GB/T 8017-2012 Determination of vapor pressure of petroleum products Reid method

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Card type: Test method

1. Method number / full name / English name / replacement relationship

• Standard number: GB/T 8017-2012
• Chinese name: Determination of vapor pressure of petroleum products Reid method
• English name: Standard test method for vapor pressure of petroleum products—Reid method
• Replacement relationship: replaces GB/T 8017—1987 "Determination of vapor pressure of petroleum products (Reid method)"
• Adoption relationship: modified adoption using the redrafting method of ASTM D323:2008 "Standard test method for vapor pressure of petroleum products (Reid method)"
• Publication/implementation: published on 2012-11-05, implemented on 2013-03-01
• Responsible committee: Subcommittee on Petroleum Fuels and Lubricants of the National Technical Committee for Standardization of Petroleum Products and Lubricants (SAC/TC 280/SC 1)
• Drafting organization: Sinopec Research Institute of Petroleum Processing
• Main drafters: Shen Zheng, Zheng Yu, Li Weihua
• Method numbers: A method, B method, C method, D method (including A method improved procedure, B method improved procedure)

2. Scope of application and non-applicability

• 1.1 This standard specifies methods for determining the vapor pressure of gasoline, other volatile petroleum products, and volatile crude oil.
• 1.2 A method is applicable to the determination of gasoline (including gasoline containing only methyl tert-butyl ether (MTBE)) and other petroleum products with vapor pressure less than 180 kPa. The improved procedure of A method is applicable to samples of gasoline and oxygenate-blended gasoline from 35 kPa to 100 kPa.
• 1.3 B method and its improved procedure use a semi-automatic horizontal bath tester, and are likewise applicable to the determination of gasoline and other petroleum products to which A method and its improved procedure apply. However, in the interlaboratory comparison tests for determining its precision, only samples of gasoline and oxygenate-blended gasoline were used.
• 1.4 C method is applicable to the determination of samples with vapor pressure greater than 180 kPa.
• 1.5 D method is applicable to the determination of aviation gasoline with vapor pressure of approximately 50 kPa.
• 1.6 This standard is not applicable to the determination of the vapor pressure of liquefied petroleum gas; for the determination method of the vapor pressure of liquefied petroleum gas, see GB/T 6602 or ASTM D6897. The precision of this method for determining the vapor pressure of crude oil has not yet been established. GB/T 11059 is a method for determining the vapor pressure of crude oil, and IP 481 is a method for determining the air-saturated vapor pressure of crude oil.
• 1.7 This standard provides special explanations for the improved procedure for oxygenate-blended gasoline samples regarding test preparation, sample transfer, verification of sample state, determination procedure, reporting of test results, and precision requirements; for details, see 4.3, 8.1.3.2, 8.1.4.2, 8.2.2, 8.2.4, 8.2.5, 8.2.6.1, 9.2, 9.2.9, 9.4, 9.3.5, 12.2, 13.1.1 Table 1 and 13.1.2 Table 2 (clause numbers require confirmation against the source standard (source-text extraction)).
• Note (1.5 Note): Because the original atmospheric pressure in the gas chamber offsets the external atmospheric pressure, the Reid vapor pressure is the absolute vapor pressure under 37.8 °C, expressed in kilopascals. The Reid vapor pressure differs from the vapor pressure of the sample due to the evaporation of some relatively lower molecular weight sample components in the confined space and the presence of water vapor and air.

3. Method principle

• 4.1 The liquid chamber of the vapor pressure tester is filled with a cooled sample and connected to the gas chamber that has been heated in the bath to 37.8 °C. The assembled tester is immersed in a bath at 37.8 °C until a constant pressure is observed. After appropriate correction, this reading is reported as the Reid vapor pressure.
• 4.2 All four methods use liquid chambers and gas chambers of the same volume. B method uses a semi-automatic tester, immersed in a horizontal bath, and reaches equilibrium while rotating. B method may also use a Bourdon spring pressure gauge or pressure sensor. C method uses a double-opening liquid chamber. D method has stricter limits on the ratio of the volumes of the liquid chamber and gas chamber.
• 4.3 The improved procedures of A method and B method are for the determination of oxygenate-blended gasoline samples; during the determination, the interiors of the gas chamber, liquid chamber, and sample transfer connection device shall be kept dry and free of water.

