The recirculation manifold provides three outlet ports. A three-inch outlet passes pumpage to a three-inch, fifty-foot
discharge hose and on to the delivery hoses and nozzles. Two-inch outlets are provided for recirculation of a portion of the
pumpage. One of the two-inch outlets (RECIRC 2) allows full flow recirculation; the other two-inch outlet (RECIRC 1) has a
reduced bore to limit recirculation to five gpm.
The pumping subsystem design incorporates a recirculation capability to continuously filter the pumpage, and maintain
pumpage pressure and temperature within safe limits for continuous operation. The system provides two modes of
recirculation: RECIRC 1 from the recirculation manifold limits recirculation to five gpm (normal fueling operation) while
RECIRC 2 allows full flow recirculation from the recirculation manifold. Each mode routes the pumpage through two-inch
hoses and a cross-wye fitting assembly to the fuel drum inlets.
The diesel engine (1), fuel tank (2), fuel selector valve (3), fuel filter (4), and fuel supply line (5) and return line (6) comprise
the diesel power subsystem, figure 4. A splined adapter flexible coupling (7) on the engine output shaft mates with a flexible
coupling (8) attached to the input shaft of the fuel transfer pump to provide system power.
Figure 4. AAFARS Power Subsystem
The diesel is a compression ignition engine: ignition is achieved by compressing a fuel-air mixture in a cylinder until the heat
generated by compression causes the mixture to ignite. The resulting combustion causes the mixture to expand, forcing the
piston to move. The diesel engine is a two cylinder, direct injection engine. An individual fuel injector and injection pump
supplies pressurized fuel alternately to each cylinder.
An on-board fuel tank is the normal fuel source for engine operation. However, a fuel selector valve allows selection of an
external fuel source, if desired. A fuel filter/water coalescer in the supply line removes impurities and water from the fuel,
regardless of source. The engine fuel pump continuously supplies fuel to the fuel injection pumps; a fuel return line allows
surplus fuel to return to the fuel tank.