Fire alarm
Fire alarm is a system that, as the word itself says, reports that a fire has occurred as soon as possible. With the very rapid announcement of a fire, it creates the possibility of rescuing people and preventing the occurrence of significant economic costs. It is a system that does not bring direct economic gain but is intended to save human lives and prevent the creation of economic losses. The fire alarm system is designed in accordance with the risk of fire on the building in question in order to take into account the economic aspect of capital and operating costs. The goal of the fire alarm system according to Siemens is:
“Minimize damage through reliable and early detection.”
In 2019, more than 2.5 million fires were recorded worldwide (according to CTIF World Fire Statistics Center), of which almost fifteen thousand (15,000) in Croatia. The fires worldwide killed 19.2 thousand people and injured over 68 thousand people.
Legislation
A fire alarm is designed if it is required by law in Croatia on the basis of the “Ordinance on Fire Alarm Systems” (PSDP) deriving from the “Fire Protection Act” (ZZOP). The mentioned ordinance refers to the standard HRN DIN VDE 0833 (parts 1 and 2), which defines in more detail the method of designing the system. A fire alarm can be installed in any building that its owner wants. While some types of buildings are required to install a fire alarm system, and according to the PSDP these are:
- buildings and premises for which, by applying the appropriate method of fire risk assessment (eg TVRB 100, Euroalarm, etc.), the obligation to install a fire alarm system as a special fire protection measure has been established
- buildings and premises that are obliged to install a fire alarm system as a special fire protection measure determined on the basis of special regulations
- buildings and premises for which the obligation to install a fire alarm system is prescribed by special construction conditions in the field of fire protection
A building that has a fire alarm system needs to monitor the entire building with some exceptions defined by the ordinance (PSDP). Examples of rooms that are allowed to be excluded from the control area are sanitary rooms, stairs without fire load that make up a separate fire sector, etc.
In order to make fire alarm system schemes clear throughout the globe, there are internationally recognized fire alarm elements according to multiple standards. Some of the relevant standards are ISO / DIS 6790.2 (the standard has been officially withdrawn), BS 1635, NFPA 170. In our area, the most commonly used symbols are according to ISO / DIS 6790.2.
Fire alarm system elements
The fire alarm system and its parts must meet the provisions of the standards of the HRN EN 54 series, and it consists of the following elements (mandatory and optional parts of the fire alarm system):
- automatic fire detector
- fire alarm control panel
- alarm device
- manual call point
- power supply
- fire alarm transmission device
- fire alarm reception center
- device for controlling fire protection devices
- automatic fire protection device
- fault signal transmission device
- interference reception center
The fire alarm system has two versions in terms of the accuracy of reporting the location of the fire, they are:
- Individual addressing (addressable system) – the fire control panel can identify exactly which detector detected the fire.
- Line addressing (classic / conventional system) – the fire alarm control panel can only recognize on which fire alarm line the detector that detected the fire is located.
In order to reduce the possibility of a false alarm, it is necessary to select the correct fire detector for a specific room. The main parameters of choosing an automatic fire detector are the type of fire load, ambient conditions, purpose and geometric shape of the room. The main groups of automatic fire detectors are:
- point smoke detector
- line smoke detector
- aspiration smoke detector
- point temperature detector
- line temperature detector
- multifunctional detector monitors multiple measured quantities (temperature, smoke and CO)
- flame detector
The maximum monitoring area of automatic detectors is determined by the standard HRN DIN VDE 0833, while a more detailed selection of the quantity and type of detectors is determined according to the specifications of the manufacturer of each individual detector. Selecting the appropriate sensor reduces the time of fire detection, which increases the likelihood that the fire will be contained before human casualties and significant damage.
Manual call point are installed at a height of 1.4 + 0.2 meters. And if the emergency lighting in the room is provided, it must illuminate the manual call point.
Firefighting
In Croatia, according to the “Fire Act“, each fire alarm system should be set up so that in the event of a fire, a trained person will notice and take the prescribed steps to control the fire and eventually extinguish it. This is addressed in one of the following ways:
- The fire alarm control panel is located in a room where there is a 24/7 duty
- The fire alarm center sends information to the place where the 24/7 duty is in charge of the building in question
- The fire alarm system sends a direct signal to the fire brigade in charge of the area where the building is located
According to statistics from one of the leading brands in fire alarm systems, false alarms that occurred without an actual fire range from 90% to 95%. Since false reports of fire are charged under the Firefighting Act, in order to reduce operating costs it is good to avoid it if it is possible to directly connect the fire alarm control panel with the fire brigade.
The wire used for the fire alarm loop should be fireproof, with the exceptions defined through the applicable standards.
Alarms from fire alarm system should be audible and visual. If the siren is used, the audible signal must be different from other danger signals and must not be used for other purposes. A more advanced way of alerting is with the help of a voice messaging system. Messages are sent to people who are in the endangered area in order to facilitate the evacuation and rescue of the endangered.
System test
After installation, the fire alarm system must be tested by an authorized person in accordance with HRN DIN 0833 part 1 and the Ordinance on the conditions for testing stable fire alarm and extinguishing systems. Authorized person / company receives authorization from the Ministry of the Interior (MUP). The list of authorized persons / companies can be found in the Official Gazette and the website of the Ministry of the Interior.
The first test may not be performed by a person / company that manufactured or installed the system or its elements, or is not the owner or user of the system. After the successful testing of the system and the completion of the commissioning protocol, the system was officially put into operation and concluded within minutes. During operation, the system should be periodically tested at least once a year. After upgrading or changing part of the fire alarm system, it must be tested again by an authorized person / company. To test the system, it is necessary to have a project that is accurate with current system implementation.
Summary
A fire alarm is a system that reduces the risk of accidents in the buildings it monitors. Timely information on the occurrence of fires is crucial in firefighting and rescuing people. The system should be designed according to the purpose of the space it monitors. The result is an acceptable cost (capital and operational) and timely fire detection with minimal possibility of false alarm.