SECTION 4 DE-18 USER MANUAL
39
4.7 COMPRESSOR
LUBRICATION SYSTEM,
FUNCTIONAL DESCRIPTION
Refer to Figure 4-6 and Figure 4-7. The DE-18
Series Compressor delivers oil-free compressed air,
but it requires lubricant to maintain its high speed
bearings and gears in running order.
A gear-type pump draws lube oil from the integral
sump and delivers it at a rate of 25gpm (79Lpm), and
a pressure equal to approximately 100 psig (7.6
barg). An external bypass valve maintains the set
flow, while protecting the pump against undesirable
over-pressures. A thermal mixing valve, set to open
at 85°F (29°C) ensures fast oil warm-up by
bypassing oil around the heat exchanger. The lube
oil is sequentially pumped through a heat exchanger,
the first and second stage compressor cooling
jackets, a high efficiency, replaceable element filter,
and a multi-port manifold, where the 100°F (38°C)
filtered outflow is distributed to bearing and gear
lubrication points on the compressor and the gear
box. Filtered oil is also used to actuate the hydraulic
actuator linked to the inlet control valve.
The controller senses and displays the filter outlet
pressure and temperature. As a safety measure,
unless oil pressure builds up to 30 psig (2.1 barg)
within 15 seconds after startup, the controller shuts
down the unit. In addition, if the pressure drop across
the filter ports exceeds 20 psi (1.4 bar), the controller
displays a maintenance requirement message.
All lubricated points return the oil to the sump by
gravity. Vents on the compressor timing gear covers
and the gear box are also piped into the sump, to
avoid releasing oil vapor. The sump is vented to
atmosphere via a breather which includes an oil
vapor trap.
4.8 BUFFER AIR SYSTEM,
FUNCTIONAL DESCRIPTION
A small supply of cooled, compressed air is taken
downstream of the aftercooler moisture separator,
and used to feed the buffer air system. This
compressed air goes through a control air filter, and
then through a pressure regulator, where the
pressure is reduced from the compressor operating
pressure to 5-10 psig unloaded (read from locally-
mounted pressure gauge). This clean, compressed
air supply is fed to both first and second compression
stages. This air provides a positive pressure buffer to
the seals between the compression air and oil sides
of the stages, assuring oil-free air. The buffer air is
then drained from each stage.
4.9 ENGINE FUEL SYSTEM,
FUNCTIONAL DESCRIPTION
Refer to Figure 4-8. Fuel can be supplied to the
engine by either the on board tank or through the
auxiliary connections on the outside of the base
frame. The onboard tank is capable of holding
enough fuel for an eight hour shift. The electronic fuel
gauge on the controller senses fuel level and will
announce a low fuel warning and shutdown the
compressor package before the fuel system loses its
prime.
When using the auxiliary fuel connections the fuel
control valve handle must be in the up position to
allow fuel to be routed properly. Auxiliary fuel must
be supplied at a height above the fuel control valve to
ensure adequate gravity feed. Fuel returning from
the engine is routed to a fuel cooler, if required, and
then back to the fuel control valves before returning
to the fuel tank.
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