2.1.2.1
Timer Defrost Controller
Controller shall
include an adjustable timer to control frequency of
cycles; [defrost
initiating thermostat;] adjustable program timer to
control sequence
of defrost cycle; [defrost terminating thermostat;] manual
override switch;
selector switch; and status pilot light.
2.1.2.2
Demand Defrost Controller
Controller shall include an automatic, solid-state circuitry to initiate
defrost cycle based on sensing adjustable temperature difference of air
moving across coil in direct proportion to frost build-up; thermostat to
terminate defrost; adjustable lockout to prevent initiation of defrost
during pull-down after defrost cycle; manual override switch; and status
pilot light.
2.2
[COMPRESSOR] [CONDENSING] UNITS
Factory fabricated, assembled and tested, packaged, ready for full capacity
operation after terminal point connection and field charging with operating
fluids. Units shall conform to ARI 520, ASHRAE 23, and ASHRAE 15. Provide
two charges of lubricating oil for each compressor. The first charge shall
be used during the operating test period, and at the end of this period
shall be withdrawn and replaced with the second charge. Equipment using
R-11, R-12, R-113, R-114, R-115, or R-500 as a refrigerant will not be
permitted. Refrigerants shall have an Ozone Depletion Factor (ODF) of 0.05
or less. The ODF shall be in accordance with the "Montreal Protocol on
Substances that Deplete the Ozone Layer," September 1987, sponger by the
United Nations Environment Program.
2.2.1
Capacity Criteria
**************************************************************************
NOTE: Show the capacity and saturated suction
temperature, saturated condensing temperature,
superheat, and subcooling on the drawings.
**************************************************************************
Application capacity rating shown shall include suction superheat and
liquid subcooling. Compressor design saturated condensing temperature and
saturated suction temperature limits shall not be exceeded.
2.2.2
Reciprocating Compressors
[Hermetic] [Open], [direct] [V-belt] drive reciprocating piston type,
designed and constructed for indicated compression ratio service. [Design
welded hermetic compressors for high compression ratio heat pump and low
temperature refrigeration service.] Machine cylinder blocks and heads from
aged, fine-grained, cast iron. [Provide ammonia service compressor
cylinder blocks and heads with self-draining water- or refrigerant-cooled
jackets where recommended by the manufacturer.] [Freeze-protect water
jackets.] Forge crankshafts of steel or cast nodular iron. Dynamically
balance rotating parts, including crankshaft and power transmission
components. Design compressors to operate at partial loads without
vibration greater than full load vibration and be capable of continuous
operation at lowest partial load. Piston speed shall not exceed
manufacturer's recommendation or 4 1/2 m/s 875 fpm, whichever is lesser.
Provide main journals and ferrous and bronze connecting rods with
SECTION 15602N
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