ASTM D5304 Standard Test Method for Assessing Middle Distillate Fuel Storage Stability by Oxygen Overpressure
6. Apparatus
6.1 Sample or Blank Container, a brown borosilicate glass bottle capable of holding 100 mL of sample but with total volume less than 200 mL, or a Test Method D525 glass insert. A top closure of aluminum foil, perforated with small holes for breathing, will be required if there is more than one sample per pressure vessel.
6.2 Pressure Vessel(s) (Reactor(s)), designed for safe operating pressures of 800 kPa (100 psig) in oxygen service (Warning - See 4.1.) equipped with a pressure gauge. (Warning - The pressure for the procedure in this test method is 800 kPa (absolute) (100 psig). Many pressure gauges are calibrated in kPa (gauge). For such gauges, the test pressure would be 700 kPa (gauge). Maximum gauge gradations should be 20 kPa (5 psig)). The gauge should be calibrated against standards, and capable of holding the four sample containers. Pressure vessels having internal volumes from 250 mL to 8000 mL have been used and found to be suitable. If 250 mL vessels such as Test Method D525 oxidation vessels are used, four will be required. The larger volume pressure vessels can accommodate multiple sample or blank containers). The pressure vessel(s) (reactor(s)) must be obtained only from commercial sources.
6.3 Heater, capable of maintaining the test temperature at 90 °C +/- 1 °C for the duration of the test. Ensure heater temperature uniformity. Heater shall be capable of holding the pressure vessel(s) (reactor(s)) described in 6.2. Static (non-forced air) ovens and unstirred liquid medium baths, such as the Test Method D525 water bath, are unsuitable. Use of these heaters will give erroneous results due to nonuniformity of temperature.) The reactor should be placed in an oven so that the entire reactor is uniformly receiving heat. (Warning - Use of an explosion-proof oven is required.)
6.4 Drying Oven, forced air operated at 110 °C +/- 5 °C. Static ovens or vacuum ovens are not suitable.
6.5 Water Aspirator or Vacuum Pump, as a source of vacuum.
6.6 Aluminum Dish (disposable), capable of holding 47 mm diameter filters and 30 mL of adherent insolubles solvent.
6.7 Analytical Balance, capable of weighing to the nearest 0.1 mg.
6.8 Filtration System - Arrange the following components as shown in Fig. 1.
6.8.1 Funnel and Funnel Base, with filter support for a 47 mm diameter membrane and a locking ring or spring action clip.
6.8.2 Ground/Bond Wire, 0.912 mm to 2.59 mm (No. 10 through No. 19) bare-stranded, flexible, stainless steel, or copper installed in the flasks and grounded as shown in Fig. 1.
6.8.3 Receiving Flask, 1.5 L or larger borosilicate glass vacuum filter flask, which the filtration apparatus fits into, equipped with a sidearm to connect to the safety flask.
6.8.4 Safety Flask, 1.5 L or larger borosilicate glass vacuum filter flask equipped with a sidearm to connect the vacuum system. A fuel and solvent resistant rubber hose through which the grounding wire passes shall connect the sidearm of the receiving flask to the tube passing through the rubber stopper in the top of the safety flask.
6.9 Hot Plate, capable of operating at low heat so that 10 mL of toluene placed in the aluminum dish described in 6.6 will require 10 min to 25 min to evaporate.
6.10 Thermometer, conforming to the requirements prescribed in Specification E1. Temperature measuring devices such as ASTM 61C (IP No. 63C), liquid-in-glass thermometers, thermocouples, or platinum resistance thermometers that provide equivalent or better accuracy and precision may be used.
6.11 Forceps, approximately 12 cm long, flat-bladed, with non-serrated, non-pointed tips.
7. Reagents and Materials
7.1 Purity of Reagents - Reagent grade chemicals shall be used in all tests. Unless otherwise indicated, it is intended that all reagents 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 or precision of the determination.
7.2 Nylon Membrane Filters, plain, 47 mm diameter, pore size 0.8 µm.
7.3 Hydrocarbon Solvent - Hexanes, heptane, isooctane, or petroleum ether with residue upon evaporation of less than 0.001 % and boiling range between 35 °C and 100 °C are satisfactory. Filter before use with the filter specified in 7.2.
7.4 Oxygen - Use 99.5 % minimum oxygen from cylinders with two stage regulators capable of delivering up to 1600 kPa (200 psig). The secondary regulator should be calibrated against standards to deliver 800 kPa +/- 10 kPa (100 psig +/- 1 psig). (Warning - Oxygen at elevated temperature and pressure is capable of causing explosion or fire.)
7.5 Adherent Insolubles Solvent (TAM) - An equal volume mixture of toluene, acetone, and methanol (TAM). Filter before use with the filter specified in 7.2.
