Flashcards in Chapter 15- Foam Equipment And Systems Deck (13):
Name the three ways foam extinguishes and/or prevents fire.
Separating (barrier between fuel and fire)
Cooling (lowers the temp of the fuel)
Suppressing (smothering, prevents release of vapors)
What are the two categories of Class B fuels?
What is the range of foam concentrate for Class A foam?
0.1% to 1.0%
What are the four ways foam can be proportioned?
What are two uses for Class B foam?
Extinguish fires involving flammable and combustible liquids
Suppress vapors from unignited spills
What is the proportioning range for Class B foams?
1% to 6%
Three types of foam and ratio of finished foam to foam solution
Low Expansion. 20:1
Medium Expansion. 20:1 to 200:1
High Expansion. 200:1 to 1000:1
Four factors that determine rate of foam application.
Type of foam concentrate
Fuel on fire?
Type of fuel (hydrocarbon or polar solvent)
Whether fuel spilled or in a tank
How to calculate the foam application rate from a nozzle
Divide the nozzle flow rate by the area (sq ft). ie .25 gpm/sq ft
Fluoroprotein foam characteristics
Security blanket for long-term vapor suppression
Flows more easily than regular protein foam
High heat resistance and water retention
Can be made alcohol resistant
AFFF foam characteristics
Most commonly used
Reduces surface tension of water below that of fuel
Forms a film across fuel
Vapor excluding film is released ahead of foam blanket
Followed by more insulation by foam blanket
As it drains its water, more film is made "healing"
Can be made in alcohol resistant forms but should be applied gently
What type of foam system is on our rigs?
Variable flow Variable rate direct injection system
The foam concentrate injection is controlled by monitoring the water flow and controlling the speed of a positive displacement foam concentrate pump.