1、Designation: D7683 11D7683 17Standard Test Method forCloud Point of Petroleum Products and Liquid Fuels (SmallTest Jar Method)1This standard is issued under the fixed designation D7683; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revisio
2、n, the year of last revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon () indicates an editorial change since the last revision or reapproval.1. Scope Scope*1.1 This test method covers the determination of the cloud point of petroleum products, biodiesel, a
3、nd biodiesel blends that aretransparent in layers 40 mm in thickness, using an automatic instrument.1.2 The measuring range of the apparatus is from -6565 C to 51C,+51 C, however the precision statements were derivedonly from samples with cloud point temperatures from -5050 C to +6C.+6 C.1.3 The val
4、ues 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 responsibilityof the user of this standard to establish appropriate
5、safety and health practices and determine the applicability of regulatorylimitations prior to use.1.5 This international standard was developed in accordance with internationally recognized principles on standardizationestablished in the Decision on Principles for the Development of International St
6、andards, Guides and Recommendations issuedby the World Trade Organization Technical Barriers to Trade (TBT) Committee.2. Referenced Documents2.1 ASTM Standards:2D2500 Test Method for Cloud Point of Petroleum Products and Liquid FuelsD4057 Practice for Manual Sampling of Petroleum and Petroleum Produ
7、ctsD4177 Practice for Automatic Sampling of Petroleum and Petroleum ProductsD6708 Practice for Statistical Assessment and Improvement of Expected Agreement Between Two Test Methods that Purportto Measure the Same Property of a Material2.2 Energy Institute Standards:3IP219 Test Method for Cloud Point
8、 of Petroleum Products3. Terminology3.1 Definitions:3.1.1 biodiesel, nfuel comprising mono-alkyl esters of long-chain fatty acids derived from vegetable oils or animal fats,designated B100.3.1.1.1 DiscussionBiodiesel is typically produced by a reaction of vegetable oil or animal fat with an alcohol
9、such as methanol or ethanol in thepresence of a catalyst to yield mono-esters and glycerin. The fuel typically may contain up to 14 different types of fatty acids thatare chemically transformed into fatty acid methyl esters (FAME).3.1.2 biodiesel blend (BXX), nblend of biodiesel fuel with petroleum-
10、based diesel fuel designated BXX, where XX is thevolume percentage (as a whole number without the percentage sign) of biodiesel.1 This test method is under the jurisdiction ofASTM Committee D02 on Petroleum Products, Liquid Fuels, and Lubricants and is the direct responsibility of SubcommitteeD02.07
11、 on Flow Properties.Current edition approved Feb. 15, 2011May 1, 2017. Published April 2011May 2017. Originally approved in 2011. Last previous edition approved in 2011 as D7683 11.DOI: 10.1520/D768311.10.1520/D7683-17.2 For referencedASTM standards, visit theASTM website, www.astm.org, or contactAS
12、TM Customer Service at serviceastm.org. For Annual Book of ASTM Standardsvolume information, refer to the standards Document Summary page on the ASTM website.3 Available from Energy Institute, 61 New Cavendish St., London, WIG 7AR, U.K., http:/www.energyinst.org.uk.This document is not an ASTM stand
13、ard and is intended only to provide the user of an ASTM standard an indication of what changes have been made to the previous version. Becauseit may not be technically possible to adequately depict all changes accurately, ASTM recommends that users consult prior editions as appropriate. In all cases
14、 only the current versionof the standard as published by ASTM is to be considered the official document.*A Summary of Changes section appears at the end of this standardCopyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States13.1.3 cloud point
15、, nin petroleum products and biodiesel fuels, the temperature of a liquid specimen when the smallestobservable cluster of hydrocarbonwax crystals first occurs upon cooling under prescribed conditions.3.1.3.1 DiscussionThe cloud point occurs when the temperature of the specimen is low enough to cause
16、 hydrocarbonwax crystals to precipitate. Ina 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 af
17、terextensive crystallization has taken place. The hydrocarbonwax crystals that precipitate at lower temperatures are typically, but notexcluded to, straight chain hydrocarbons commonly called “wax crystals.”straight-chain hydrocarbons and lipids.3.2 Definitions of Terms Specific to This Standard:3.2
18、.1 small test jar method, nin cloud point test methods, automatic test procedure using a small sample size, prescribedcooling rate, specimen receptacle, and optical system for detection of crystal formation.3.2.1.1 DiscussionThe prescribed cooling rate is described in 11.4, the specimen receptacle i
19、s described in 6.3, and the optical system for detectionof crystal formation is described in A1.2.3.3.2.2 D2500/IP219 equivalent cloud point, ntemperature of a specimen, in integers, calculated by applying a bias androunding the results of this test method to the next lower integer (see 12.2).3.2.2.
