for freeze protection. The concentrate is mixed half and half
with water to make a 20 percent solution of surfactant which is
referred to as 100 percent AFFF in this handbook.
e) Concentrates are diluted with water to the maximum
extent practicable, consistent with maximizing realism,
activating AFFF sensors, and minimizing cost. Foaming action
should vary from site-to-site, based on water hardness.
Experimentation at each site is required. The diluted AFFF
surrogate is referred to as 100 percent AFFF in this handbook.
Handling System. The foam system for fire training
should consist of bulk storage for concentrate, a mixing tank
for preparing 20 percent solutions, a proportioning device (see
hose stations), and suitable transfer means between each. Where
usage rates are practical and tank truck deliveries are
available, bulk tank storage may be the most economical method.
The 40 percent concentration, used for the design delivery
quantity should ensure that the concentrate remains pumpable
without heating under possible ambient conditions. Provide
spill prevention provisions around the bulk storage area. If
the bulk storage tank is underground, ensure that the pump
design includes a provision for pump priming.
a) If bulk tank storage is inappropriate, provisions
should be made for 204 kg bulk 208 L drum storage and handling.
b) A solution tank should be provided in the
utilities building for mixing the concentrate with water to make
100 percent solution (20 percent active surfactant, 80 percent
inert). The tank should be sized to hold 120 percent of the
maximum daily 100 percent AFFF usage. Supporting equipment
should facilitate manual batch mixing. Each day the design
amount of concentrate should be pumped into the solution tank
from the bulk tank or from 208 L drums after which the
calculated amount of water should be added.
c) The solution tank should have, but not be limited
to, a graduated sight glass, a gage port, inlets and outlets,
high level alarm, low level pump shutoff, drain, and a vent.
Tank inlets should extend to the bottom of the tank and have
expansion nozzles to reduce foaming. Aspects of the design