ASTM E1719-2012(2018) Standard Test Method for Vapor Pressure of Liquids by Ebulliometry.pdf

1、Designation: E1719 12 (Reapproved 2018)Standard Test Method forVapor Pressure of Liquids by Ebulliometry1This standard is issued under the fixed designation E1719; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of last re

2、vision. 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 describes procedures for determinationof the vapor pressure of liquids by ebulliometry (boiling pointmeasure

3、ments). It is applicable to pure liquids and azeotropesthat have an atmospheric boiling point between 285 and 575 Kand that can be condensed completely and returned to theebulliometer boiler, that is, all materials must be condensableat total reflux. Liquid mixtures may be studied if they do notcont

4、ain non-condensable components. Liquid mixtures thatcontain trace amounts of volatile but completely condensablecomponents may also be studied, but they will produce vaporpressure data of greater uncertainty. Boiling point temperaturesare measured at applied pressures of 1.0 to 100 kPa (7.5 to 760to

5、rr).1.2 The values stated in SI units are to be regarded asstandard. No other units of measurement are included in thisstandard.1.3 There is no ISO equivalent to this standard.1.4 This standard does not purport to address all of thesafety concerns, if any, associated with its use. It is theresponsib

6、ility of the user of this standard to establish appro-priate safety, health, and environmental practices and deter-mine the applicability of regulatory limitations prior to use.For specific hazard statements, see Section 8.1.5 This international standard was developed in accor-dance with internation

7、ally 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:2D1193 Speci

8、fication for Reagent WaterD2879 Test Method for Vapor Pressure-Temperature Rela-tionship and Initial Decomposition Temperature of Liq-uids by IsoteniscopeE1 Specification for ASTM Liquid-in-Glass ThermometersE177 Practice for Use of the Terms Precision and Bias inASTM Test MethodsE1142 Terminology R

9、elating to Thermophysical PropertiesE1194 Test Method for Vapor PressureE1970 Practice for StatisticalTreatment ofThermoanalyticalData3. Terminology3.1 Definitions:3.1.1 The following terms are applicable to this test methodand can be found in Terminology E1142; boiling temperatureand vapor pressure

10、.3.1.2 For definitions of other terms used in this test method,refer to Terminology E1142.3.2 Definitions of Terms Specific to This Standard:3.2.1 ebulliometera one-stage, total-reflux boiler designedto minimize superheating of the boiling liquid.3.2.2 manostata device for maintaining constant vacuu

11、mor pressure.3.2.3 superheatingthe act of heating a liquid above theequilibrium boiling temperature for a particular applied pres-sure.3.3 Symbols:A, B, C = Antoine vapor pressure equation constants (log10,kPa, K) for the Antoine vapor pressure equation:log10P = AB/(T+C).P = vapor pressure, kPa.T =

12、absolute temperature, K.4. Summary of Test Method4.1 A specimen is charged to the ebulliometer boiler. Theebulliometer is connected to a manostat, and coolant iscirculated through the ebulliometer condenser. The manostat isset at a low pressure, and the specimen is heated to the boilingtemperature.

13、The boiling temperature and manostat pressureare recorded upon reaching a steady-state, and the manostatpressure is raised to a higher value.Asuitable number (usuallyfive or more) of boiling temperature points are recorded at1This test method is under the jurisdiction ofASTM Committee E37 on Thermal

14、Measurements and is the direct responsibility of Subcommittee E37.01 on Calo-rimetry and Mass Loss.Current edition approved April 1, 2018. Published May 2018. Originallyapproved in 1995. Last previous edition approved in 2012 as E1719 12. DOI:10.1520/E1719-12R18.2For referenced ASTM standards, visit

15、 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.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959

16、. United StatesThis international standard was developed in 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 Ba

17、rriers to Trade (TBT) Committee.1successively higher controlled pressures. The pressure-temperature data are fitted to the Antoine vapor pressureequation. Vapor pressure values required for specific reportsare then computed from the derived equation.4.2 The capability of the entire apparatus (ebulli

18、ometer,thermometer, manostat, etc.) is checked periodically by theprocedure described in Annex A1. This procedure consists ofmeasuring the boiling temperature data for a pure referencesubstance such as water and comparing the derived vaporpressure data to the known reference values.5. Significance a

19、nd Use5.1 Vapor pressure is a fundamental thermodynamic prop-erty of a liquid. Vapor pressure and boiling temperature dataare required for material safety data sheets (MSDS), theestimation of volatile organic compounds (VOC), and otherneeds related to product safety. Vapor pressures are importantfor

