ASTM D5772 Standard Test Method for Cloud Point of Petroleum Products and Liquid Fuels (Linear Cooling Rate Method)
1. Scope
1.1 This test method covers the description of the determination of the cloud point of petroleum products and biodiesel fuels that are transparent in layers 40 mm in thickness by an automatic instrument using a linear cooling rate.
1.2 This test method covers the range of temperatures from -60 °C to 49 °C with temperature resolution of 0.1 °C, however, the range of temperatures included in the 1997 interlaboratory cooperative test program only covered the temperature range of -56 °C to +34 °C.
1.3 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.
1.4 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.
1.5 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
2. Referenced Documents
2.1 ASTM Standards:
D2500 Test Method for Cloud Point of Petroleum Products and Liquid Fuels
D4057 Practice for Manual Sampling of Petroleum and Petroleum Products
D4177 Practice for Automatic Sampling of Petroleum and Petroleum Products
2.2 Energy Institute Standard:
IP 219 Test Method for Cloud Point of Petroleum Products
3. Terminology
3.1 Definitions:
3.1.1 biodiesel, n - a fuel comprised of mono-alkyl esters of long-chain fatty acids derived from vegetable oils or animal fats, designated B100.
3.1.1.1 Discussion - Biodiesel is typically produced by a reaction of vegetable oil or animal fat with an alcohol such as methanol or ethanol in the presence of a catalyst to yield mono-esters and glycerin. The fuel typically may contain up to 14 different types offatty acids that are chemically transformed into fatty acid methyl esters (FAME).
3.1.2 biodiesel blend, n - a blend of biodiesel fuel with petroleum-based diesel fuel designated BXX, where XX is the volume percentage of biodiesel.
3.1.3 cloud point, n - in petroleum products and biodiesel fuels, the temperature of a liquid specimen when the smallest observable cluster of wax crystals first occurs upon cooling under prescribed conditions.
3.1.3.1 Discussion - The cloud point occurs when the temperature of the specimen is low enough to cause wax crystals to precipitate. In a homogeneous liquid, the cloud is always noted first at the location in the specimen where the specimen temperature is the lowest. The cloud point is the temperature at which the crystals first occur, regardless of their location in the specimen, and not after extensive crystallization has taken place. The wax crystals that precipitate at lower temperatures are typically, but not excluded to, straight-chain hydrocarbons and lipids.
3.1.3.2 Discussion - The purpose of the cloud point method is to detect the presence of the wax crystals in the specimen; however, trace amounts of water and inorganic compounds may also be present. The intent of the cloud point method is to capture the temperature at which the liquid fuel in the specimen begins to change from a single liquid phase to a two-phase system containing solid and liquid. It is not the intent of this test method to monitor the phase transition of the trace components, such as water.
3.2 Definitions of Terms Specific to This Standard:
3.2.1 automatic cloud point, n - the temperature of a specimen when the appearance of the cloud is determined under the conditions of this test method.
3.2.1.1 Discussion - The cloud point in this test method is determined by an automatic instrument using an optical device for detection of the crystal formation. The apparatus and the conditions are different from those established for Test Method D2500, although, according to interlaboratory examination, the results have been determined to be equivalent to Test Method D2500.
3.2.2 linear cooling rate method, n - in cloud point test methods, test procedure using prescribed cooling rate, specimen receptacle, and optical system for detection of crystal formation.
3.2.2.1 Discussion - The prescribed cooling rate is described in 11.6; the specimen receptacle is described in Annex A1, and the optical system for the detection of crystal formation is described in Annex A1.
3.2.3 D2500/IP 219 equivalent cloud point, n - the temperature of a specimen, in integers, calculated by rounding the results of this test method to the next lower integer.
3.2.3.1 Discussion - This test method produces results with 0.1 °C resolution. Should the user wish to provide results with a similar format to Test Method D2500, then this calculation can be performed. Some apparatus can perform this calculation automatically.
