1、Designation: D1070 03 (Reapproved 2017)Standard Test Methods forRelative Density of Gaseous Fuels1This standard is issued under the fixed designation D1070; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of last revision.
2、 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 These test methods cover the determination of relativedensity of gaseous fuels, including liquefied petroleum gases,in the gaseous s
3、tate at normal temperatures and pressures. Thetest methods specified are sufficiently varied in nature so thatone or more may be used for laboratory, control, reference, gasmeasurement, or in fact, for any purpose in which it is desiredto know the relative density of gas or gases as compared to thed
4、ensity of dry air at the same temperature and pressure.1.2 The procedures appear in the following sections:SectionMethod A, Ac-Me Gravity Balance 79Method B, Ranarex Recording and Indicating Gravitometer 10-11Method C, UGC Gravitometer 1214NOTE 1The test methods and apparatus described herein are re
5、pre-sentative of methods and apparatus used broadly in industry. Manufactur-ers instructions for specific models should be consulted for further detailsand as supplements to the information presented here. In addition toinstrumentation described below additional equally accurate and satisfac-tory in
6、struments may be available.1.3 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.1.4 This standard does not purport to address all of thesa
7、fety 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.1.5 This international standard was developed in accor-dance with interna
8、tionally recognized principles on standard-ization established in the Decision on Principles for theDevelopment of International Standards, Guides and Recom-mendations issued by the World Trade Organization TechnicalBarriers to Trade (TBT) Committee.2. Referenced Documents2.1 ASTM Standards:2D5503 P
9、ractice for Natural Gas Sample-Handling and Con-ditioning Systems for Pipeline Instrumentation (With-drawn 2017)33. Terminology3.1 Definitions:3.1.1 densitymass per unit of volume of the fuel gas or airbeing considered.3.1.2 gaseous fuelmaterial to be tested, as sampled, with-out change of compositi
10、on by drying or otherwise.3.1.3 relative densityratio of the density of the gaseousfuel, under the observed conditions of temperature andpressure, to the density of dried air, of normal carbon dioxidecontent, at the same temperature and pressure.3.1.3.1 DiscussionIn these test methods the term “rela
11、tivedensity” has replaced the term “specific gravity.” The term,specific gravity, as used in a previous edition of these testmethods, was used incorrectly.3.1.4 relative humidityratio of actual pressure of existingwater vapor to maximum possible pressure of water vapor inthe atmosphere at the same t
12、emperature, expressed as apercentage.4. Summary of Test Methods4.1 Displacement BalancesThis test method is based onthe balancing of the weight of a fixed volume of gas atatmospheric pressure against the weight of dry air across thecenter of gravity of a balance beam. The amount of this“deflection,”
13、 subject to correction, for humidity, high CO2content or other factor measures the relative density. Instru-ments of this class may be either visual or chart recording.4.2 Kinetic EnergyThis test method measures the ratio ofthe change in kinetic energy between an impeller and animpulse wheel operati
14、ng in gas and a second impeller and1These test methods are under the jurisdiction of ASTM Committee D03 onGaseous Fuels and is the direct responsibility of Subcommittee D03.03 onDetermination of Heating Value and Relative Density of Gaseous Fuels.Current edition approved April 1, 2017. Published Apr
15、il 2017. Originallyapproved in 1952. Last previous edition approved in 2010 as D1070 03(2010) .DOI: 10.1520/D1070-03R17.2For 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
16、 to the standards Document Summary page onthe ASTM website.3The last approved version of this historical standard is referenced onwww.astm.org.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United StatesThis international standard was developed in
17、 accordance with internationally recognized principles on standardization established in the Decision on Principles for theDevelopment of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.1impulse wheel operating in
18、 a reference gas (generally air). Therelative torque of the impulse wheels is measured and providesa value for relative density since the relative torque is propor-tional to the gas and air densities.5. Significance and Use5.1 These test methods provide accurate and reliable meth-ods to measure the