4. Reagents and materials (purity / preparation)

• Cleaning reagents: 32 °C hot water, naphtha, acetone, dry air (see 8.2.6.1).
• Purity and preparation of other reagents: not provided in the available source.

5. Instruments and equipment

• 5 Apparatus: the apparatus used in A method, C method, and D method is given in Annex B. The apparatus used in B method is given in Annex C.
• B.1 Vapor pressure test apparatus: consists of two chambers, the upper chamber being the gas chamber and the lower chamber being the liquid chamber.
  • B.1.1 Gas chamber: a cylindrical container with an inner diameter of 51 mm±3 mm (requires confirmation against the source standard (source-text extraction)) and a length of 254 mm±3 mm; the inner diameter of the fitting at one end is not less than 4.7 mm, and it is provided with a 6.35 mm pressure gauge connection; the opening at the other end with a diameter of about 12.7 mm is connected to the liquid chamber.
  • B.1.2 Liquid chamber (single-opening type): a cylindrical container with the same inner diameter as the gas chamber, and its volume shall satisfy the requirement that the volume ratio of the gas chamber to the liquid chamber be within 3.8 to 4.2 (source-text extraction shows "3.8 to 2", requires confirmation against the source standard (source-text extraction)); one end has an opening with a diameter of 12.7 mm, and the other end is completely closed.
  • B.1.3 Aviation gasoline: the volume ratio of the assembled liquid chamber to the gas chamber shall be between 3.95 and 4.05.
  • B.1.4 Liquid chamber (double-opening type): near the bottom is installed a 6.35 mm valve B, and at the connection between the two chambers there is a 12.7 mm straight-through fully open valve A; the volume of the liquid chamber includes only the volume between the two valves.
  • B.1.5 The volume of the double-opening liquid chamber is calculated from below the closing point of valve A, and the volume above the closing point of valve A (including the fitting portion) is regarded as part of the gas chamber volume.
  • B.1.6 Connection method of the gas chamber and liquid chamber: any connection method may be used, and the male thread of the fitting shall be installed on the liquid chamber; a vent hole may be used to ensure that the gas chamber is at atmospheric pressure when closed.
  • B.1.7 Volumes of the gas chamber and liquid chamber: measure with water to determine whether the volume ratio is within the range of 3.8 to 4.2.
• B.2 Pressure gauge: Bourdon spring pressure gauge, diameter 100 mm to 150 mm, 6.35 mm male threaded connection, and the diameter of the connecting pipe between the Bourdon tube and the gas chamber shall not be less than 4.7 mm. The range and graduations are according to Table B.1. If the difference between readings exceeds 1% of the pressure gauge range, it shall be considered inaccurate.
• Table B.1 Pressure gauges and graduations:
  • Reid vapor pressure ≤27.5 kPa: range 0 to 35 kPa, maximum numerical graduation 5.0 kPa, maximum fine graduation 0.5 kPa
  • 20.0 to 75.0 kPa: range 0 to 100 kPa, maximum numerical graduation 15.0 kPa, maximum fine graduation 0.5 kPa
  • 70.0 to 180.0 kPa: range 0 to 200 kPa, maximum numerical graduation 25.0 kPa, maximum fine graduation 1.0 kPa
  • 70.0 to 250.0 kPa: range 0 to 300 kPa, maximum numerical graduation 25.0 kPa, maximum fine graduation 1.0 kPa
  • 200.0 to 357.0 kPa: range 0 to 400 kPa, maximum numerical graduation 50.0 kPa, maximum fine graduation 1.5 kPa
  • ≥350.0 kPa: range 0 to 700 kPa, maximum numerical graduation 50.0 kPa, maximum fine graduation 2.5 kPa
  • Note: In the range of 0 to 35 kPa, a pressure gauge with a diameter of 90 mm may be used.
• B.3 Cooling bath: capable of completely containing the sample container and liquid chamber, maintaining the temperature at 0 °C to 1 °C.
• B.4 Water bath: capable of immersing the vapor pressure tester to at least 25.4 mm above the top of the gas chamber, maintaining the water bath temperature at 37.8 °C±0.1 °C.
• B.5 Thermometer: a thermometer meeting the requirements of number GB-54 in standard GB/T 514.
• B.6 Pressure measuring device: the range shall be suitable for calibrating the pressure gauge used, with a minimum accuracy of 0.5 kPa, and the subdivision graduation shall not be greater than 0.5 kPa.
• B.7 Deadweight tester: for calibrating pressure gauge readings greater than 180 kPa, a deadweight tester may be used instead of a pressure measuring device.
• B.8 Sample transfer connection device: the stopper tightly fitted on the mouth of the sample container has two holes, each inserted with a tube; the short tube delivers the sample, and the long tube reaches the bottom of the container.
• C.1 Vapor pressure tester: see B.1.1 to B.1.7.
• C.2 Pressure gauge (gauge or pressure sensor): Bourdon spring tube pressure gauge (see B.2), pressure gauge, or suitable pressure sensor or digital pressure reading device, which shall be kept away from the vapor pressure tester and equipped with a quick connector.
• C.3 Cooling bath: warning same as B.1.4.
• C.4 Water bath: capable of allowing the vapor pressure tester to be immersed horizontally, and the tester can rotate forward and reverse on its axis 350°, with constant temperature in the bath at 37.8 °C±0.1 °C.
• C.5 Thermometer: see B.5.
• C.6 Pressure measuring device: see B.6.
• C.7 Drive coupling: used for the connection of the B method vapor pressure tester with the pressure measuring device.
• C.8 Gas chamber protective tube: inner diameter 3 mm, length 114 mm, inserted at the pressure measuring end of the gas chamber.
• C.9 Sample transfer connection device: see B.8.

