KEYS TO PRACTICAL FIREFIGHTING WITH FOAM 23/04/2024 1 KEYS TO PRACTICAL FIREFIGHTING WITH FOAM Aim at understanding the followings: • 1. Foam triangle and foam tetrahedron • 2. Foam expansion ratio • 3. Foam application rate • 4. Foam application methods 23/04/2024 2 KEYS TO PRACTICAL FIREFIGHTING WITH FOAM 23/04/2024 3 KEYS TO PRACTICAL FIREFIGHTING WITH FOAM Fire/Foam: Triangle and Tetrahedron FIRE • As a spontaneous chemical reaction • Tetrahedron’s 4th element for continuity of fire – chain reaction (layer of each element rolling-in continually). 05/06/2024 FOAM • Triangle’s 3 elements present: foam conc., water and air • As a foam solution goes through nonspontaneous, physical change. • Tetrahedron’s 4th element of – mechanical agitation, the activation of the trinity. 4 KEYS TO PRACTICAL FIREFIGHTING WITH FOAM Mechanical Agitation • Mechanical Agitation of foam solution, a common phenomenon is achieved in household applications by fast stirring. Industrially, it is achieved by forced movement of foam solution through chamber that drags along air nucleating air in the solution, causing smaller foam bubble structures to form finished foam. It can also be achieved by directly beating the solution with a propeller and the speedy air produces highly expanded foam. • The size of mixing chamber or nozzle, direct hitting of the solution by propeller and speed of air blowing increase the expansion ratio. The 4th element is the activator of the foam formation. Foam Expansion Ratio • Mixture run: drafts along air • Effect of nozzle size/design • Blower compressed air 05/06/2024 6 KEYS TO PRACTICAL FIREFIGHTING WITH FOAM Expansion Ratio Expansion ratio is calculated by dividing the volume of finished foam by the volume of foam solution used to create it. For example, an expansion ratio of 20:1 means that one liter of foam solution, after aeration, will fill a 20-litre container with expanded foam. 05/06/2024 7 Foam Expansion Ratio 05/06/2024 8 KEYS TO PRACTICAL FIREFIGHTING WITH FOAM FOAM EXPANSION RATIO/ EQUIPMENT Low Expansion Foam/Branch—<20:1 High Expansion Foam Generator Medium Expansion Foam/—<200:1 High Expansion Foam Generator— >200:1 KEYS TO PRACTICAL FIREFIGHTING WITH FOAM Application Rate Foam Concentrate Needed Formula: •The formula for calculating the required foam concentrate at a flammable liquid Foam Concentrate Needed= Area×Critical Application Rate (CAR)×Eduction Rate (ER)×15 •Here are the components: •Area: area of spill or tank(usually in square feet). •Critical Application Rate (CAR): Minimum flow of finished foam per square foot. 0.1gpm/ft for hydrocarbon fuel and it is 0.2gpm/ft square for polar solvent •Eduction Rate (ER): 3% for hydrocarbon fuels and 6% for polar solvents •Maximum application time: 15 minutes (See NFPA 11). •Foam Expansion Ratio: how much the foam solution expands when it’s discharged. Hydrocarbon fuel: gasoline, diesel, jp4, heptane, kerosene). Polar Solvents – Flammable liquids that are water miscible or will mix with water. (eg. ketones, esters, alcohol, mtbe, amine. 05/06/2024 10 KEYS TO PRACTICAL FIREFIGHTING WITH FOAM Application Rate What amount of foam concentrate needed for firefighting? SUMMARY (Thoreau’s wisdom: perception— seeing is deeper than looking) Foam Concentrate Volume Needed = Area/20 (for hydrocarbon fuel) Foam Concentrate Volume Needed= Area/5 (for polar solvents) What volume of water would be needed for each firefighting? 1.62X Area and 6.5XArea. 05/06/2024 11 FOAM: Uses and Throw FOAM EXPANSION RATIO USES FOAM THROW Low Expansion Widespread hydrocarbon fires, storage tanks and holding tanks. >15 meters Medium Expansion Smaller surfaces in solvent storage and cellars in partial or closed area. < 10meters High Expansion Dry products with mixed risks in stores and warehouses. Immediate area and self-spread • Expansion is strongly dependent on the type of foam concentrate and the type of hose used. • Protein foam concentrates are usually suitable for Low and Medium expansion. • Synthetic foam concentrates are suitable for Low, Medium and High Expansion. KEYS TO PRACTICAL FIREFIGHTING WITH FOAM Foam Application Method Bounced in Front/Bank-in Technique • 23/04/2023 Vertical Backdrop Technique 13 KEYS TO PRACTICAL FIREFIGHTING WITH FOAM Application Method Lobbed /Raindown Technique 05/06/2024 Bounced Off Roof Technique 14 KEYS TO PRACTICAL FIREFIGHTING WITH FOAM Broken with Fingers 05/06/2024 15 Questions / contributions? 05/06/2024 17
