ASTM D5188 Standard Test Method for Vapor-Liquid Ratio Temperature Determination of Fuels (Evacuated Chamber and Piston Based Method)
6. Apparatus
6.1 Apparatus suitable for use shall employ a small volume test chamber incorporating a transducer for pressure measurements and associated equipment for thermostatically controlling the chamber temperature, evacuating the test chamber prior to sample introduction, or expanding the volume after sample introduction by a moveable piston, and cleaning and purging the chamber following the test. Critical elements of the apparatus shall meet the following specifications:
6.1.1 Test Chamber, constructed of stainless steel or aluminum, designed to contain between 5 mL and 50 mL of liquid plus vapor with a tolerance of +/- 1 % of the nominal capacity.
NOTE 3 - The test chamber volumes of the instruments used for the 1991 cooperative test program to determine the precision and bias statements were between 5 mL and 15 mL of liquid plus vapor with a tolerance of +/- 1 % of the nominal capacity.
6.1.2 Pressure Transducer, minimum operational range from 1 kPa to 177 kPa (0 psia to 25.6 psia) with minimum resolution of 0.1 kPa (0.01 psi) and minimum accuracy of +/- 0.8 kPa (+/- 0.12 psi). The pressure measurement system shall include associated electronics and readout devices to display the resulting pressure reading.
6.1.3 Heater, thermostatically controlled heater capable of maintaining the test chamber within 0.1 °C of the set temperature for a minimum of 5 minutes.
NOTE 4 - The use of automated instruments that automatically adjust the temperature, after sample injection, to give a pressure of 101.3 kPa (14.69 psia) is allowed.
6.1.4 Platinum Resistance Thermometer, used to measure the temperature of the test chamber, having a minimum temperature range of 36 °C to 80 °C, minimum resolution of 0.1 °C (0.2 °F) and minimum accuracy of +/- 0.1 °C (+/- 0.2 °F).
6.2 Vacuum Pump, (when required to produce the vacuum), capable of reducing the pressure in the test chamber to less than 0.01 kPa (0.001 psia).
6.3 Syringes, (if required for sample introduction), gas-tight, 1 mL to 20 mL capacity with minimum accuracy and precision of +/- 1 %.
6.4 Bath, iced water or air, for chilling the samples and syringe (if required) to between 0 °C and 1 °C (32 °F to 34 °F).
6.5 Pressure Measuring Device, capable of measuring local station pressure with an accuracy of 0.20 kPa (0.03 psi) or better, at the same elevation relative to sea level as the apparatus in the laboratory.
6.5.1 When a mercury manometer is not used as the pressure measuring device, the calibration of the pressure measuring device employed shall be periodically checked (with traceability to a nationally recognized standard) to ensure that the device remains within the required accuracy specified in 6.5.
6.6 McLeod Vacuum Gage or Calibrated Electronic Vacuum Measuring Device for Calibration, to cover at least the range from 0.01 kPa to 0.67 kPa (0.1 mm Hg to 5 mm Hg). The calibration of the electronic vacuum measuring device shall be regularly verified in accordance with the annex section on Vacuum Sensors (A6.3) of Test Method D2892.
7. Reagents and Materials
7.1 Purity of Reagents - Unless otherwise indicated, all reagents shall conform to the specifications of the Committee on Analytical Reagents of the American Chemical Society where such specifications are available. Lower purities can be used, provided it is first ascertained that the reagent is of sufficient purity to permit its use without lessening the accuracy of the determination. Reagents used for performance checks (see 10.3) shall be of at least 99 % purity.
7.2 Propan-2-ol, Anhydrous, (less than 0.1 % H2O). (Warning - Flammable.)
NOTE 5 - It has been reported that, if not originally inhibited against it, propan-2-ol can contain peroxides. When this occurs, an explosion is possible when the storage of the vessel or other equipment such as a dispensing bottle, is near empty and approaching dryness.
7.3 Toluene, (Warning - Toluene is flammable and a health hazard.)
7.4 n -pentane, (Warning - Flammable, health hazard.)