6. Recommended operating conditions

• Water bath temperature: 37.8 °C±0.1 °C (8.1.4.1, 8.1.4.2, 8.2.3, 9.3.3, B.4, C.4).
• Cold bath temperature: 0 °C~1 °C (B.3, 7.5, 8.1.3.1).
• The liquid level of the bath in which the gas chamber is placed shall be at least 24.5 mm above the top of the gas chamber (8.1.4.1, 8.1.4.2); in 8.2.3, the water bath liquid level shall be at least 25 mm above the top of the air chamber; in B.4, at least 25.4 mm.
• The liquid chamber and the sample transfer connection device shall be placed in the cold bath for more than 10 min (8.1.3.1); for the A method improved procedure, place for more than 20 min (8.1.3.2).
• The gas chamber shall be kept in the water bath for more than 10 min (8.1.4.1); for the A method improved procedure, keep for more than 20 min (8.1.4.2).
• The time from taking the gas chamber out of the water bath to completing the connection with the liquid chamber shall not exceed 10 s (8.2.2, 9.3.2).
• Start reading after the apparatus has been placed in the water bath for at least 5 min (8.2.5.1, 9.3.5.1).
• The reading interval shall be not less than 2 min (8.2.5.1, 9.3.5.1).
• Number of shakes: shake the apparatus vigorously up and down 8 times (8.2.3); complete not less than 5 shakes and readings (8.2.5.1).
• Pressure reading accurate to 0.25 kPa (8.2.5.1, 9.3.5.1, 12.1).
• The pressure value of the pressure gauge compared with the pressure measuring device shall be within ±1.0 kPa of the uncorrected vapor pressure (8.2.5.2, 9.3.5.2).

