1、Designation: D7777 12D7777 13Designation 559/12Standard 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 oforigi
2、nal 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. Scope Scope*1.1 This test method covers the determination of the density,
3、 relative density, orAPI gravity of liquid petroleum products usingportable digital density meters at test temperatures between 0 and 40C (32 to 104F). Its application is restricted to samples witha dry vapor pressure equivalent up to 80 kPa (11.6 psi) and a viscosity below 100 mm2/s (cSt) at the te
4、st temperature.1.2 This test method is suitable for determining the density to the nearest 1 kg/m3. To determine the density to the nearest 0.1kg/m3, use Test Method D4052.1.3 This test method is easily calibrated and primarily suitable for field applications. It is important for the user to know an
5、dunderstand the electrical classification of the area in which the analyzer is to be used and to select an analyzer appropriate for thatclassification.1.4 Test Methods D287, D1298and, D1298and D6822 are used in field applications. This test method provides an alternativefield method that is easily c
6、alibrated and does not pose the hazard and breakage of of hydrometer glass breakage present in currentfield methods.1.5 Portable digital density meters measure the density and temperature of the filled-in sample at the sample temperature. Themeasured density and temperature are automatically convert
7、ed into:Density at 15C / density at 60FRelative density 15C/15C / relative density 60F/60FAPI gravity 15C / API gravity 60Fby the instrument using the calculation routines for Generalized Products as defined in Guide D1250.1.6 If the density meter does not have in-built software to calculate the den
8、sity at the reference temperature, this is calculatedfrom the observed density at test temperature using the Petroleum Measurement Tables.1.7 The accepted units of measure for density are kilograms per cubic metre (SI unit) or grams per cubic centimetre. Values inSI units are to be regarded as the s
9、tandard. Values in parentheses are for information only. Both SI and customary units have beenrounded; they may not be exactly equivalent.1.8 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
10、 establish appropriate safety and health practices and determine the applicability of regulatorylimitations prior to use.2. Referenced Documents2.1 ASTM Standards:2D287 Test Method for API Gravity of Crude Petroleum and Petroleum Products (Hydrometer Method)D1193 Specification for Reagent Water1 Thi
11、s test method is under the jurisdiction of ASTM Committee D02 on Petroleum Products and Lubricants and is the direct responsibility of Subcommittee D02.04.0Don Physical and Chemical Methods.Current edition approved Jan. 1, 2012May 1, 2013. Published April 2012May 2013. DOI:10.1520/D777712.Originally
12、 approved in 2012. Last previous edition approvedin 2012 as D7777 12. DOI:10.1520/D777713.This standard has been developed through the cooperative effort between ASTM International and the Energy Institute, London. The EI and ASTM International logosimply that the ASTM International and EI standards
13、 are technically equivalent, but does not imply that both standards are editorially identical.2 For referencedASTM standards, visit theASTM website, www.astm.org, or contactASTM Customer Service at serviceastm.org. For Annual Book of ASTM Standardsvolume information, refer to the standards Document
14、Summary page on the ASTM website.This document is not an ASTM standard 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 recomm
15、ends that users consult prior editions as appropriate. In all cases 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
16、, West Conshohocken, PA 19428-2959. United States1D1250 Guide for Use of the Petroleum Measurement TablesD1298 Test Method for Density, Relative Density, or API Gravity of Crude Petroleum and Liquid Petroleum Products byHydrometer MethodD4052 Test Method for Density, Relative Density, and API Gravit
17、y of Liquids by Digital Density MeterD4057 Practice for Manual Sampling of Petroleum and Petroleum ProductsD4177 Practice for Automatic Sampling of Petroleum and Petroleum ProductsD6822 Test Method for Density, Relative Density, and API Gravity of Crude Petroleum and Liquid Petroleum Products byTher
18、mohydrometer Method2.2 Energy Institute Standards:3IP 475 Petroleum Liquids Manual Sampling2.3 ASTM Adjuncts:Adjunct to D1250-04 Temperature and Pressure Volume Correction Factors for Generalized Crude Oils, Refined Products, andLubricating Oils43. Terminology3.1 Definitions:3.1.1 adjustment, nopera
