Foam Based Fire Suppression

Specifications

1. Types of Foam
   • AFFF (Aqueous Film Forming Foam): A type of foam that forms a thin film over the fuel surface, suppressing fire by cutting off the oxygen supply. AFFF is ideal for Class B (flammable liquid) fires such as oil and gasoline.
   • AR-AFFF (Alcohol-Resistant Aqueous Film Forming Foam): This foam is designed for use on alcohol-based fires and other polar solvent fires, as it resists the effects of alcohol and similar substances.
   • FFFP (Film-Forming Fluoroprotein Foam): FFFP foam is highly effective for Class B fires and provides a protective film that prevents reignition, commonly used in aviation and petroleum industries.
   • High-Expansion Foam: This type of foam generates large volumes of foam and is used in confined spaces like hangars, tunnels, and warehouses for quick suppression.
   • Protein Foam: Made from natural proteins, this foam is used for fires involving flammable liquids, particularly those with a higher risk of heat generation.
2. Foam Concentrate
   • Concentration: The foam concentrate is mixed with water at a specific ratio, typically between 3% to 6% for AFFF, to produce the desired foam output. The specific concentration is determined based on the type of fire and the foam application method.
   • Storage: Foam concentrates are typically stored in liquid form in foam tanks or foam pumps. The concentrate must be compatible with water quality and should be stored in temperature-controlled environments to prevent degradation.
   • Shelf Life: Foam concentrates generally have a 5 to 10-year shelf life when stored properly, with periodic testing to ensure performance.
3. Application Methods
   • Manual Application: Portable foam extinguishers and foam-based fire hoses are used to manually apply foam to fires. These systems are commonly found in smaller facilities and portable firefighting kits.
   • Fixed Foam Suppression Systems: Fixed systems, such as foam chambers, foam monitors, or foam nozzles, are strategically installed at high-risk areas. These systems can be activated automatically or manually.
   • Deluge Foam System: A deluge system is used in large industrial facilities, where foam is dispersed over an entire area through open nozzles upon activation. This system is particularly effective for tank farms, chemical storage areas, and airports.
   • Foam Pourers and Foam Guns: Foam pourers and foam guns are used for high-accuracy applications, such as extinguishing fires in tanks, pits, or large open areas. These systems create a high-flow rate of foam, rapidly covering the fire source.
4. System Components
   • Foam Concentrate Tanks: Tanks are used to store foam concentrate. These tanks are usually corrosion-resistant and designed to withstand high pressures and extreme temperatures.
   • Water Supply: The water supply to foam systems is crucial, typically connected to a dedicated water pump that ensures consistent flow. Systems can be powered by electric or diesel pumps.
   • Proportioning Devices: Proportioning devices mix the correct amount of foam concentrate with water. These devices can be manual, automatic, or in-line proportioners, ensuring the proper foam-to-water ratio.
   • Foam Delivery Nozzles: Foam delivery is done through specialized nozzles or foam guns that are designed to distribute the foam uniformly over the fire area.
   • Control Panel: The fire suppression system is controlled through an integrated control panel, which can activate alarms, pumps, and foam delivery devices when a fire is detected.
5. Activation and Control
   • Automatic Activation: Foam systems are typically equipped with heat sensors, smoke detectors, or flame detectors to automatically trigger the suppression system when a fire is detected.
   • Manual Activation: In some cases, a manual trigger is available for human intervention, particularly in smaller-scale systems.
   • Flow Control: Flow meters and pressure gauges are used to monitor and regulate the flow of foam and water, ensuring the system is activated effectively.
6. Coverage Area and Flow Rate
   • Coverage Area: The coverage area of a foam system depends on the size of the fire hazard. Larger areas, such as chemical storage facilities, tank farms, and airports, require larger foam suppression systems.
   • Flow Rate: The flow rate of foam systems can range from 100 GPM (gallons per minute) for smaller applications to 10,000 GPM or more for industrial-scale applications. The required flow rate is determined by the size of the area to be protected and the nature of the fire hazard.
7. Maintenance and Testing
   • Regular Testing: Foam suppression systems must be inspected and tested regularly according to NFPA 11 (Standard for Low-, Medium-, and High-Expansion Foam Systems). Routine tests include foam concentrate checks, flow tests, and ensuring the proportioning system is working correctly.
   • Foam Quality Testing: The foam concentrate should be tested for effectiveness, typically by checking its expansion ratio and drainage time to ensure proper performance.
   • Hydraulic Tests: Regular hydraulic testing ensures the foam system’s flow rate and pressure are maintained within the required operational parameters.