20、1 DiscussionThis test method produces results with 0.1C0.1 C resolution. Should the user wish to provide results with a similar format to TestMethod D2500, then this calculation can be performed. Some apparatus can perform this calculation automatically.4. Summary of Test Method4.1 After inserting t
21、he glass test jar containing the specimen into the automatic apparatus and initiating the test program, thespecimen is heated, if necessary, to the designated temperature and then cooled by prescribed rates. (See 11.4.) The test specimenis continuously monitored for appearance of hydrocarbon crystal
22、s with a light emitter and a light receiver through coaxial typecoaxial-type optical fibers. (See A1.2.3.)When the crystallization in the specimen is detected by the optical system, the temperatureis recorded to 0.1C0.1 C resolution. The specimen is then heated to facilitate the start of the next te
23、st.5. Significance and Use5.1 The cloud point of petroleum products and biodiesel fuels is an index of the lowest temperature of their utility for certainapplications. Wax crystals of sufficient quantity can plug filters used in some fuel systems.5.2 Petroleum blending operations require precise mea
24、surement of the cloud point.5.3 This test method can determine the temperature of the test specimen at which wax crystals have formed sufficiently to beobserved as a cloud with a resolution of 0.1C.0.1 C.5.4 This test method provides results that, when corrected for bias and rounded to the next lowe
25、r integer (see 12.2), have beenfound equivalent to Test Method D2500.5.5 This test method determines the cloud point in a shorter time period than required by Test Method D2500.6. Apparatus6.1 Automatic ApparatusThe automatic cloud point apparatus described in this test method is a microprocessor co
26、ntrolledmicroprocessor-controlled apparatus that is capable of heating and cooling a test specimen at prescribed rates, optically observingthe first appearance of hydrocarbon wax crystals, and recording the temperature of the test specimen. A detailed description of theapparatus is provided in Annex
27、 A1.6.2 Temperature Measuring Temperature-Measuring DeviceThe temperature measuring temperature-measuring device in thespecimen chamber shall be capable of measuring the temperature from -6565 C to 51C51 C at a resolution of 0.1C.0.1 C.6.3 Test JarClear, cylindrical borosilicate glass with a flat bo
28、ttom with an approximate capacity of 12 mL.Approximately 4.5mL of sample specimen is contained when filled to the scribed line. During the test, the test jar is fitted with a test jar cap assemblyon its top. See A1.1.2 for more details on the test jar.6.4 Metallic Block BathMetallic block with a cyl
29、indrical hole to fit the test jar. The metallic block assembly shall have aprovision for cooling/heating. A temperature sensor is embedded in the metallic block to monitor its temperature.D7683 1727. Reagents and Materials7.1 Cleaning AgentsCapable of cleaning and drying the test jar and test jar ca
30、p assembly, after each test. Chemical agents suchas alcohol and petroleum-based solvents have been found suitable to use. (WarningFlammable.) (Warning May be harmfulby itself or when evaporated.)8. Sampling8.1 Obtain a sample in accordance with Practice D4057 or by Practice D4177.8.2 A minimum volum
31、e of 4.5 mL of sample is required for each test.8.3 Samples of very viscous materials may be warmed until they are reasonably fluid before they are tested. However, no sampleshould be heated more than is absolutely necessary to facilitate pouring the sample into the instrument test jar. (WarningExer
32、cise care when selecting the preheating temperature. Samples which are fluid at ambient room temperature can also have alow flash point. Use higher preheating temperatures only on samples known to be solid near ambient room temperature.)8.4 The sample shall not be heated above 60C.60 C. When the sam
33、ple is heated above 60C60 C allow the sample to coolbelow 60C60 C before filtering or inserting into the apparatus.8.5 When moisture is present, remove the moisture by a method,method such as filtration through dry, lint-free filter paper,paperuntil the oil is perfectly clear, but make such filtrati
34、on at a temperature at least 14C14 C above the expected cloud point.NOTE 1Moisture will be noticed in the sample as a separate phase or as a haze throughout the entire sample. Generally, a slight haze will not interferewith the detection of the wax cloud.9. Preparation of Apparatus9.1 Prepare the in
