ASTM D323 for vapor pressure of petroleum products (Reid method)
PROCEDURE C FOR PETROLEUM PRODUCTS HAVING REID VAPOR PRESSURES ABOVE 180 kPa (26 psi)
15. Introduction
15.1 With products having vapor pressure over 180 kPa (26 psi) see Note 10), the procedure described in Sections 7-11 is hazardous and inaccurate. Consequently, the following sections define changes in apparatus and procedure for the determinations of vapor pressures above 180 kPa. Except as specifically stated, all the requirements of Sections 1-11 shall apply.
NOTE 10 - If necessary, either Procedure A or B can be used to determine if the vapor pressure of a product is above 180 kPa.
16. Apparatus
16.1 Apparatus as described in Annex A1 using the liquid chamber with two openings.
16.2 Pressure Gage Calibration - A dead-weight tester (see A1.7) can be used in place of the mercury manometer as a pressure measuring device (see A1.6) for checking gage readings above 180 kPa (26 psi). In 6.1.1, 8.1, 11.4, and 11.5.3 where the words pressure measuring device and pressure measuring device reading appear, include as an alternative dead-weight tester and calibrated gage reading respectively.
17. Hazards
17.1 The precaution in 6.1.6 shall not apply.
18. Sampling
18.1 Sections 7.3, 7.3.1, 7.4 and 7.5 shall not apply.
18.2 Sample Container Size - The size of the sample container from which the vapor pressure sample is taken shall not be less than 0.5 L (1 pt) liquid capacity.
19. Preparation for Test
19.1 Paragraphs 10.1 and 10.2 shall not apply.
19.2 Any safe method of displacement of the test sample from the sample container that ensures filling the liquid chamber with a chilled, unweathered sample may be employed. The following, 19.3-19.5, describe displacement by self-induced pressure.
19.3 Maintain the sample container at a temperature sufficiently high to maintain superatmospheric pressure but not substantially over 37.8°C (100°F).
19.4 Completely immerse the liquid chamber, with both valves open, in the water cooling bath for a sufficient length of time to allow it to reach the bath temperature of 0 to 4.5°C (32 to 40°F).
19.5 Connect a suitable ice-cooled coil to the outlet valve of the sample container (see Note 11).
NOTE 11 - A suitable ice-cooled coil can be prepared by immersing a spiral of approximately 8 m (25 ft) of 6.35-mm (0.25-in.) copper tubing in a bucket of ice water.
20. Procedure
20.1 Paragraphs 11.1 and 11.2 shall not apply.
20.2 Connect the 6.35-mm (0.25-in.) valve of the chilled liquid chamber to the ice-cooled coil. With the 12.7-mm (0.5 in.) valve of the liquid chamber closed, open the outlet valve of the sample container and the 6.35-mm (0.25-in.) valve of the liquid chamber. Open the liquid chamber 12.7-mm (0.5-in.) valve slightly and allow the liquid chamber to fill slowly. Allow the sample to overflow until the overflow volume is 200 mL or more. Control this operation so that no appreciable drop in pressure occurs at the liquid chamber 6.35-mm (0.25-in.) valve. In the order named, close the liquid chamber 12.7-mm (0.5-in.) and 6.35-mm (0.25-in.) valves; and then close all other valves in the sample system. Disconnect the liquid chamber and the cooling coil.
NOTE 12 - Warning: Combustible. Keep away from heat, sparks, and open flame. Keep container closed. Use only with adequate ventilation. Avoid prolonged breathing of vapor or spray mist. Avoid prolonged, repeated contact with skin.
NOTE 13 - Precaution: In addition to other precautions, provide a safe means of disposal of liquid and vapor escaping during this whole operation.
20.2.1 To avoid rupture because of the liquid-full condition of the liquid chamber, the liquid chamber must be quickly attached to the vapor chamber and the 12.7-mm (0.5-in.) valve opened.
20.3 Immediately attach the liquid chamber to the vapor chamber and open the liquid chamber 12.7-mm (0.5-in.) valve. Not more than 25 s shall pass in completing the assembly of the apparatus after filling the liquid chamber, using the following sequence of operations:
20.3.1 Remove the vapor chamber from the water bath.
20.3.2 Connect the vapor chamber to the liquid chamber.
20.3.3 Open the liquid chamber 12.7-mm (0.5-in.) valve.
20.4 If a dead-weight tester is used instead of the mercury manometer as a pressure measuring device (see 16.2), apply the calibration factor in kilopascals (pounds-force per square inch) established for the pressure gage to the uncorrected vapor pressure. Record this value as the calibrated gage reading and use in Section 8 in place of the pressure measuring device reading.
