ASTM E1719-2005 Standard Test Method for Vapor Pressure of Liquids by Ebulliometry《用沸点测定法测定液体蒸气压力的标准试验方法》.pdf

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1、Designation: E 1719 05Standard Test Method forVapor Pressure of Liquids by Ebulliometry1This standard is issued under the fixed designation E 1719; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of last revision. A number

2、 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 describes procedures for determinationof the vapor pressure of liquids by ebulliometry (boiling pointmeasurements). It is a

3、pplicable 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 notcontain non-condens

4、able 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 760torr).1.2 SI unit

5、s are the standard.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 theresponsibility of the user of this standard to establish appro-priate safety and health practices and determine the ap

6、plica-bility of regulatory limitations prior to use. For specific hazardstatements, see Section 8.2. Referenced Documents2.1 ASTM Standards:2D 1193 Specification for Reagent WaterD 2879 Test Method for Vapor Pressure-Temperature Rela-tionship and Initial Decomposition Temperature of Liquidsby Isoten

7、iscopeE1 Specification for ASTM ThermometersE 1142 Terminology Relating to Thermophysical PropertiesE 1194 Test Method for Vapor PressureE 1970 Practice for Statistical Treatment of Thermoanalyti-cal Data3. Terminology3.1 Definitions:3.1.1 The following terms are applicable to this test methodand ca

8、n be found in Terminology E 1142; boiling temperatureand vapor pressure.3.1.2 For definitions of other terms used in this test methodrefer to Terminology E 1142.3.2 Definitions of Terms Specific to This Standard:3.2.1 ebulliometera one-stage, total-reflux boiler de-signed to minimize superheating of

9、 the boiling liquid.3.2.2 manostata device for maintaining constant vacuumor pressure.3.2.3 superheatingthe act of heating a liquid above theequilibrium boiling temperature for a particular applied pres-sure.3.3 Symbols:Symbols:A, B, C = Antoine vapor pressure equation constants (log10,kPa, K) for t

10、he Antoine vapor pressure equation: log10P= AB/(T+C).P = vapor pressure, kPa.T = 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 manosta

11、t isset at a low pressure, and the specimen is heated to the boilingtemperature. 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 recor

12、ded atsuccessively 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 (ebulliometer,thermometer, manosta

13、t, etc.) is checked periodically by theprocedure described in Annex A1. This procedure consists ofmeasuring the boiling temperature data for a pure reference1This test method is under the jurisdiction ofASTM Committee E37 on ThermalMeasurements and is the direct responsibility of Subcommittee E37.01

14、 on TestMethods and Recommended Practices.Current edition approved March 1, 2005. Published April 2005. Originallyapproved in 1995. Last previous edition approved in 1997 as E 1719 97.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm

15、.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.substance such as water and comparing the derived vaporpressur

16、e data to the known reference values.5. Significance and 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 relat

17、ed to product safety. Vapor pressures are importantfor prediction of the transport of a chemical in the environ-ment; see Test Method E 1194.6. Interferences6.1 This test method is limited to materials that are ther-mally stable over the measurement temperature range. Boilingtemperatures that drift

18、monotonically (not cyclically) up ordown and specimen discoloration and smoking are indicationsof thermal instability due to decomposition or polymerization.See Test Method D 2879 (9.3 and Note 16 therein). Vaporpressure data may be measured at temperatures below theinitial decomposition or polymeri

19、zation temperature; see 9.7and 10.2.6.2 The test method is 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

20、.1 EbulliometerA vapor-lift-pump, stirred-flask, orequivalent type of ebulliometer.7.1.1 For Example, a Vapor-Lift-Pump Ebulliometer3Fig.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

21、 liquid and vaporon a thermometer well. The boiler (e), 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-c

22、onstructed of270-mm lengths of 5-mm outside diameter glass 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

23、 through a 200-mmreflux condenser (b); see 7.3. The side 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

24、be left to observethe smoothness of boiling and the return rate (drop rate) ofcondensed vapor into the 125-mL boiler return reservoir.7.1.1.1 For example, a Swietoslawski-type ebulliometer4may be used instead.7.1.2 For example, a Stirred-Flask Ebulliometer, Fig. 2shows an example of a stirred-flask

25、ebulliometer, which is aone-stage, total-reflux boiler equipped 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 positi

26、oned diagonally towardthe bottom of the flask. The bottom half of the boiler haspowdered glass fused to the inner surface to promote smoothboiling.5The 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 t

27、hermometer well must bepositioned to allow a magnetic stirring bar to rotate freely in3Further details can be found in Olson, J. D., Journal of Chemical EngineeringData, Vol 26, 1981, pp. 5864. The ebulliometer shown in Fig. 1 is available fromLab Glass, Inc., P.O. Box 5067, Fort Henry Drive, Kingsp

