1、Designation: D6822 12API Designation: Manual of Petroleum Measurement Standards (MPMS), Chapter 9.3Standard Test Method forDensity, Relative Density, and API Gravity of CrudePetroleum and Liquid Petroleum Products byThermohydrometer Method1This standard is issued under the fixed designation D6822; t
2、he number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, 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.
3、 Scope*1.1 This test method covers the determination, using a glassthermohydrometer in conjunction with a series of calculations,of the density, relative density, or API gravity of crudepetroleum, petroleum products, or mixtures of petroleum andnonpetroleum products normally handled as liquids and h
4、avinga Reid vapor pressures of 101.325 kPa (14.696 psi) or less.Values are determined at existing temperatures and corrected to15C or 60F by means of a series of calculations andinternational standard tables.1.2 The initial thermohydrometer readings obtained areuncorrected hydrometer readings and no
5、t density measure-ments. Readings are measured on a thermohydrometer at eitherthe reference temperature or at another convenient tempera-ture, and readings are corrected for the meniscus effect, thethermal glass expansion effect, alternate calibration tempera-ture effects and to the reference temper
6、ature by means ofcalculations and Adjunct to D1250, Guide for Use of thePetroleum Measurement Tables (API MPMS Chapter 11.1).1.3 Readings determined as density, relative density, or APIgravity can be converted to equivalent values in the other unitsor alternate reference temperatures by means of Int
7、erconver-sion Procedures or Adjunct to D1250, Guide for Use of thePetroleum Measurement Tables (API MPMS Chapter 11.1), orboth, or tables as applicable.1.4 The initial thermohydrometer reading shall be recordedbefore performing any calculations. The calculations requiredin Section 7 shall be applied
8、 to the initial thermohydrometerreading with observations and results reported as required bySection 8 prior to use in a subsequent calculation procedure(measurement ticket calculation, meter factor calculation, orbase prover volume determination).1.5 Annex A1 contains a procedure for verifying or c
9、ertify-ing the equipment of this test method.1.6 The values stated in SI units are to be regarded asstandard. The values given in parentheses are for informationonly.1.7 This standard does not purport to address all of thesafety concerns, if any, associated with its use. It is theresponsibility of t
10、he user of this standard to establish appro-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use.2. Referenced Documents2.1 ASTM Standards:2D1250 Guide for Use of the Petroleum Measurement TablesD1298 Test Method for Density, Relative Density (Sp
11、ecificGravity), or API Gravity of Crude Petroleum and LiquidPetroleum Products by Hydrometer Method (API MPMSChapter 9.1)D6300 Practice for Determination of Precision and BiasData for Use in Test Methods for Petroleum Products andLubricantsE100 Specification for ASTM Hydrometers2.2 API Standards:3MP
12、MS Chapter 9.1 Hydrometer Test Method for Density,Relative Density (Specific Gravity) or API Gravity ofCrude Petroleum and Liquid Petroleum Products (ASTMTest Method D1298)MPMS Chapter 11.12004, including Addendum12007 Temperature and Pressure Volume Correction1This test method is under the jurisdic
13、tion of ASTM Committee D02 onPetroleum Products and Lubricants and the API Committee on Petroleum Measure-ment, and is the direct responsibility of Subcommittee D02.02.09 on DensityDetermination (API MPMS Chapter 9.0).Current edition approved April 1, 2012. Published August 2012. Originallyapproved
14、in 2002. Last previous edition approved in 2008 as D6822-02(2008). DOI:10.1520/D6822-12.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards volume information, refer to the standards Document Summa
15、ry page onthe ASTM website.3Available from American Petroleum Institute (API), 1220 L. St., NW, Wash-ington, DC 20005-4070, www.api.org.1*A Summary of Changes section appears at the end of this standard.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-295
16、9, United States.Factors for Generalized Crude Oils, Refined Products, andLubricating Oils2.3 ASTM Adjuncts:Adjunct to D1250, Guide for Use of the Petroleum Measure-ment Tables (API MPMS Chapter 11.1)43. Terminology3.1 Definitions of Terms Specific to This Standard:3.1.1 API gravity (API), na specia
17、l function of relativedensity 60/60F, represented by:API 5 141.5 / relative density 60/60F!# 2 131.5 (1)3.1.1.1 DiscussionNo statement of reference temperatureis required, as 60F is included in the definition.3.1.2 density, nthe mass of liquid per unit volume at 15Cand 101.325 kPa with the standard
