Specifications

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 1.1 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 and secured to the
intermediate supports without rolling.
3. Provide sufficient isolation valves and condenser volume to hold full refrigerant charge in the
condenser during servicing or provide a separate pumpout system and storage tank sufficient
to hold the charge of the largest unit being furnished.
4. The water sides shall be designed for a minimum of 150 psig or as specified elsewhere. Vents
and drains shall be provided.
5. Evaporator minimum refrigerant temperature shall be 33°F.
6. An electronic expansion valve shall control refrigerant flow to the evaporator. Fixed orifice
devices or float controls with hot gas bypass are not acceptable because of inefficient control
at low load conditions. The liquid line shall have a moisture indicating sight glass.
7. The evaporator and condenser shall be separate shells. A single shell containing both vessel
functions is not acceptable because of the possibility of internal leaks.
8. Reseating type spring loaded pressure relief valves according to ASHRAE-15 safety code
shall be furnished. The evaporator shall be provided with single or multiple valves. The
condenser shall be provided with dual relief valves equipped with a transfer valve so one
valve can be removed for testing or replacement without loss of refrigerant or removal of
refrigerant from the vessel. Rupture disks are not acceptable.
9. The evaporator, including water heads, suction line, and any other component or part of a
component subject to condensing moisture shall be insulated with UL recognized 3/4 inch
closed cell insulation. All joints and seams shall be carefully sealed to form a vapor barrier.
10. Provide factory-mounted and wired, thermal dispersion water flow switches on each vessel to
prevent unit operation with no water flow.
C. Prime Mover: Permanent-magnet, synchronous motor of the hermetic type, of sufficient size to
efficiently fulfill compressor horsepower requirements. Motor shall be liquid refrigerant cooled with
internal thermal overload protection devices embedded in the winding of each phase. Motor shall be
compatible with variable frequency drive operation.
D. Variable Frequency Drive (VFD)
1. The chiller shall be equipped with a Variable Frequency Drive (VFD) to automatically
regulate each compressor speed in response to cooling load and compressor pressure lift. The
chiller control shall coordinate compressor speed and guide vane position to optimize chiller
efficiency.
2. Each compressor circuit shall be equipped with a line reactor.
52 Catalog WMC-4