Transcript Class A Foam 101 - Marysville, Ohio

Class A Foam 101
Marysville Division of Fire 2009
Class A vs. Class B Foam

Class B Foam is repelled by hydrocarbons
- Oleophobic

Class A Foam likes hydrocarbons Oleophillic
Class A Foam
Contains surfactants which decrease
surface tension of water
 Contains emulsifiers which enhance
“stickiness” to organic molecules
 Similar to Class B foam in that it contains
ingredients which make tiny bubbles
 Biodegradable

What is surface tension?
Force which makes water bead up
 Surfactants decrease surface tension
 Reduction of surface tension allows the
water to spread out more on a surface
and more likely to soak into that surface.

– Increases moisture content
– Decreases the temperature
What does an emulsifier do?

Emulsifiers (in foam) bind with
hydrocarbon fuels and work to break them
down into smaller droplets and
encapsulate them. So, when a Class A
fuel burns, the emulsifier binds with the
burnt surface.
Advantages of Class A Foam
Spreads out and
soaks into fuels
 Binds with fuel
 Covers the fuel with a
cooling blanket
 “Sticky Water”

Why don’t we use Class A foam on
gasoline too?

Class A foam does not
work well on liquids
that have polar
solvents. (i.e.
ethanol)
Proportioning

Class A foam is
typically proportioned
from 0.3% to 1%.

Our default will be to
initiate at 0.5% and
titrate to desired
effect up to 1%.
Class A Parameters
Useable from 20o to 120o F, with freezing
at 6o
 20 Yr shelf life if stored in sealed
container, 1 yr if stored in apparatus
reservoir tank.
 Avoid mixing with Class B foam, it
congeals into a sludge.

Class A Foam uses

Class A foam has been used for years on
initial attack, overhaul and exposure
protection.
– Permeates voids and cavities
– Increases moisture content
Hale Foam System

Hale Foam Logix
System
– 30 gallon Class A
Foam Concentrate
– Default at 0.5% foam
at 150 GPM
Hale Foam System

Red Button: On/Off

When turned “on” a
red light will come on
the bar graph under
the numerical display
Hale Foam System

“I” Button: Mode
button. Switch
between flow, %,
total flow and total
foam
Hale Foam System

↓ and ↑ button:
change foam
percentage
We will default at .5%,
but can be increased
for deep seated fires
or increased effect.
Hale Foam System

If the display reads “0” or “Lo A”, the
concentrate is nearing empty or is empty
Hale Foam System

When done with the
foam:
– Turn off (red button
(light goes out))
– Flush the hose line
until only water come
out
– Reload hose and refill
Class A Foam tank
Questions?

Based on NFPA 1145, Use of Class A Foam
in Manual Structural Firefighting, 2006
Edition