ASTM D5190 Vapor Pressure of Petroleum Products (Automatic Method)
ASTM D5190 Standard Test Method for Vapor Pressure of Petroleum Products (Automatic Method)
12. Procedure
12.1 Sample Transfer - Remove the sample from the cooling bath or refrigerator, dry the exterior of the container with absorbent material, uncap, and insert a chilled transfer tube apparatus (see Fig. 1). Quickly take the chilled sample cup and place it, in an inverted position, over the sample delivery tube of the transfer apparatus. Invert the entire system rapidly so that the sample cup is upright with the end of the delivery tube touching the bottom of the sample cup. Fill the sample cup to overflowing. Withdraw the delivery tube from the sample cup while allowing the sample to continue flowing up to the moment of complete withdrawal.
NOTE 7 - Precaution: In addition to other precautions make provisions for suitable restraint (for example, catch pan) and disposal of the overflowing or spilled gasoline to avoid fire hazard.
12.2 Quickly couple the sample cup to the instrument and start the analysis in accordance with the manufacturer's instructions for operation of the instrument. The total time between opening the chilled sample container and securing the sample cup to the instrument shall not exceed 1 min.
12.3 At the completion of the test, record the uncorrected dry vapor pressure reading from the digital meter to the nearest 0.l kPa (0.01 psi). If the instrument does not automatically calculate the DVPE, record the uncorrected vapor pressure reading and calculate the DVPE using Eq 1 (see 13.1).
13. Calculation
13.1 Calculate a DVPE, using the following equation. This corrects the instrument reading for the relative bias found in the 1991 interlaboratory cooperative test program (see Note 10) between the dry vapor pressure measured in accordance with Test Method D4953, Procedure A and this test method:
DVPE = (0.954 X) + A
where:
X = measured total vapor pressure, in units consistent with A, and
A = 1.94 kPa (0.281 psi).
