MIL-HDBK-1027/1B
solution undergoes an expansion of 6.5 to 1 when passing through
the nozzle, which produces around 61 L of expanded AFFF/water
solution (foam) after discharge.
4.3
Potassium Bicarbonate. Potassium bicarbonate, PKP, is
a dry chemical extinguishing agent. PKP has two main
undesirable characteristics for use in fire training. It is
extremely diffusive, that is it spreads in all directions like
smoke and remains airborne, and it is corrosive to metal and
painted surfaces.
a) Substitute. A substitute was identified as grade
No. 2 sodium bicarbonate powder with an apparent density of
3
approximately one g/cm . Sodium bicarbonate is similar to PKP in
all respects. However, No. 2 grade powder is composed of large
particles, i.e., 90 percent of the particles are larger than 44
microns whereas 90 percent of PKP particles are smaller than 44
3
microns. PKP has an apparent density of approximately 2 g/cm .
Larger particles make sodium bicarbonate less diffusive. The
substitute powder is coated with silicon and therefore not
soluble in water. The silicon coating should breakdown in time
and then the sodium bicarbonate should dissolve in the water.
Sodium bicarbonate powder's chemical composition is:
COMPONENTS
WEIGHT/PERCENT
Sodium bicarbonate, No. 2 grade
93.4
Attaclay
4.0
Mica
2.0
Silicone fluid
0.6
100.0
b) Sodium bicarbonate is available in a variety of
dry containers. It should be delivered and stored in bulk
quantities. Storage should be kept dry.
c) Sodium bicarbonate should then be transferred to
the refill station where the proper weight is poured through a
funnel into portable extinguishers. The same scales can be used
for PKP and CO2 refill.
PKP cylinders come in 8 and 12 kg sizes
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