19、relative density of gaseous fuels on anintermittent or continuous basis. These measurements arefrequently used for regulatory or contract compliance custodytransfer and process control.6. Sampling6.1 The sample shall be representative of the gas to bemeasured and shall be taken from its source witho
20、ut change inform or composition. Sampling of natural gases should be inaccordance with Practice D5503.METHOD AAcMe GRAVITY BALANCE(Four-Spring Type)7. Apparatus7.1 AcMe Gravity Balance (Four-Spring Type), pressure-tight cylindrical container mounted on a base board. Inside thecontainer is a balance
21、beam with a sealed float at the back andgraduated scale at the front. The beam is suspended at thecenter by thin flat springs. A window for viewing the scale isprovided at the front of the container. The balance beam maybe locked by a cam mechanism when the instrument is not inuse. Valves for introd
22、ucing gas and air samples are provided.7.2 Carrying Case, for transportation or storage.7.3 Air Dryer, to dehydrate air samples (silica gel).7.4 Tripod, to support the balance firmly.7.5 Pressure-Vacuum Pump, to transfer samples and adjustpressure in the balance.7.6 Mercury Manometer, 760 mm, to mea
23、sure pressure inthe balance.7.7 Aneroid Barometer, temperature compensated to convertbalance pressure readings to absolute pressures. (Absolutepressure not corrected to sea level.)7.8 Rubber Hose, 6.35-mm (14-in.) inside diameter, fourlengths with brass swivel connections to join the balance to itso
24、perating accessories.7.9 Sampling Hose, 6.35 mm (14 in.) with swivel connec-tions and two male 6.35-mm (14-in.) pipe adapters.7.10 Additional ApparatusRefer to the manufacturersliterature for further information on sizes, assembly, and otherdetails applicable to specific models.8. Procedure8.1 Assem
25、ble and set up the balance in accordance with themanufacturers instructions, making certain that it is firmlysupported, level, and is not disturbed during the entire test.Take and record the following four readings:8.1.1 Average Barometric ReadingRead the aneroid ba-rometer at the beginning and end
26、of each test, and record theaverage of these two readings.8.1.2 Air Reading:8.1.2.1 Admit air through first valve and air dryer untilatmospheric pressure is reached. Record temperature in thebalance. Close first valve.8.1.2.2 Open second valve and pull a vacuum of about 650mm, then close second valv
27、e. Unlock the balance beam byturning locking level counterclockwise. The beam will then bein an unbalanced position with the zero above the hairlineindicator.8.1.2.3 Observe the scale from such a position that thereflection of your eye in the look glass is centered on thehairline. Admit air through
28、first valve and air dryer until thebeam begins to fall. Then pinch down the flow of air throughfirst valve so that the air can be cut off at exactly the rightinstant to keep the beam in the balanced position. Observe thescale noting how far the zero swings above and below thehairline. The beam is ba
29、lanced when the zero of the scale isswinging an equal amount above and below the hairline.8.1.2.4 When balance is obtained, lock instrument and readand record the air vacuum shown on the manometer. Recordthe temperature within the balance.8.1.3 Gas Reading:8.1.3.1 Close the valve on the air dryer an
30、d close Valve 1.Then open Valve 2 and pull a vacuum of about 650 mm on thebalance.8.1.3.2 Open gas supply valve and admit gas to the balanceuntil the pressure reads about 650 mm. (Do not exceedmanometer maximum reading or the balance may be dam-aged.)8.1.3.3 Repeat 8.1.3.1 and 8.1.3.2 three times. T
31、he thirdtime will leave only about 0.05 % air in the balance. If thebalance is purged by flowing gas through it, the purging shouldbe continued until two successive readings (8.1.3.4) check.8.1.3.4 Unlock the instrument and release gas pressurethrough Valve 2 until balanced position of beam is reach
32、ed.Follow the same method as described for the air reading in8.1.2.4. When balance is obtained, lock the instrument andrecord the gas pressure shown on the manometer. Record thetemperature in the balance.NOTE 2When the gas supply is under a vacuum or has a high contentof hydrocarbons heavier than et
33、hane, keep the gas pressure within thebalance below that in the source line or container to avoid condensation inthe balance. If necessary, readjust instrument to balance on gas at avacuum about 20 mm higher than that in the sampling source.8.1.4 Air Check Reading:8.1.4.1 Close gas supply valves. Op
34、en second valve and pulla vacuum of about 650 mm.8.1.4.2 Admit air through the air dryer to the balance untilatmospheric pressure is reached. Close first valve.8.1.4.3 Repeat 8.1.4.1 and 8.1.4.2 at least three times oruntil two successive readings (8.1.4.4) will check.8.1.4.4 Open second valve and p
