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19 Cards in this Set
- Front
- Back
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How does foam extinguish a fire? |
Dilutes the air around with water vapour Isolates fuel from oxygen Forms a floating barrier on the surface Intercepts radiating heat Cools the fuel |
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What are the 3 types of foam expansion and the ratio? |
Low expansion - 2:1 to 20:1 Medium expansion - 20:1 to 200:1 High expansion - 200:1 to 2000:1 |
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What do lfb use? |
Low and high Mark 3 uses 12:1 |
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What % concentration is used on hydrocarbons |
3% |
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What % concentration is used on polar solvents |
6% |
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What 4 things can impact the effectiveness of foam |
Concentrate in good condition Correct mixture Good maintenance Correct pressure used |
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What are the 3 factors that form foam |
Quantity of concentrate Volume of air mixed Size of bubbles |
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What principle is used to form foam? |
Venturi principle |
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Name the nozzle used for foam? |
Aspirator |
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What is the most effective pressure and flow setting on a branch aspirator? |
6 bar pressure 400lpm |
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Using the akron ground monitor what is the pressure and flow rate required |
950lpm 7 bar pressure |
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What are the 4 types of application |
Gentle application Raindown Rolling on Off wall |
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How does gentle application work? |
Aiming as far away as possible using full trajectory |
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How does raindown application work |
Aim the foam above the fuel in the air so the foam drifts down Not so useful in windy conditions or large fires |
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What is rolling on application |
Aim at the ground At front of fuel until foam builds and spreads Advantages are it pushes radiating heat away from branch operator |
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What is off the wall application |
Aim at the wall of a building or object deflecting it to form a layer of foam on fuel Disadvantages as it drives radiating heat towards branch operator |
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Care & considerations when using low expansion foam |
Open branch away from fire until foam is produced Make sure there is enough foam available Surrounding risks should be cooled with covering jets Preserve the foam blanket Don't walk or carry hoses through foam
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What is high expansion foam used for? |
Basement fires |
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Considerations when using high expansion fires |
Disorientating for firefighters Hearing is impaired Unable to see signs of building collapse Pockets of flammable gases will remain and cause a mini backdraft Difficult to travel and locating fire |
