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Product Description
gered rows and mechanically expanded into corrosion
resistant aluminum alloy fins with full height fin collars.
They have a design working pressure of 450 PSIG
(31 bar). Each coil is rested to 495 PSIG (34 bar).
Multiple fans move air through the coils. They are
dynamically and statically balanced, direct drive with
corrosion resistant glass fiber reinforced composite
blades molded into low noise, full airfoil cross section,
providing vertical air discharge from extended orifices
for efficiency and low sound. Each fan is located in a
separate compartment to prevent cross flow during fan
cycling. Guards of heavy gauge, PVC coated galvanized
steel are provided.
The fan motors are high efficiency, direct drive, 6-pole,
3-phase, Class- "F," current overload protected, totally
enclosed (TEAO) type with double sealed, permanently
lubricated ball bearings.
Oil Separator/System
The external oil separator, with no moving parts and
designed for minimum oil carry-over, is mounted in
the discharge line of the compressor. The high pressure
discharge gas is forced around a 90 degree bend. Oil is
forced to the outside of the separator through centrifugal
action and captured on wire mesh where it drains to the
bottom of the oil separator and into the compressor.
The oil (YORK "L" oil – a POE oil used for all refriger-
ant applications), which drains back into the compressor
through a replaceable 0.5 - 3.0 micron oil filter, and oil
supply solenoid, is at high pressure. This high pressure
"oil injection" forces the oil into the compressor where
it is gravity fed to the gears and bearings for lubrication.
After lubricating the gears and bearings, it is injected
through orifices on a closed thread near the suction end
of the rotors. The oil is automatically injected because
of the pressure difference between the discharge pres-
sure and the reduced pressure at the suction end of the
rotors. This lubricates the rotors as well as provides
an oil seal against leakage around the rotors to assure
refrigerant compression (volumetric efficiency). The
oil also provides cooling by transferring much of the
heat of compression from the gas to the oil keeping
discharge temperatures down and reducing the chance
for oil breakdown. Oil injected into the rotor cage flows
JOHNSON CONTROLS
into the rotors at a point about 1.2x suction. This assures
that a required minimum differential of at least 30 PSID
(2.1 bar) exists between discharge and 1.2x suction, to
force oil into rotor case, a minimum of 10 PSID (0.6
bar) is all that is required to assure protection of the
compressor. Oil pressure safety is monitored as the
difference between suction and the pressure of the oil
entering the rotor case.
Maximum working pressure of the oil separator is 450
PSIG (31 bar). A relief valve is installed in the oil sep-
arator piping. This will soon be incorporated into the oil
separator. Oil level should be above the midpoint of the
"lower" oil sight glass when the compressor is running.
Oil level should not be above the top of the "upper" sight
glass. Oil temperature control is provided through liq-
uid injection activated by the microprocessor, utilizing
a discharge temperature sensor, and a solenoid valve.
Oil Cooling
Oil cooling is provided by routing oil from the oil sep-
arator through several of the top rows of the condenser
coils and back to the compressor.
Capacity Control
The compressors will start at the minimum load position
and provide a capacity control range from 10% - 100% of
the full unit load using a continuous function slide valve.
The microprocessor modulates the current signal to a
3-way pressure regulating capacity control valve which
controls command compressor capacity, independent of
system pressures, and balances the compressor capacity
with the cooling load. Loading is accomplished by vary-
ing pressure through the pressure regulating capacity
control valve to move the slide valve against the spring
pressure to promote stable smooth loading.
Automatic spring return of the slide valve to the min-
imum load position will ensure compressor starting at
minimum motor load.
Power and Control Panel
All controls and motor starting equipment are factory
wired and function tested. The panel enclosures are
designed to IP55 and are manufactured from powder
painted galvanized steel.
FORM 201.18-NM7
17
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