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3.5.2 CLASS B FOAM
HYDROCARBONS
Fuels that are mostly distilled from crude oil or
vegetable matter. Will not mix with water.
AFFF (Aqueous Film Forming Foam)
AR (Alcohol Resistant Foam)
UNIGNITED
May apply at less than rates for
ignited. Be capable of increasing
to ignited rates if needed.
MEDIUM EXPANSION NOZZLE
for vapor suppression
3.5.2 SETTING FOAM PERCENTAGE
The foam percentage is controlled by an orifi ce plate that is installed in the nozzle at the mouth of the concentrate inlet (see fi gure
2.5.3). The MASTER FOAM comes with orifi ce plates for 0.5%, 1%, 3% and 6%. Each orifi ce plate is marked with the percentage
and nozzle fl ow rate. The fl ow rate on the orifi ce plate must match the fl ow rate marked on the nozzle's baffl e. The chart in fi g 2.5.2a
gives the nominal rates of foam usage. Accuracy of proportioning is fairly insensitive to nozzle inlet pressure. The graph in fi gure
2.5.2b gives expected percentages for various inlet pressures.
To install the orifi ce plate in the nozzle simply push it into the bore at the concentrate inlet on the nozzle. The orifi ce plate has an
O-ring to hold it in place.
To remove the orifi ce plate, hook a small object (such as a screwdriver or Allen wrench) into the hole in the orifi ce plate and pull it
out. Take care not to damage the orifi ce. Note: The hole in the 6% orifi ce plate is big enough that your fi nger can be used to pull it
out instead of a tool.
WATER FLOW
(GPM)
EXAMPLE: 500 GPM OF WATER AT 3% USES 15.5 GPM OF CONCENTRATE
NOTE: FLOWS SHOWN ARE NOMINAL. ACTUAL RESULTS MAY VARY BASED ON BRAND
AND CONDITION OF FOAM
©Copyright Task Force Tips, Inc. 2003 - 2011
LIQUID FUEL - CLASS B
Apply with
CONCENTRATE FLOW RATE IN GPM
0.5%
250
1.3
350
1.8
500
2.5
750
3.8
Fig 2.5.2a Concentrate Usage Chart
POLAR SOLVENTS
A fl ammable liquid that mixes with water.
Examples are alcohol's, amines, ethers, esters,
aldehydes, and ketones. In fi refi ghting, any
fl ammable liquid which destroys regular foam is
generally referred to as a polar solvent.
AR (Alcohol Resistant Foam)
Application rates:
Use foam manufacturer's
recommendations for
handheld nozzles.
MEDIUM EXPANSION NOZZLE
for vapor suppression
FOAM PERCENTAGE
1%
3%
2.6
7.8
3.5
10.8
5.1
15.5
7.6
23.2
6
UNIGNITED
Apply with
6%
16
22.3
31.9
47.9
LIZ-030 September 27, 2011 Rev07
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