Foam Flashcards
Types of foam
Low expansion
High expansion
Low expansion foam details
i. Class A (ordinary combustibles/wildland)
ii. Class B (flammable liquids)
1. Protein foam
2. Fluoroprotien foam
3. Film forming flouroprotien foam (FFFP)
4. Aqueous film forming foam (AFFF) (Low expansion mechanical foam)
5. AFFF with Alcohol Resistant Concentrate (ARC) or Alcohol Type Concentrate (ATC)
6. Micro-Blaze Out
Types of fuel requiring foam application
hydrocarbons and polar solvants
Hydro carbon fuel facts
i. Floats on water
ii. Hydrophobic
iii. Gasoline, kerosene, fuel oil, benzene, naphtha, jet fuel, crude oil
iv. Typically give off black smoke
Polar solvents fuel facts
i. Hydrophilic
ii. Alcohols, acetones, lacquer thinners, ketones, esters, acids, isopropyl
iii. Usually burns cleaner than hydrocarbons
iv. Flame is sometimes not visible
How does the foam work?
a. Smothering- preventing air and flammable vapors from combining
b. Separating – intervening between the fuel and the fire
c. Cooling – water in the foam lowers the temperatures of fuel and adjacent surfaces
d. Suppressing – preventing the release of flammable vapors
Why do we use foam
a. Many agents can extinguish a class B fire, however, foam provides
i. Firefighter safety
ii. Prevention of fuel ignition or re-ignition
iii. Suppression of flammable vapors
iv. Post fire security
What is surface tension?
a. The ability of water to bind together
b. Foam will decrease the surface tension and allow the foam to float on top
Type of incidents that require foam
a. Tank truck rollovers
b. Tank car derailments
c. Fuel spills at an automobile accident
d. Chemical spills
e. Spills of paint, motor oil, lacquer thinner, and other flammable liquids stored in warehouses and department stores.
What is foam not effective on?
a. Class C electrical fires
b. Pressurized gas
c. Combustible metals
Foam generation (five things you need for foam)
a. Foam concentrate
b. Foam proportioner (55psi friction loss)
c. Foam solution
d. Aeration
e. Finished foam
Foam tetrahedron
a. Foam concentrate
b. Water
c. Air
d. Mechanical agitation
Foam is generated by:
a. Mixing foam concentrate with water to make a foam solution
b. Mechanical agitation occurs as water and foam concentrate pass through hose
c. Aeration of the foam solution as it leaves the nozzle or is introduced before leaving the nozzle, making finished foam.
Does foam last forever?
- Finished foam doesn’t last forever. As foam drains, it becomes dry. Dry foam looks the same but allows for the release of vapors. Dry foam is also called skeletal foam. The bigger expansion, the slower the drainage
Foam application techniques
a. Bounce off
b. Bank in
c. Lofting/rain down
d. NO PLUNGE!
TFD’s SOPs regarding foam
a. TFD engines carry 10gal of AFFF (class B) and 20 gallons of class A foam in a tank
b. Foam concentrate proportioned at 3% or 6% for class B. Max hose lay is 250ft
c. Foam concentrate proportioned at 0.1-1.0% for class A. Max hose lay is 350ft
d. 95gpm proportioner
e. 30 degree fog pattern
Application rate for hydrocarbon spills
i. 0.1 gpm foam solution per sqft
ii. 20ftx50ft gasoline spill
iii. 1000sqft*0.1gpm of foam=100gpm of foam solution
iv. 3% concentrate * 100gpm = 3 gallons of concentrate/minute
v. Minimum 10minute supply * 3 gpm of concentrate = 30 gallons of foam concentrate needed.
Ignited hydrocarbon spills
i. 0.15 gpm foam solution per sqft
ii. 20ftx50ft gasoline spill
iii. 1000sqft*0.15gpm of foam=150gpm of foam solution
iv. 3% concentrate * 150gpm = 4.5 gallons of concentrate/minute
v. Minimum 10minute supply * 4.5 gpm of concentrate = 45 gallons of foam concentrate needed.
Application on unignited fuels
i. May use a reduced percentage of solution to suppress vapors
ii. Try to have enough on hand in case of ignition
Special hazards regarding gasoline blending
i. Blending a polar solvent with a hydrocarbon
ii. Performed at a refinery level
iii. Results in a slightly polar hydrocarbon with a high vapor pressure and low surface tension
iv. Methyl Tertiary Butyl Ether – MTBE
v. Methanol – Ethanol
vi. Must use AFFF/ARC (found at station 1)
Safety considerations when applying foam
a. Identify the hazard
b. Preserve the blanket
i. No apply water to foam!
ii. No walk through foam!
iii. No drag hose through foam!
c. Wind direction
d. Flowing fuel
e. Backup lines
Why do foam eductors fail?
a. Mismatched eductors and nozzles
b. Air leaks in pick up tube or hose connection
c. Improper flushing after use
d. Kinked discharged hose line
e. Nozzle elevation
f. Too much hose between educator and nozzle
g. Incorrect inlet pressure to educator
h. Partially closed nozzle
Why do people like Class A foam so much?
a. Transitional period to class A foam
b. Departments throughout the nation are transitioning to class A foam
c. Foam concentration between 0.1-1.0%
d. Benefits/safety concerns
i. Quicker knockdown – results in more tenable atmosphere
ii. Easer overhaul due to adsorption of water into material
iii. Uses less water thus less water damage
iv. Can be used for pre-treatment in wildland fires
v. Makes thing slippery!
What the Czech is wet water?
a. Wet water is still good for decreasing the surface tension of water. However there is no foaming action so there is no barrier. Works well on deep seated fires.
b. 1 bottle/500 gallon tank
c. Bad because you have to empty and refill the tank each time to get the correct ratio
