1、Designation: D 287 92 (Reapproved 2006)An American National StandardStandard Test Method forAPI Gravity of Crude Petroleum and Petroleum Products(Hydrometer Method)1This standard is issued under the fixed designation D 287; the number immediately following the designation indicates the year oforigin
2、al adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon (e) indicates an editorial change since the last revision or reapproval.This standard has been approved for use by agencies of the Department of Def
3、ense. This test method has been adopted for use bygovernment agencies to replace Method 401 of Federal Test Method Standard No. 791b.1. Scope1.1 This test method covers the determination by means ofa glass hydrometer of the API gravity of crude petroleum andpetroleum products normally handled as liq
4、uids and having aReid vapor pressure (Test Method D 323) of 26 psi (180 kPa)or less. Gravities are determined at 60F (15.56C), or con-verted to values at 60F, by means of standard tables. Thesetables are not applicable to nonhydrocarbons or essentiallypure hydrocarbons such as the aromatics.NOTE 1Th
5、e international version of this test method is described inTest Method D 1298.1.2 The values stated in inch-pound units are to be regardedas standard. The values given in parentheses are mathematicalconversions to SI units that are provided for information onlyand are not considered standard.1.3 Thi
6、s standard does not purport to address all of thesafety concerns, if any, associated with its use. It is theresponsibility of the user of this standard to establish appro-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use. For specific hazardst
7、atements, see 8.3.2. Referenced Documents2.1 ASTM Standards:2D 323 Test Method for Vapor Pressure of Petroleum Prod-ucts (Reid Method)D 1250 Guide for Use of the Petroleum MeasurementTablesD 1298 Test Method for Density, Relative Density (SpecificGravity), or API Gravity of Crude Petroleum and Liqui
8、dPetroleum Products by Hydrometer MethodE1 Specification for ASTM Liquid-in-Glass ThermometersE 100 Specification for ASTM Hydrometers2.2 IP Standards:3Specifications for IP Standard ThermometersIP Specifications for Petroleum Hydrometers3. Terminology3.1 Definitions:3.1.1 API gravitya special funct
9、ion of relative density(specific gravity) 60/60F (15.56/15.56C), represented by:API gravity, deg 5141.5/sp gr 60/60F!2131.5 (1)No statement of reference temperature is required, since60F is included in the definition.4. Summary of Test Method4.1 This test method is based on the principle that thegra
10、vity of a liquid varies directly with the depth of immersionof a body floating in it. The floating body, which is graduatedby API gravity units in this method, is called an API hydrom-eter.4.2 The API gravity is read by observing the freely floatingAPI hydrometer and noting the graduation nearest to
11、 theapparent intersection of the horizontal plane surface of theliquid with the vertical scale of the hydrometer, after tempera-ture equilibrium has been reached. The temperature of thesample is read from a separate accurate ASTM thermometer inthe sample or from the thermometer which is an integral
12、part ofthe hydrometer (thermohydrometer).5. Significance and Use5.1 Accurate determination of the gravity of petroleum andits products is necessary for the conversion of measuredvolumes to volumes at the standard temperature of 60F(15.56C).5.2 Gravity is a factor governing the quality of crude oils.
