ASTM D5771 Standard Test Method for Cloud Point of Petroleum Products and Liquid Fuels (Optical Detection Stepped Cooling Method)
6. Apparatus
6.1 Optical Cloud Point Apparatus - The automated cloud point apparatus (see Fig. 2) described in this test method consists of a microprocessor controller that is capable of controlling one or more independent test cells. The apparatus shall include provisions for independently controlling the temperature of each cell according to the specified cooling profile, continuously monitoring the specimen temperature, detecting the appearance ofthe cloud point at the bottom of the test jar without removing it from the jacket, and displaying the 0.1 °C or 1.0 °C result (see Fig. 1 and Fig. 3).
6.2 Temperature Probe, IEC 751 Class A: ΔT = +/- (0.15 + 0.002 |T|), capable of measurement from −50 °C to +80 °C. The temperature probe shall be in contact with the bottom of the test jar.
6.3 Test Jar, clear cylindrical glass, mirrored flat bottom, 34 mm +/- 0.5 mm outside diameter, 1.4 mm +/- 0.15 mm wall thickness, 120 mm +/- 0.5 mm height, thickness of the bottom 2.0 mm +/- 0.5 mm, marked with a line to indicate the sample height 54 mm +/- 0.5 mm above the inside bottom.
6.4 Jacket, brass, cylindrical, flat bottom, 113 mm +/- 0.2 mm in depth, 45 mm +/- 0.1 mm inside diameter. It must be cooled according to the cooling profile specified.
6.5 Cooling System, either an external system equipped with a circulating pump and capable ofmaintaining a temperature at least 10 °C below the last required jacket temperature level (see Table 1 and Fig. 3), or an internal system capable of maintaining the required jacket temperatures (see Table 1 and Fig. 3).
6.6 Cork Disk, 6 mm +/- 0.2 mm thick, to fit loosely inside the jacket. Felt may be used but special attention must be given to the potential for moisture in the felt disk. The felt must be dried before each test.
6.7 Cork Ring, to fit snugly around the outside ofthe test jar and loosely inside the sample cell. Its purpose is to prevent the test jar from touching the jacket.
7. Reagents and Materials
7.1 Cleaning Solvents, suitable for cleaning and drying the test cell, such as petroleum naphtha and hexane.
7.2 Methyl Alcohol, Anhydrous, for use as cooling medium in circulating bath cooling system, when used.
7.3 Sodium Sulfate - A reagent grade of anhydrous sodium sulfate should be used when required. (Warning - Flammable. Liquid causes eye burns. Vapor harmful. May be fatal or cause blindness if swallowed or inhaled.)
7.4 Lint-free filter paper may be used as a drying medium.
