Understanding Fire Suppression Systems  

by admin on September 20, 2010

Gaseous fire suppression referred to the use of inert gas and certain chemical agents to extinguish fire. It also often termed as Clean Agent Fire Suppression. The use of this method in extinguishing fire is presided over by the NFPA Standard for Clean Agent Fire Extinguishing Systems.  
The fire suppression system makes use of an agent, agent storage containers, fire detectors, agent release valves, fire detectors, dispersion nozzles and agent delivery piping. It also makes use of fire detection systems such as actuation signalling and wiring control panel. In few cases, the agent can also be delivered through a solid propellant gas generator that can give off chemically active gas or inert gas.  
To be able to extinguish fire, there are four specific ways on how agents work on a fire suppression system. These methods combined are better known as the Fire Tetrahedron. Here are the four methods of extinguishing fire along with their representative agents.
1. Reduction/ isolation of fuel- in this step, no agents are used as primary source of fire control.  
 
2. Reduction of heat
•    HFC-227ea (MH227, FM-200)
•    Novec 1230
•    HFC-125 (ECARO-25)
3. Reduction/ isolation of oxygen
•    CO2 carbon dioxide
•    Argonite / IG-55 (ProInert)
•    IG-541 Inergen
•    IG-100 (NN100)
4. Inhibition of chain reaction of components mentioned above
•    FE-13
•    FE-227
•    FE-25
•    MH227
•    FM-200
•    Halons
•    Halon 1301
•    Freon 13T1
•    NAF P-IV
•    NAF S-III
•    Triodide (Trifluoroiodomethane).

Application  
Generally, there are 2 methods on how to apply an extinguishing agent. You can either do total flooding or local application.  
Total flooding- systems that work on total flooding applies extinguishing agents to a 3-dimensional enclosed area. The agent is allowed to be concentrated to reach a certain volume percentage of the agent in air. When the specific volume is reached, it is already adequate to put off a fire. Such systems are operated automatically using detection controls. It can also be operated manually using a system actuator.  
Local application- systems working in this type of method applies extinguishing agents directly to the fire using a 2-dimensiona are or a 3-dimensional region that surrounds the object on fire.  
The difference of these two methods is that total flooding does not have physical barriers that enclosed a fire space while local application does. When using automatic extinguishing systems, the term local application does not mean that the fire suppression system is using wheeled machines or portable fire extinguishers.

Safety precautions  
Suffocation  
Carbon dioxide, which is one of the primary representative agents of a fire suppression system, can present a health risk when in an enclosed space. Suffocation is one of the primary effects of inhaling carbon dioxide. There are many incidents where people are killed by the release of carbon dioxide.  
 
To prevent suffocation, safety systems should be installed as soon as a warning alarm is turned on in case of fire. The warning should be either be a loud siren or something visually seen so that people can be aware of the presence of carbon dioxide, especially in an enclosed area. Evacuation of the area should be implemented. Proper awareness of the effects of carbon dioxide and maintenance of fire extinguisher systems should also be taken care of to ensure safety. 
 
Barotrauma  
The pressure that is caused by the release of extinguishing and inert agents, including IG-100, IG-55 and IG-55, can actually be enough to break windows, and even walls. It can also harm people and other properties. Proper precaution is advised.


About the Author:
This article was provided by Gemini Fire Ltd a UK company that offers specialist fire suppression systems.
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