35、strument for operation in accordance with the manufacturers instructions.10. Calibration and Standardization10.1 Ensure that all of the manufacturers instructions for calibrating, checking, and operating the apparatus are followed.10.2 A sample with a well documented well-documented cloud point can
36、be used to verify the performance of the automaticapparatus. Alternatively, a sample that has been extensively tested in a cloud point cross-check program can be used. Suchverification materials can also be prepared from intra-companyintracompany cross-checks.11. Procedure11.1 Pour the sample specim
37、en into the test jar to the scribed mark. When necessary, heat the sample in a bath or oven untilit is just sufficiently fluid to pour into the test jar. Samples with an expected cloud point above 36C36 C or samples which appearsolid at room temperature can be heated above 45C,45 C, but they shall n
38、ot be heated above 60C.60 C.11.2 Insert the charged test jar into the metallic block bath, and install the test jar cap assembly snugly.11.3 Enter the expected cloud point and start the operation of the apparatus according to the manufacturers instruction.in-structions. From this point on, the appar
39、atus automatically controls the series of procedures, which includes the sample preheatingfunction if the apparatus is so programmed prior to the start of the automatic procedure. (WarningExercise care when selectingthe preheating temperature. Samples which are fluid at ambient room temperature can
40、also have a low flash point. Use higherpreheating temperatures only on samples known to be solid near ambient room temperature.)11.4 After the sample preheating is completed, the metallic block bath is cooled down automatically at a typical rate of 33 Cto 4C/min.4 Cmin.At a temperature at least 20C2
41、0 C above the expected cloud point, the cooling rate slows down to 0.80.8 Cto 1.1C/min.1.1 Cmin. During the cooling, the optical system monitors for appearance of the crystals.11.5 In the event a cloud point is detected prematurely during the fast cooling rate, as determined by the apparatus, the sp
42、ecimenshall be reheated to a higher temperature, at least 30C30 C warmer than the temperature of premature detection, and then cooledas described in 11.4, while the optical system monitors for appearance of the crystals.11.6 At the detection of the cloud point, the specimen temperature is displayed
43、to the nearest 0.1C0.1 C and held on the digitaldisplay. The metallic block bath starts heating automatically for the next test.12. Report12.1 Report the temperature recorded in 11.6 to 0.1C0.1 C as the cloud point D7683 (Small Test Jar Method).12.2 When specified, correct the results recorded in 11
44、.6 with the relative bias in accordance with 13.3, then round to the nextlower integer (a colder temperature) and report as the Test Method D2500 equivalent cloud point in accordance with Test MethodD7683.D7683 17313. Precision and Bias413.1 PrecisionThe precision of this test method as determined b
45、y the statistical examination of the interlaboratory test resultsis as follows:13.1.1 RepeatabilityThe difference between successive test results, obtained by the same operator using the same apparatusunder constant operating conditions on identical test material, would in the long run, in the norma
46、l and correct operation of thistest method, exceed the following only in one case in twenty.1.47C,1.47 C, valid range -5050 C to +6C+6 C13.1.2 ReproducibilityThe difference between two single and independent test results, obtained by different operators workingin different laboratories on identical
47、test material, would in the long run, in normal and correct operation of this test method, exceedthe following only in one case in twenty.2.45C,2.45 C, valid range -5050 C to +6C+6 C13.2 BiasSince there is no accepted reference material suitable for determining the bias for the procedure in this tes
48、t method,bias has not been determined.13.3 Relative BiasThe Degree ofAgreement between results by Test Method D7683 and Test Method D2500/IP219Resultson the same materials produced by Test Method D7683 and Test Method D2500 have been assessed in accordance with proceduresoutlined in Practice D6708.
49、The findings are:The degree of agreement between results from Test Method D7683 and Test Method D2500/IP219 can be further improved byapplying the bias-correction bias correction outlined in Eq 1. Sample-specific bias, as defined in Practice D6708, was observed forsome samples after applying the bias correction.Predicted YD2500!5bias2corrected XD7683!5XD7683!11.68C (1)where:X = result obtained by Test Method D7683, andbias-corrected X = predicted Y = result that would have been obtain