18、unit of measurement beingkilograms per cubic metre (kg/m3).3.1.2.1 DiscussionOther reference temperatures, such as20C, may be used for some products or in some locations.Less preferred units of measurement, for example, kg/L org/mL, are still in use.3.1.3 observed values, nhydrometer readings observ
19、ed ata temperature other than the defined reference temperature.3.1.3.1 DiscussionThese values are only hydrometerreadings and not density, relative density, or API gravity at thetemperature.3.1.4 relative density, nthe ratio of the mass of a givenvolume of liquid at a specific temperature to the ma
20、ss of anequal volume of pure water at the same or different tempera-ture. Both reference temperatures shall be explicitly stated.3.1.4.1 DiscussionCommon reference temperatures in-clude 15/15C, 60/60F, 20/20C, and 20/4C. The historicterm specific gravity may still be found.3.1.5 thermohydrometer, na
21、 glass hydrometer with aself-contained thermometer.4. Summary of Test Method4.1 The density or API gravity, after temperature equilib-rium has been reached, is read by observing the freely floatingthermohydrometer and noting the graduation nearest to theapparent intersection of the horizontal plane
22、surface of theliquid with the vertical scale of the hydrometer after tempera-ture equilibrium has been reached. The observed thermohy-drometer reading is reduced to the reference temperature valueby means of the Petroleum Measurement Tables (the appropri-ate adjunct to Guide D1250/API MPMS Chapter 1
23、1.1) andobserved temperature from the enclosed thermometer.5. Significance and Use5.1 Density and API gravity are used in custody transferquantity calculations and to satisfy transportation, storage, andregulatory requirements. Accurate determination of density orAPI gravity of crude petroleum and l
24、iquid petroleum productsis necessary for the conversion of measured volumes tovolumes at the standard temperatures of 15C or 60F.5.2 Density andAPI gravity are also factors that indicate thequality of crude petroleum. Crude petroleum prices are fre-quently posted against values in kg/m3or in degrees
25、 API.However, this property of petroleum is an uncertain indicationof its quality unless correlated with other properties.5.3 Field of ApplicationBecause the thermohydrometerincorporates both the hydrometer and thermometer in onedevice, it is more applicable in field operations for determiningdensit
26、y or API gravity of crude petroleum and other liquidpetroleum products. The procedure is convenient for gatheringmain trunk pipelines and other field applications where limitedlaboratory facilities are available. The thermohydrometermethod may have limitations in some petroleum densitydeterminations
27、. When this is the case, other methods such asTest Method D1298 (API MPMS Chapter 9.1) may be used.5.4 This procedure is suitable for determining the density,relative density, or API gravity of low viscosity, transparent oropaque liquids, or both. This procedure, when used for opaqueliquids, require
28、s the use of a meniscus correction (see 7.2).Additionally for both transparent and opaque fluids the read-ings shall be corrected for the thermal glass expansion effectand alternate calibration temperature effects before correctingto the reference temperature. This procedure can also be usedfor visc
29、ous liquids by allowing sufficient time for the thermo-hydrometer to reach temperature equilibrium.6. Apparatus6.1 Glass Thermohydrometers, as specified in SpecificationE100 (shown in Fig. 1), and graduated in:6.1.1 Kilograms/cubic metre (kg/m3) and degrees Celsiusfor density hydrometers, as shown i
30、n Table 1.6.1.2 Degrees API (API) and degrees Fahrenheit for hy-drometers measuring in API Gravity, as shown in Table 2.6.1.3 The user should ascertain that the instruments used forthis procedure conform to the requirements set out above withrespect to materials, dimensions, and scale errors. In cas
31、eswhere the instrument is provided with a calibration certificateissued by a recognized standardizing body, the instrument isclassed as certified and the appropriate corrections for themeniscus effect, the thermal glass expansion effect, and alter-native calibration temperature effects shall be appl
32、ied to theobserved readings prior to corrections. Instruments that satisfythe requirements of this test method, but are not provided witha recognized calibration certificate, are classed as uncertifiedand the appropriate corrections for the meniscus effect, thethermal glass expansion effect, and alt
33、ernative calibrationtemperature effects shall be applied to the observed readingsprior to corrections.6.2 Hydrometer Cylinders, clear glass, plastic, or metal. Forconvenience of pouring, the cylinder may have a pouring lip.The inside diameter shall be at least 25 mm (1 in.) greater thanthe outside d
34、iameter of the thermohydrometer used. The heightof the cylinder shall be such that the bottom of the thermohy-drometer clears the bottom of the cylinder by at least 25 mm (1in.) when suspended in the sample test portion.6.2.1 For field testing, a sample thief of suitable dimensionsmay be more conven
