9. Sample Preparation
9.1 For recommended practice for obtaining, handling, and preparing coke samples, refer to Practice D346, Method D2013, Test Methods D2234, and Practice D4057. See Section 6.
9.2 Crush 50 g of coke so that the entire sample will pass through a 75 µm (No. 200) sieve. Dry the crushed sample in a drying oven at 115 +/- 5°C to constant mass (approximately 8 h). Cool in a desiccator.
NOTE 4 - Constant mass is considered to be achieved when change in mass is less than +/- 0.05 g after a 30 min test drying period.
10. Pycnometer Calibration (Determination of Pycnometer Volume)
NOTE 5 - Caution: Commercial pycnometers (specific gravity bottles) can either have not been calibrated at 25°C or else not calibrated to the accuracy required for this test method, so it is necessary that the pycnometer volume be determined.
10.1 Clean the pycnometer and its stopper with detergent, rinse thoroughly with water then with acetone. Place in a desiccator to dry, then weigh the empty pycnometer together with its stopper to 0.1 mg (mass Wo). The temperature of the pycnometer is to be close to room temperature when its weight is determined.
NOTE 6 - Precaution: Do not handle the pycnometer with bare fingers. Finger cots or surgical gloves can be worn, or tongs can be used, when handling the pycnometer to prevent moisture from fingers influencing the weight.
10.2 Fill the pycnometer with freshly boiled (to remove air) and cooled distilled water, and replace the stopper. Immerse the pycnometer up to the neck in the 25° +/- 0.1°C water bath for 1 h. Use the lead weights to prevent tipping. Replace water that leaves the capillary during this period. A syringe is convenient for this purpose.
10.3 At the end of the temperature stabilization period, check the capillary to be certain it is completely filled. Remove excess water on the stopper by dabbing with filter paper. If water is inadvertently removed from the capillary it must be replaced. Remove the pycnometer from the 25°C bath, rinse immediately with acetone, dry, and weigh to 0.1 mg (mass W3).
NOTE 7 - Caution: Avoid any heating after the pycnometer is removed from the 25°C bath. Heating will expand the water and cause loss from the capillary. Water is not to be added to the capillary after the pycnometer is removed from the 25°C bath. The purpose for the immediate acetone rinse is to contract the contents so it will recede in the capillary. Ethyl alcohol can be used in place of acetone. If laboratory temperature is 25°C or above, a water bath maintained at about 20°C should be provided to cool the pycnometer for about 1 min then dry and weigh. Do not chill the pycnometers so cold that moisture from the atmosphere will condense on them and make accurate weighing impossible.
10.4 Calculate the volume, v, of the pycnometer in cubic centimetres using Eq 2. Round off to 0.001 cm3.
where:
Wo = mass of the empty pycnometer, g,
W3 = mass of the water filled pycnometer, g, and
ρw = density of water at 25°C = 0.9970 g/cm3.
NOTE 8 - Caution: If this test method is performed at a temperature other than 25 +/- 0.1°C as stated in Note 2, then ρw is the density of water at the temperature chosen for the measurement. The density of water at temperatures other than 25°C is available in numerous standard reference journals.
10.5 Repeat 10.1-10.4 seven times over a two to three day period. Individual values should not deviate from the mean by more than +/- 0.0015 cm3. Use the mean value in all calculations using Eq 3. Re-determine the pycnometer volume every three months. The mass, Wo, should remain constant to within +/- 0.001 g.
11. Determination of the Density of Xylene
11.1 Follow the procedure in 10.1-10.3, but use xylene instead of water. Calculate the density, rx, of xylene at 25°C in g/cm3 using Eq 3. Round off to 0.0001 g/cm3.
NOTE 9 - Caution: Avoid any heating after the pycnometer is removed from the 25°C bath. Heating will expand the xylene and cause loss from the capillary. Xylene is not to be added to the capillary after the pycnometer is removed from the 25°C bath.
where:
Wo = mass of the empty pycnometer, g,
W2 = mass of the xylene-filled pycnometer, g, and
v = pycnometer volume, cm3.