7. Sampling and sample preparation

• The determination of 7.1 vapor pressure is extremely sensitive to sample evaporation loss and changes in composition, requiring necessary measures and careful operation during sample handling. The content of this chapter applies to the determination of vapor pressure of all other samples except those with vapor pressure higher than 180 kPa.
• 7.2 Sampling shall be carried out in accordance with GB/T 4756. Steps such as sampling and sealing shall be strictly carried out in accordance with GB/T 4756, and the sampling amount shall be controlled at 70%~80% of the volume of the sampling container.
• 7.3 Dimensions of the sample container: The test sample for vapor pressure determination shall be taken from the sample contained in the 1 L sample container, and the sample container shall contain 70%~80% of sample. The precision of this method was established from tests extracting samples from 1 L containers. For arbitration tests, a container of 1 L capacity shall be used.
• 7.4 For the determination of Reid vapor pressure, the test sample taken from the sample container for the first time shall be used. The remaining sample in the container shall not be used for a second vapor pressure test. If a second test is required, a new sample shall be used.
• 7.4.1 The sample shall be protected from excessive heating before the test.
• 7.4.2 Samples in containers showing signs of leakage shall not be used for the test. Such samples shall be discarded and a new sample shall be taken.
• 7.5 Sample handling temperature: Before opening the sample container, the container and the sample therein must be cooled to 0 °C~1 °C.
• 8.1.1 Confirm the amount of test sample loaded in the container: When the sample temperature reaches between 0 °C~1 °C, take out the container and wipe it dry. Confirm that the liquid volume is 70%~80% of the container.
  • 8.1.1.1 If the sample amount is less than 70% of the container, it cannot be used.
  • 8.1.1.2 If the sample amount in the container exceeds 80%, pour out some to bring it within the range of 70%~80%. The poured-out sample shall not be returned to the container.
  • 8.1.1.3 If necessary, re-cover the container and place the sample container back into the cold bath.
• 8.1.2 Air saturation of the sample in the sample container:
  • 8.1.2.1 Non-transparent container: When the sample temperature is 0 °C~1 °C, take out the container and wipe it dry, quickly open and close the sample container lid, being careful not to let water enter. After re-covering the container, shake vigorously. Then place it back into the cold bath for at least 2 min.
  • 8.1.2.2 Transparent container: The procedure of 8.1.2.1 shall be repeated twice.
  • 8.1.2.3 Repeat the procedure of 8.1.2.1 two more times, place the sample container back into the cold bath until the test procedure of 8.2 begins.
• 8.1.3 Preparation of the liquid chamber:
  • 8.1.3.1 Samples without added oxygen-containing compounds: Completely immerse the opened and upright liquid chamber and the sample transfer connection device in a 0 °C~1 °C cold bath, and leave for more than 10 min.
  • 8.1.3.2 A method improved procedure: Completely immerse the sealed and upright liquid chamber and the sample transfer connection device in a 0 °C~1 °C refrigerator or cold bath, the cold bath liquid level shall not cover the top of the threaded opening of the liquid chamber, and leave for more than 20 min. Warning: The liquid chamber and sample transfer connection device shall be kept dry.
• 8.1.4 Preparation of the gas chamber:
  • 8.1.4.1 Samples without added oxygen-containing compounds: The gas chamber and pressure gauge are cleaned according to 8.2.6 and then connected. Immerse the gas chamber in a water bath at 37.8 °C±0.1 °C, so that the water bath liquid level is at least 24.5 mm above the top of the gas chamber, and maintain for more than 10 min.
  • 8.1.4.2 A method improved procedure: The gas chamber and pressure gauge are cleaned according to 8.2.6 and then connected. Immerse the sealed gas chamber in a water bath at 37.8 °C±0.1 °C, so that the water bath liquid level is at least 24.5 mm above the top of the gas chamber, and maintain for more than 20 min. Warning: The gas chamber shall be kept dry.
• 10.4 Sampling (C method):
  • 10.4.1 7.3~7.5 is not suitable for use.
  • 10.4.2 Capacity of the sample container: The capacity of the sample container from which the test sample is taken shall not be less than 10.5 (unit requires confirmation against the source standard (source-text extraction)).
• 10.5 Preparation for the test (C method):
  • 10.5.1 8.1.1 and 8.1.2 are not applicable.
  • 10.5.2 Any safe method of transferring the test sample from the sample container may be used, provided that the liquid chamber is filled with cooled test sample.
  • 10.5.3 Maintain the temperature of the sample container sufficient to obtain superatmospheric pressure, but basically not exceeding 37.8 °C.
  • 10.5.4 Completely immerse the liquid chamber, together with both valve ports, in the cold bath, so that the liquid chamber temperature reaches 0 °C~4.5 °C.
  • 10.5.5 Connect a suitable ice-cold coil to the outlet valve of the sample container. Note: The ice-cold coil is made by immersing a copper tube of total length 8 m and diameter 6.35 mm in an ice water tank.

