ASTM D2274 for oxidation stability of distillate fuel oil (Accelerated method)
7. Apparatus
NOTE 2 - It is suggested that all equipment be calibrated according to manufacturer's instructions on a periodic basis to assure consistency of results.
7.1 Oxidation Cell, of borosilicate glass, as shown in Fig. 1, shall consist of a test tube, condenser, and oxygen delivery tube. This cell is identical to that used in Test Method D943.
7.2 Heating Bath, with a thermostatically controlled liquid medium, shall be capable of maintaining the bath temperature at 95 more or less 0.2°C (203 more or less 0.4°F). It shall be fitted with a suitable stirring device to provide a uniform temperature throughout the bath. It shall be large enough to hold the desired number of oxidation cells immersed to a depth of approximately 350 mm. Further, the bath construction must permit shielding the fuel samples in the oxidation cells from light while they are undergoing oxidation.
7.3 Flowmeters, shall have a capability of measuring 3 more or less 0.3 L/h of oxygen. One flowmeter shall be provided for each oxidation cell.
7.4 Filter Drying Oven, shall be capable of safely evaporating the solvent at 80° more or less 2°C (176° more or less 4°F) for the drying of filter materials.
7.5 Glassware Drying Oven, shall be capable of drying glassware at 105° more or less 5°C (221 more or less 9°F).
7.6 Filter Assembly, see Fig. 2, shall be capable of holding the filters described in 7.7.
7.7 Filter Media, 47 mm diameter cellulose ester surfactant-free membrane filters with a nominal pore size of 0.8 µm.
7.7.1 Single filters are to be used for prefiltration.
7.7.2 A matched weight pair of filters or alternatively, a preweighed control and sample, filters shall be used for determination of filterable insolubles
7.8 Evaporating Vessel, borosilicate glass beaker, 200-mL capacity, tall style.
7.9 Hot Plate, capable of heating a liquid in the evaporating vessel (7.8) to 135°C (275°F).
8. Reagents and Materials
8.1 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. 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.
8.2 Purity of Water - Unless otherwise indicated, reference to water shall be understood to mean reagent water as defined by Type III of Specification D1193.
8.3 2.2,4-trimethylpentanel (Iisooctane) , 99.75 % purity prefiltered through a filter medium of the type specified in 7.7.
8.4 Oxygen, 99.5 % purity or better. When the oxygen is delivered through a plant system of piping, a filter shall be provided adjacent to the constant temperature bath to prevent the introduction of line debris or moisture into the oxidation cells; a pressure regulator adequate to maintain a constant flow of gas through the apparatus shall also be used. A tank of oxygen of the specified purity can be used provided it is equipped with a two-stage pressure regulator. (Warning - Oxygen vigorously accelerates combustion. Do not use equipment having exposed surfaces containing oil or grease.)
8.5 Trisolvent, a mixture of equal volumes of acetone, methanol, and toluene. See 8.1. (Warning - It is particularly important that technical, commercial, practical, or industrial grades (however they are designated by the particular manufacturer) are not to be used, as their use may lead to apparently increased levels of adherent insolubles.) (Warning - Fire hazard, toxic.)
