TM 5-1940-322-10
0003 00
THEORY OF OPERATION (Contd)
FUNCTION OF THE FUEL SYSTEM
Each engine has its own fuel system except that fuel is drawn from a common fuel
tank. The fuel systems are identical. Fuel gravity feeds from fuel tank to main shut-
off valve. From this point, fuel is drawn through the system using the fuel pump.
Fuel splits into two separate fuel lines: one for port and other for starboard.
Once fuel has reached the starboard fuel shut-of valve and valve is open, fuel flows
to fuel/water separator, lubricity fuel filter, fuel pump, fuel filter, fuel injector pump,
fuel high-pressure supply lines, and fuel injectors. Excess fuel not used by fuel
injectors will flow into the low-pressure fuel return line and back into fuel tank. The
fuel tank vent line is routed through port side battery compartment and upward
along the port side of the boat.
FUNCTION OF THE AIR INTAKE AND EXHAUST SYSTEM
Each engine is equipped with a breathing tube located on the left side of the engine
block. A flexible tube from each engine is routed to a filter bracket and is connected
to the breather filter. Noncondensed vapors are vented into the engine compartment.
The port and the starboard engines have individual air intake exhaust systems. The
systems are identical except that the port engine discharges exhaust gases to port
side and the starboard engine discharges exhaust gases to starboard side. Both port
and starboard exhaust systems are cooled by raw water from the hydrojets.
FUNCTION OF THE FIRE SUPPRESSION SYSTEM
The engine compartment fire suppression system consists of a single fore
extinguisher automatically activated when the temperature sensor on the top of the
bottle reaches 175F (79.4C). During discharge, shut down engines as soon as
possible so extinguishing agent (FM200) can flood engine compartment with an
electrically nonconductive, non corrosive vapor and residue-free extinguishing agent
that stops the combustion process through both physical and chemical means.
FM200 (CF3CHFCF3) is an electrically nonconductive and residue-free
extinguishing agent that requires no clean up. FM200 is an effective heat transfer
agent that removes heat energy from the fire to the extent that combustion reaction
cannot sustain itself. However, in order for the fire suppression system to be
effective, both engine compartment access hatches must be kept closed.
If the fire extinguisher has been discharged, report fire extinguisher discharge to
supervisor. Refer to gauge on top of tank to determine if system is fully charged.
In addition to the fire suppression system, there is a portable hand-held fire
extinguisher stowed on the starboard wall of the forward cockpit. If the seal is
broken, determining if the extinguisher has been discharges is done by weighing it;
8-1/2 lb empty, and 13-1/2 lb full.
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