20、 prediction of the transport of a chemical in the environ-ment; see Test Method E1194.6. Interferences6.1 This test method is limited to materials that are ther-mally stable over the measurement temperature range. Boilingtemperatures that drift monotonically (not cyclically) up ordown and specimen d

21、iscoloration and smoking are indicationsof thermal instability due to decomposition or polymerization.See Test Method D2879 (9.3 and Note 8 therein). Vaporpressure data may be measured at temperatures below theinitial decomposition or polymerization temperature; see 9.7and 10.2.6.2 The test method i

22、s limited to materials that boilsmoothly under the operation conditions of the ebulliometer.Materials that “bump” continually, boil erratically, or ejectmaterial through the condenser are not suitable for study bythis test method.7. Apparatus7.1 Ebulliometer3A vapor-lift-pump, stirred-flask, orequiv

23、alent type of ebulliometer.7.1.1 For Example, a Vapor-Lift-Pump Ebulliometer4Fig.1 shows the dimensions for an example twin-arm ebulliometer,which is a one-stage, total-reflux boiler equipped with avapor-lift pump to spray slugs of equilibrated liquid and vaporon a thermometer well. The boiler (e),

24、which is constructedfrom concentric pieces of 200-mm glass tubing (5 and 10-mmoutside diameter), has powdered glass fused to the heatedsurface to promote smooth boiling. The boiler is wrapped withan electrical heater. Twin vapor-lift pumps (d-constructed of270-mm lengths of 5-mm outside diameter gla

25、ss tubing) sprayliquid and vapor slugs on a 100-mm thermometer well (c) thatis wrapped with a glass spiral to promote thermal equilibration.The vapor-lift pumps dissipate the effects of superheating. Theebulliometer is connected to the manostat through a 200-mmreflux condenser (b); see 7.3. The side

26、 view in Fig. 1 shows aseptum port and stopcock (f and i) where materials may becharged to the apparatus. Except for the condenser, septumport, and stopcock, the entire ebulliometer is insulated with asuitable case or wrapping. A window should be left to observethe smoothness of boiling and the retu

27、rn rate (drop rate) ofcondensed vapor into the 125-mL boiler return reservoir.7.1.1.1 For example, a Swietoslawski-type ebulliometer5may be used instead.7.1.2 For example, a Stirred-Flask Ebulliometer, Fig. 2shows an example of a stirred-flask ebulliometer, which is aone-stage, total-reflux boiler e

28、quipped with a magnetic stirrerto circulate the boiling liquid past a thermometer well which isimmersed in the liquid. The boiler is a 250-mL, round-bottomed, single-neck boiling flask modified with a 7-mminside diameter thermometer well positioned diagonally towardthe bottom of the flask. The botto

29、m half of the boiler haspowdered glass fused to the inner surface to promote smooth3An ebulliometer can be assembled from readily available lab glassware.4Olson, J. D., Journal of Chemical Engineering Data, Vol 26, 1981, pp. 5864.5Malanowski, S., Fluid Phase Equilibria, Vol 8, 1982, pp. 197219.FIG.

30、1 Vapor-Lift-Pump EbulliometerE1719 12 (2018)2boiling.6The thermometer well is positioned to have a lengthof at least 20 mm below the surface of the liquid when 125 mLof liquid is charged to the flask. The thermometer well must bepositioned to allow a magnetic stirring bar to rotate freely inthe bot

31、tom of the flask. The magnetic stirrer dissipates theeffects of superheating. The flask is connected to the manostatthough a reflux condenser; see 7.3.An electrical heating mantlecovers the lower half of the flask; see 7.2. The upper half of theflask is insulated with a suitable wrapping.NOTE 1Ebull

32、iometers that use thermometer wells that are immerseddirectly in the boiling liquid are more susceptible to data errors due tosuperheating. Vapor-lift-pump ebulliometers are preferred except if“bumping” occurs, as discussed in 6.2 and 9.5.7.1.3 Other EbulliometersOther ebulliometers, forexample, tho

33、se that require smaller specimen charges, may beused if the operation and capability of the ebulliometer isdemonstrated by the procedure described in Annex A1.7.2 Heater or Heating MantleAn electrical heater orheating mantle equipped with a suitable controller of powerinput. Indirect heating by circ

34、ulating a thermostatted hot fluidthrough a jacketed boiler may be used.7.3 Condenser, which shall be of the fluid-cooled, reflux,glass-tube type, having a condenser jacket of at least 200 mmin length. A smaller condenser may be used, particularly forsmaller volume systems, provided that no condensed

