1、Designation: D7777 12559/12Standard Test Method forDensity, Relative Density, or API Gravity of Liquid Petroleumby Portable Digital Density Meter1This standard is issued under the fixed designation D7777; the number immediately following the designation indicates the year oforiginal adoption or, in
2、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. Scope1.1 This test method covers the determination of the density,relative density, or API gr
3、avity of liquid petroleum productsusing portable digital density meters at test temperaturesbetween 0 and 40C (32 to 104F). Its application is restrictedto samples with a dry vapor pressure equivalent up to 80 kPa(11.6 psi) and a viscosity below 100 mm2/s (cSt) at the testtemperature.1.2 This test m
4、ethod is suitable for determining the densityto the nearest 1 kg/m3. To determine the density to the nearest0.1 kg/m3, use Test Method D4052.1.3 This test method is easily calibrated and primarilysuitable for field applications. It is important for the user toknow and understand the electrical class
5、ification of the area inwhich the analyzer is to be used and to select an analyzerappropriate for that classification.1.4 Test Methods D287 and D1298 are used in field appli-cations. This test method provides an alternative field methodthat is easily calibrated and does not pose the hazard andbreaka
6、ge of current field methods.1.5 Portable digital density meters measure the density andtemperature of the filled-in sample at the sample temperature.The measured density and temperature are automatically con-verted into:Density at 15C / density at 60FRelative density 15C/15C / relative density 60F/6
7、0FAPI gravity 15C / API gravity 60Fby the instrument using the calculation routines for Gener-alized Products as defined in Guide D1250.1.6 If the density meter does not have in-built software tocalculate the density at the reference temperature, this iscalculated from the observed density at test t
8、emperature usingthe Petroleum Measurement Tables.1.7 The accepted units of measure for density are kilogramsper cubic metre (SI unit) or grams per cubic centimetre. Valuesin SI units are to be regarded as the standard. Values inparentheses are for information only. Both SI and customaryunits have be
9、en rounded; they may not be exactly equivalent.1.8 This 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 regu
10、latory limitations prior to use.2. Referenced Documents2.1 ASTM Standards:2D287 Test Method for API Gravity of Crude Petroleum andPetroleum Products (Hydrometer Method)D1193 Specification for Reagent WaterD1250 Guide for Use of the Petroleum Measurement TablesD1298 Test Method for Density, Relative
11、Density (SpecificGravity), or API Gravity of Crude Petroleum and LiquidPetroleum Products by Hydrometer MethodD4052 Test Method for Density, Relative Density, and APIGravity of Liquids by Digital Density MeterD4057 Practice for Manual Sampling of Petroleum andPetroleum ProductsD4177 Practice for Aut
12、omatic Sampling of Petroleum andPetroleum Products2.2 Energy Institute Standards:3IP 475 Petroleum Liquids Manual Sampling1This test method is under the jurisdiction of ASTM Committee D02 onPetroleum Products and Lubricants and is the direct responsibility of SubcommitteeD02.04.0D on Physical and Ch
13、emical Methods.Current edition approved Jan. 1, 2012. Published April 2012. DOI:10.1520/D777712.This standard has been developed through the cooperative effort between ASTMInternational and the Energy Institute, London. The EI and ASTM Internationallogos imply that the ASTM International and EI stan
14、dards are technically equiva-lent, but does not imply that both standards are editorially identical.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 Do
15、cument Summary page onthe ASTM website.3Available from Energy Institute, 61 New Cavendish St., London, WIG 7AR,U.K., http:/www.energyinst.org.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.2.3 ASTM Adjuncts:Adjunct to D1250-04 Tempe
16、rature and Pressure VolumeCorrection Factors for Generalized Crude Oils, RefinedProducts, and Lubricating Oils43. Terminology3.1 Definitions:3.1.1 adjustment, noperation of bringing the portabledigital density meter to a state of performance suitable for itsuse, by setting or adjusting the instrumen
17、t constants.3.1.2 API gravity, nspecial function of relative density(specific gravity) SG60F/60F, represented by:API 5 141.5 / SG60F/60F! 131.53.1.2.1 DiscussionRelative density SG15C/15C is alsoapplied.3.1.3 calibration, noperation that establishes the relation-ship between the reference density of
18、 standards and thecorresponding reading of the instrument.3.1.3.1 validation, noperation of checking the calibrationof the portable digital density meter at a single point close tothe required operating point.3.1.4 density, nmass per unit volume at a given tempera-ture.3.1.4.1 DiscussionStandard uni
