TIMING BELT AND
RELIEF VA LV E
Figure 6-6. AFFF single-speed injection pump.
AFFF Two-Speed Injection Pump
is used when fire-fighting flow rates exceed 250 gpm
for hangar bay and deck-edge sprinklers and 450 gpm
The AFFF two-speed injection pump (fig. 6-7) is
for bilge sprinklers. The motor on the two-speed pump
designed to meet the demand for either a low or a high
receives power from a motor controller supplied by a
fire-fighting capability. The two-speed AFFF pump
power panel that receives main ship's power from both
consists of a positive displacement pump rated at
the ship's service switchboard and the emergency
175 psi, a motor, and a reducer, coupled together with
service switchboard. The power panel is equipped with
flexible couplings and mounted on a steel base. The
an automatic bus transfer (ABT) to ensure a constant
pump is designed to inject AFFF concentrate into the
supply of electrical power to the two-speed pump. The
seawater supply at a constant flow rate, depending on
motor controller has provisions for both local and
the pressure and demand of fire-fighting requirements.
remote control. From the local control station, the
AFFF concentrations will exceed 6 percent in most
pump can be started at either high or low speed.
cases. The low-speed mode is used for individual
Remote control stations are segregated into high and
AFFF demand hose reel stations. The high-speed mode
low demand stations. High demand stations, such as
Figure 6-7. AFFF two-speed injection pump.