specified. The inapplicable fouling factor will be
deleted. Water-cooled condensers may be used for
refrigerant storage in lieu of a separate liquid
receiver, if the condenser storage capacity is 20
percent in excess of the fully charged system.
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Unit shall be of the tube-in-tube, shell-and-coil, shell-and-tube, or
concentric tube type and be provided as an integral part of the
self-contained unit. Water-wetted metals shall be [copper] [or] [90/10]
[or] [70/30] [copper-nickel], except that heads may be ferrous metal in
systems with chemically treated recirculating water. Unit shall be rated
for not less than 2758 kPa 400 psi refrigerant side and 862 kPa 125 psi
water side pressure service at operating temperatures. Unit shall be
supplied with water as indicated. Water supply, return and control system
wetted parts shall be copper, bronze or stainless steel. Water supply,
return connections and piping internal to unit shall be copper with brazed
or threaded copper or bronze fittings, terminating in a threaded
connection. Piping arrangement shall include valved access for
recirculation of acidic scale removal chemicals and isolation pressure taps
to determine pressure drop and water flow. Performance shall be based on
an allowable water velocity not less than 0.9 m/s 3 fps nor more than 3 m/s
10 fps with a fouling factor of [0.001] [0.0005]. A separate condenser
shall be provided for each compressor circuit. Control shall be set for
refrigerant condensing temperature of [_____] degrees C degrees F. Units
which use a once-thru water-source shall be fitted with a strainer
protected solenoid shut-off valve. The valve shall be a fully automatic,
self-contained temperature regulating valve with integral thermometer.
Mercury shall not be used in thermometers.
2.8.3
Compressor
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NOTE: Delete this paragraph if a remote condensing
unit is specified.
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Compressor shall be direct drive, semi-hermetic or hermetic reciprocating,
or scroll type capable of operating at partial load conditions. Compressor
shall be capable of continuous operation down to the lowest step of
unloading as specified. Compressors of 26 kW 7.5 tons and larger shall be
provided with capacity reduction devices to produce automatic capacity
reduction of at least 50 percent. If standard with the manufacturer, two
or more compressors may be used in lieu of a single compressor with
unloading capabilities, in which case the compressors will operate in
sequence, and each compressor shall have an independent refrigeration
circuit through the condenser and evaporator. Each compressor shall start
in the unloaded position. Each compressor shall be provided with vibration
isolators, crankcase heater, [lubrication pump,] thermal overloads, and
[high] [high and low] pressure safety cutoffs and protection against short
cycling.
2.8.4
Refrigeration Circuit
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NOTE: Filter-driers are optional and may be deleted
on most precharged systems. Delete the last two
sentences except when needed for a self-contained
heat pump with an integral water-cooled condenser.
SECTION 15700A
Page 29
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