19、ts of density are kg/m3(SIunit) or mg/cm3. Less preferred units, for example, kg/L org/mL, are still in use.3.1.5 relative density (specific gravity), nratio of the massof a given volume of a liquid at a temperature t1to the mass ofan equal volume of pure water at a temperature t2. Bothtemperatures
20、shall be explicitly stated.3.1.5.1 DiscussionThe unit SG has no dimension. Com-mon reference temperatures include 15C/15C, 60F/60F,20C/20C, and 20C/4C.4. Summary of Test Method4.1 The test sample is brought to a temperature close to thatof the density meter. If present, the density meters softwarepr
21、ogram for calculating the density at the reference tempera-ture is selected, and the oscillating U-tube of the density meteris filled with the test portion in accordance with the manufac-turers instructions. After stabilizing, the density meters in-built software calculates the density at the refere
22、nce tempera-ture. If the density meter does not have in-built software tocalculate the density at the reference temperature, this iscalculated from the observed density at test temperature usingthe Petroleum Measurement Tables.4The apparatus system isregularly checked using reagent grade water.5. Si
23、gnificance and Use5.1 The density, relative density, or API gravity of petro-leum products are important quality indicators and are used inquantity calculations or to satisfy application, transportation,storage, and regulatory requirements.5.2 This test method should not be used to determinedensity
24、for custody transfer quantity calculations, particularlywhere mass or weight is the unit of quantity measurement. TestMethod D4052 is appropriate for these applications.6. Apparatus6.1 Portable Digital Density MeterCapable, once cali-brated, of determining density with an accuracy of 61 kg/m3,fitted
25、 with a temperature sensing device capable of measuringtemperatures to 60.5C, a pump mechanism for filling andemptying the U-tube and a digital display of the results. Somedensity meters have in-built software for calculating thedensity at 15C from the observed density at test temperature.Some densi
26、ty meters have a mechanism for adjusting the meterduring calibration; for others, this adjustment is carried outusing the in-built software.NOTE 1The meter may also have a memory for storing results, or afacility for connecting the meter to either a printer or a computer, or both.6.1.1 If the meter
27、has in-built software it shall have beentype tested to ensure that its firmware duplicates the PetroleumMeasurement Tables over the working temperatures and den-sity ranges of the test method.6.1.2 If the meter is to be used in an environment where arisk assessment has identified that a flammable at
28、mosphere islikely to be present, the use of a portable digital density meterwith proper safety rating for the zone the instrument is beingoperated in and the gas group that is being handled ismandatory.6.1.3 The instrument shall be capable of converting themeasured density and temperature into:Densi
29、ty at 15C / density at 60FRelative density 15C/15C / relative density 60F/60FAPI gravity 15C / API gravity 60Faccording to Guide D1298. The instrument shall be capableof meeting the precision requirements described in this testmethod.6.2 Source of Low-Pressure AirFor drying the U-tube.NOTE 2An aquar
30、ium air pump fitted with a tube filled with adesiccant has been found to be suitable.6.3 Density Meter Stand(Optional).6.4 SyringeGlass or plastic (see Note 3), approximately10 mL capacity with a Luer fitting (optional).NOTE 3Many plastic syringes designed for medical use are suppliedwith a coating
31、of lubricant in the barrel. Some of these coatings candissolve in the test portion samples altering the sample density. It istherefore recommended that only syringes specified as non-lubricatedshould be used.7. Reagents and Materials7.1 WaterConforming to Specification D1193, Type III.7.2 Cleaning S
32、olventGeneral purpose reagent grade, forcleaning the U-tube.NOTE 4Heptane or 40-60 Petroleum Spirit have been found to besuitable.7.3 Propan-2-olGeneral purpose reagent for cleaning theU-tube.4Available from ASTM International Headquarters. Order Adjunct No.ADJD1250CD or ADJD1250CS. Original adjunct
33、 produced in 2004.D7777 1227.4 Certified Reference Material (CRM)With a densityapproximating to the material under test, whose expansivity isin accordance with the Petroleum Measurement Tables (seeNote 5).NOTE 5While single compound hydrocarbons such as dodecane aresuitable, it has been found that t
34、heir expansivity is not described well byeither the Petroleum Measurement Table 54 or ADJD1250CD4), and acorrection has to be applied. See Table A1.2 on predicted densities atvarious temperatures for dodecane.8. Sampling8.1 Use only representative samples obtained as describedin the Practices D4057,
35、 D4177,orIP 475 unless otherwisespecified for test specimens and test units. The samplingprocedure for the calibration or adjustment of the apparatus, orboth, and for testing is as follows:8.1.1 Make sure that the portable digital density meter is inthermal equilibrium with the ambient temperature.