13、However, the gravity of a petroleum product is an uncertainindication of its quality. Correlated with other properties,1This test method is under the jurisdiction of ASTM Committee D02 onPetroleum Products and Lubricants and is the direct responsibility of SubcommitteeD02.02.0A on Temperature, Densi
14、ty, Physical Properties.Current edition approved May 1, 2006. Published June 2006. Originallyapproved in 1928. Last previous edition approved in 2000 as D 287 92 (2000)e1.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Ann
15、ual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.3Available from the Institute of Petroleum, 61 New Cavendish St., LondonWIM, 8AR, England.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959,
16、 United States.gravity can be used to give approximate hydrocarbon compo-sition and heat of combustion.6. Apparatus6.1 Hydrometers, of glass, graduated in degrees API aslisted in Table 1 and conforming to Specification E 100,ortheIP Specifications for Petroleum Hydrometers.6.2 Thermometers, having a
17、 range from 5 to +215F andconforming to the requirements for Thermometer 12F asprescribed in Specification E1 or Thermometer 64F of theSpecifications for IPStandardThermometers.Athermometer isnot required if a thermohydrometer is employed.NOTE 2TheASTM Gravity Thermometer 12F has 0.5F subdivisionsan
18、d allowable 60.25F scale error. The thermometers incorporated inthermohydrometers have 2F subdivisions and allowable 61F scaleerror.6.3 Hydrometer Cylinders, of metal, clear glass, or plastic.For convenience in pouring, the cylinder may have a lip on therim. The inside diameter of the cylinder shall
19、 be at least 25 mmgreater than the outside diameter of the hydrometer used in it.The height of the cylinder shall be such that the length of thecolumn of sample it contains is greater by at least 25 mm thanthe portion of the hydrometer which is immersed beneath thesurface of the sample. For field te
20、sting, a sampling thief ofsuitable dimensions may be used.7. Temperature of Test7.1 The gravity determined by the hydrometer method ismost accurate at or near the standard temperature of 60F(15.56C). Use this or any other temperature between 0 and195F (18 and + 90C) for the test, so far as it is con
21、sistentwith the type of sample and necessary limiting conditionsshown in Table 2.8. Procedure8.1 For referee testing, use the long plain form of hydrom-eter (1H to 10H). For field testing, use the thermohydrometer.8.2 Adjust the temperature of the sample in accordance withTable 2. For field testing,
22、 test temperatures other than thoselisted in Table 2 may be used. The hydrometer cylinder shall beapproximately the same temperature as the sample to be tested.8.3 Transfer the sample into the clean hydrometer cylinderwithout splashing, so as to avoid the formation of air bubblesand to reduce to a m
23、inimum the evaporation of the lowerboiling constituents of the more volatile samples. (WarningExtremely flammable. Vapors may cause flash fire.) For themore volatile samples, transfer to the hydrometer cylinder bysiphoning. (WarningDo not start the siphon by mouth.) Usea rubber aspirator bulb. Remov
24、e any air bubbles formed, afterthey have collected on the surface of the sample, by touchingthem with a piece of clean filter paper before inserting thehydrometer. For field testing, make the gravity measurementdirectly in the sampling thief. Place the cylinder containing thesample in a vertical pos
25、ition in a location free from air currents.Take precautions to prevent the temperature of the sample fromchanging appreciably during the time necessary to completethe test. During this period, the temperature of the surroundingmedium should not change more than 5F (2C).8.4 Lower the hydrometer gentl
26、y into the sample and, whenit has settled, depress it about two scale divisions into the liquidand then release it; keep the rest of the stem dry, as unnecessaryliquid on the stem changes the effective weight of the instru-ment, and so affects the reading obtained. With samples of lowviscosity, a sl
27、ight spin imparted to the instrument on releasingassists in bringing it to rest, floating freely away from the wallsof the hydrometer cylinder. Allow sufficient time for thehydrometer to become completely stationary and for all airbubbles to come to the surface. This is particularly necessary inthe
28、case of the more viscous samples.8.5 When the hydrometer has come to rest, floating freely,and the temperature of the sample is constant to 0.2F (0.1C),read the hydrometer to the nearest scale division. The correctreading is that point on the hydrometer scale at which thesurface of the liquid cuts t
29、he scale. Determine this point byplacing the eye slightly below the level of the liquid and slowlyraising it until the surface, first seen as a distorted ellipse,appears to become a straight line cutting the hydrometer scale.8.6 To make a reading with nontransparent liquids, observethe point on the
