Specifications

13JOHNSON CONTROLS
FORM 160.80-EG1 (511)
Mechanical Specications
STANDARD UNIT
General
The YORK YS Rotary Screw Chiller is completely factory-
packaged, including evaporator, condenser, sub-cooler,
oil separator, compressor, motor, lubrication system,
control center and refrigerant isolation valves. The factory
package consists of a “leak tight” design. All units ship as
standard with a full charge of refrigerant and oil. Units can
also be shipped in sections (optional) to accommodate
job site requirements.
The services of a Johnson Controls factory-trained, eld
service representative are incurred to supervise or perform
the nal leak testing, charging, the initial start-up, and
concurrent operator instructions.
Heat Pump
The YS is capable of providing simultaneous heating
and cooling when ordered with the optional heat pump
package. The unit can supply leaving condenser water
temperatues up to 140°F (60°C)
Compressor
The Frick Rotary Twin Screw Compressor is engineered
and constructed to meet the exact requirements of the
industrial refrigeration market. It utilizes state-of-the-art
technology to provide the most reliable and energy-
efcient compressor available at all operating conditions.
The compressor operates at 3750 RPM for 60 Hertz and
2975 RPM for 50 Hertz. The compressor housing is made
of cast iron, precision-machined to provide minimal clear-
ance for the rotors. Compressor housing has a design
working pressure (DWP) of 300 psig (2068 kPa) minimum,
and hydro-tested at 544 psig (3751 kPa).
The rotors are manufactured from forged steel and use
asymmetric proles. The compressor incorporates a
complete anti-friction bearing design for reduced power
and increased reliability. Four separate cylindrical roller
bearings handle radial loads. Two 4-point angular contact
ball bearings handle axial loads. Together, they maintain
accurate rotor positioning at all pressure ratios, thereby
minimizing blow-by and maintaining efciency.
A check valve is installed in the compressor discharge
housing (suction housing for S4 and S5 compressor) to
prevent compressor rotor back spin because of system
refrigerant pressure gradients during shutdown.
The open-drive compressor shaft seal consists of preci-
sion ceramic seal faces, metallic bellows, rotating member,
PTFE ‘C’-Ring static seal, and multi-port oil injection ring.
The seal cavity is maintained at intermediate pressure
with its oil discharged to the oil drain from the compressor.
Combining intermediate pressure with direct oil injection
provides cool, non-foaming lubricant to the seal assuring
a longer lifespan.
Capacity Control
Capacity control is achieved by use of a slide valve which
provides fully modulating capacity control from 100% to
10% of full load. The slide valve is actuated by oil pressure,
controlled by external solenoid valves via the OptiView
Control Center.
Oil Separator
The oil separator is a horizontal design without moving
parts. Effective oil separation is achieved by gravity drop-
out of oil from the refrigerant gas as velocity decreases
upon entering the separator, and by mesh pads to provide
nal gas/oil separation before gas enters the condenser.
The oil separator is designed for 345 psig (2378 kPa)
design working pressure, tested at 517 psig (3565 kPa),
and stamped in accordance with ASME Boiler and Pres-
sure Vessel Code, Section VIII - Division 1.
Each vessel has a refrigerant relief device(s) set at 300
psig (2068 kPa). A. When required by the refrigeration
safety code, each vessel has a dual refrigerant relief
device(s).
Lubrication
The main unit oil reservoir is located in the oil separator.
The compressor also has an oil reservoir located at the
rotor bearings to provide lubrication during start-up, coast
down, and in the event of a power failure. During opera-
tion, system pressure differential provides proper oil ow
without the need of an auxiliary oil pump. This minimizes
energy consumption.
The chiller is shipped with a 3 Micron absolute oil lter,
ensuring a clean oil system and superior compressor
life. An external, replaceable cartridge oil lter is supplied
with manual isolation stop valves for ease of servicing.
An optional dual oil lter housing with isolation valves is
available on all units. This allows immediate switching
from one lter to the other, eliminating downtime during
lter changes. The off-line oil lter can be changed during
chiller operation.
A 500 watt (115 volt - 1-phase - 60/50Hz) immersion
oil heater is located in the oil separator reservoir, tem-
perature actuated to efciently remove refrigerant from
the oil. Oil heater power supply is factory wired from
the control panel. A factory-piped refrigerant-cooled oil
cooler is provided as standard. No auxiliary water pip-
ing is required. An oil eductor automatically removes oil
which may have migrated to the evaporator and returns
it to the compressor.