8. Analytical procedure

• 8.2.1 Transfer of the test sample: Take the cooled sample container out of the cold bath, open the lid, insert the cooled sample transfer connection device and air tube. Empty the cooled liquid chamber as quickly as possible, place it on the sample transfer tube of the sample transfer connection device, quickly invert the entire apparatus, and finally the liquid chamber shall be kept upright, with the sample transfer connection tube extending to 6 mm from the bottom of the liquid chamber. Fill the liquid chamber with sample until it overflows, remove the pipette, and gently tap the liquid chamber against the test bench to ensure the sample is free of air bubbles. For gasoline samples with added oxygen-containing compounds, wipe the outer surfaces of the sample container and liquid chamber dry with a hygroscopic material.
• 8.2.2 Assembly of the apparatus: Immediately take the gas chamber out of the water bath and connect it as quickly as possible to the liquid chamber filled with sample, without splashing of sample and without unnecessary movements. The time from taking the gas chamber out of the water bath to completing the connection with the liquid chamber shall not exceed 10 s. For gasoline samples with added oxygen-containing compounds, after taking the gas chamber out of the water bath, quickly wipe its outer surface dry with a hygroscopic material, paying special attention to drying the connection between the gas chamber and the liquid chamber, and after removing the seal of the gas chamber, connect it as quickly as possible to the liquid chamber filled with sample.
• 8.2.3 Placing the apparatus in the bath: Invert the assembled vapor pressure tester so that the sample flows from the liquid chamber into the gas chamber. While the gas chamber is still inverted, shake the apparatus vigorously up and down 8 times. Turn the pressure gauge upward and immerse the vapor pressure tester in a water bath at 37.8 °C±0.1 °C. The vapor pressure tester shall be slightly tilted so that the connection between the liquid chamber and the gas chamber is just below the water surface, and carefully check the connection for gas or liquid leakage. If no leakage is found, immerse the vapor pressure tester in the water bath so that the water bath liquid level is at least 25 mm above the top of the air chamber. Throughout the test, observe the apparatus for gas and liquid leakage; if gas or liquid leakage is found during the test, the test is invalid. Discard the test sample and retest with a new test sample.
• 8.2.4 Sample state check for the improved procedure for gasoline samples with added oxygen-containing compounds: If the sample is contained in a transparent container, any layering phenomenon can be observed before sample transfer. If the sample is contained in a non-transparent container, thoroughly stir the remaining sample, then quickly pour a portion of the remaining sample into a clean glass container, and observe and confirm whether the sample shows a layered state. If the remaining sample is observed to be cloudy, the test may continue; for the reporting of test results for samples showing this phenomenon, see 12.2. If the sample shows a layered state, discard the test sample and the remaining sample, and retest with a new test sample.
• 8.2.5 Determination of vapor pressure:
  • 8.2.5.1 Place the assembled apparatus in the water bath for at least 5 min, then gently tap the pressure gauge and observe its reading. Remove the apparatus from the water bath and repeat the steps of 8.2.3. At time intervals of not less than 2 min, tap the pressure gauge, observe the reading, and repeat 8.2.3 until not less than 5 shakings and readings have been completed. Continue this procedure until the last two adjacent pressure readings are the same and indicate that equilibrium has been reached. Read the final pressure to the nearest 0.25 kPa. Record this value as the uncorrected vapor pressure of the test sample.
  • 8.2.5.2 Quickly remove the pressure gauge; do not attempt to remove any liquid that may be trapped in the pressure gauge. Connect the pressure gauge to the pressure measuring device. Before removing the pressure gauge, the apparatus components should first be cooled. Place the pressure gauge and the pressure measuring device under the same stable pressure, that is, the pressure value should be within ±1.0 kPa of the recorded uncorrected vapor pressure, and compare the pressure gauge reading with the pressure measuring device reading (see B.6). If a difference is observed between the readings of the pressure measuring device and the pressure gauge, when the pressure measuring device reading is higher, add this difference to the uncorrected vapor pressure; when the pressure measuring device reading is lower, subtract this difference from the uncorrected vapor pressure. Record this result as the Reid vapor pressure of the test sample.
  • Note (8.2.5.2): For the modified procedure for determining gasoline samples containing added oxygenates, if stratification is suspected during the vapor pressure determination, quickly remove the vapor pressure measuring apparatus from the bath and quickly dry the outer surfaces of the gas chamber and liquid chamber with an absorbent material. Keep the measuring apparatus upright and disconnect the gas chamber from the liquid chamber. Pour the contents of the liquid chamber into a clean, transparent glass container and observe the test sample. If the test sample is not sufficiently clear and transparent and stratification occurs, cover the glass container holding the test sample with a lid, heat it to 37.8 °C, stir the test sample thoroughly, and then observe the state of the test sample. If the test sample is still not clear and transparent and stratification occurs, the result of this test is invalid.
