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Comprehensive Guide to CAFS: Class A Foam Theory & Terminology for Firefighters

Learn about Class A foam theory, terminology, ingredients, and advantages of CAFS systems. Understand the mixing, finishing, and types of foams for different fire classes.

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Comprehensive Guide to CAFS: Class A Foam Theory & Terminology for Firefighters

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  1. CAFS On-Line Orientation Montgomery County Fire & Rescue Service Class A Foam Theory

  2. Class A Foam Theory  MCFRTA 2008

  3. Foam Terminology • General Terms • Foam Concentrate • Foam Concentrate Injection Rate (Proportioning Rate) • Foam Solution • Finished Foam • Foam Types

  4. Practical Foam Terminology Foam Concentrate (As Purchased From The Manufacturer) + Water = Foam Solution + Air & Mechanical Agitation = Finished Foam (Air Aspirated Foam Solution)  MCFRTA 2008

  5. Foam Terminology • Mixing & Finishing - where is the air added and where does the agitation occur? • At Nozzle = Nozzle Aspirated Foam System (NAFS) • At Pump = Compressed Air Foam System (CAFS)  MCFRTA 2008

  6. Foam Types Foams are typed by the fires they are designed to put out. • Class A Fires need Class A Foam • Class B Fires need Class B Foam For CAFS MCFRS will be using Class A Foam only. You will learn about Class B foam later; for now we will concentrate on Class A foam.  MCFRTA 2008

  7. Ingredients: • Foaming Agent (Creates Bubble Structure) • Wetting Agent or Surfactant (Decreases Surface Tension of Water) • Emulsifying Agent (Breaks down Molecules containing Carbon (example - Charred wood) “oleophillic” Class A Foams

  8. Class A Foams have different proportioning rates depending upon the application the agent is being used for : • Normal Range - 0.1% (one-tenth of 1 percent) up to 1.0% • This means that using a 0.5% (five-tenths of 1 percent) Class A foam concentrate proportioning rate will use 5 gallons of concentrate for every 995 gallons of water. • Nozzle Aspirated Foam • 0.3% - low expansion, 1.0% high expansion • Compressed Air Foam • 0.3% - “Wet”, 1.0% - “Dry” Class A Foams

  9. How do I Make CAFS • There are a variety of ways to power the components, but all CAFS systems have three basic systems which must work together.  MCFRTA 2008

  10. CAFS Triangle These are the components that work together to make CAFS. Air Compressor Foam Pump Water Pump  MCFRTA 2008

  11. Advantages of CAFS • Increased penetration (high energy) • Increased “soaking” ability • Clings to vertical surfaces • Lighter hose lines More efficiently uses water  MCFRTA 2008

  12. Wet vs. Dry • Refers to proportion of air to water • The more air, the dryer it is • Can also be affected by “richness” of foam mixture • If you add more foam concentrate, the finished foam will be dryer. At full dryness, the foam concentrate proportion automatically gets kicked up to 1%.  MCFRTA 2008

  13. Wet to Dry - Controlled by amount of air “Wet” “Fluid” “Dry” The more air - the “dryer” the foam  MCFRTA 2008

  14. Review Questions List what the following ingredients of Class A Foam do and explain why they help us put out Class A fires: Surfactants Emulsifiers Foaming Agents List the three parts of the CAFS triangle: List the components of finished foam: How does CAFS differ from NAFS?  MCFRTA 2008

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