Simple Sensory Identification Methods
Appearance and Color: Compliant industrial-grade mixed oil should be clear and transparent, free from obvious turbidity, suspended matter, or stratification; if the oil appears black or dark, it likely contains recycled waste oil or impurities.
Odor Identification: Normal oil carries the faint, characteristic scent of industrial oil without strong, pungent, acidic, or putrid odors; a pungent or foul smell indicates excessive sulfur content or the presence of chemical waste.
Flowability Test: Compliant oil has moderate viscosity and flows smoothly when poured; premature solidification in low-temperature environments indicates high wax content or the presence of significant amounts of low-quality animal fats.
Combustion Test: Ignite a small sample; a normal flame is stable and crackle-free, leaving minimal carbon residue. Excessive smoke, popping sounds, and significant black residue indicate substandard quality.
Identification via Key Physicochemical Indicators
Industrial-grade mixed oil is subject to specific mandatory technical standards; compliance can be determined through routine testing:
Kinematic Viscosity: The standard range is 2.5–8.0 mm²/s at 20°C and typically 1.9–6.0 mm²/s at 40°C; deviations suggest an abnormal oil blend ratio.
Density: The standard range is 810–845 kg/m³ at 20°C; abnormal values suggest contamination with other types of oil.
Flash Point: The closed-cup flash point must be no lower than 60°C; a flash point that is too low poses flammability and explosion risks.
Sulfur Content: Most industrial applications require levels below 0.05%; excessive sulfur leads to non-compliant emissions and equipment corrosion.
Cetane Number: Must be no lower than 51; failure to meet this standard directly impacts combustion efficiency.