35、ull a vacuum of about 650nm, then close second valve. Unlock instrument; admit airthrough first valve to bring the beam to the balanced positionas when taking the first air reading.D1070 03 (2017)28.1.4.5 When balance is obtained, lock instrument; read andrecord the air vacuum shown on the manometer
36、. Record thetemperature in the balance. This reading must check with thefirst air reading if the two temperatures in the balance are thesame. When test is complete close all valves on the balance.Close the cock on the air dryer to prevent moistening of silicagel.9. Calculation9.1 When an aneroid bar
37、ometer is used in the field, it shouldbe checked periodically with a mercury barometer. The barom-eter should be handled very carefully and be well packed fortransportation. If barometer reading is in inches and fractions,multiply reading by 25.4 to convert to millimetres. To convertto absolute pres
38、sure, add barometric pressure in millimetres toboth air and gas pressure readings. (If air or gas reading is onvacuum, subtract it from barometric pressure.) Divide theabsolute pressure for air by the absolute pressure for gas toobtain the relative density of the gases shown in the followingexample:
39、ManometerReadingBarometerReadingAbsolutePressureBarometer reading:753 mmAir readingGas readingAir check reading127204127+753753=626957Relative density 5absolute air pressureabsolute gas pressure 5 626/957 5 0.654(1)9.2 When there is a difference between the temperature forthe air reading and the tem
40、perature for the gas reading, thesetemperature readings should be converted to absolutetemperature, by adding 460, and used in calculations as shownby the following example:ManometerReadingAbsolutePressure,PTemperatureFAbsoluteTemperature,TBarometer reading:745 mmAir reading 95 650 66 526Gas reading
41、 197 942 68 528Air check reading 90 655 70 530Relative density 5 P air/P gas! 3 T gas/T air! (2)5650/942! 3 528/526! 5 0.693 first air reading!Relative density 5 655/942! 3 528/530! (3)50.693 air check reading!METHOD BRANAREX PORTABLE ANDSTATIONARY GRAVITOMETERS10. Apparatus10.1 Ranarex Gravitometer
42、s are typical of kinetic energyinstruments designed for use as either portable or stationaryinstruments to determine and continuously record relativedensity. Fig. 1 shows examples of portable and recordingRanarex gravitometers.10.1.1 Instrumentation based on the same operational prin-ciple contain c
43、ommon features to Ranarex models. The chassis,consisting of a main body and two chamber doors. Behindthese doors are two cylindrical gas tight each having inlet andoutlet connections. Each chamber contains an impeller and animpulse wheel, facing each other, in a manner similar to atorque converter.
44、An electric motor and drive belt rotate theimpellers at the same speed in opposite directions. Heavyaluminum covers enclose and protect the entire mechanism.10.1.2 The impeller in the lower chamber draws in acontinuous flow of the test gas and rotates it at high speedagainst the vanes of the compani
45、on impulse wheel. As therotating gas impinges on the impulse wheel vanes, it undergoesa change in kinetic energy that creates on the lower impulsewheel a torque proportional to the density of the gas. Similarly,the impeller in the upper chamber draws in a continuous flowof outside air and rotates it
46、 at the same speed as the gas but inopposite direction. As the rotating air impinges on the impulsewheel vanes, it too undergoes a change in kinetic energy thatcreates on the upper impulse wheel, a torque proportional tothe density of the air.10.1.3 The impulse wheel torques are transmitted throughp
47、ivot shafts to the external lever arms, connecting link, andindicator, which move as a system to an angular position atwhich the torques balance each other. The linkage systemserves as a mechanical computer dividing one torque by theother. At each angular position of the linkage, there is acorrespon
48、ding value for the ratio. However, since the torquesare proportional to the density of the medium in each chamber,the ratio may be expressed as follows:density of lower chamber/density of upper chamber (4)10.1.4 When the unknown gas is admitted to the lowerchamber and air is admitted to the upper ch
49、amber, the ratiobecomes as follows:density of gas/density of air 5 relative density (5)10.1.5 The relation between the value of this fraction andangular position of the linkage and indicator is determined inthe design of the instrument. The indicating scale and record-ing chart are graduated to read directly in relative density.10.1.6 Refer to the manufacturers literature for furtherinformation on sizes, assembly, and other options applicable tospecific models.FIG. 1 Examples of Portable and Recording Ranarex Gravitom-etersD1070 03 (2017)311.
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