ASTM D5972 Freezing Point of Aviation Fuels (Automatic Phase Transition Method)
6. Apparatus
6.1 Automatic Apparatus - This apparatus consists of a microprocessor-controlled test chamber that is capable of cooling and heating the test specimen, optically observing the appearance and disappearance of solid hydrocarbon crystals, and recording the temperature of the specimen. A detailed description of the apparatus is provided in Annex A1.

6.2 The apparatus shall be equipped with a specimen cup, optical detector array, light source, digital display, Peltier device, and a specimen temperature measuring device.

6.3 The temperature measuring device in the specimen cup shall be capable of measuring the temperature of the test specimen from -80 to +20°C at a resolution of 0.1°C and accuracy of 0.1°C.

6.4 The apparatus shall be equipped with fittings to permit the circulation of a liquid medium to remove heat generated by the Peltier device and other electronic components of the apparatus.

6.5 The apparatus shall be equipped with fittings to permit the circulation of purge gas to purge the test chamber containing the specimen cup of any atmospheric moisture.

7. Reagents and Materials
7.1 n-Octane - Reagent grade is suitable. (Warning - Flammable. Harmful if inhaled. Keep away from heat, sparks, and open flame.)

7.2 Cooling Medium - Liquid heat exchange medium to remove the heat generated by the Peltier device and other electronic components from the apparatus.

NOTE 1 - Some apparatus are designed to use tap water as a cooling medium to bring the specimen temperature to -60°C. To achieve cooling of the specimen to -80°C, provide circulation of the cooling medium at -30°C or lower to the apparatus. Since water freezes at 0°C, a commercial or technical grade isopropanol (see Note 1) is suitable as the cooling medium. Refer to the manufacturer's operating instructions on the relationship between the cooling medium temperature and the minimum specimen temperature.

7.3 Purge Gas - A gas such as air, nitrogen, helium, or argon with a dew point below the lowest temperature attained by the specimen under the conditions of the test. (Warning - Compressed gas under high pressure.) (Warning - Inert gas can be an asphyxiant when inhaled.

7.4 Pipette, capable of dispensing 0.15 +/- 0.01 mL of sample.

7.5 Cotton Swabs - Plastic- or paper-shaft cotton swabs to clean the specimen cup. (Warning - The use of swabs with wooden shafts may damage the mirrored surface of the specimen cup.)