• 8.2.6 Prepare the apparatus for the next test:
  • 8.2.6.1 Fill the gas chamber with hot water at 32 °C and then drain it to thoroughly remove residual liquid. Repeat this cleaning step at least five times. Clean the liquid chamber in the same manner. For testing gasoline samples containing added oxygenates, after cleaning the gas chamber in the above manner, then blow dry with dry air. Rinse the liquid chamber, gas chamber, and transfer tubing several times with naphtha, then several times with acetone, and then blow dry with dry air. Place the liquid chamber in a cold bath or refrigerator for use in the next test. For testing gasoline samples containing added oxygenates, the liquid chamber should be properly sealed before being placed in the cold bath or refrigerator for later use; the bottom of the gas chamber should also be properly sealed, and the pressure gauge prepared according to 8.2.6.3 should be connected to the gas chamber.
  • 8.2.6.2 If the gas chamber is cleaned in the water bath, when the gas chamber passes through the water surface, tightly cover the bottom and upper openings of the gas chamber to prevent the oil film of floating test sample from adhering.
  • 8.2.6.3 Preparation of the pressure gauge: Disconnect the pressure gauge from the branch pipe connected to the pressure measuring device (see B.6). Use centrifugation to remove trapped liquid in the Bourdon tube of the pressure gauge. Hold the pressure gauge with both hands, with the right palm against the face, the threaded connection of the pressure gauge facing forward, raise the arm upward and forward to an angle of 45° and extend it, then swing the arm rapidly downward through an arc of about 135°. Repeat this operation at least three times, or until the liquid is completely expelled from the pressure gauge. Connect the pressure gauge to the gas chamber (whose liquid connection has been closed) and place it in a bath at a temperature of 37.8 °C for use in the next test. Warning: The gas chamber together with the attached pressure gauge must not remain in the water bath longer than required for the next test conditions, otherwise water vapor may condense in the Bourdon tube, leading to erroneous results.
• 9.1 Sampling (B method): see Chapter 7.
• 9.2 Preparation (B method): see 8.1. When preparing the gas chamber according to 8.1.4, connect the gas chamber to the pressure gauge or pressure sensor. Immerse it horizontally and completely in the water bath. For gasoline samples containing added oxygenates, seal the gas chamber according to 8.1.4.2, then immerse it horizontally and completely in the water bath.
• 9.3 Test procedure (B method):
  • 9.3.1 Transfer of the test sample: see 8.2.1.
  • 9.3.2 Assembly of the apparatus: Immediately remove the gas chamber from the water bath and disconnect the spiral tube at the quick connector. Connect the liquid chamber filled with test sample to the gas chamber as quickly as possible. There must be no splashing or unnecessary movement. The time from removing the gas chamber from the water bath to completing the connection with the liquid chamber must not exceed 10 s. For the modified procedure for determining gasoline samples containing added oxygenates, see 8.2.2 for details.
  • 9.3.3 Placing the apparatus in the bath: When the apparatus is in a vertical position, immediately connect the spiral tube at the quick connector. Turn the apparatus downward through an angle of 20°~30° to 4 s or 5 s, allowing the test sample to flow into the gas chamber without entering the tube of the pressure gauge (gauge or pressure sensor) from the gas chamber. Place the apparatus assembly in a water bath at 37.8 °C±0.1 °C, connect the bottom end of the liquid chamber to the drive coupling, and mount the other end of the apparatus on the support bearing. Turn on the switch to start rotating the liquid chamber and gas chamber assembly. Throughout the entire test, observe the apparatus for leaks. Once a leak is found, the test is invalid.
  • 9.3.4 Sample state check in the modified procedure for gasoline samples containing added oxygenates: see 8.2.4.
  • 9.3.5 Determination of vapor pressure:
    • 9.3.5.1 After the apparatus assembly has remained in the bath for at least 5 min, tap the pressure gauge and observe the data. At time intervals of not less than 2 min, repeat tapping and observing the reading until two adjacent readings are the same (when using a sensor, tapping is not required). Read the final pressure value on the pressure gauge (gauge or pressure sensor) to the nearest 0.25 kPa, and record this value as the uncorrected vapor pressure.
