When implemented correctly in the appropriate application, chemical fire suppression systems can be very effective solutions. However, the proper design and installation of these systems requires extensive knowledge about how to protect individual plant areas from specific hazards. F.E. Moran Special Hazard Systems is intimately familiar with all types of chemical systems and has the expertise to install a system that will function safely and efficiently.
High Expansion Foam Systems - Successfully Smothering Fires
In areas where there is potential for Class A deep-seated fires such as an LNG pump or materials that are highly flammable or combustible, high expansion foam systems are ideal. When water damage is a consideration, high expansion foam systems are a viable option due to minimal water damage to structures and electrical equipment and less hazardous run-off compared to high volume sprinkler systems.
High expansion foam forms a blanket of air-filled bubbles and follows a total flooding method for areas with containment barriers surrounding flammable or combustible objects. Upon reaching high elevations, the foam can then effectively extinguish three-dimensional fires by blanketing and smothering combustion.
The piping system that delivers the foam to the foam generators must be composed of piping that is resistant to ambient corrosion. When calculating the discharge rate, foam breakdown must be considered when a sprinkler system is activated above the area.
Low Expansion Foam Systems - Controlling Two-Dimensional Fires
Fires stemming from flammable and combustible liquids respond well to low expansion foam systems. These systems are effective with two-dimensional pool fires where foam can cover the liquid with a thin layer.
The foam coats and smothers the liquid, separating the fuel from the flame, subsequently cooling the surface of the fuel.
Low expansion foam systems should only be used in applications where hazard coverage is strictly two-dimensional and can be controlled by a thin blanket of the solution.
Clean Agent Systems -Solutions for Delicate Equipment
When an area demands a quick response to fire but is sensitive to traditional agents, the appropriate solution may be a clean agent fire suppression system. If designed correctly, clean agent systems can be employed in areas that are occupied by plant personnel.
Clean agent fire suppression systems are gaseous fire extinguishants that leave no residual matter upon evaporation. These systems are designed for the total flooding of enclosures as local application is insufficient. There are two types of clean agent systems: halocarbon agents and inert gas. Halocarbon agents are chemicals that are released as gases to extinguish fires; inert gas lowers the amount of oxygen within an enclosure to control combustion.
Systems that are implemented in areas that are regularly inhabited must be designed with consideration for life safety to minimize the amount of human exposure to the agent.
Piping must be composed of a metal that is resilient against corrosion and is durable enough to endure high pressure during agent discharge.
Carbon Dioxide Systems - Effective Suppression for Uninhabited Areas
Carbon dioxide systems are effective in applications with delicate electrical equipment that could be damaged by other types of suppression systems, such as: turbine generator enclosures, computer rooms, switchgear rooms and battery storage rooms. Class B flammable liquid fires can also respond well to CO2 systems.
The objective of carbon dioxide systems is to force oxygen out of an enclosed area to contain combustion. There are four types of carbon dioxides that are utilized in plants:
- Total flooding - an area is completely filled with a fixed percentage of gas
- Local application - gas is discharged directly onto the surface where a fire is likely to ignite, ideal for areas where people would be at risk with a total CO2 flooding
- Hand hose line - to be used in the directly in the surrounding area of a hazard, plant staff must be sufficiently trained for it to be effective
- Standpipe with mobile supply - these systems are only to be used in applications where highly trained fire service personnel are immediately available
Enclosures that are typically inhabited should not utilize carbon dioxide systems because they are harmful to people. In the event of a fire, predischarge alarms and voice notification should be used to provide ample warning for people in the vicinity to reach areas of egress.
Condensed Aerosol Systems
Flexible, robust and cost-effective, condensed aerosol suppression systems have the ability to protect a wide array of equipment from flammable liquid storage to electronic equipment. Solutions such as Fireaway's Stat-X system produce minimal residual effects, making this method of protection a viable solution for sensitive applications such as switchgear enclosures or process and control rooms. In applications where there is limited space, aerosol suppression systems can be a practical option because they are installed on the wall, saving valuable floor space.
Upon activation of an aerosol fire protection system, a fine aerosol is released, attacking the flame's free radicals, effectively slowing and extinguishing the fire. Because the aerosol's particle size is so minute, it remains afloat in the air for an extended period of time, making it easy to vent out of the area following discharge. This means that very little residue settles on the equipment, making it possible to easily remove with compressed air.
There is an elevated obscuration factor with condensed aerosol systems and an activation delay should be implemented to protect inhabitants of the area. Exposure to the particulate should be avoided by facility personnel as it has not been listed for use in occupied spaces.
Case Study: Stat-X System Protects CNC Machines During Fire
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