Product Manual PM WSC/WDC 65
2.4 CHILLER COMPONENTS
A. Compressor:
1. Unit shall have a single-stage hermetic centrifugal compressor. Casing design shall
ensure major wearing parts, main bearings, and thrust bearings are accessible for
maintenance and replacement. The lubrication system shall protect machine during
coast down period resulting from a loss of electrical power.
2. The impeller shall be statically and dynamically balanced. The compressor shall be
vibration tested and not exceed a level of 0.14 IPS.
3. Movable inlet guide vanes actuated by an internal oil pressure driven piston shall
accomplish unloading. Compressors using an unloading system that requires
penetrations through the compressor housing or linkages, or both that must be
lubricated and adjusted are acceptable provided the manufacturer provides a five-
year inspection agreement consisting of semi-annual inspection, lubrication, and
annual change out of any compressor seals. A statement of inclusion must
accompany any quotations.
4. If the compressor is not equipped with guide vanes for each stage and movable
discharge diffusers, then furnish hot gas bypass and select chillers at 5% lower
kW/ton than specified to compensate for bypass inefficiency at low loads.
B. Lubrication System: The compressor shall have an independent lubrication system to provide
lubrication to all parts requiring oil. Provide a heater in the oil sump to maintain oil at
sufficient temperature to minimize affinity of refrigerant, and a thermostatically controlled
water-cooled oil cooler. Coolers located inside the evaporator or condenser are not
acceptable due to inaccessibility. A positive displacement oil pump shall be powered through
the unit control transformer.
C. Refrigerant Evaporator and Condenser:
1. Evaporator and condenser shall be of the shell-and-tube type, designed,
constructed, tested and stamped according to the requirements of the ASME Code,
Section VIII. Regardless of the operating pressure, the refrigerant side of each
vessel will bear the ASME stamp indicating compliance with the code and indicating
a test pressure of 1.3 times the working pressure but not less than 100 psig. Provide
intermediate tube supports at a maximum of 18 inch spacing.
2. Tubes shall be enhanced for maximum heat transfer, rolled into steel tube sheets and
sealed with Locktite or equal sealer. The tubes shall be individually replaceable.
3. Provide isolation valves and sufficient volume to hold the full refrigerant charge in
the condenser or provide a separate pumpout system with storage tank..
4. The water sides shall be designed for a minimum of 150 psig or as specified
elsewhere. Vents and drains shall be provided.
5. Chilled water minimum refrigerant temperature shall be 33°F.
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