Specifications

centrifugal chiller. Chillers shall have no more than two
oil-free, magnetic bearing, semi-hermetic centrifugal
compressors (no exceptions). Each compressor shall
have an integrated variable-frequency drive operating
in concert with inlet guide vanes for optimized full and
part load efciency. On two-compressor units, the
evaporator and condenser refrigerant sides and the
expansion valve shall be common and the chiller shall
be capable of running on one compressor with the
other compressor or any of its auxiliaries inoperable or
removed.
2.3 DESIGN REQUIREMENTS
A. General: Provide a complete water-cooled, semi-
hermetic oil-free centrifugal compressor water chiller as
specied herein. The unit shall be provided according
to standards indicated in Section 1.2. In general, unit
shall consist of one or two magnetic bearing, completely
oil-free centrifugal compressors, refrigerant, condenser
and evaporator, and control systems including integrated
variable frequency drive, operating controls and
equipment protection controls. Chillers shall be charged
with refrigerant HFC-134a. If manufacturer offers a
chiller using any HCFC refrigerant, manufacturer shall
provide, in writing, documentation signed by an ofcer of
the company assuring refrigerant availability and price
schedule for a 20-year period.
B. The entire chiller system, including all pressure vessels,
shall remain above atmospheric pressure during all
operating conditions and during shut down to ensure
that non-condensables and moisture do not contaminate
the refrigerant and chiller system. If any portion of the
chiller system is below atmospheric pressure during
either operation or shut down, the manufacturer shall
include, at no charge:
1. A complete purge system capable of removing non-
condensables and moisture during operation and
shut-down.
2. A 20-year purge maintenance agreement
that provides parts, labor, and all preventative
maintenance required by the manufacturer’s
operating and maintenance instructions.
3. The manufacturer shall also include at no charge
for a period of 20 years an annual oil and refrigerant
analysis report to identify chiller contamination due
to vacuum leaks. If the analysis identies water, acid,
or other contaminant levels higher than specied by
the manufacturer, the oil and/or refrigerant must be
replaced or returned to the manufacturer’s original
specication at no cost to the owner.
4. The manufacturer shall include a factory-installed and
wired system that will enable service personnel to
readily elevate the vessel pressure during shutdown
to facilitate leak testing.
C. Performance: Refer to chiller performance rating.
D. Acoustics: Sound pressure for the unit shall not exceed
the following specied levels. Provide the necessary
acoustic treatment to chiller as required. Sound data
shall be measured in dB according to AHRI Standard
575 and shall include overall dBA. Data shall be the
highest levels recorded at all load points.
Octave Band
Overall
dBA
63 125 250 500 1000 2000 4000 8000
2.4 CHILLER COMPONENTS
A. Compressors:
1. The unit shall utilize magnetic bearing, oil-free, semi-
hermetic centrifugal compressors. The compressor
drive train shall be capable of coming to a controlled,
safe stop in the event of a power failure.
2. The motor shall be of the semi-hermetic type,
of sufcient size to efciently fulll compressor
horsepower requirements. It shall be liquid refrigerant
cooled with internal thermal sensing devices in the
stator windings. The motor shall be designed for
variable frequency drive operation.
a. If the compressor design requires a shaft seal
to contain the refrigerant, the manufacturer shall
supply a 20 year parts and labor warranty on the
shaft seal and a lifetime refrigerant replacement
warranty if a seal failure leads to refrigerant
loss, or the chiller manufacturer shall assume
all costs to supply and install a self contained
air conditioning system in the mechanical space
sized to handle the maximum heat output of the
open drive motor. The energy required to operate
this air conditioning system shall be added to
the chiller power at all rating points for energy
evaluation purposes.
b. If the compressor/motor uses any form of
antifriction bearing (roller, ball, etc), the chiller
manufacturer shall provide the following at no
additional charge:
• A 20-year bearing warranty and all
preventative maintenance as specied by
the manufacturer’s published maintenance
instructions.
• At start up, a three-axis vibration analysis and
written report to establish bearing condition
baseline.
• An annual three-axis vibration analysis and
written report indicating bearing condition.
CAT 602-4 • MAGNITUDE
®
MODEL WMC CHILLERS 18 www.DaikinApplied.com
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