6. Apparatus
6.1 A schematic diagram of the apparatus is shown in Fig.1.
The component parts are described as follows:
6.1.1 Test Vessel, made of borosilicate glass as shown in Fig.2, consisting of a jacketed sample tube fitted with an air inlet capillary, baffle plate, and air outlet tube. The two parts of each test vessel should be marked and preferably used as a pair. Interchanged parts may be used so long as the resultant test vessel conforms to the stated dimensions.
6.1.2 Pressure Gage, covering the range from 0 to 35kPa, with divisions at least every 2kPa, and an accuracy of 1.5kPa.
6.1.3 Thermometers:
6.1.3.1 Air Thermometer, for measuring compressed air temperature. ASTM Precision Thermometer having a range from -20 to 102°C, graduated in 0.2°C and conforming to the requirements for Thermometer 12C as prescribed in Specification E1 is suitable. A temperature sensor of at least equivalent performance is also suitable. Care shall be taken to avoid restricting the air path with the thermometer bulb or any adapterused.
6.1.3.2 Sample Thermometer, for measuring the temperature of the sample during preparation and trial runs. ASTM Precision Thermometer having a range from –20 to 102°C, graduated in 0.2°C and conforming to the requirements for Thermometer 12C as prescribed in Specification E1 is suitable. A temperature sensor of at least equivalent performance is also suitable.
6.1.4 Heater, to bring the compressed air up to measurement temperature. A coil of copper tubing immersed in the circulating bath(see6.1.5) is suitable at 25°C, but additional heating is necessary at 50 and 75°C. This can be obtained by an additional bath, or by using a separate steam or electric heat exchanger. The temperature of the air shall be measured by a thermometer located as close as possible to the testing vessel and meeting the specifications shown in 6.1.3.
NOTE 3 - The application of thermal insulation to the pipework carrying the heated compressed air is recommended.
6.1.5 Circulating Bath, approximately 10L capacity with a rate of flow of 10L/min and capable of maintaining the test cell at a temperature of 25, 50, or 75°C within more or less 60.1°C.
NOTE 4 - Use of water in the bath has been found to minimize electrostatic effects.
NOTE 5 - The application of thermal insulation to the pipework carrying the heated bath fluid is recommended.
Warning - The use of glass vessels with glass host fittings for circulating 75°C (167°F) bath medium is potentially dangerous. Back pressure in excess of a gage pressure of 70kPa (10 psi) can be generated when the bath medium is pumped at the required rate; this can cause fracture of the glass or slippage of the hose connections. Use of a pressure relief valve set at 70kPa(10psi) is recommended. Inaddition, use of a safety shield is recommended.
6.2 Balance, capable of measuring density, accurate to 0.5kg/m3.
6.3 Sinker, having around or tapered bottom of 5 or 10mL displacement, 80.0 more or less 1.5mm length. If the sinker contains a thermometer, it shall be usable between 25 and 75°C.
6.4 Oven, capable of heating samples to 10°C above the test temperature.
6.5 Timer, readable to 0.1 min, with an accuracy of better than 0.1%.
6.6 Pump, with a nonpulsating output and capable ofmaintaining an air flow of 40 L/min at a pressure of 20 kPa (optional, see 7.4).
