automatically load and unload compressor at preset minimum and maximum
pressure settings, respectively. Provide means for automatic release of
pressure within cylinders when the unit is operating without load. Also
provide means for manual or automatic unloading of cylinders during
starting of unit. Equip compressor with a timed control to stop compressor
after a 10-minute unloaded period if air is not used.
2.1.2
Safety Controls
Provide safety controls to shutdown [each] compressor on high discharge air
temperature or low oil pressure for pressure lubricated compressor and low
oil level for splash lubricated compressor. Set high temperature shutdown
at [54] [_____] degrees C [130] [_____] degrees F. Indicate each shutdown
condition by a light on the compressor control panel.
2.1.3
Accessories
Provide pressure gages and relief valves on intercoolers and on the
aftercoolers. Provide [totally enclosed belt guards,] discharge check
valves, and pressure switches.
2.1.4
Noise
84 dBA maximum sound level one meter from compressor unit.
2.2
HIGH PRESSURE COMPRESSED AIR DRYER
Include component equipment, inter-connecting piping, wiring and controls,
mounted in a cabinet and requiring only the connection to utilities.
Degrease dryer cabinet, prime coat, and finish coat with baked enamel.
Contractor shall furnish integral components whether specifically required
by this specification or not. Air shall leave the dryer at a temperature
of [_____] degrees C F and a dew point of [_____] degrees C F, based on an
inlet temperature of [38] [_____] degrees C [100] [_____] degrees F.
Pressure drop shall not exceed [21] [_____] kPa [3] [_____] psi. Provide
complete internal tubing, wiring, and piping, such that only connections to
air inlet and outlet, to refrigerant compressor contactor, and to
condensate drain are necessary.
2.2.1
Construction
Heat sink type dryer consisting of a mechanical refrigeration system
equipped with an automatic temperature shutdown switch to prevent freezing,
a large aluminum granule heat sink to allow a minus 16 degrees C 4 degree F
automatic temperature control, regenerative air to air exchanger, and main
compressed air cooling exchanger. Refrigeration system shall cool thermal
mass heat sink which shall, in turn, lower compressed air temperature to
dry air. A direct air to refrigerant gas heat exchanger is not acceptable.
Dryer shall have no internal traps or filters and shall have large
internal air passages to minimize pressure drop.
2.2.2
Air Circuit
Include the following:
a.
Regenerative heat exchanger: ASTM A 269, Type 304L seamless
stainless steel tube construction, inlet compressed air to outlet
compressed air heat exchanger designed to reduce cooling load at
design conditions minus 7 degrees C 20 degrees F by inlet air
SECTION 15212N
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