36、If theinstrument has been transferred from a much warmer or muchcolder place immediately before use, wait for several minutesbefore measuring. Do not transfer the instrument frequentlybetween places with very different ambient temperatures, ashumidity condensations may cause measuring errors.8.1.2 M
37、ake sure to have the samples at or above ambienttemperature. Do not fill samples which are much colder(5C/9F) than the ambient temperature. This may generatehumidity condensation on the oscillating U-tube sensor, caus-ing incorrect measurements and potentially harming the instru-ment.8.1.3 Follow th
38、e manufacturers instructions for fillingsamples into the instrument. If the sampling system of theportable density meter is not completely free of liquid, drain itfirst as much as possible. Then fill a first portion of the sampleand drain it immediately. Then fill the sample portion to bemeasured.8.
39、1.4 Fill the samples gently. Ensure that gas bubbles are notpresent in the oscillating U-tube sensor once filling is com-pleted. If gas bubbles are present in the oscillating U-tubesensor, drain this sample and gently refill with a new sample.8.2 After the measurement is finished, drain the sample a
40、smuch as possible. If samples of similar composition are to bemeasured immediately after, rinse the U-tube by filling andemptying U-tube with the sample at least three times, see Note7. If the instrument is not being used for extended periods oftime after a measurement or if strongly colored or visc
41、oussamples or samples which may cause deposits in the oscillatingU-tube sensor have been measured, remove sample residues byrinsing with proper solvent. The rinsing solvent has to beselected according to its ability to dissolve residues of themeasured sample. If the solvent used to remove sampleresi
42、dues is not volatile by itself, the use of a volatile secondsolvent to remove residues of the first solvent is recommended.Follow the manufacturers instructions for further cleaningrequirements.9. Calibration and Adjustment of the Instrument9.1 At least once every 12 months, verify the correctfuncti
43、oning of the meter using a Certified Reference Material(CRM) (see 7.4 and Note 5).NOTE 6It is recommended that this apparatus verification is carriedout either by the manufacturer or a qualified third party laboratoryspecializing in the measurement of density.9.2 Check that the U-tube is clean and d
44、ry and if necessaryclean and dry in accordance with the recommended cleaningprocedure given in Appendix X1.9.3 Clean the outside of the filling tube with cleaningsolvent and wipe dry.9.4 Bring the CRM and the density meter to thermalequilibrium.9.5 Meters with In-Built Software:9.5.1 Select the dens
45、ity at reference temperature program inaccordance with the manufacturers instructions.9.5.2 Fill the U-tube with the CRM and check that there areno air bubbles present. If there are bubbles, empty and refill.Allow the meter to stabilize. Record the density of the CRM.If the CRM is a single compound
46、hydrocarbon, apply acorrection to the result, see Note 5 and Table A1.2. The resultobtained shall be equal to or less than R/1.414 from thecertified value of the CRM, where R is the reproducibility ofthis test method.9.5.3 If the value obtained does not meet these criteria,clean the U-tube and rever
47、ify using the CRM. If the valueobtained still fails to meet this criteria, either carry out arecalibration following the manufacturers instructions or re-turn the meter to the manufacturer for servicing and adjust-ment.9.6 Meters without In-Built Software:9.6.1 Fill the U-tube with the CRM and check
48、 that there areno air bubbles present. If there are bubbles, empty and refill.Allow the meter to stabilize. Record the density of the CRMand the test temperature. Using either the Petroleum Measure-ment Table 54 or ADJD1250CD,4calculate the density of theCRM at reference temperature. If the CRM is a
49、 singlecompound hydrocarbon apply corrections to the result. Fordodecane, see Table A1.2. The result obtained shall be equal toor less than R/1.414 from the certified value of the CRM,where R is the reproducibility of this test method.9.6.2 If the value obtained does not meet these criteria,clean the U-tube and reverify using the CRM. If the valueobtained still fails to meet this criteria return the meter to themanufacturer for servicing and adjustment.10. Procedure10.1 Meters with In-Built Software:10.1.1 Sele
