Provide a control panel fitted with a discharge pressure gage, suction
pressure gage, separate high pressure cutout with manual reset, separate
low pressure cutout, low water temperature cutout with manual reset,
compressor operating control, and manual off-auto switch. Provide oil
pressure gage and low-oil-pressure cutout switch with manual reset for
chillers with positive displacement type oil pumps. Provide signal lights
or other visual "failed" indications for high pressure, low pressure, and
oil pressure protection devices. Multicompressor units shall be provided
with a lead/lag selector switch. Provide a timer to prevent compressors
from short cycling whenever stopped by safety controls. Time delay shall
be not less than [_____] minutes. Pumpdown cycle of the nonrecycling start
type shall be provided for each compressor 70 kW 20 tons or larger.
Provide a minimum 100 mm 4 inch alarm bell and alarm bell circuit to
actuate bell in event of machine cutout on protective devices, except when
low-pressure cutout is used as an operating control. Provide system
capacity control to adjust chiller output to a minimum of [_____] percent
of full load capacity without cycling operating compressor and to
automatically recycle system on power interruption. Provide start-up and
head pressure controls to allow for system operation at all ambient
temperatures down to [_____] degrees C degrees F.
2.2.6
Motors and Starters
Provide [across-the-line magnetic] [reduced voltage] type motor starters
conforming with NEMA ICS 1 and NEMA ICS 2. Provide phase failure, over
voltage and low voltage protection. Provide induction electric motors
conforming with NEMA MG 1.
2.2.7
Factory Charging
Dehydrate, purge, and charge refrigerant circuit with refrigerant and oil
at factory. Factory oil and refrigerant charge shall be full amount
required for operation, if within limits permitted by the Department of
Transportation; otherwise, a holding charge shall be furnished. Field
charging, where only a holding charge is shipped, shall be accomplished
without breaking permanent refrigerant connections.
2.3
COMPRESSOR UNITS
ARI 520. Provide factory-assembled compressor units driven by electric
motors. Provide with valves, refrigerant piping, instruments and controls.
Provide standard equipment, optional equipment, and accessories specified
in ARI 520. Entire unit shall be mounted on a welded steel base. Provide
initial charge of refrigerant grade lubricating oil. Compressors shall
operate at partial load conditions without increase in vibration over that
normally experienced at full load; and shall be capable of continuous
operation down to lowest step of unloading as specified.
2.3.1
Reciprocating Compressors
Compressors shall have integrally cast housing of close-grained iron with
oil-level bull's eye, cast cylinder heads, cast-aluminum or forged-steel
connecting rods, and cast-iron or forged-steel crankshaft. Main bearings
shall be sleeve-insert type. Provide forced-feed, positive-displacement
type lubrication systems with oil strainer and reversible oil pump. Shaft
seals in open-type units shall be mechanical type. Suction and discharge
valves shall be flange connected, wrench operated, rising stem, with cap.
Rotating parts shall be factory statically and dynamically balanced.
SECTION 15601N
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