RWF ROTARY SCREW COMPRESSOR UNITS
OPERATION
S70-600 IOM
Page 12
OPERATION and START-UP INSTRUCTIONS
The Frick RWF Rotary Screw Compressor Unit is an inte-
grated system consisting of seven major subsystems:
1.Control Panel (See publications S90-010 O, M, & CS).
2.Compressor
3.Compressor Lubrication System
4.Compressor Oil Separation System
5.Compressor Hydraulic System
6.Compressor Oil Cooling System
7. Compressor Easy-Start System
The information in this section of the manual provides the
logical step-by-step instructions to properly start up and
operate the RWF Rotary Screw Compressor Unit.
THE FOLLOWING SUBSECTIONS MUST BE READ AND
UNDERSTOOD BEFORE ATTEMPTING TO START OR
OPERATE THE UNIT.
SGC COMPRESSOR
The Frick RWF rotary screw compressor utilizes mating
asymmetrical profile helical rotors to provide a continuous
flow of refrigerant vapor and is designed for both high-pres-
sure and low-pressure applications. The compressor
incorporates the following features:
1. High capacity roller bearings to carry radial loads at both
the inlet and outlet ends of the compressor.
2. Heavy-duty, four-point angular contact ball bearings to
carry axial loads are mounted at the discharge end of com-
pressor.
3. Balance pistons located in the inlet end of the compres-
sor to reduce axial loads on the axial load bearings and
increase bearing life.
4. Moveable slide valve to provide fully modulating capac-
ity control from 100% to approximately 10% of full load ca-
pacity.
5. VOLUMIZER® volume ratio control to allow infinitely vari-
able volume ratio from 2.2 to 5.0 during compressor opera-
tion for all models.
6. A hydraulic unloader cylinder to operate the slide stop
and slide valve.
7. Bearing and casing design for 350 PSI discharge pres-
sure. This PSI rating applies only to the compressor and
does not reflect the design pressure of the various sys-
tem components.
8. All bearing and control oil vented to closed thread in the
compressor instead of suction port to avoid performance
penalties from superheating suction gas.
9. Shaft seal design to maintain operating pressure on seal
well below discharge pressure, for increased seal life.
10. Oil injected into the rotors to maintain good volumetric and
adiabatic efficiency even at very high compression ratios.
11. Shaft rotation clockwise facing compressor, suitable for
all types of drives. SEE FOLLOWING CAUTION.
Compressor rotation is clockwise
when facing the compressor drive
shaft. (See Figure 12) The compres-
sor should never be operated in reverse rotation as bear-
ing damage will result.
MPRE
R
Figure 12
12. Dual compressor casing design for very low airborne
noise transmission.
13. Suction flange is 300 psig ANSI type.
14. Integral suction strainer is provided.
15. "D" Flange adapter for bolting directly to motor.
COMPRESSOR LUBRICATION SYSTEM
The lubrication system on an RWF screw compressor unit
performs several functions:
1. Provides lubrication to bearings and seal.
2. Provides a cushion between the rotors to minimize noise
and vibrations.
3. Helps keep the compressor cool and prevents
overheating.
4. Provides an oil supply to hydraulically actuate the slide
valve and slide stop.
5. Provides oil pressure to the balance pistons to help in-
crease bearing life.
6. Provides an oil seal between the rotors to prevent rotor
contact or gas bypassing.
The compressor unit may be equipped with either a no
pump or a demand pump lubrication system. Additionally,
either system may contain dual oil filters and liquid injec-
tion, water-cooled, or thermosyphon oil cooler for compres-
sor oil cooling.
NO PUMP OIL SYSTEM
The RWF screw compressor unit is designed to be
self-lubricating. Oil being supplied to the compressor from
the oil separator is at system head pressure. Within the
compressor, oil porting to all parts of the compressor is
vented back to a point in the compressor’s body that is at a
pressure lower than compressor discharge pressure. The
compressor’s normal operation makes the compressor unit
operate essentially as its own oil pump. All oil entering the
compressor is moved by the compressor rotors out the com-
pressor outlet and back to the oil separator.
For normal high-stage operation an oil pump is not required.
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