ASTM E1719-2012 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:E171905 Designation: E1719 12Standard 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

2、revision. 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 determination of the vapor pressure of liquids by ebulliometry (boiling pointmeas

3、urements). It is applicable to pure liquids and azeotropes that have an atmospheric boiling point between 285 and 575 K andthat can be condensed completely and returned to the ebulliometer boiler, that is, all materials must be condensable at total reflux.Liquid mixtures may be studied if they do no

4、t contain non-condensable components. Liquid mixtures that contain trace amountsof volatile but completely condensable components may also be studied, but they will produce vapor pressure data of greateruncertainty. Boiling point temperatures are measured at applied pressures of 1.0 to 100 kPa (7.5

5、to 760 torr).1.2 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.1.3 There is no ISO equivalent to this standard.1.4 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is

6、the responsibilityof the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatorylimitations prior to use. For specific hazard statements, see Section 8.2. Referenced Documents2.1 ASTM Standards:2D1193 Specification for Reagent WaterD28

7、79 Test Method for Vapor Pressure-Temperature Relationship and Initial Decomposition Temperature of Liquids byIsoteniscopeE1 Specification for ASTM Liquid-in-Glass ThermometersE177 Practice for Use of the Terms Precision and Bias in ASTM Test MethodsE1142 Terminology Relating to Thermophysical Prope

8、rtiesE1194 Test Method for Vapor PressureE1970 Practice for Statistical Treatment of Thermoanalytical Data3. Terminology3.1 Definitions:3.1.1 The following terms are applicable to this test method and can be found in Terminology E1142; boiling temperature andvapor pressure.3.1.2 For definitions of o

9、ther 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 designed to minimize superheating of the boiling liquid.3.2.2 manostata device for maintaining constant vacuum or pressure.3.2.3 superh

10、eatingthe act of heating a liquid above the equilibrium boiling temperature for a particular applied pressure.3.3 Symbols: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 = absolute temper

11、ature, K.1This test method is under the jurisdiction of ASTM Committee E37 on Thermal Measurements and is the direct responsibility of Subcommittee E37.01 on Calorimetryand Mass Loss.Current edition approved MarchApril 1, 2005.2012. Published April 2005.July 2012. Originally approved in 1995. Last p

12、revious edition approved in 19972005 asE171997.E1719 05. DOI: 10.1520/E1719-05.10.1520/E1719-12.2For 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

13、 Summary page on the ASTM website.1This 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 reco

14、mmends 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.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.4. Summary of

15、 Test Method4.1 A specimen is charged to the ebulliometer boiler. The ebulliometer is connected to a manostat, and coolant is circulatedthrough the ebulliometer condenser. The manostat is set at a low pressure, and the specimen is heated to the boiling temperature.The boiling temperature and manosta

16、t pressure are recorded upon reaching a steady-state, and the manostat pressure is raised toa higher value. A suitable number (usually five or more) of boiling temperature points are recorded at successively highercontrolled pressures. The pressure-temperature data are fitted to the Antoine vapor pr

17、essure equation. Vapor pressure valuesrequired for specific reports are then computed from the derived equation.4.2 The capability of the entire apparatus (ebulliometer, thermometer, manostat, etc.) is checked periodically by the proceduredescribed in Annex A1. This procedure consists of measuring t

18、he boiling temperature data for a pure reference substance such aswater and comparing the derived vapor pressure data to the known reference values.5. Significance and Use5.1 Vapor pressure is a fundamental thermodynamic property of a liquid. Vapor pressure and boiling temperature data arerequired f

19、or material safety data sheets (MSDS), the estimation of volatile organic compounds (VOC), and other needs related toproduct safety. Vapor pressures are important for prediction of the transport of a chemical in the environment; see Test MethodE1194.6. Interferences6.1 This test method is limited to

20、 materials that are thermally stable over the measurement temperature range. Boilingtemperatures that drift monotonically (not cyclically) up or down and specimen discoloration and smoking are indications ofthermal instability due to decomposition or polymerization. See Test Method D2879 (9.3 and No

21、te 168 therein). Vapor pressuredata may be measured at temperatures below the initial decomposition or polymerization temperature; see 9.7 and 10.2.6.2 The test method is limited to materials that boil smoothly under the operation conditions of the ebulliometer. Materials that“bump” continually, boi

