12. Procedure
12.1 Clean the pycnometer and its stopper with detergent and rinse thoroughly with water then with acetone and dry in a desiccator.
12.2 Weigh the pycnometer with its stopper to 0.1 mg (mass Wo). The temperature of the pycnometer is to be close to ambient room temperature. (See Note 6.)
12.3 Introduce approximately 10 g of the dried and cooled analysis sample into the clean, dry, pycnometer. Less sample can be used but should not be less than 5 g.
12.4 Replace the stopper, remove any coke adhering to the outer pycnometer surface, and re-weigh. The difference between this mass and Wo is the sample mass (mass Ws).
12.5 Fill the pycnometer with enough xylene to wet and cover the sample and swirl gently to aid wetting and to displace air. Add additional xylene until the pycnometer is about two-thirds full and place it, without stopper, in the vacuum desiccator at as low an absolute pressure (or high a vacuum) as possible to remove air from the coke but to avoid excessive evaporation of the xylene. If a means is available, vibrate the pycnometer gently and intermittently while in the desiccator to assist in the elimination of air. Leave under vacuum until all bubbling stops. It is recommended that time under vacuum be at least 30 min.
12.6 Remove the pycnometer from the desiccator, fill it with xylene, and place it in the 25 +/- 0.1°C bath with stopper in place. Immerse the pycnometer up to the neck in the water bath for 1 h. Use the lead weights to prevent tipping. Replace xylene that leaves the capillary during this period. A syringe is convenient for this purpose.
12.7 At the end of the temperature stabilization period, check the capillary to be certain it is completely filled. Remove excess xylene on the stopper by dabbing with filter paper. If xylene 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 W1).
12.8 Upon completion of the test procedure, clean and dry the pycnometers. To facilitate cleaning of the pycnometers, remove a portion of the xylene and replace with acetone. Then shake this xylene/acetone mixture and facilitate removal of the petroleum coke from the pycnometers. Clean the pycnometers as specified in 10.1 before reuse.
13. Calculation
13.1 Determine the density of the sample in g/cm3 from Eq 4 as follows:
