ASTM D7112 for stability and compatibility of heavy fuel oils and crude oils
ASTM D7112 Standard Test Method for Determining Stability and Compatibility of Heavy Fuel Oils and Crude Oils by Heavy Fuel Oil Stability Analyzer (Optical Detection)
7. Apparatus
7.1 PORLA Heavy and Crude Oil Stability and Compatibility Analyzer - See Figs. 1 and 2.
7.1.1 A portion of the apparatus is shown diagrammatically in Fig. 2 and is comprised of the following parts:
7.1.1.1 Sample Cup, light weight, inert cups designed to fit the sample carousel, with a smooth, flat bottom, volume approximately 100 mL. Typically, aluminum cups have been used.
7.1.1.2 Sample Carousel, typically a four-position sample cup holder delivering the sample cups sequentially to the measurement position.
7.1.1.3 Mixer Lift System, vertically moving lift system, forming a seal with the sample cup in the measurement position and incorporating a mechanical stirrer which starts to rotate when the seal is made. It also incorporates delivery lines for n-heptane and xylene addition, the circulation line for passing the sample through the detector and the exhaust line, which empties the sample cup after analysis.
7.1.1.4 Aromatic Solvent Pump, accurate and adjustable ceramic piston pump, capable of delivering xylene at a rate of 0.01 to 0.5 mL/s.
7.1.1.5 Parafffinic Solvent Pump, accurate and adjustable ceramic piston pump, capable of delivering n-heptane at a rate of 0.01 to 0.5 mL/s.
7.1.1.6 Circulation Pump, accurate and adjustable ceramic piston pump used to circulate the sample under test through the detector system.
7.1.1.7 Exhaust Pump, accurate and adjustable ceramic piston pump used to empty the sample cup at the end of the measurement.
7.1.1.8 Detector System, (see Fig. 3) optical detector through which the sample solution is continuously circulated. The detector is composed of a visible light source and a photodiode for recording the light reflecting from asphaltene particles in the test sample.
7.1.1.9 Hot Plate, a temperature controlled heating system may be located below the sample cups, which will warm up the sample so that the titration may be performed at an elevated temperature. The temperature of the hot plate should be adjustable between 20 and 100°C.
7.1.2 Computer, controls the measurement and calibration programs and is an interface between the operator and the analyzer.
7.1.3 PORLA Step Measurement Screen, computer display, allowing data about the sample and operator to be input as well as showing the results of each titration (see Fig. 4).
7.1.4 Parameter Screen, computer display, allows all of the measurement cycle parameters to be adjusted from the default values and also allows the pump calibration procedure to be run (see Fig. 5).
8. Reagents and Materials
8.1 Purity of Reagents - Reagent grade chemicals shall be used in all tests. Unless otherwise indicated, 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 determined that the reagents are of sufficiently high purity to permit their use without lessening the accuracy of the determination.
8.2 Xylene (C8H10) - The xylene used is generally a mixture of ortho, meta, and para isomers and may contain some ethyl benzene. (Warning - Flammable, health hazard.)
8.3 n-heptane (C7H16) - (Warning - Flammable, health hazard.)