22、l erratically, or eject material through the condenser are not suitable for study by this test method.7. Apparatus7.1 Ebulliometer3A vapor-lift-pump, stirred-flask, or equivalent type of ebulliometer.7.1.1 For Example, a Vapor-Lift-Pump Ebulliometer4Fig. 1 shows the dimensions for an example twin-ar

23、m ebulliometer,which is a one-stage, total-reflux boiler equipped with a vapor-lift pump to spray slugs of equilibrated liquid and vapor on athermometer well. The boiler (e), which is constructed from concentric pieces of 200-mm glass tubing (5 and 10-mm outsidediameter), has powdered glass fused to

24、 the heated surface to promote smooth boiling. The boiler is wrapped with an electricalheater. Twin vapor-lift pumps (d-constructed of 270-mm lengths of 5-mm outside diameter glass tubing) spray liquid and vaporslugs on a 100-mm thermometer well (c) that is wrapped with a glass spiral to promote the

25、rmal equilibration. The vapor-lift pumpsdissipate the effects of superheating. The ebulliometer is connected to the manostat through a 200-mm reflux condenser (b); see7.3. The side view in Fig. 1 shows a septum port and stopcock (f and i) where materials may be charged to the apparatus. Exceptfor th

26、e condenser, septum port, and stopcock, the entire ebulliometer is insulated with a suitable case or wrapping. A windowshould be left to observe the smoothness of boiling and the return rate (drop rate) of condensed vapor into the 125-mLboiler returnreservoir.7.1.1.1 For example, a Swietoslawski-typ

27、e ebulliometer5may be used instead.7.1.2 For example, a Stirred-Flask Ebulliometer, Fig. 2 shows an example of a stirred-flask ebulliometer, which is a one-stage,total-reflux boiler equipped with a magnetic stirrer to circulate the boiling liquid past a thermometer well which is immersed inthe liqui

28、d. The boiler is a 250-mL, round-bottomed, single-neck boiling flask modified with a 7-mm inside diameter thermometerwell positioned diagonally toward the bottom of the flask. The bottom half of the boiler has powdered glass fused to the innersurface to promote smooth boiling.6The thermometer well i

29、s positioned to have a length of at least 20 mm below the surface ofthe liquid when 125 mL of liquid is charged to the flask. The thermometer well must be positioned to allow a magnetic stirringbar to rotate freely in the bottom of the flask. The magnetic stirrer dissipates the effects of superheati

30、ng. The flask is connectedto the manostat though a reflux condenser; see 7.3. An electrical heating mantle covers the lower half of the flask; see 7.2. Theupper half of the flask is insulated with a suitable wrapping.3Further details can be found in Olson, J. D., Journal of Chemical Engineering Data

31、, Vol 26, 1981, pp. 5864. The ebulliometer shown in Fig. 1 is available from LabGlass, Inc., P.O. Box 5067, Fort Henry Drive, Kingsport, TN 37663.3An ebulliometer can be assembled from readily available lab glassware.4Further details can be found in Malanowski, S., Fluid Phase Equilibria, Vol 8, 198

32、2, pp. 197219. A Swietoslawski-type ebulliometer is available from Reliance GlassWorks, 17 Gateway Road, Bensenville, IL 60106.4Olson, J.D., Journal of Chemical Engineering Data, Vol 26, 1981, pp. 5864.5The stirred-flask ebulliometer shown in Fig. 2 (with the inner boiling surface coated with powder

33、ed glass) is available from Lab Glass, Inc., P.O. Box 5067, Fort HenryDrive, Kingsport, TN 37663.5Malanowski, S., Fluid Phase Equilibria, Vol 8, 1982, pp. 197219.6This procedure was described by Willingham, et al, Journal of Research NBS, Vol 35, 1945, pp. 219244.6The stirred-flask ebulliometer show

34、n in Fig. 2 (with the inner boiling surface coated with powdered glass) is available from Lab Glass, Inc., P.O. Box 5067, Fort HenryDrive, Kingsport, TN 37663.E1719 122NOTE 1Ebulliometers that use thermometer wells that are immersed directly in the boiling liquid are more susceptible to data errors

35、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, for example, those that require smaller specimen charges, may be used if theoperation and capability of the ebulliometer is demonstrat

