ASTM_D_2780_-_92_2007.pdf

Designation:D 2780 92(Reapproved 2007)An American National StandardStandard Test Method forSolubility of Fixed Gases in Liquids1This standard is issued under the fixed designation D 2780;the 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(e)indicates an editorial change since the last revision or reapproval.1.Scope1.1 This test method covers the determination of the solu-bility of fixed gases in liquids.It is suitable for gases andliquids that do not react with each other and are compatiblewith borosilicate glass,mercury,stainless steel,PTFE(poly-tetrafluoroethylene),and FPM(vinylidene fluoride-hexafluoropropylene copolymer)under the conditions of the test.This testmethod also covers the determination of the concentration offixed gases in solutions which are not saturated with the gas.1.2 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 regulatory limitations prior to use.For specific hazardstatements see 6.1,6.2,8.3,8.4.2,and 9.3.1.3 The values stated in SI units are to be regarded as thestandard.The values in parentheses are for information only.2.Referenced Documents2.1 ASTM Standards:2D 831 Test Method for Gas Content of Cable and CapacitorOilsD 2883 Test Method for Reaction Threshold Temperature ofLiquid and Solid MaterialsD 4057 Practice for Manual Sampling of Petroleum andPetroleum ProductsE 260 Practice for Packed Column Gas Chromatography3.Summary of Test Method3.1 Aspecimen of the test liquid is saturated with a fixed gasunder specified conditions of temperature and pressure.Thesaturation step may be eliminated if it is desired to determinethe concentration of fixed gas in a liquid sample suitablypresented for analysis.Aportion of the solution of gas in liquidis transferred to a gas extraction apparatus in which the fixedgas is quantitatively removed from the liquid.The separatedgas is transferred to a gas buret in which its volume isdetermined.4.Significance and Use4.1 The solubility of fixed gases in liquids is an importantengineering parameter in the design of hydraulic systems.It isa measure of the amount of gas which can be released fromsolution when a system undergoes changes in pressure andtemperature.Theoretical considerations permit approximatevalues of gas solubility to be computed with reasonableaccuracy.In this test method,dissolved gases are separatedphysically from a liquid and measured volumetrically.The testmethod permits subsequent analysis of separated gases by anyappropriate method.5.Apparatus5.1 Ambient Pressure Saturator,suitable for the saturationof liquids with fixed gases at various temperatures at ambientpressure is shown in Fig.1.The system comprises four parts:5.1.1 Gas Supply and Pressure Regulator,5.1.2 Gas Dispersion Element,5.1.3 Heating Mantle,to fit 1000-mL separatory funnel(Fig.1),and5.1.4 Temperature Measurement and Control Devices.NOTE1In the event that it is desired to saturate a liquid with a toxicor flammable gas,the use of this system is not recommended,unlesssuitable means are provided for the collection and disposal of the escapinggas.5.2 Elevated Pressure Saturator,used to saturate liquidswith gases at pressures other than ambient.A suitable vessel,usable at pressures up to 608 kPa(6 atm),is illustrated in Fig.2.The vessel consists of a 2.5 L stainless steel bomb with athermostatic control jacket.A valve at one end is connected toa pressure gage and gas supply.A valve at the other end isprovided with a fitting that connects directly to the gasextraction apparatus.5.2.1 Thermostatic Control,for jacket of saturator.5.2.2 Shaker,reciprocating,horizontal.5.2.3 Vacuum Pump,rotary.1This test method is under the jurisdiction of ASTM Committee D02 onPetroleum Products and Lubricants and is the direct responsibility of SubcommitteeD02.11 on Engineering Sciences of High Performance Fluids and Solids.Current edition approved May 1,2007.Published June 2007.Originallyapproved in 1969.Last previous edition approved in 2002 as D 2780 92(2002)e1.2For 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 Summary page onthe ASTM website.1Copyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959,United States.5.2.4 Transfer Line,with two male socket joint 12/2 fittings.5.3 Gas Extraction System,3as shown schematically in Fig.3.A detailed drawing of the extraction chamber is shown inFig.4.The apparatus provides for the separation of dissolvedgases from a liquid by repeatedly forcing the liquid containinggas to pass through a narrow annular