Hanbell RC2-AVI Series, Manual

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8
Notes:
1. When Hanbell screw compressors operate in partial or full load at application limits, motor coil and discharge
temperature will rise simultaneously. In order to keep compressors’ safe running continuously, Hanbell
recommends usage of the following additional cooling devices :
(1)Oil cooler or (2)Liquid injection to chamber or (3)Liquid injection to motor.
Please refer to Hanbell selection software for application of additional cooling system.
2. Hanbell recommends monitoring oil pressure and keeping it 4 kg/cm
2
g over the suction pressure for adequate seal,
lubrication by pressure differential switch passively or by additional oil pump actively. Especially under operation
conditions with low condensing temperature and high evaporating temperature like application in flooded water-
cooled chillers, high-low pressure differential tends to be less than 4kg/cm
2
g, installation of oil pump is
recommended to ensure adequate oil pressure.
Contact Hanbell to verify potential operating conditions outside the application limits as shown.
3. The minimum discharge superheat is recommended to be kept 10K higher than the condensing temperature
(normally discharge superheat is around 20K for R134a) to avoid liquid’s filling back to compressor and lubrication
failure.
3. Lubricants
The main functions of lubrication oil in screw compressors are lubrication, internal sealing, and cooling. The design of
positive pressure differential lubrication system makes RC2-AVI series normally omit an extra oil pump which is
necessary for reciprocating compressors. However, in some special applications, it is still necessary to install an extra
oil pump to screw compressors for safety.
Bearings installed in RC2-AVI series compressors require a small and steady quantity of oil for lubrication. Oil injection
into the compression chamber creates a film of oil for sealing in the compression housing to increase efficiency and
also can dissipate part of compression heat.
Please pay more attention to the oil temperature, which is crucial to compressor bearings’ life. Oil has a much lower
viscosity at high temperatures. Too low viscosity of oil will result in poor lubrication and heat dissipation in the
compressor. Viscosity is recommended to keep over 10mm
2
/s at any temperatures for oil. Oil temperature in the oil
sump should be kept above the saturated condensing temperature to prevent refrigerant migration into lubrication
system.
If the compressor operates under critical operating conditions, an extra oil cooler is required – please refer to Hanbell
selection software for the required capacity and oil flow of the extra oil cooler. High-viscosity oil is recommended to
apply in high operating conditions because high discharge temperatures will make viscosity of oil lower. Oil return from
the evaporator may be insufficient in such as refrigeration systems, flooded chillers…etc. , in which it’s difficult for oil to
be carried back and it may cause oil loss in the compressor. If the system encounters the oil return problem, then an
extra 2
nd
oil separator is recommended to be installed between the compressor discharge port and the condenser.
RC2-140AVI~620AVI RC2-830AVI~1270AVI