Sullair LS-25 Operator's Manual And Parts List page 16

Section 2
DESCRIPTION
180°F/82°C (195°F/91°C for 24KT machines), due
to the heat of compression, the thermal valve be-
gins to close and a portion of the fluid then flows
through the cooler. From the cooler, the fluid flows
to the filter and on to the compressor unit. The fluid
filter has a replaceable 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 re-
duced, causing the fluid stop valve to close and iso-
late the compressor unit from the cooling system.
Water-cooled models have a water pressure switch
to prevent operation with inadequate water pres-
sure.
2.5 COMPRESSOR DISCHARGE SYSTEM, FUNC-
TIONAL DESCRIPTION
Refer to Figure 2-4.
charges the compressed air/fluid moisture through
a discharge check valve into the combination re-
ceiver/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:
1. It acts as a primary fluid separator.
2. It serves as the compressor fluid sump.
3. It houses the final fluid separator elements.
The compressed air/fluid mixture enters the receiv-
er and is directed against a baffle in the tank. The
direction of movement is changed and its velocity
significantly reduced, thus causing the large
droplets of fluid to fall to the bottom of the receiv-
er/sump. The fractional percentage of fluid remain-
ing in the compressed air collects on the surface of
the dual separator elements as the compressed air
flows through them. Two return lines (or scavenge
tubes) lead from the bottom of each separator ele-
ment to the inlet region of the compressor unit.
Fluid collecting on the bottom of each separator is
returned to the compressor by a pressure differ-
ence between the receiver and the compressor
inlet. 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. A gauge, located on the instrument panel, will
be in the red zone, or the display on Supervisor with
prealarm will show indication, when excessive pres-
sure drop through the separators develops. At this
10
The compressor unit dis-
time, separator element replacement is necessary.
The receiver is an ASME pressure vessel. A com-
bination minimum pressure/check valve, located
downstream from the separator, assures a mini-
mum receiver pressure of 50 psig (3.5 bar) 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 if the sump pressure
exceeds 200 psig (13.8 bar).
All compressor models with electro-mechanical
control are equipped with a high pressure shutdown
switch to shut down the compressor at 25 psi above
rated pressure. On compressors with Supervisor
controller, this setting is field-programmable. This
prevents the pressure relief valve from opening
under routine conditions, thereby preventing fluid
loss through the pressure relief valve.A tempera-
ture switch will shut down the compressor if the dis-
charge temperature reaches 240°F (115°C).
DO NOT remove caps, plugs, and/or other compo-
nents when compressor is running or pressurized.
Stop compressor and relieve all internal pressure
before doing so.
Fluid is added to the sump via a capped fluid filler
opening, placed on the tank to prevent over-filling of
the sump. A sight glass enables the operator to vi-
sually monitor the sump fluid level.
2.6 CONTROL SYSTEM, FUNCTIONAL DESCRIP-
TION
Refer to Figures 2-5A through 2-5D
chanical), or 2-6A through 2-6D
Spiral Valve). The purpose of the compressor con-
trol system is to regulate the amount of air being
compressed to match the amount of compressed
air being used. The capacity control system con-
sists of a spiral valve, pressure regulators, pres-
sure switch, pilot valve, an inlet butterfly valve
and a Sullicon Control. The functional description
of the control system is described below in four dis-
tinct phases of operation. The following description
text applies to all LS-25-150 compressors. For ex-
planatory purposes, this description will apply to a
compressor with an operating range of 100 to 110
psig (6.9 to 7.6 bar). A compressor with any other
(Electro-me-
(Supervisor with