How does FM200 put out a fire? And would it work if it was activated after the fire has got out of control?
I’ve search the net and read that FM200 puts out fire by chemical and physical ways, may I know what exactly does the "chemical and physical" way means? Also I know that it is primarily designed to be activated at the initial stage of a fire, but if I only activate the FM200 system after the fire in the room has gone out of control, would the FM200 still be able to put out the fire?
FM200 is an HFC hydroflorocarbon and works in a similar fashion to the CFC and HCfc like Halon that it was designed to replace.
Most people understand the fire triangle (Heat fuel oxygen) remove any one an a fire is no longer possible. However in recent years the fire triangle has been modified to include a fourth Item (chemical reaction). The triangle then becomes a four sided pyramid (tetrahedron)
CFC, HFC, HCFC extinguishing chemicals work by interrupting the chemical process of combustion. (Slow or stop the rapid oxidation) . the other three sides of the tetrahedron are physical means where you do one of the following:
1.Remove heat by cooling with water or some other means like absorption of heat through a phase change of a material. Liquid CO2 turing to a gas absorbs heat.
2.)Remove or displace oxygen. Prevent oxygen from getting to the fire. CO2 is heavier than air so it forms a temporary barrier and also displaces oxygen. The result is starving the fire of its oxygen.
3.) removing the fuel. An example of this is an oil pipeline fire where you can shut off the fuel supply from an upstream valve.
I suspect that the physical extinguishing property of FM200 is a combination of Oxygen displacement and temperature reduction which would be secondary effects. the primary extinguishing action would be the interference of the chemical reaction of the combustion process.
Extinguishers are rated to handle specific sized fires. Once a fire gets "out of control" or beyond the level which the extinguisher can handle it will not extinguish the fire. It will have some brief effect that can slow it down but it depends upon how large the fire is.
Closed room fire suppression systems like those found in a ships engine room or a moder computer room also rely upon the isolation and sealing of the room. basically you kill the ventilation and close the doors to prevent oxygen from entering then the gas is released and in the case of CO2 flooding it takes some time to fill the room to smoother the flames..
If the doors are left open or the ventilation remains running the extinguisher may not be effective. On most of these systems there can be automatic means to kill ventilation motors and operate dampers to help seal the room (and may include killing electrical power). So even if the fire is out of control activating the system will slow the fire down by providing containment and reducing its supply of oxygen.
CFC & HFC systems are designed to quickly extinguish fires BEFORE they become out of control. Sine they do not hurt electrical components like water or dry chemical would the idea it to use them without the fear to causing more damage to the equipment. By using these extinguishers earlier in the stage of a fire you prevent the fire from getting out of control and limit the damage.
We are using the same system here in our District Cooling Plant at Dubai. We use this system particularly in electrical rooms where you cannot provide sprinklers. FM200 as we all know is an inert gas and suppresses fire by taking out the oxygen from fire immediately.
FM200 can still able to suppress fire even if it is gone out of control as long as it is inside the the room and still being contained. That’s why minimum of 2 hours fire rated steel doors and an air seal is being used in all access to contain such fire. Also Fire dampers should be closed in order to achieve fire suppression effective.
References :
FM200 is an HFC hydroflorocarbon and works in a similar fashion to the CFC and HCfc like Halon that it was designed to replace.
Most people understand the fire triangle (Heat fuel oxygen) remove any one an a fire is no longer possible. However in recent years the fire triangle has been modified to include a fourth Item (chemical reaction). The triangle then becomes a four sided pyramid (tetrahedron)
CFC, HFC, HCFC extinguishing chemicals work by interrupting the chemical process of combustion. (Slow or stop the rapid oxidation) . the other three sides of the tetrahedron are physical means where you do one of the following:
1.Remove heat by cooling with water or some other means like absorption of heat through a phase change of a material. Liquid CO2 turing to a gas absorbs heat.
2.)Remove or displace oxygen. Prevent oxygen from getting to the fire. CO2 is heavier than air so it forms a temporary barrier and also displaces oxygen. The result is starving the fire of its oxygen.
3.) removing the fuel. An example of this is an oil pipeline fire where you can shut off the fuel supply from an upstream valve.
I suspect that the physical extinguishing property of FM200 is a combination of Oxygen displacement and temperature reduction which would be secondary effects. the primary extinguishing action would be the interference of the chemical reaction of the combustion process.
Extinguishers are rated to handle specific sized fires. Once a fire gets "out of control" or beyond the level which the extinguisher can handle it will not extinguish the fire. It will have some brief effect that can slow it down but it depends upon how large the fire is.
Closed room fire suppression systems like those found in a ships engine room or a moder computer room also rely upon the isolation and sealing of the room. basically you kill the ventilation and close the doors to prevent oxygen from entering then the gas is released and in the case of CO2 flooding it takes some time to fill the room to smoother the flames..
If the doors are left open or the ventilation remains running the extinguisher may not be effective. On most of these systems there can be automatic means to kill ventilation motors and operate dampers to help seal the room (and may include killing electrical power). So even if the fire is out of control activating the system will slow the fire down by providing containment and reducing its supply of oxygen.
CFC & HFC systems are designed to quickly extinguish fires BEFORE they become out of control. Sine they do not hurt electrical components like water or dry chemical would the idea it to use them without the fear to causing more damage to the equipment. By using these extinguishers earlier in the stage of a fire you prevent the fire from getting out of control and limit the damage.
References :