Sulfated Ash

Description

Determines the mass fraction of the non-combustible residue of metal-containing additives in oil, which is critical for protecting DPFs and catalysts.

Every gram of excess ash in motor or gas engine oil is a nail in the coffin of your equipment's expensive diesel particulate filter (DPF), catalytic converter, or gas engine valves. Sulfated ash is formed during the combustion of metal-containing detergent and anti-wear additives (salts of calcium, magnesium, zinc, barium). The RENA laboratory conducts this strict analysis to guarantee: your oil truly belongs to the safe Low SAPS or Mid SAPS class (like RENA Energo Gas 40 LA) and will not kill the ecological systems of a modern engine. The test according to ISO 3987 (or ASTM D874) requires meticulous precision and prolonged thermal treatment. An oil sample (about 20-50 grams) is precisely weighed in a porcelain or platinum crucible. First, the oil is carefully heated to auto-ignition and burned, leaving a porous carbonaceous residue. After cooling, this residue is treated with concentrated sulfuric acid ($H_2SO_4$). The acid reacts with metal oxides, converting them into heat-resistant sulfates. Next, the crucible is placed in a high-temperature muffle furnace (Nabertherm) and calcined at a hellish 775 °C until complete carbon burnout and a constant mass of light ash is achieved. After re-cooling in a desiccator, the crucible is weighed on analytical balances (RADWAG) with an accuracy of ten-thousandths of a gram. The mass fraction of ash is calculated as the ratio of the residue mass to the original sample mass in percent.