Fire Detection
It has become an absolute requirement from the South African government for fire protection on buildings which meet certain criteria. The rules around fire detection are stringent and it is essential to ensure your facility remains compliant. This will reduce your overall risk and ensure if the worst happens, you are not disadvantaged from an insurance perspective.
The most common types of fire detection systems available are conventional and addressable systems but all Fire detection systems comprise of the following basic components:
- Control panel – this is the main control unit and will indicate if there are any faults on the line or where the fire / smoke is.
- Cable – it has become part of the new SANS building code that a particular type of fire resistant cable needs to be utilised. Known as PH120 will last for 2 hours at 900° Celsius. If you are planning a new installation this type of cable has to be used to remain compliant.
- Devices – the most common devices include: – Optical smoke detectors – Heat detectors – Manual call points (red “break in an emergency” box”) – Sounders / strobes – There are other devices for more specialised applications such as beams and rise-of-heat detectors but these are only used in very specific applications.
Gas suppression systems are typically used in smaller areas where high-value and sensitive equipment is housed such as a server room or where water could possibly add to the problem of the fire such as in an electrical distribution room.
Components to the system
All fire detection system require the following basic components: A Control Panel, Cable and devices such as smoke detectors. Here we will explore each device in a bit more detail.
Control Panel:
There are 2 basic formats of fire detection systems – conventional and addressable. Conventional is more cost effective and works on zones known as “loops” and will indicate that there is a fire on that loop – but each loop can have a number of devices on it so you may only know there is a fire on the 2 nd floor but not know where exactly.
With an addressable system, you will know exactly where the origin of the fire (or smoke) is but these systems are more costly. The Control panel acts as a control panel of an alarm system does and that is to activate an alarm is fire / smoke is detected. It is important (and a requirement by law) to test your fire detection system at least once a year – although more frequent testing and maintenance is advised.
Cable:
If you are installing a new fire system, it is important to know that there is still a great deal of cable known as FR20 on the market – going for cheap. Will this cable work? Short answer is yes BUT it’s important to know that SANS (South African National Standards) has declared that all new installations need to use the fire resistant cable known as PH120 which will last for 2 hours at 900° Celsius. If you are planning a new installation this type of cable has to be used to remain compliant. If your building has FR20 cable already in it, that is fine but a new install has to be PH120.
Devices:
- Optical Smoke Detector: Using infrared scattering technology, the smoke density can be detected. The detector receives very weak infrared light under normal smokeless condition. If smoke particles enter the chamber, the received light signal will increase by scattering. When smoke density reaches a pre-set level, the detector will alarm out.
- Ionization smoke detector: Using a radioisotope to produce ionization in air; a difference due to smoke is detected and an alarm is generated. Ionization detectors are more sensitive to the flaming stage of fires than optical detectors, while optical detectors are more sensitive to fires in the early smouldering stage. Which is better? Ionisation detectors are typically more cost effective than optical smoke detectors but as mentioned above, optical detectors should detect a fire earlier unless it’s already a full flame. It is thus good practice to use a combination of both types of devices a device which combines both types of technologies.
- Heat Detectors: Heat detectors come in either a “fixed temperature” or a “raise-of-heat” variants. Pretty self-explanatory, a fixed temperature detector will go into alarm mode if a certain temperature is reached while a raise-of-heat is more measures the ambient temperature and the rate of change. If the change is too much, it will alarm. These types of devices are typically used in kitchens or a workshop where welding would take place and smoke would naturally be present.
- Reflected Beam Smoke Detectors: These were designed for spacious rooms, open areas, and high ceilings. They are typically used for large volume areas or areas which have high ceiling such as warehouses and large retail stores and churches etc.
- Call Point: This is simply the “red emergency box” which if a person notices a fire will break the emergency glass sending the alarm panel into an immediate alarm – bearing in mind, with normal detectors you would require at least two detectors to detect fire or smoke before sending the panel into and alarm mode – this is known as a “double-knock”.
- Strobe / Sounder: If there is a fire, you need to know about it! The device which is going to let you know there’s a fire a either a strobe (flashing red light) or a sounder (alarm) or most commonly a combination device which does both.
Conventional Systems
Smaller buildings and applications would probably opt for a “conventional” fire-detection system as these are far more cost effective to buy and because they are fairly simple to install, the cost of installation is usually lower.
Conventional fire detection systems typically work on a 2, 4, 8 or 16 loop (or zones) configuration. Devices are connected to the panel using fire-resistant cable and if a fire or smoke is detected, the fire panel will go into alarm mode. The alarm will alert you as to what area (zone) the fire is coming from but this could be as vague as “4 th floor”
Depending on the type of system, usually 15 to 20 devices can be installed per loop.
It is still important to service and test your fire detection system at least once a year if not more frequently. We would reccomend a maintenance plan and Service Level Agreement (SLA) for your fire detection systems.
Addressable Systems
In order to asses exactly where a fire is originating from, you would require an addressable fire system. Addressable systems do cost more than conventional fire systems but it will tell you with a much higher degree of accuracy as to the exact location of the fire e.g. 3 rd floor HR office. This in turn, reduces your response time and thus potentially lowering your damage caused by the fire.
Addressable fire systems are near “limitless” in the size of the system you require as the panels are expandable to your exact needs.
Gas Suppression
When you have expensive, sensitive equipment such as that found in server room, it becomes relevant not to use conventional water suppression systems to douse a potential fire as this in turn will damage or destroy your valuable equipment and data. This is where gas suppression systems are utilised. Historically CO2 was the common gas of choice but is extremely dangerous and potentially lethal if there are any persons in the area at the time of discharge. Most commonly used gas now is FM200 gas which is a waterless system which will discharge into the area at risk within 10 seconds and suppresses the fire immediately.
The components of the gas suppression system are similar to your fire systems with the added suppression system added to it which will include the gas bottle, pipes and dga We work with experts in the fire field in order to ensure your system is correctly designed, installed and certified.
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