36、ed by the procedure described in Annex A1.7.2 Heater or Heating MantleAn electrical heater or heating mantle equipped with a suitable controller of power input.Indirect heating by circulating a thermostatted hot fluid through a jacketed boiler may be used.7.3 Condenser, which shall be of the fluid-c

37、ooled, reflux, glass-tube type, having a condenser jacket of at least 200 mm inlength. A smaller condenser may be used, particularly for smaller volume systems, provided that no condensed specimen is foundin the cold trap.NOTE 2Suitable condenser designs include Allihn, Graham, Liebig, and equivalen

38、t condensers.7.4 Coolant Circulating SystemCooling water below 300 K, circulated through the condenser for tests on materials that freezebelow 273 K and boil above 325 K at the lowest applied pressure. For other test materials, a circulating thermostat shall be usedthat is capable of supplying coola

39、nt to the condenser at a temperature at least 2 K above the freezing point and at least 30 K belowthe boiling point at the lowest applied pressure.NOTE 3The suitability of the circulating coolant temperature shall be demonstrated by the absence of freezing of the specimen in the condenser andthe abs

40、ence of specimen in the cold traps at the conclusion of the test.7.5 Cold Trap, capable of freezing or condensing the test material, connected in series to the condenser. Ice plus water, dry iceplus solvent, or liquid nitrogen may be used as the cold trap coolant, depending on the characteristics of

41、 the test material.7.6 Temperature Measuring DeviceLiquid-in-glass thermometers accurate to 0.1 K (after calibration and immersioncorrections), or any other thermometric device of equal or better accuracy. See Specification E1.FIG. 1 Vapor-Lift-Pump EbulliometerE1719 1237.7 Thermometer Well FluidAlo

42、w-volatility, thermally inert fluid such as silicone oil or glycerin, charged to the thermometerwell of the ebulliometer. The amount of fluid added should be such that the fluid level in the thermometer well is not above theflask boundary when the ebulliometer is at the measurement temperature.7.8 P

43、ressure Regulating SystemA manostat, capable of maintaining the pressure of the system constant within 60.07 kPa(60.5 torr). Connect the pressure regulating system to the exit of the cold trap.AT-connection from the pressure regulating systemnear the exit of the cold trap should be used to connect t

44、he manometer. A ballast volume may be used to dampen pressurefluctuations.7.9 Pressure Measuring SystemA manometer, capable of measuring absolute pressure with an accuracy of 60.07 kPa (60.5torr).7.9.1 A comparative ebulliometer may be used to measure pressure. The comparative ebulliometer is connec

45、ted to the samepressure-controlled atmosphere as the test ebulliometer and contains a reference fluid (for example, distilled water). The observedboiling temperature in the comparative ebulliometer is used to compute the applied pressure from the known vaporpressure-temperature relationship of the r

46、eference fluid.7.10 Software, to perform multiple linear regression analysis on three variables.8. Safety Precautions8.1 There shall be adequate provisions for the retention and disposal of spilled mercury if mercury-containing thermometers,pressure measurement, or controlling devices are used.8.2 V

47、apor pressure reference materials (AnnexA1) and many test materials and cold trap fluids will burn.Adequate precautionsshall be taken to eliminate ignition sources and provide ventilation to remove flammable vapors that are generated during operationof the ebulliometer.8.3 Adequate precautions shall

48、 be taken to protect the operator in case debris is scattered by an implosion of glass apparatusunder vacuum.9. Procedure9.1 Start with clean, dry apparatus. Verify the operation and capability of the apparatus as described in Annex A1 for a newebulliometer setup or an ebulliometer setup that has no

49、t been used recently.9.2 Charge a specimen of appropriate volume to the ebulliometer boiler. Charge 75 6 1 mL for the vapor-lift ebulliometer (Fig.1). Close all stopcocks on the vapor-lift ebulliometer. Charge 125 6 1 mLfor the stirred-flask ebulliometer (Fig. 2).Add a magneticstirring bar to the stirred-flask ebulliometer. Connect the stirred-flask ebulliometer to the reflux condenser.9.3 Connect the ebulliometer reflux condenser to the cold trap. Connect the cold trap exit to a glassware T-connection. Connectone side of the T-connection to the manostat and