Frick RWB II 480, Установка, эксплуатация и обслуживание

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RWB II ROTARY SCREW COMPRESSOR UNITS
OPERATION
S70-200 IOM
Page 17
with a large spring that creates 30 psi of pressure in the oil
separator (above suction pressure), for lubrication of the com-
pressor.
DO NOT ATTEMPT TO SERVICE THE COLD START VALVE.
PLEASE CONTACT THE FRICK SERVICE DEPARTMENT.
Once the compressor is running it will begin to force gas to
the condenser at connection P2. As the condenser heats up
it will begin to rise in pressure as the compressor suction
pulls down in pressure. As soon as differential pressure is
developed between the condenser and suction, these pres-
sures act across a piston inside the cold-start valve to par-
tially overcome the spring force. When the differential pres-
sure reaches and exceeds 30 psi, the piston fully overcomes
the spring force and powers the valve fully open for very low
operating pressure drop.
For booster applications, the valve is equipped with a lighter
spring which produces 15 psi oil pressure above suction pres-
sure before it fully powers open.
The RWB II package is also equipped with a suction check
valve bypass. The oil separator will slowly bleed down to sys-
tem suction pressure when the unit is stopped. This allows
the compressor drive motor to have an easier start, and the
discharge check valve will seat more tightly. See the "SUC-
TION CHECK VALVE BYPASS" section for operation.
NOTE: For alarm descriptions and shutdown or cutout
parameters, see publication S90-010 O.
COLD START VALVE
DEMAND PUMP OIL SYSTEM
This system is designed to provide adequate compressor
lubrication for some high stage applications that operate with
low differential pressure across the compressor suction and
discharge and all booster applications.
During the period from start-up to normal operation the oil
pressure alarm and oil pressure cutout setpoints will vary
according to formulas built into the microprocessor control
program.
NOTE: For alarm descriptions and shutdown or cutout
parameters, see publication S90-010 O.
COMPRESSOR OIL SEPARATION SYSTEM
The RWB II is an oil flooded screw compressor. Most of the
oil discharged by the compressor separates from the gas
flow in the oil charge reservoir. Some oil, however, is dis-
charged as a mist which does not separate readily from the
gas flow and is carried past the oil charge reservoir. One or
more coalescer filter elements then COALESCE the oil mist
into droplets which fall to the bottom of the coalescer section
of the oil separator. The return of this oil to the compressor is
controlled by a throttling valve on both high stage and booster
applications (see Figure 18).
NOTE: Open throttling valve only enough to keep coa-
lescer end of separator free of oil.
The sight glass located near the bottom of the coalescer
section of the oil separator should remain empty during nor-
mal operation. If an oil level develops and remains in the sight
glass, a problem in the oil return separation system or com-
pressor operation has developed. Refer to MAINTENANCE
for information on how to correct the problem.
OIL SEPARATION SYSTEM
Figure 17
Figure 18