Foam Flashcards
How does foam suppress fires?
Smothers, penetrates, cools
What is class A foams main purpose?
Lower the surface tension of water
What concentration of class A foam is typically used?
.3-.5%.
At .3%, 1/3 of a gallon of concentrate is used per 100 gallons of water. 1 and 2/3 gallon of concentrate is used per 500 gallons of water. Thus, one 5 gallon bucket of foam will last through 3 tanks of water.
Three typical class A foam applications
Direct, foam line, protective
What is direct foam application?
Water is mixed with foam and applied through standard nozzle to penetrate into fuel
What foam concentration settings are on the TFT class B foam eductor
.25 and .5%
What does the foam flush do?
Flows water through the foam injection lines downstream of the foam pump.
What must be done before flowing class B foam through your foam system?
Must flush the foam lines and foam manifold.
What is the advantage of protein class B foams?
Bio-degrade able, flow and spread slower but provide a foam blanket that is more heat resistive and durable.
What is the advantage of synthetic class B foam?
Better flow, faster knockdown
What percentage of class B foam is used by SBCoFD
1%
How many gallons of 1% class b foam concentrate are needed for 500 gallons
5 gallons. At 1% it takes 100 gallons of water per gallon of foam.
How many sq. feet of area can a type one engine with 500 gallons water and 5 gallons of 1% class b foam cover?
300 sq feet, 17x17 ft square or 20 ft diameter circle
Class B foam application methods
Rain down, roll on, bank down
3 types of educators used in SBCoFD
Elkhart, angus, TFT
3 types of nozzles used for class B foam application
Select a flow, la nozzle, medium expansion nozzle
What nozzles are used for class a foam application
Mad dog, salty, bubble cup
What type of nozzle should not be used for class b foam application
Automatic
How do you calculate back pressure on a foam eductor
Add nozzle pressure, hose friction loss, and elevation pressure loss = back pressure on eductor
At what back pressure will the foam educators not work?
130 psi unless the foam proportion is no more than 1%, than 140 psi is acceptable
What is the maximum length of the hose lay during a class b foam evolution based on?
Back pressure on the eductor
What is the pressure needed to flow the Elkhart foam nozzle?
200 psi
What is the pressure needed to flow the angus foam eductor
150 psi
What is the pressure needed to flow the TFT foam eductor
200 psi