    • 9.3.5.2 Quickly remove the pressure gauge (gauge or pressure sensor) from the apparatus, then connect the pressure gauge or pressure sensor to the pressure measuring device (see B.6). Place the pressure gauge (gauge or pressure sensor) and the pressure measuring device under the same stable pressure, which should be within ±1.0 kPa of the recorded uncorrected vapor pressure, and compare the pressure gauge (gauge or pressure sensor) reading with the pressure measuring device reading (see B.6). If a difference is observed between the readings of the pressure measuring device and the pressure gauge (gauge or pressure sensor), when the pressure measuring device reading is higher, add this difference to the uncorrected vapor pressure; when the pressure measuring device reading is lower, subtract this difference from the uncorrected vapor pressure. Record this result as the Reid vapor pressure of the test sample. Note: see 8.2.5.2 note.
  • 9.3.6 Prepare the apparatus for the next test:
    • 9.3.6.1 See 8.2.6.1.
    • 9.3.6.2 See 8.2.6.2.
    • 9.3.6.3 Preparation of the pressure gauge (gauge or pressure sensor): In normal operation, liquid must not flow into the pressure gauge (gauge or pressure sensor). If liquid enters the pressure gauge (gauge or pressure sensor), clean the pressure gauge according to the procedure of 8.2.6.3. The pressure sensor has no grooves and will not retain liquid. Ensure that there is no liquid at the fasteners or spiral tube of the T type handle, and blow clean with a strong stream of dry air through the tubing. Connect the pressure gauge (gauge or pressure sensor) to the gas chamber, with the liquid connection in the air chamber closed. Place it in a bath at 37.8 °C for the next test. Warning: The air chamber together with the attached pressure gauge (gauge or pressure sensor) must not remain in the water bath longer than required for the next test conditions, otherwise water vapor may condense in the Bourdon tube, leading to erroneous results.
• 10.1 Overview (C method): For products with vapor pressure higher than 180 kPa, the methods described in Chapter 7 to Chapter 8 are dangerous and inaccurate. Unless otherwise specified, all requirements from Chapter 1 to 9.3 shall be followed. Note: If necessary, both the A method and the B method can be used to determine the vapor pressure of products with vapor pressure higher than 180 kPa.
• 10.2 Apparatus (C method):
  • 10.2.1 Apparatus with a double-opening liquid chamber as described in Appendix B.1.4.
  • 10.2.2 Calibration of the pressure gauge: For pressure gauge readings above 180 kPa determined by this method, use a deadweight tester (see B.7) as the pressure measuring device (see B.6). In 6, 8, 8.2.6.3, and 12.1, where the pressure measuring device (see B.6) and its readings appear, they may be replaced by the deadweight tester and calibrated pressure gauge readings, respectively.
• 10.3 Safety precautions (C method): 6.7 not applicable.
• 10.6 Test procedure (C method):
  • 10.6.1 8.2.1 and 8.2.2 should not be used.
  • 10.6.2 Connect the φ6.35 mm valve of the cooled liquid chamber to the ice-cold coil. Close the φ12.7 mm valve of the liquid chamber, open the outlet valve of the sample container and the φ6.35 mm valve of the liquid chamber. Slowly open the φ12.7 mm valve of the liquid chamber to allow the liquid chamber to fill slowly. Allow the test sample to overflow until the overflow amount reaches 200 mL or more. Control this operation so that no significant pressure drop occurs at the φ6.35 mm valve of the liquid chamber. Close the φ12.7 mm valve and the φ6.35 mm valve of the liquid chamber in the indicated order, then close all other valves in the sample system to disconnect the liquid chamber from the cooling coil. Warning: Flammable, keep away from heat sources, sparks, and open flames. Keep containers closed, provide adequate ventilation during operation, and avoid prolonged breathing of its vapors or spray. Avoid prolonged repeated skin contact. Warning: In addition to other precautions, take safety measures to handle the liquid and vapor discharged throughout the process. Since the liquid chamber is filled with test sample, prevent rupture. Quickly connect the liquid chamber to the gas chamber and keep the φ12.7 mm valve open.
  • 10.6.3 Immediately connect the liquid chamber and gas chamber, and open the φ12.7 mm valve of the liquid chamber. After filling the liquid chamber, the time required to complete the assembly of the apparatus must not exceed 25 s. The operating procedure is as follows: a) Remove the gas chamber from the water bath. b) Connect the gas chamber to the liquid chamber. c) Open the φ12.7 mm valve of the liquid chamber.
  • 10.6.4 If a deadweight tester is used instead of the pressure measuring device (see 10.2.2), add a correction factor, expressed in kilopascals, to the uncorrected vapor pressure. Record this value as the corrected pressure reading, in place of the pressure measuring device corrected reading in 12.1.
• 11.1 Overview (D method): To determine the vapor pressure of aviation gasoline, the following clauses describe variations in apparatus and method. Unless otherwise specified, the requirements from Chapter 1 to Chapter 8 apply.
• 11.2 Apparatus (D method): The volume ratio of the gas chamber to the liquid chamber shall be within the range of 3.95~4.05 (see B.1.3).
• 11.3 Sampling (D method): See Chapter 7.
• 11.4 Preparation for the test (D method): Check the pressure gauge (or pressure sensor). Before each vapor pressure determination, use a pressure measuring device (see B.6 and B.7) to check the reading of the pressure gauge at 50 kPa to ensure it meets the requirements of B.2. This preliminary check is supplementary to the calibration in 8.2 or 9.3.5.
• 11.5 Test procedure (D method): See 8.2.