35、 specimenis found in the cold trap.NOTE 2Suitable condenser designs include Allihn, Graham, Liebig,and equivalent condensers.7.4 Coolant Circulating SystemCooling water below 300K, circulated through the condenser for tests on materials thatfreeze below 273 K and boil above 325 K at the lowest appli

36、edpressure. For other test materials, a circulating thermostat shallbe used that is capable of supplying coolant to the condenser ata temperature at least 2 K above the freezing point and at least30 K below the boiling point at the lowest applied pressure.NOTE 3The suitability of the circulating coo

37、lant temperature shall bedemonstrated by the absence of freezing of the specimen in the condenserand the absence of specimen in the cold traps at the conclusion of the test.7.5 Cold Trap, capable of freezing or condensing the testmaterial, connected in series to the condenser. Ice plus water,dry ice

38、 plus solvent, or liquid nitrogen may be used as the coldtrap coolant, depending on the characteristics of the testmaterial.7.6 Temperature Measuring DeviceLiquid-in-glass ther-mometers accurate to 0.1 K (after calibration and immersioncorrections), or any other thermometric device of equal orbetter

39、 accuracy. See Specification E1.7.7 Thermometer Well FluidA low-volatility, thermallyinert fluid such as silicone oil or glycerin, charged to thethermometer well of the ebulliometer. The amount of fluidadded should be such that the fluid level in the thermometerwell is not above the flask boundary w

40、hen the ebulliometer isat the measurement temperature.7.8 Pressure Regulating SystemA manostat, capable ofmaintaining the pressure of the system constant within 60.07kPa (60.5 torr). Connect the pressure regulating system to theexit of the cold trap. A T-connection from the pressureregulating system

41、 near the exit of the cold trap should be usedto connect the manometer. A ballast volume may be used todampen pressure fluctuations.7.9 Pressure Measuring SystemA manometer, capable ofmeasuring absolute pressure with an accuracy of 60.07 kPa(60.5 torr).7.9.1 A comparative ebulliometer may be used to

42、 measurepressure. The comparative ebulliometer is connected to thesame pressure-controlled atmosphere as the test ebulliometerand contains a reference fluid (for example, distilled water).The observed boiling temperature in the comparative ebulli-ometer is used to compute the applied pressure from t

43、he knownvapor pressure-temperature relationship of the reference fluid.7.10 Software, to perform multiple linear regression analy-sis on three variables.8. Safety Precautions8.1 There shall be adequate provisions for the retention anddisposal of spilled mercury if mercury-containingthermometers, pre

44、ssure measurement, or controlling devicesare used.8.2 Vapor pressure reference materials (Annex A1) andmany test materials and cold trap fluids will burn. Adequateprecautions shall be taken to eliminate ignition sources andprovide ventilation to remove flammable vapors that aregenerated during opera

45、tion of the ebulliometer.6The stirred-flask ebulliometer shown in Fig. 2 (with the inner boiling surfacecoated with powdered glass) is available from Lab Glass, Inc., P.O. Box 5067, FortHenry Drive, Kingsport, TN 37663.FIG. 2 Stirred-Flask EbulliometerE1719 12 (2018)38.3 Adequate precautions shall b

46、e taken to protect theoperator in case debris is scattered by an implosion of glassapparatus under vacuum.9. Procedure9.1 Start with clean, dry apparatus. Verify the operation andcapability of the apparatus as described in AnnexA1 for a newebulliometer setup or an ebulliometer setup that has not bee

47、nused recently.9.2 Charge a specimen of appropriate volume to the ebulli-ometer boiler. Charge 75 6 1 mL for the vapor-lift ebulliom-eter (Fig. 1). Close all stopcocks on the vapor-lift ebulliometer.Charge 125 6 1 mL for the stirred-flask ebulliometer (Fig. 2).Add a magnetic stirring bar to the stir

48、red-flask ebulliometer.Connect the stirred-flask ebulliometer to the reflux condenser.9.3 Connect the ebulliometer reflux condenser to the coldtrap. Connect the cold trap exit to a glassware T-connection.Connect one side of the T-connection to the manostat and theother side to the manometer. If a co

49、mparative ebulliometer isused as the manometer, charge the reference fluid to thecomparative ebulliometer and connect it through a cold trap tothe T-connection.9.4 Start the condenser coolant flow. Set the manostat forthe lowest pressure to be studied. (This pressure shouldproduce a boiling temperature at least 30 K above the con-denser coolant temperature.) Turn on the magnetic stirrer ifusing a stirred-flask ebulliometer. Turn on the electrical heater,and heat the specimen to produce steady-state reflux.A30-mmreflux zone should be visible in the bottom of a 200