Chapter 4 Compressor and Package Unit Operation
UD-series Screw Compressor
4.1 Lubricating Oil (Refrigerant Oil)
4-3
Precautions for Handling Polyolester (POE) Oil
This type of oil has high hygroscopicity as polyalkylene glycol, and also exhibits hydrolyzability under
high temperature environments. Moisture entry must be avoided. Therefore, special attention must be
paid as with PAG when handling POE.
Finish the charging in as short a time as possible after opening the pail to minimize exposure
to air.
Make sure that all oil in a pail is used in a single charging. Any remaining oil must be stored
indoors with the can lid closed tightly. Do not attempt to store it for a long time.
Because POE can hydrolyze, make sure to perform an oil analysis regularly in the package to
see if any abnormal conditions are present.
4.1.4 Lubricating Oil Control Criteria
Lubricating oils that are controlled by the criteria are classified into the following categories:
(1) Synthetic oils: Polyalkylene glycols (PAG)
(2) Mineral oils: Naphthenic base oils and paraffinic base oils
(3) Synthetic oils: Alkylbenzene (AB) and Polyalphaolefine (PAO)
(4) Synthetic oils: Polyolesters (POE)
Oil sampling and analysis is recommended every six months.
If the following control criteria are not satisfied, replace the oil.
◆
Note that the water content of PAG shall be excluded from the above oil replacement criteria.
Refer to the Note *1 in the table below.
The analysis items and the criteria are shown in the following tables. Please note that these control
criteria may be changed without notice.
Table 4-3 Synthetic Oil (PAG)
Item
Criteria
(a) Color phase
ASTM color scale: 4.0 or less
(b) Total acid number (TAN) 0.1 mg KOH/g or less
(c) Kinematic viscosity
Within ±10 % from that of fresh oil
(d) Water content
2000 mass ppm or less
Note1
(e) Degree of contamination Degree of contamination measured by mass method (Millipore value)
shall be 15 mg/100 mL or less
Table 4-4 Mineral Oil and Synthetic Oil (AB, PAO)
Item
Criteria
(a) Color phase
ASTM color scale: 6.0 or less
(b) Total acid number (TAN) 0.3 mg KOH/g or less
(c) Kinematic viscosity
Within ±15 % from that of fresh oil
(d) Water content
100 mass ppm or less
(e) Degree of contamination Degree of contamination measured by mass method (Millipore value)
shall be 15 mg/100 mL or less
Table 4-5 Synthetic Oil (POE)
Item
Criteria
(a) Color phase
ASTM color scale: 4.0 or less
(b) Total acid number (TAN) 0.2 mg KOH/g or less
