RXB PLUS ROTARY SCREW COMPRESSOR UNITSS70-101 IOM
Page 32
OPERATION
SINGLE-PORT LIQUID INJECTION
The single-port liquid injection system is designed to permit
liquid refrigerant injection into one port on the compressor
at any given moment and operate as outlined.
Solenoid valve SV7 is energized by the microprocessor when
the temperature element (TE3), installed in the piping after
the oil filter, exceeds the LICO setpoint. High pressure liq-
uid refrigerant is then supplied to the temperature control
valve TCV1. The temperature control valve is equalized to
a constant back pressure by the differential pressure con-
trol valve PDCV (see LIQUID INJECTION ADJUSTMENT
PROCEDURE). The differential pressure control valve uses
discharge gas to maintain downstream pressure. The gas
downstream of the differential pressure control valve is bled
off to the compressor suction to ensure steady and con-
stant operation of the valve.
BOOSTER APPLICATION - Discharge gas from the high-
stage compressor is required to assist the differential pres-
sure control valve (PDCV) in providing the temperature con-
trol valve (TCV) with a constant back pressure.
A solenoid valve SV6 is installed before the differential pres-
sure control valve (PDCV) to prevent migration of high pres-
sure gas during shut down.
COMPRESSOR OIL COOLING SYSTEMS
The RXB PLUS unit can be equipped with one of several
systems for controlling the compressor oil temperature. They
are single or dual-port liquid injection, thermosyphon or
water-cooled oil coolers. Each system is automatically con-
trolled, independent of compressor loading or unloading. Oil
cooling systems maintain oil temperature within the follow-
ing ranges:
LIQUID INJECTION EXTERNAL*
OIL COOLING OIL COOLING
R-717 110 - 130
O
F. 110 - 130
O
F
R-22 130 - 150
O
F. 110 - 130
O
F
* Thermosyphon oil cooling (TSOC) or Water-cooled oil cool-
ing (WCOC).
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