunction with specialists.
Third-party irritants should not interfere with the operation of installed detectors: for example, smells from the kitchen can provoke a reaction of smoke sensors. Thermal sensors should be placed at a distance from sources of artificial heat.
Multisensor sensors increase the efficiency of the fire alarm, especially if it is installed in a multi-story building. A variant is possible in which a combined circuit of fire alarm sensors communicating with each other via radio control is provided.
The warning system is set up 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. For this, the systems are periodically checked and reconfigured. Some models are equipped with protection against insects, dust, moisture and other irritants.
The complete set of fire protection systems includes instructions for installation and operation. Subject to the recommendations specified by the manufacturer, the devices can last a long time.
Fire alarm diagram
A wide range of security systems is presented on the Russian market, but the Bolid security and fire alarm is considered the most popular and widespread.
The Bolid security and fire system represents a set of technical means, the action of which is aimed at collecting data from various sirens and sensors and converting them into information that is transmitted to operators in the event of a fire or penetration into a protected area by third parties.
The Bolid signaling functionality allows you to:
- Carry out constant surveillance of the object using surveillance cameras.
- Alarm in case of equipment failure.
- Determining the place of violation of the protected perimeter.
- Automatic activation of the fire extinguishing system when a fire occurs.
- Rapid detection of temperature rise, smoke, or ignition.