Compressed Air Foam Systems

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Author:
koollyT
ID:
257107
Filename:
Compressed Air Foam Systems
Updated:
2014-01-17 17:39:00
Tags:
2014 engineer exam
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Description:
Compressed Air Foam Systems
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  1. Foam concentrate in its simplest form is
    basically a heavily concentrated dish washing
    detergent. that is
    Class A Foam
  2. Hydrocarbon based surfactant that when
    added to water, enables the water to
    penetrate the burning surface by reducing the
    surface tension of the water. THAT IS ?
    Class A Foam
  3. How much more effective is Class A
    Foam over plain water?
    • Foam Solution3 x better than water
    • Aspirated Foam 5 x better than water
    • CAFS 10 x better than water
  4. CAFS Theory
    • Class A foam
    • increases the ability
    • of water to penetrate
    • fuel sources as much
    • as 1,000 times better
    • by reducing surface
    • tension.
  5. Class A foam enhances
    • waters’ ability to cool by
    • as much as 300%.
    • Because Class A foam has
    • an affinity for water
    • (hydrophilic), it spreads
    • more rapidly, thus cooling
    • much quicker
  6. The “7 Bubble Theory”
    • It must be understood that the “7 bubble theory” is
    • an approximate number of bubbles created by
    • compounding the single “water/foam” droplet into
    • seven equal “air/foam” bubbles through the
    • introduction of compressed air.
    • • The actual number may be less in a “wetter” foam
    • and more in a “drier” foam
  7. What is important to know about
    proper CAFS operation
    • Ability to change the
    • type of foam generated


    • Bubbles are created in
    • the discharge hose

    • Foam solution must be
    • in line prior to the
    • injection of air to
    • prevent “slug flow”
    • Smooth bore nozzles
    • are used for CAF
  8. Ability to change the
    type of foam generated
    • “Wet” foam for direct
    • attack and overhaul

    • “Dry” foam for exposure
    • protection and
    • pretreating brush
  9. Bubbles are created in
    the discharge hose ARE CALLED ?
    (Scrubbing)
  10. Smooth bore nozzles
    are used for CAF . WHICH SIZE?
    15/16” for “Wet” foam

    • 1 1/2” Shut‐off butt / no
    • tip for “Dry” foam
  11. What is important to know about
    proper CAFS operation
    • Fog nozzles will break up
    • the CAF bubbles and
    • convert CAF back into
    • water/foam solution

    • When the bale is closed, air
    • pressure continues to build
    • up in the line. When the
    • bale is opened, the pressure
    • equalizes resulting in strong
    • nozzle reaction

    • Pistol‐grip shut off butts are
    • used due to the high initial
    • nozzle reaction
  12. “Wet” Foam at 0.3% IS USED TO ?
    • Direct Attack and
    • Overhaul (melted ice cream)
  13. Dry Foam at 0.5‐1.0% IS USED TO?
    • Structure Protection and Pretreating Vegetation
    • (shaving cream)
  14. What are the advantages of CAFS
    • Lighter hose lines ‐ 1/3 normal weight
    • Increased discharge distances
    • Uses less Class A Foam Concentrate
    • No water hammer
    • Hose lines not affected by kinks @100 psi
  15. WHAT IS Slug Flow?
    • conditions (no foam solution in the line
    • results in erratic discharge at nozzle)

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