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Vol. 2.6 © 2020 Hanbell Precise Machinery Co., Ltd. All rights reserved
4.5.1 Oil temperature control in the oil tank
Oil temperature should be kept above ET+20°C
by oil heater to avoid the liquid refrigerant
remains in the oil tank. If the concentration of refrigeration dissolved in the lubricant is too high,
then it will reduce the viscosity and effectiveness of the lubricating oil and the bearings will be more
easily damaged. Therefore, the heater must be used to evaporate the liquid refrigerant and
recirculate back into the system. By using temperature sensor, the oil temperature inside the tank
can be controlled and when the oil temperature is lower than ET+20°C, the heaters should be
turned on to evaporate the liquid refrigerant; when the oil temperature is higher than 45°C, the
heater is turned off. In general, when the compressor is running, the heat generated by the rotating
parts can help maintaining the oil temperature.
T3
＜
ET+20°C turn on oil heater Compressor running is strictly prohibited
T3
＞
45°C
turn off oil heater
T3
＞
CT+10°C warning
T3
＞
CT+15°C shut down
Note
：
1. ET is the evaporation temperature of the system during operation and shut down. Saturated
temperature can be obtained by using the evaporator pressure.
2. CT is the condensation temperature of the system during operation. Saturated temperature can
be obtained by using the condenser pressure.
3. The oil heater must be controlled independently and needs to be turned on during temporary
shut down or 24 hours before restart. Oil temperature control stated above is still required during
operation.
Warning
：
Do not start the machine when the oil temperature is lower than ET + 20
℃
！
Warning
：
Excessively high oil temperature indicates insufficient oil for compressor circulation or
heat imbalance. Continuous running will cause damage to the machine.
Oil heater specifications
Two UL approved 500W oil heaters have been equipped in the oil tank as standard
accessories. Specifications
：
500W/ 220V; IP 54; UL approved
Note1: The oil temperature inside the oil tank could be kept in normal range because heat
is transferred to oil from bearings and gear during running. But if large amount of
oil is returned from the evaporator or ambient temperature is low, oil temperature
might be insufficient. Hence, oil heaters should be used to make sure the oil from
oil pump is free of liquid refrigerant and temperature in oil tank is in safe range.
Warning
：
If lubricant mixes with liquid refrigerant, bearings and gears cannot be lubricated
effectively. This will result in damage to the compressor.
Note2: There are oil separators installed for effective oil separation at oil return and
refrigerant return ports in RT series compressors. Please refer to item 13&14 in
Figure 4.4. Besides, gears are installed in the gear casing to efficiently minimize
fluctuation of oil level due to high-speed rotation. Furthermore, the gear casing
also reduces oil to mix with refrigerant flow so oil flow from the compressor to the
system could be minimized.