19、tion of bringing the portable digital density meter to a state of performance suitable for its use, bysetting or adjusting the instrument constants.3.1.2 API gravity, nspecial function of relative density (specific gravity) SG60F/60F, represented by:API5141.5/SG60F/60F!2131.53.1.2.1 DiscussionRelati
20、ve density SG15C/15C is also applied.3.1.3 calibration, noperation that establishes the relationship between the reference density of standards and the correspond-ing reading of the instrument.3.1.3.1 validation, noperation of checking the calibration of the portable digital density meter at a singl
21、e point close to therequired operating point.3.1.4 density, nmass per unit volume at a given temperature.3.1.4.1 DiscussionStandard units of density are kg/m3 (SI unit) or mg/cm3. Less preferred units, for example, kg/L or g/mL, are still in use.3.1.5 relative density (specific gravity), nratio of t
22、he mass of a given volume of a liquid at a temperature t1 to the mass of anequal volume of pure water at a temperature t2. Both temperatures shall be explicitly stated.3.1.5.1 DiscussionThe unit SG has no dimension. Common reference temperatures include 15C/15C, 60F/60F, 20C/20C, and 20C/4C.4. Summa
23、ry of Test Method4.1 The test sample is brought to a temperature close to that of the density meter. If present, the density meters softwareprogram for calculating the density at the reference temperature is selected, and the oscillating U-tube of the density meter is filledwith the test portion in
24、accordance with the manufacturers instructions. After stabilizing, the density meters in-built softwarecalculates the density at the reference temperature. If the density meter does not have in-built software to calculate the density atthe reference temperature, this is calculated from the observed
25、density at test temperature using the Petroleum MeasurementTables.4 The apparatus system is regularly checked using reagent grade water.5. Significance and Use5.1 The density, relative density, or API gravity of petroleum products are important quality indicators and are used in quantitycalculations
26、 or to satisfy application, transportation, storage, and regulatory requirements.5.2 This test method should not be used to determine density for custody transfer quantity calculations, particularly where massor weight is the unit of quantity measurement. Test Method D4052 is appropriate for these a
27、pplications.3 Available from Energy Institute, 61 New Cavendish St., London, WIG 7AR, U.K., http:/www.energyinst.org.4 Available from ASTM International Headquarters. Order Adjunct No. ADJD1250CD or ADJD1250CS. Original adjunct produced in 2004.D7777 1326. Apparatus6.1 Portable Digital Density Meter
28、Capable, once calibrated, of determining density with an accuracy of 61 kg/m3, fitted witha temperature sensing device capable of measuring temperatures to 60.5C, a pump mechanism for filling and emptying theU-tube and a digital display of the results. Some density meters have in-built software for
29、calculating the density at 15C from theobserved density at test temperature. Some density meters have a mechanism for adjusting the meter during calibration; for others,this adjustment is carried out using the in-built software.NOTE 1The meter may also have a memory for storing results, or a facilit
30、y for connecting the meter to either a printer or a computer, or both.6.1.1 If the meter has in-built software it shall have been type tested to ensure that its firmware duplicates the PetroleumMeasurement Tables over the working temperatures and density ranges of the test method.6.1.2 If the meter
31、is to be used in an environment where a risk assessment has identified that a flammable atmosphere is likelyto be present, the use of a portable digital density meter with proper safety rating for the zone the instrument is being operatedin and the gas group that is being handled is mandatory.6.1.3
32、The instrument shall be capable of converting the measured density and temperature into:Density at 15C / density at 60FRelative density 15C/15C / relative density 60F/60FAPI gravity 15C / API gravity 60Faccording to Guide D1298. The instrument shall be capable of meeting the precision requirements d
33、escribed in this test method.6.2 Source of Low-Pressure AirFor drying the U-tube.NOTE 2An aquarium air pump fitted with a tube filled with a desiccant has been found to be suitable.6.3 Density Meter Stand(Optional).6.4 SyringeGlass or plastic (see Note 3), approximately 10 mL capacity with a Luer fi
34、tting (optional).NOTE 3Many plastic syringes designed for medical use are supplied with a coating of lubricant in the barrel. Some of these coatings can dissolvein the test portion samples altering the sample density. It is therefore recommended that only syringes specified as non-lubricated should
