2200LZJE-HO-C6-N_2013.12.
Chapter 4 Operation of Compressor and Unit
Compound 2-stage Screw Compressor 2016**C
4.1 Lubricant (Refrigerant Oil)
4-1
Chapter 4 Operation of Compressor and Unit
4.1
Lubricant (Refrigerant Oil)
Lubrication management is very significant to keep the compressor in a good operating condition.
Take the following notes when managing lubricant.
4.1.1 Precautions for Selecting the Lubricant
Selection of the lubricant should depend on the type of the refrigerant, the type of the
evaporator used with the compressor, and the conditions under which the compressor is
operated. Also to be considered when selecting lubricant are the properties of the oil that include
not only the viscosity but also such characteristics as solubility in refrigerant, separability from
refrigerant, low temperature fluidity, high temperature thermal stability, etc. We therefore
recommend to contact our sales offices or service centers for choice of a specified brand for
your system.
Lubricant used for compressors must have a viscosity appropriate for lubricating the bearings
and other components in the compressors. The viscosity to be considered in this case should be
the viscosity the oil shows at the oil inlet of the compressor. The viscosity of the lubricant
significantly changes depending on the type of the refrigerant used in combination with the oil. If
the refrigerant dissolves in the oil (or the oil and refrigerant are inter-soluble), the viscosity of the
oil drops to a level remarkably below the level required for operation of the compressor under
some operating conditions. On the contrary, if the refrigerant does not dissolve in the oil (or the
oil and refrigerant are non-inter-soluble), the viscosity may become too high when the supply oil
temperature is low. For this reason, the lubricant must be selected such that it is supplied to the
compressor with an appropriate viscosity (kinematic viscosity of 13 - 40 mm
2
/s) in the operating
state.
The circulation of the lubricant for the entire system must be considered. After lubricating and
cooling each part of the compressor, the lubricant is discharged with refrigerant gas. Most of the
oil which is discharged from this compressor is trapped by the oil separator and is cycled to the
compressor. A small quantity of refrigerant oil goes to the condenser and the evaporator. The
lubricant is required to have sufficient fluidity and stability inside parts with different
temperatures.
Be careful since polyolester synthetic oil (POE) cannot be used with ammonia
refrigerant.
4.1.2 Recommended
Lubricants
When selecting lubricant, not only compatibility with refrigerant but also effects on O-rings must be
considered. To prevent compressor malfunctions, we recommend the lubricant described below.
4.1.2.1 Recommended Lubricants for Ammonia Refrigerant
Polyalkylene Glycols (PAG) based synthetic oils
Brand
Kinematic viscosity
(40°C) mm
2
/s
Manufacturer
Type
JOMO Freol PN46
46
JX Nippon Oil and
Energy Corporation
PAG
"JOMO Freol PN46" is the only type of inter-soluble oils that can be used with an ammonia refrigerant.
