Section 2
DESCRIPTION
7
thermal valve bypass begins to close and a portion
of the fluid then flows through the cooler. From the
cooler, the fluid flows to the main filter and on to the
compressor unit. The fluid filter has a replacement
element and an integral pressure bypass valve.
The fluid stop valve prevents fluid from filling the
compressor unit when the compressor is shut
down. When the compressor is operating, the fluid
stop valve is held open by air pressure from the
compressor unit allowing a free flow of fluid from
the receiver/sump back to the compressor unit. On
shutdown, the compressor unit pressure is
reduced, causing the fluid stop valve to close and
isolate the compressor unit from the cooling sys-
tem.
2.5 COMPRESSOR DISCHARGE SYSTEM, FUNC-
TIONAL DESCRIPTION
Refer to Figures 2-2, 2-3A and 2-3B. The compres-
sor unit discharges the compressed air/fluid mois-
ture through a discharge check valve into the com-
bination receiver/sump. The discharge check valve
prevents air in the receiver from returning to the
compression chamber after the compressor has
been shut down. The receiver has three functions:
• It acts as a primary fluid separator.
• Serves as the compressor fluid sump.
• Houses the final fluid separator elements.
The compressed air/fluid mixture enters the receiv-
er and is directed against the ends of the tank. The
direction of movement is changed and its velocity
significantly reduced, thus causing large droplets of
fluid to form and fall to the bottom of the
receiver/sump. The fractional percentage of fluid
remaining in the compressed air collects on the sur-
faces of the dual separator elements as the com-
pressed air flows through them. Two return lines (or
scavenge tubes) lead from the bottom of each sep-
arator element to the interstage of the compressor
unit. Fluid collecting on the bottom of each separa-
tor is returned to the compressor by a pressure dif-
ference between the receiver and the compressor.
Sight glasses are located in the return lines to
observe this fluid flow. There are also orifices in this
return line (protected by strainers) to assure proper
flow. By pressing the dP1 pad on the Supervisor II,
the operator may monitor the condition of the sep-
arator elements by reading differential pressure on
the digital display. At a differential of 10 psid (0.7
bar) or greater, the operator will be told to service
the separator element. At this time, separator ele-
ment replacement is necessary.
The receiver is an ASME pressure vessel. A combi-
nation minimum pressure/check valve, located
downstream from the separator, assures a mini-
mum receiver pressure of 160 psig (11bar) during
full load operation. This pressure is necessary for
proper air/fluid separation and proper fluid circula-
tion while supplying air to the system. This valve
also acts as a check valve preventing compressed
air in the service line from bleeding back into the
receiver on shutdown and during operation on the
compressor in an unloaded condition.
A pressure relief valve (located on the wet side of
the separator) is set to open at rated tank pressure.
The compressor is also equipped with high pres-
sure shutdown protection to shut down at high MAX
P1 setpoint. This prevents the relief valve from
opening. High temperature probes are provided to
shut down the compressor.
DO NOT remove caps, plugs, and/or other compo-
nents when compressor is running or pressur-
ized.
Stop compressor and relieve all internal pressure
before doing so.
Fluid is added to the sump via a capped fluid filler
opening, located on the tank to prevent overfilling of
the sump. A sight glass enables the operator to
visually monitor the sump fluid level.
2.6 CAPACITY CONTROL SYSTEM, FUNCTIONAL
DESCRIPTION
Refer to Figures 2-3A, 2-3B, 2-4A, 2-4B, 2-4C, 2-
4D and 2-4E. The purpose of the compressor con-
trol system is to regulate the compressor air intake
to match the amount of compressed air being uti-
lized. At 0 to 10 percent air output, the control sys-
tem will automatically unload the compressor and
reduce power consumption. The unload sump pres-
sure can be set using the unload control regulator
valve (140-175 psig).
The Control System consists of an inlet poppet
valve, blowdown solenoid valve, pneumatic
blowdown valve, control pressure regulator,
unload pressure regulator, sequencing sole-
noid valve, and a control line filter located prior
to the controls.
The functional description of the Control System is
described below in five distinct phases of the com-
pressor operation. For explanation purposes, this
description will apply to compressors with an oper-
ating range of 350 to 360 psig (24.1 to 24.8 bar). A
compressor with any other pressure range would
operate in a similar manner except for the stated
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