ASTM D874 method for sulfated ash from lubricating oils and additives
6. Apparatus
6.1 Evaporating Dish or Crucible; 50 to 100-mL for samples containing more than 0.02 mass % sulfated ash, or 120 to 150-mL for samples containing less than 0.02 mass % sulfated ash, and made of porcelain, fused silica, or platinum. (Warning - Do not use platinum when the sample is likely to contain elements such as phosphorus, which attack platinum under the conditions of the test.)
NOTE 5 - For best results on samples containing less than 0.1 mass % sulfated ash, platinum dishes are used. The precision values shown in Section 13 for this type of sample were so obtained.
6.2 Electric Muffle Furnace - The furnace shall be capable of maintaining a temperature of 775 more or less 25°C and preferably have apertures at the front and rear to allow a slow natural draft of air to pass through the furnace.
6.3 Balance, capable of weighing to 0.1 mg.
7. Reagents
7.1 Purity of Reagents - Reagent grade chemicals shall be used in all tests. Unless otherwise indicated, it is intended that all reagents shall conform to the specifications of the Committee on Analytical Reagents of the American Chemical Society, where such specifications are available, or to other recognized standards for reagent chemicals. Other grades may be used, provided it is first ascertained that the reagent is of sufficiently high purity to permit its use without lessening the accuracy of the determination.
7.2 Purity of Water - Unless otherwise indicated, references to water shall be understood to mean reagent water defined by Types II or III of Specification D1193.
7.3 Low-Ash Mineral Oil - White oil having a sulfated ash lower than the limit capable of being determined by this method.
NOTE 6 - Determine the sulfated ash of this oil by the procedure given in 9.1-9.11 below using 100 g of white oil weighed to the nearest 0.5 g in a 120 to 150-mL platinum dish. Deduct the sulfuric acid blank as described in 9.11.
7.4 Sulfuric Acid (relative density 1.84) - Concentrated sulfuric acid (H2SO4). (Warning - Poison. Corrosive. Strong oxidizer.)
7.5 Sulfuric Acid (1 + 1) - Prepare by slowly adding 1 volume of concentrated sulfuric acid (relative density 1.84) to 1 volume of water with vigorous stirring. (Warning - Mixing this acid into water generates considerable heat. When necessary, cool the solution before adding more acid. Do not allow the solution to boil.)
7.6 Propan-2-ol. (Warning - Flammable, can be explosive when evaporated to or near dryness.)
7.7 Toluene. (Warning - Flammable, toxic.)
7.8 Quality Control (QC) Samples, preferably are portions of one or more liquid petroleum materials that are stable and representative of the samples of interest. These QC samples can be used to check the validity of the testing process as described in Section 12.
8. Sampling
8.1 Obtain samples in accordance with the instructions in Practice D4057 or D4177. The sample shall be thoroughly mixed before removal of the laboratory test portion.
