Compressor Cooling And Lubrication System; Compressor Discharge System - Functional Description - Sullair 4500P User Manual

4500P-7500 USER MANUAL
compressor unit, the fluid is separated from the air.
At this time, the air flows through an aftercooler and
separator, and then to the service line while the fluid
is cooled and filtered in preparation for reinjection.
2.3 COMPRESSOR COOLING
AND LUBRICATION SYSTEM
- FUNCTIONAL
DESCRIPTION
Refer to Figure 2-3 or Figure 2-4. The cooling and
lubrication system (air-cooled models) consists of a
fan, fan motor, radiator aftercooler/fluid cooler,
full flow fluid filter,
interconnecting hoses. Water-cooled models have
two shell and tube heat exchangers instead of a
radiator cooler.
The pressure in the receiver tank starts the fluid flow
by forcing the fluid from the high pressure area of the
tank to an area of lower pressure in the compressor.
Fluid flows from the bottom of the receiver tank to the
thermal valve that is fully open when the fluid
temperature is below 185°F (85°C) [195°F (91°C) for
24KT and pressures rated above 150 psig]. The fluid
passes through the thermal valve, the main filter, and
directly to the compressor where it lubricates, cools
and seals the rotors, and the compression chamber.
As the discharge temperature rises above 185°F
(85°C), due to the heat of compression, the thermal
valve begins to close and a portion of the fluid then
flows through the cooler. From the cooler the fluid
flows to the fluid filter and on to the compressor. A
portion of the fluid flow to the compressor is routed to
the anti-friction bearings
compressor rotors.
The fluid filter has a replacement element and an
integral bypass valve.
Lubrication Change
Maintenance, Fluid Filter and Separator on page 25.
Water-cooled models have a water pressure switch
to prevent operation when the water pressure is too
low.
2.4 COMPRESSOR DISCHARGE
SYSTEM - FUNCTIONAL
DESCRIPTION
Refer to Figure 2-3 or Figure 2-4. The compressor
discharges the compressed air/fluid mixture into the
combination receiver tank. The receiver has three
basic functions:
15
thermal valve, and
which support the
Refer to Section 3.6
Recommendations and
1. It acts as a primary fluid separator.
2. Serves as the compressor fluid sump.
3. Houses the final fluid separator.
The compressed air/fluid mixture enters the receiver
tank and flows through an internal baffle system that
changes the flow's direction and velocity, which
causes most of the fluid to fall to the bottom of the
receiver tank. A small amount of fluid remaining in
the compressed air collects on the surface of the
separator element as the air flows through the
separator.
A return line (or scavenge tube) leads from the
bottom of the separator dry side to a medium
pressure region in the compressor. Scavanged fluid
is returned by a pressure differential between the
receiver and compressor.
A visual sight glass is located on the return line to
observe this flow. This return line also has an orifice
(protected by a strainer) to ensure an unobstructed
flow. The separator system reduces the fluid carry-
over to less than 1ppm.
The WS Controller will show an abnormal pressure
drop through the separator if the element becomes
plugged. (Refer to Section 3.6 Lubrication Change
Recommendations and Maintenance, Fluid Filter and
Separator.) It will also shut down the compressor if
the discharge temperature reaches 235°F (113°C).
A minimum pressure/check
downstream from the separator maintains the
receiver pressure at 50 psig (3.4 bar) during load
conditions. This pressure level is necessary for
proper air/fluid separation and sufficient fluid
circulation.
A terminal check valve is a sub-component of the
minimum pressure/check
compressed air in the service line from back-flowing
into the receiver on shutdown or when the
compressor is operating in an unload condition. Also,
a pressure relief valve on the compressor's wet side
opens if the receiver tank pressure exceeds its
rating.
WARNING
Stop the compressor and relieve all internal
pressure before removing caps, plugs, and/or other
components when the compressor is running or
pressurized.
Add fluid to the receiver tank through the capped
SECTION 2
valve located
valve that prevents