35、ient than a hydrometer cylinder. Theliquid level shall be level with the top of the thief.4Available from ASTM International Headquarters. Order Adjunct No.ADJD1250CD. Original adjunct produced in 2004.D6822 1226.3 Temperature Bath, to control temperature close to thebulk hydrocarbon temperature or
36、to control temperature closeto the reference temperature of 15C or 60F.7. Procedure7.1 Effect of Test Temperature:7.1.1 The density or API gravity determined by the thermo-hydrometer method is most accurate at or near the referencetemperature of 15C or 60F. Other temperatures within therange of the
37、enclosed thermometer may be used, if consistentwith the type of sample and the necessary limiting conditionsshown in Table 3.7.1.2 Bring the sample to the test temperature which shall besuch that the sample is sufficiently fluid but not as high as tocause the loss of light components, or so low as t
38、o result in theappearance of wax in the test portion.NOTE 1The volume and density, the relative density, and the APIcorrections in the volume correction procedures are based on the averageexpansions of a number of typical materials. Since the same coefficientswere used in compiling each set of table
39、s, corrections made over the sametemperature interval minimize errors arising from possible differencesbetween the coefficient of the material under test and the standardcoefficients. This effect becomes more important as temperatures divergefrom the reference temperature.FIG. 1 Typical Thermohydrom
40、eter DesignsD6822 123NOTE 2The hydrometer reading is obtained at a temperature appro-priate to the physic-chemical characteristics of the material under test.This temperature is preferably close to the reference temperature, or whenthe value is used in conjunction with bulk oil measurements, within
41、3Cof the bulk temperature (see 5.3).7.1.3 For crude petroleum, bring the sample close to thereference temperature or, if wax is present, to 9C above itspour point or 3C above its cloud point, whichever is higher.7.1.4 If the test temperature is significantly different fromthe reference temperature o
42、f 15C or 60F, the expansion orcontraction of the glass may affect the calibration of thethermohydrometer. A hydrometer correction factor (HYC) maybe applied to the measured density value to provide a correctedreading.7.1.5 Convert the thermohydrometer scale reading to basedensity, if necessary, as f
43、ollows:Step 1. Convert the thermohydrometer scale reading todensity in kg/m3if necessary, using either Eq 2 or Eq 3. ForAPI gravity:density 5 141.5 * 999.016! / 131.5 1 API! (2)For Relative Density:density 5 141.5 / R.D.! 131.5 (3)Leave the result left un-rounded.Step 2. Calculate the thermohydromet
44、er temperature expan-sion correction factor using the appropriate equation below (t isobserved temperature):For a Base Temperature (Tb) of 60F:HYC 5 1.0 0.00001278 t 60! 0.0000000062 t 60!2(4)For a Base Temperature (Tb) of 15C:HYC 5 1.0 0.000023 t 15! 0.00000002 t 15!2(5)For a Base Temperature (Tb)
45、of 20C:HYC 5 1.0 0.000023 t 20! 0.00000002 t 20!2(6)Leave the result left un-rounded.Step 3. Multiply the density in kg/m3by HYC and round theresult to 4 places past the decimal to obtain the glass expansioncorrected density.Step 4. Using the appropriate section of Adjunct to D1250,Guide for Use of
46、the Petroleum Measurement Tables (APIMPMS Chapter 11.1) (section 11.1.6.2 or 11.1.7.2), perform aType 2 (or 2M) calculation with the observed temperature tocorrect the glass expansion corrected density to base density.Round the output to 4 places past the decimal.Step 5. Convert the base density in
47、kg/m3to API gravity orRelative Density, if desired, using either Eq 7 or Eq 8. For APIgravity:API 5 141.5 / density / 999.016! 131.5 (7)For Relative Density:RD 5 density / 999.016 (8)Example 1:Sample: Crude OilObserved Temp: 77FObserved API gravity: 33.2Base Temp: 60FStep 1: 858.2924347298.Step 2: 0
48、.9997809482.Step 3: 858.1044Step 4: 864.8264Step 5: 32.0 API0.86567 R.D.Example 2:Sample: Crude OilObserved Temp: 25CObserved density: 858.29Base Temp: 15CStep 1: 858.29Step 2: 0.9997680.Step 3: 858.0909Step 4: 865.2075 kg/m3Step 5: 31.9 API0.86606 R.D.Example 3:Sample: Crude OilObserved Temp: 77COb
49、served R.D.: 0.85914Base Temp: 60FStep 1: 858.294606.Step 2: 0.9997809482.Step 3: 858.1066Step 4: 864.8286Step 5: 32.0 API0.86568 R.D.TABLE 1 Density ThermohydrometersASTM Hydrometer No. Density, Range, kg/m3300H 600 to 650301H 650 to 700302H 700 to 750303H 750 to 800304H 800 to 850305H 850 to 900306H 900 to 950307H 950 to 1000308H 1000 to 1050309H 1050 to 1100HydrometerTotal length, mm 374 to 387Body diameter, mm 18 to 25Stem diameter, mm, min 4.0Hydrometer ScaleStandard temperature, C 15Subdivis
