Accurate Determination Scheme for Apparent Viscosity of Engine Oil
Overview
Engine oil is the core lubricating medium ensuring the normal operation of engines. Its apparent viscosity directly affects low-temperature starting performance, lubrication effectiveness, and engine operating losses. Apparent viscosity refers to the viscous resistance exhibited by a fluid under specific shear conditions, serving as a key indicator for evaluating the low-temperature service performance of engine oil. It is widely used in automotive manufacturing, petrochemicals, quality inspection, and other fields.
Experimental Purpose
Accurately determining the apparent viscosity of engine oil in low-temperature environments can verify whether the oil's low-temperature fluidity meets standards, avoiding issues such as difficult cold starts and accelerated component wear caused by abnormal viscosity. This experiment is conducted in accordance with GB/T 6538 and ASTM D5293 standards. The adopted SH110 Automatic Apparent Viscosity Tester fully complies with the above standard requirements, featuring high-precision temperature control and intelligent detection functions to quickly output reliable test results.
Experiment Start
Test Samples: Engine oil to be tested (free of suspended solids and moisture, reserved after pretreatment)
Test Instruments & Accessories:
1.SH110 Automatic Kinematic Viscosity Tester (including main control system, stator measurement unit, cold bath circulation system, etc.)
2.Standard calibration oils (Models: 190CL, 250CL, 320CL)
3.Auxiliary accessories such as 20ml pipettes, cleaning reagents, and silicone hoses
Operational Steps
1. Instrument Installation and Debugging: Connect the circulating cold bath to the main unit with rubber tubes, fill with sufficient alcohol medium to ensure no leakage; connect the power supply and check that components such as the temperature sensor and circulation pump are properly connected.
2. Sample Pretreatment: Sample 10-20ml in accordance with GB/T 4756, remove solid particles larger than 5μm to avoid air entrainment in the sample; if the sample temperature is lower than the room temperature dew point, warm it to room temperature before opening the container for sampling.
3. Instrument Calibration:
- Current Calibration: Set the cold bath temperature to -40℃ and the stator temperature to -20℃, add 3500mPa·s calibration oil, start the calibration program, adjust the current to stabilize the motor speed at 240rpm, and save the calibration data.
- Constant Calibration: Select 3 types of standard oils covering the sample's viscosity range, inject them into the stator cup in sequence, set the calibration temperature and standard oil viscosity values, the instrument will automatically test and calculate calibration constants.
4. Sample Testing: Use a pipette to take 5ml of sample and inject it into the stator cup, ensuring the sample fills the gap between the stator and rotor with the liquid level 1mm above the rotor; enter information such as oil product number, tester, and test temperature on the touch screen, click "Start", the instrument will automatically start the circulation pump and motor, and monitor temperature and speed in real time.
5. Result Processing: After the experiment, the instrument automatically fits the curve to calculate the apparent viscosity, allowing direct viewing, saving of data, or output of test reports via the printing function; the waste sample is discharged through a negative pressure pump, and the instrument is cleaned for later use.
Data Analysis and Result Evaluation
Test results show that the apparent viscosity of the engine oil to be tested ranges from 1200 to 18500mPa·s within the temperature range of -5~-30℃, meeting the requirements of relevant industry quality standards. The instrument's temperature control accuracy reaches ±0.1℃, with test result error less than ±2% and good repeatability; after calibration with standard oils, data accuracy is further improved, providing reliable technical support for engine oil quality judgment and formula optimization.