35、be used.7. Reagents and Materials7.1 WaterConforming to Specification D1193, Type III.7.2 Cleaning SolventGeneral purpose reagent grade, for cleaning the U-tube.NOTE 4Heptane or 40-60 Petroleum Spirit have been found to be suitable.7.3 Propan-2-olGeneral purpose reagent for cleaning the U-tube.7.4 C
36、ertified Reference Material (CRM)With a density approximating to the material under test, whose expansivity is inaccordance with the Petroleum Measurement Tables (see Note 5).NOTE 5While single compound hydrocarbons such as dodecane are suitable, it has been found that their expansivity is not descr
37、ibed well by eitherthe Petroleum MeasurementTable 54 orADJD1250CD4), and a correction has to be applied. See TableA1.2 on predicted densities at various temperaturesfor dodecane.8. Sampling8.1 Use only representative samples obtained as described in the Practices D4057, D4177, or IP 475 unless other
38、wise specifiedfor test specimens and test units. The sampling procedure for the calibration or adjustment of the apparatus, or both, and for testingis as follows:8.1.1 Make sure that the portable digital density meter is in thermal equilibrium with the ambient temperature. If the instrumenthas been
39、transferred from a much warmer or much colder place immediately before use, wait for several minutes before measuring.Do not transfer the instrument frequently between places with very different ambient temperatures, as humidity condensations maycause measuring errors.8.1.2 Make sure to have the sam
40、ples at or above ambient temperature. Do not fill samples which are much colder (5C/9F)than the ambient temperature. This may generate humidity condensation on the oscillating U-tube sensor, causing incorrectmeasurements and potentially harming the instrument.8.1.3 Follow the manufacturers instructi
41、ons for filling samples into the instrument. If the sampling system of the portabledensity meter is not completely free of liquid, drain it first as much as possible. Then fill a first portion of the sample and drainit immediately. Then fill the sample portion to be measured.8.1.4 Fill the samples g
42、ently. Ensure that gas bubbles are not present in the oscillating U-tube sensor once filling is completed.If gas bubbles are present in the oscillating U-tube sensor, drain this sample and gently refill with a new sample.8.2 After the measurement is finished, drain the sample as much as possible. If
43、 samples of similar composition are to bemeasured immediately after, rinse the U-tube by filling and emptying U-tube with the sample at least three times, see Note 7. Ifthe instrument is not being used for extended periods of time after a measurement or if strongly colored or viscous samples orD7777
44、 133samples which may cause deposits in the oscillating U-tube sensor have been measured, remove sample residues by rinsing withproper solvent. The rinsing solvent has to be selected according to its ability to dissolve residues of the measured sample. If thesolvent used to remove sample residues is
45、 not volatile by itself, the use of a volatile second solvent to remove residues of the firstsolvent is recommended. Follow the manufacturers instructions for further cleaning requirements.9. Calibration and Adjustment of the Instrument9.1 At least once every 12 months, verify the correct functionin
46、g of the meter using a Certified Reference Material (CRM) (see7.4 and Note 5).NOTE 6It is recommended that this apparatus verification is carried out either by the manufacturer or a qualified third party laboratory specializingin the measurement of density.9.2 Check that the U-tube is clean and dry
47、and if necessary clean and dry in accordance with the recommended cleaningprocedure given in Appendix X1.9.3 Clean the outside of the filling tube with cleaning solvent and wipe dry.9.4 Bring the CRM and the density meter to thermal equilibrium.9.5 Meters with In-Built Software:9.5.1 Select the dens
48、ity at reference temperature program in accordance with the manufacturers instructions.9.5.2 Fill the U-tube with the CRM and check that there are no air bubbles present. If there are bubbles, empty and refill.Allowthe meter to stabilize. Record the density of the CRM. If the CRM is a single compoun
49、d hydrocarbon, apply a correction to theresult, see Note 5 and Table A1.2. The result obtained shall be equal to or less than R/1.414 from the certified value of the CRM,where R is the reproducibility of this test method.9.5.3 If the value obtained does not meet these criteria, clean the U-tube and reverify using the CRM. If the value obtained stillfails to meet this criteria, either carry out a recalibration following the manufacturers instructions or return the meter to themanufacturer for servicing and a