30、hydrometer scale to which the sample risesabove its main surface, placing the eye slightly above the planesurface of the liquid. This reading requires a correction.Determine this correction for the particular hydrometer in useby observing the height above the main surface of the liquid towhich the s
31、ample rises on the hydrometer scale when thehydrometer in question is immersed in a transparent liquidhaving a surface tension similar to that of a sample under test.8.7 Observe the temperature of the sample to the nearest0.25F (0.1C) immediately before and after the observation ofthe gravity, the l
32、iquid in the cylinder being thoroughly butcautiously stirred with the thermometer (Note 3), and thewhole of the mercury thread being immersed. Should thesetemperature readings differ by more than 1F (0.5C), repeatthe temperature and gravity observations when the temperatureof the sample has become m
33、ore stable. Record the mean of thethermometer reading before and after the final hydrometerreading, to the nearest 1F, as the temperature of the test.NOTE 3When thermohydrometers are used, stir the sample by care-fully raising and lowering the hydrometer. It is satisfactory in this case toread the t
34、hermometer scale after the hydrometer reading has beenobserved. Read the thermometer to the nearest 1F (0.5C).9. Calculation9.1 When gravities have been observed on opaque liquidsusing the procedure given in 8.6, subtract the correction fromthe hydrometer reading observed.9.2 Correct all hydrometer
35、readings to 60F (15.56C),using Tables 5A or Tables 5B of Guide D 1250.TABLE 1 Available Hydrometers Scaled, Degrees APIDesignation TypeAPI Range, deg ScaleSeries Total Each Unit Division Error1H to 10H long plain 1 to 101 12 0.1 0.121H to 40H short plain 0 to 101 6 0.1 0.251H to 60H thermo 1 to 101
36、12 0.1 0.171H to 74H thermo 1 to 41 12 0.1 0.1Athermo 15 to 51 8AEight-degree range thermohydrometers are available.D 287 92 (2006)210. Report10.1 Report the corrected hydrometer reading as degreesAPI (API) or as API Gravity.11. Precision and Bias11.1 The precision of this test method as obtained by
37、statistical examination of interlaboratory test results is asfollows:11.1.1 RepeatabilityThe difference between successivetest results obtained by the same operator with the sameapparatus under constant operating conditions on identical testmaterial, would in the long run, in the normal and correcto
38、peration of the test method, exceed 0.2 API only in one casein twenty.11.1.2 ReproducibilityThe difference between two singleand independent results, obtained by different operators, work-ing in different laboratories on identical test material, would inthe long run, in the normal and correct operat
39、ion of the testmethod, exceed 0.5 API only in one case in twenty.NOTE 4The precision for this method was not obtained in accordancewith RR: D02-1007.NOTE 5This precision statement applies only to measurements madeat temperatures differing from 60F (15.56C) by less than 18F (10C).11.2 BiasBias for th
40、is method has not been determined.12. Keywords12.1 API gravity; crude petroleum; hydrometer; thermohy-drometer; thermometerASTM International takes no position respecting the validity of any patent rights asserted in connection with any item mentionedin this standard. Users of this standard are expr
41、essly advised that determination of the validity of any such patent rights, and the riskof infringement of such rights, are entirely their own responsibility.This standard is subject to revision at any time by the responsible technical committee and must be reviewed every five years andif not revise
42、d, either reapproved or withdrawn. Your comments are invited either for revision of this standard or for additional standardsand should be addressed to ASTM International Headquarters. Your comments will receive careful consideration at a meeting of theresponsible technical committee, which you may
43、attend. If you feel that your comments have not received a fair hearing you shouldmake your views known to the ASTM Committee on Standards, at the address shown below.This standard is copyrighted by ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959,United State
44、s. Individual reprints (single or multiple copies) of this standard may be obtained by contacting ASTM at the aboveaddress or at 610-832-9585 (phone), 610-832-9555 (fax), or serviceastm.org (e-mail); or through the ASTM website(www.astm.org).TABLE 2 Limiting Conditions and Testing TemperaturesSample
45、 Type Gravity LimitsInitial Boiling PointLimitsOther Limits Test TemperatureHighly volatile lighter than 70 API Cool to 35F (2C) or lower in original closedcontainer.Moderately volatile heavier than 70 API below 250F (120C) Cool to 65F (18C) or lower in original closedcontainer.Moderately volatile a
46、nd viscous heavier than 70 API below 250F (120C) Viscosity too highat 65F (18C)Heat to minimum temperature for sufficientfluidity.Nonvolatile heavier than 70 API above 250F (120C) Any temperature between 0 and 195F (18and 90C) as convenient.Mixtures of nonpetroleum prod-ucts or essentially pure hy-drocarbons60 6 0.25F (15.56 6 0.1C)D 287 92 (2006)3