28、ort, TN 37663.4Further details can be found in Malanowski, S., Fluid Phase Equilibria, Vol 8,1982, pp. 197219. A Swietoslawski-type ebulliometer is available from RelianceGlass Works, 17 Gateway Road, Bensenville, IL 60106.5The stirred-flask ebulliometer shown in Fig. 2 (with the inner boiling surfa

29、cecoated with powdered glass) is available from Lab Glass, Inc., P.O. Box 5067, FortHenry Drive, Kingsport, TN 37663.FIG. 1 Vapor-Lift-Pump EbulliometerE1719052the bottom of the flask. The magnetic stirrer dissipates theeffects of superheating. The flask is connected to the manostatthough a reflux c

30、ondenser; 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 1Ebulliometers that use thermometer wells that are immerseddirectly in the boiling liquid are more susceptible to data errors due tosuperhe

31、ating. Vapor-lift-pump ebulliometers are preferred except if“bumping” occurs, as discussed in 6.2 and 9.5.7.1.3 Other EbulliometersOther ebulliometers, for ex-ample, those that require smaller specimen charges, may beused if the operation and capability of the ebulliometer isdemonstrated by the proc

32、edure described in Annex A1.7.2 Heater or Heating MantleAn electrical heater orheating mantle equipped with a suitable controller of powerinput. Indirect heating by circulating a thermostatted hot fluidthrough a jacketed boiler may be used.7.3 Condenser, which shall be of the fluid-cooled, reflux,gl

33、ass-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 specimenis found in the cold trap.NOTE 2Suitable condenser designs include Allihn, Graham, Liebig,and equivalent condensers.7.4 Co

34、olant 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 appliedpressure. For other test materials, a circulating thermostat shallbe used that is capable of supplying coolant to the condenser a

35、ta 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 coolant temperature shall bedemonstrated by the absence of freezing of the specimen in the condenserand the absence of specimen in the

36、 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 plus solvent, or liquid nitrogen may be used as the coldtrap coolant, depending on the characteristics of the testmaterial.7.6 Tem

37、perature Measuring DeviceLiquid-in-glass ther-mometers accurate to 0.1 K (after calibration and immersioncorrections), or any other thermometric device of equal orbetter accuracy. See Specification E1.7.7 Thermometer Well FluidA low-volatility, thermallyinert fluid such as silicone oil or glycerin,

38、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 when the ebulliometer isat the measurement temperature.7.8 Pressure Regulating SystemA manostat, capable ofmaintaining the pressure

39、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 near the exit of the cold trap should be usedto connect the manometer. A ballast volume may be used todampen pressure fluctuations

40、.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 measurepressure. The comparative ebulliometer is connected to thesame pressure-controlled atmosphere as the test ebulliometerand c

41、ontains a reference fluid (for example, distilled water).The observed boiling temperature in the comparative ebulli-ometer is used to compute the applied pressure from the knownvapor pressure-temperature relationship of the reference fluid.7.10 Software, to perform multiple linear regression analy-s

42、is on three variables.8. Safety Precautions8.1 There shall be adequate provisions for the retention anddisposal of spilled mercury if mercury-containing thermom-eters, pressure measurement, or controlling devices are used.8.2 Vapor pressure reference materials (Annex A1) andmany test materials and c

43、old trap fluids will burn. Adequateprecautions shall be taken to eliminate ignition sources andprovide ventilation to remove flammable vapors that aregenerated during operation of the ebulliometer.8.3 Adequate precautions shall be taken to protect theoperator in case debris is scattered by an implos

44、ion of glassapparatus under vacuum.9. Procedure9.1 Start with clean, dry apparatus. Verify the operation andcapability of the apparatus as described inAnnexA1 for a newebulliometer setup or an ebulliometer setup that has not beenused recently.9.2 Charge a specimen of appropriate volume to the ebulli

45、-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).FIG. 2 Stirred-Flask EbulliometerE1719053Add a magnetic stirring bar to the stirred-flask ebulliometer.Connect

46、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 comparative ebulliometer isused a

47、s 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

48、-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-mm longreflux condenser at steady-state. Decrease the heatin

49、g power ifthe reflux zone extends above half the height of the condenser.The reflux return rate from the condenser at steady-state shouldbe at least two drops/s.9.5 See 6.2 if the specimen “bumps”. If “bumping” invali-dates the test, two remedies can be tried to see whether it iseliminated: the test can be repeated at a higher initial pressure,or a stirred-flask ebulliometer can be tried in place of thevapor-lift-pump ebulliometer.NOTE 4“Bumping” in the ebulliometer boiler is usually caused by theinability of the apparatus to dissipate the effects of superheating o