Detection of Lubricating Oil Oxidation Stability

2026-07-03

Detection of Lubricating Oil Oxidation Stability

1. Overview of the Test Substance

Lubricating oil is widely used in steam turbine units, transformers, gasoline engines and other equipment, consisting of two core components: base oil and functional antioxidant additives. During equipment operation, lubricating oil is prone to oxidative deterioration under long-term high-temperature and oxygen-rich environments, generating acidic substances, sludge and sediments, which corrode metal parts, block oil circuits and greatly shorten the service life of the unit.

The oxidation stability of lubricating oil is a core indicator for evaluating the service life and quality of oil products. It directly determines whether in-service oil can remain in use, and new oil must also pass oxidation stability testing before leaving the factory. The widely adopted industry detection method is the rotating oxygen bomb method, corresponding to standard SH/T0193, and it is also compatible with international standards including ASTM D2272, D4742 and IP229.

2. Experimental Purpose

The rotating oxygen bomb method is used to test the oxidation stability of lubricating oil and measure the oxidation induction period of oil samples, so as to evaluate the antioxidant capacity of new lubricating oil, in-service turbine oil, mineral insulating oil and engine oil.

The test follows the industry standard SH/T0193 Determination of Oxidation Stability of Lubricating Oils by Rotating Oxygen Bomb Method, and the SH0193C fully automatic rotating oxygen bomb tester is adopted to complete the whole test. With a metal bath structure and fully automatic operation, the equipment accurately completes the full process of constant temperature control, oxygen charging, leak detection, curve recording, inflection point identification and result output.

Note: This equipment is not applicable to the testing of antioxidant-added mineral insulating oil with a viscosity greater than 12mm²/s at 40℃.

3. Preparation of Test Samples and Instruments

Test samples: turbine oil / mineral insulating oil / engine lubricating oil, deionized water, standard copper oxide wire

Test instruments

SH0193C fully automatic rotating oxygen bomb tester (metal bath version)
Supporting accessories: glass sample cup, oxygen bomb sealing ring, PTFE thermal insulation cover, oxygen cylinder and connecting pipeline, U-shaped retrieval hook
Auxiliary tools: clean wiping cloth, cleaning agent

4. Operation Procedures

Place the instrument on a flat and stable test bench away from direct air flow, and ensure the power cord is reliably grounded. Connect the gas circuit plug at the rear of the instrument to the oxygen cylinder pipeline, and check that the O-ring of the oxygen bomb is free from cracks or damage.
Turn on the power supply. The 7-inch color touch screen will automatically enter the main interface. Go to the parameter setting page, enter the sample number, and set the test temperature according to the oil type: 150℃ for turbine oil and 140℃ for ordinary mineral insulating oil. Enter the laboratory ambient temperature at the same time.
Pretreat the oxygen bomb as required by the standard, and manually complete 2 cycles of oxygen charging and pressure relief. The system automatically calculates the target oxygen charging pressure based on room temperature. The standard initial pressure is 620kPa at 25℃, and the instrument automatically adjusts the charging pressure when the room temperature deviates from 25℃.
Put the oil sample, standard proportioned water and copper oxide wire into the glass sample cup, place it steadily on the magnetized cup holder, and slowly lower it into the oxygen bomb chamber. Evenly tighten the three-point nuts to seal the pressure chamber cover, and close the needle valve of the bath tank.
Click "Automatic Oxygen Charging" on the touch screen. The equipment will automatically charge the dual-channel oxygen bombs to the set pressure. After charging, automatic leak detection will be activated. If no air leakage is detected, the heating and rotating mechanisms will start automatically. The oxygen bomb rotates at a constant speed of 100r/min with a 30° angle to the horizontal plane.
Cover the bath with the PTFE thermal insulation cover. The instrument collects temperature and pressure data in real time, automatically draws the pressure-time curve, and continuously monitors the oxidation induction inflection point.
When the test is finished, the equipment will trigger an audible and visual alarm automatically, cut off the heating power, and print the test report via the built-in thermal printer. After the bath cools down, open the needle valve to release pressure, disassemble the oxygen bomb, take out the sample cup, and retrieve the magnetic cup holder with the U-shaped hook.
After cooling to room temperature, clean all components including the oxygen bomb, glass cup and copper wire, and dry them for later use. Historical test data can be queried on the touch screen, or exported in CSV/Excel format via a USB flash drive for archiving on a computer.

5. Data Analysis and Result Evaluation

The core indicator of the test is the oxidation induction period (unit: minute). A longer induction period indicates stronger antioxidant capacity and longer service life of the oil. This instrument has a temperature control error of ±0.1℃, a pressure measurement accuracy of ±2‰, and a parallel test deviation of ≤3% for the same sample, with test results meeting industry standard requirements.

Reference test values: For new turbine oil tested at 150℃, the induction period ranges from 300 to 1200 minutes; below 100 minutes is the warning threshold, and oil change is recommended when the value is below 60 minutes. For new mineral insulating oil tested at 140℃, an induction period of ≥120 minutes is considered qualified.

The instrument is equipped with an automatic pressure-holding leak detection function for stable and reliable data. It can store more than 1,000 sets of test records, supports automatic result printing, and allows data export in CSV/Excel format via USB flash drive for archiving.

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Detection of Lubricating Oil Oxidation Stability