9. Qualitative and Quantitative and Calculation Formulas

• 12.1 Report the results observed in 8.2.5 and 9.3.5, after correction for any difference between the pressure gauge (meter) and the pressure measuring device, to the nearest 0.25 kPa, as the Reid vapor pressure of the sample.
• 12.2 For reporting test results of samples with added oxygenates, if turbidity is observed and confirmed in the sample or test specimen, add "H" after the test result as a note.
• Calculation formula: not provided in the available source (the standard reports directly from the corrected pressure reading and does not give a calculation formula).

10. Precision

• 13.1 Precision: Use the following provisions to judge the reliability of test results (95% confidence level).
• 13.1.1 Repeatability: The difference between two results of consecutive tests on the same sample by the same operator using the same apparatus shall not exceed the value in Table 1.
• Table 1 Repeatability:
  • A method, range 0~35 kPa, repeatability 0.7 kPa
  • A method, range 35~100 kPa (gasoline), repeatability 3.2 kPa
  • A method improved procedure, range 35~100 kPa, repeatability 3.65 kPa
  • A method, range 110~180 kPa, repeatability 2.1 kPa
  • B method, range 35~100 kPa (gasoline), repeatability 1.2 kPa
  • B method improved procedure, range 35~100 kPa, repeatability 4.00 kPa
  • C method, range >180 kPa, repeatability 2.8 kPa
  • D method, range approximately 50 kPa (aviation gasoline), repeatability 0.7 kPa
  • Note: For repeatability of samples with 100 kPa–110 kPa, refer to the repeatability range for samples with 35 kPa–100 kPa.
• 13.1.2 Reproducibility: The difference between two single and independent test results on the same sample obtained by different operators working in different laboratories using different apparatus shall not exceed the value in Table 2.
• Table 2 Reproducibility:
  • A method, range 0~35 kPa, reproducibility 2.4 kPa
  • A method, range 35~100 kPa (gasoline), reproducibility 5.2 kPa
  • A method improved procedure, range 35~100 kPa, reproducibility 5.52 kPa
  • A method, range 110~180 kPa, reproducibility 2.8 kPa
  • B method, range 35~100 kPa (gasoline), reproducibility 4.5 kPa
  • B method improved procedure, range 35~100 kPa, reproducibility 5.38 kPa
  • C method, range >180 kPa, reproducibility 4.9 kPa
  • D method, range approximately 50 kPa (aviation gasoline), reproducibility 1.0 kPa
  • Note: For reproducibility of samples with 100 kPa–110 kPa, refer to the reproducibility range for samples with 35 kPa–100 kPa.
• 13.2 Bias:
  • 13.2.1 Absolute bias: Because there is no acceptable reference material suitable for determining the bias of this method, the bias cannot be determined. The bias between the vapor pressure of this method and the true vapor pressure has also not been determined.
  • 13.2.2 Relative bias: There is no obvious statistical bias between the vapor pressure results of gasoline determined by the A method and the B method.

11. Report

• 12.1 Report the results observed in 8.2.5 and 9.3.5, after correction for any difference between the pressure gauge (meter) and the pressure measuring device, to the nearest 0.25 kPa, as the Reid vapor pressure of the sample.
• 12.2 For test results of samples with added oxygenates