| Foam-based chemical tank protection systems utilize foam to create a blanket on the surface of flammable liquids, preventing vapor formation and extinguishing fires by smothering and cooling the fuel, and preventing reignition. Foam is an aggregate of water, chemical compounds, and air-filled bubbles that float on the surface of combustible liquids.
Extinguishing Principles:
- Smothering: Foam covers the liquid surface, preventing oxygen from reaching the fuel and thus extinguishing the fire.
- Cooling: Foam, being mostly water, also has a cooling effect on the burning fuel.
- Preventing Vapor Formation: Foam prevents the formation of flammable vapor mixtures, which reduces the risk of re-ignition.
System Components
- Foam Concentrate: A chemical solution that, when mixed with water and air, creates the foam.
- Proportioning System: Devices that mix the foam concentrate with water at the correct ratio, such as bladder tanks, foam pumps, or inline inductors.
- Foam Discharge Devices: Equipment like foam chambers, foam makers, and foam pourers that deliver the foam to the tank surface.
Types of Foam usually accepted by Industries
- Aqueous Film-Forming Foam AFFF): Effective for flammable liquids, forming a thin, water-based film on the surface.
- Alcohol-Resistant AFFF (AR-AFFF): Designed for polar solvent fires, forming a polymer layer to prevent foam destruction.
- Fluoroprotein Foam: Used in hydrocarbon processing for storage tank fires.
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Applications:
- Flammable Liquid Storage Tanks: Protecting tanks in refineries, chemical plants, and other facilities.
- Tank Farms: Protecting areas with multiple storage tanks.
- Other Hazardous Areas: Aircraft hangars, ship holds, and other locations with flammable materials.
Advantages of Foam Systems:
- Effective for Flammable Liquids: Foam is particularly effective for extinguishing fires involving flammable liquids.
- Reduced Vapor Formation: Foam prevents the release of flammable vapors, which can be a significant fire hazard.
- Preventing Reignition: Foam helps prevent the fire from reigniting by keeping the fuel surface covered.
· Considerations:
- Foam Type: The type of foam used depends on the type of flammable liquid being protected.
- Proportioning: The correct mixing ratio of foam concentrate to water is crucial for effective foam formation.
- System Design: Foam systems need to be designed and installed properly to ensure effective fire protection.
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