Theory and Method
Sediment in residual fuel oils consists of insoluble organic and inorganic material including asphaltene particles, catalytic fines, and other contaminants suspended in the fuel matrix. Asphaltenes are high-molecular-weight hydrocarbons in a metastable colloidal state; temperature changes, blending with incompatible stocks, or prolonged storage can trigger their precipitation as sludge. This settled material, reported as total sediment and expressed as a percentage by mass, directly reflects fuel quality and storage suitability. Fuels that exceed the maximum sediment threshold can foul handling equipment, block shipboard separators, and disrupt burner performance.
ISO 10307 specifies a two-stage approach to total sediment determination. The first stage applies accelerated aging, either thermal (heating at 100°C for 24 hours) or chemical (adding hexadecane before heating), to simulate storage stress and expose any tendency toward asphaltene precipitation. Both procedures reveal latent instability in the fuel before the filtration stage begins. The QualiTST™ 10307 handles this aging step in its integrated metal bath, maintaining temperature at ±0.5°C throughout the run while the programmable timer manages the aging duration automatically.
The filtration stage follows aging. The instrument draws the aged sample through a glass-fiber filter under controlled vacuum at 100°C, capturing insoluble material on the filter medium. Solvent washing removes residual soluble oil from the filter; after drying, the operator weighs the filter to determine the total mass of collected sediment. The result yields the Total Sediment Potential (TSP) or Total Sediment Aged (TSA) value per ISO 10307, indicating whether the fuel will form deposits during real-world storage and handling conditions.
