ASTM D5773 Standard Test Method for Cloud Point of Petroleum Products and Liquid Fuels (Constant Cooling Rate Method)
6. Apparatus
6.1 Automatic Apparatus - The automatic cloud point apparatus described in this test method consists of a test chamber controlled by a microprocessor that is capable of controlling the heating and cooling of the test specimen, optically observing the first appearance of a cloud of wax crystals and recording the temperature of the specimen described in detail 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 Peltier device shall be capable ofheating or cooling the test specimen at a constant rate of 1.5 °C/min +/- 0.1 °C/min.

6.4 The temperature-measuring device in the specimen cup shall be capable of measuring the temperature of the test specimen from -40 °C to +70 °C at a resolution of 0.1 °C.

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

NOTE 4 - Some apparatus are designed to use ambient air as a cooling medium. In such cases, a built-in fan is available to provide circulation of air and there is no need for fittings as described for a liquid cooling medium. The function of the cooling medium is to remove heat from the electronic components. The choice of the cooling medium has no impact whatsoever on the test results.

6.6 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 Cooling Medium - Air, tap water, or other liquid heat exchange medium sufficient to remove heat generated by the Peltier device and other electronic components from the apparatus. To achieve specimen cooling to -40 °C, supply circulation of liquid cooling medium at +25 °C or lower to the apparatus. For an apparatus which relies on air as cooling medium, the ambient air temperature has to be below +30 °C to achieve specimen cooling to -40 °C.

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

7.3 Precision Volume Dispensing Device, capable of dispensing 0.15 mL +/- 0.01 mL of sample.

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