1、Designation: E1194 17Standard Test Method forVapor Pressure1This standard is issued under the fixed designation E1194; 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
2、 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 measuring thevapor pressure of pure liquid or solid compounds. No singletechnique is able to measure vapor pressures from 1 1011
3、to100 kPa (approximately 1010to 760 torr). The subject of thisstandard is gas saturation which is capable of measuring vaporpressures from 1 1011to 1 kPa (approximately 1010to 10torr). Other methods, such as isoteniscope and differentialscanning calorimetry (DSC) are suitable for measuring vaporpres
4、sures above 0.1 kPa An isoteniscope (standard) procedurefor measuring vapor pressures of liquids from 1 101to 100kPa (approximately 1 to 760 torr) is available in Test MethodD2879. A DSC (standard) procedure for measuring vaporpressures from 2 101to 100 kPa (approximately 1 to 760torr) is available
5、in Test Method E1782. A gas-saturationprocedure for measuring vapor pressures from 1 1011to 1kPa (approximately 1010to 10 torr) is presented in this testmethod. All procedures are subjects of U.S. EnvironmentalProtection Agency Test Guidelines.1.2 The gas saturation method is very useful for providi
6、ngvapor pressure data at normal environmental temperatures (40to +60C). At least three temperature values should be studiedto allow definition of a vapor pressure-temperature correlation.Values determined should be based on temperature selectionssuch that a measurement is made at 25C (as recommended
7、 byIUPAC) (1),2a value can be interpolated for 25C, or a valuecan be reliably extrapolated for 25C. Extrapolation to 25Cshould be avoided if the temperature range tested includes avalue at which a phase change occurs. Extrapolation to 25Cover a range larger than 10C should also be avoided. Ifpossibl
8、e, the temperatures investigated should be above andbelow 25C to avoid extrapolation altogether. The gas satura-tion method was selected because of its extended range,simplicity, and general applicability (2). Examples of resultsproduced by the gas-saturation procedure during an interlabo-ratory eva
9、luation are given in Table 1. These data have beentaken from Reference (3).1.3 The values stated in SI units are to be regarded asstandard. No other units of measurement are included in thisstandard.1.4 This standard does not purport to address all of thesafety problems, if any, associated with its
10、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.2. Referenced Documents2.1 ASTM Standards:3D2879 Test Method for Vapor Pressure-Temperature Rela-tionship and Initia
11、l Decomposition Temperature of Liq-uids by IsoteniscopeE691 Practice for Conducting an Interlaboratory Study toDetermine the Precision of a Test MethodE1782 Test Method for Determining Vapor Pressure byThermal Analysis2.2 U.S. Environmental Protection Agency Test Guidelines:Toxic Substances Control
12、Act Test Guidelines; Final Rules,Vapor Pressure43. Terminology Definition3.1 vapor pressurea measure of the volatility in units of orequivalent to kg/m2(pascal) of a substance in equilibrium withthe pure liquid or solid of that same substance at a giventemperature (4).4. Summary of Gas-Saturation Me
13、thod4.1 Pressures less than 1.33 kPa may be measured using thegas-saturation procedure (4).4.2 In this test method, an inert carrier gas (for example N2)is passed through a sufficient amount of compound to maintainsaturation for the duration of the test. The compound may becoated onto an inert suppo
14、rt (for example glass beads) or it may1This test method is under the jurisdiction of ASTM Committee E50 onEnvironmental Assessment, Risk Management and Corrective Actionand is thedirect responsibility of Subcommittee E50.47 on Biological Effects and Environ-mental Fate.Current edition approved March
15、 1, 2017. Published March 2017. Originallyapproved in 1987. Last previous edition approved in 2007 as E1194 which waswithdrawn March 2013 and reinstated in March 2017. DOI: 10.1520/E1194-17.2The boldface numbers in parentheses refer to the list of references at the end ofthis test method.3For refere
16、nced 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.4Federal Register, Vol 50, No. 188, 1985, pp. 3927039273.Copyright ASTM
17、International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United StatesThis international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for theDevelopment of International Standa
18、rds, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.1be in a liquid or solid granular form. The compound is removedfrom the gas stream using a suitable agent (sorbent or coldtrap). The amount of the test sample collected is then measured
19、using gas chromatography or any other sensitive and specifictechnique capable of suitable mass detection limit for theintended purpose.5. Significance and Use5.1 Vapor pressure values can be used to predict volatiliza-tion rates (5). Vapor pressures, along with vapor-liquid parti-tion coefficients (
20、Henrys Law constant) are used to predictvolatilization rates from liquids such as water. These values arethus particularly important for the prediction of the transport ofa chemical in the environment (6).6. Reagents and Materials6.1 The purity of the substance being tested shall bedetermined and do
21、cumented as part of the effort to define thevapor pressure. If available, all reagents shall conform to thespecifications of the Committee on Analytical Reagents of theAmerican Chemical Society.56.2 Every reasonable effort should be made to purify thechemical to be tested. High sample purity is requ
22、ired foraccurate evaluation of vapor pressure using direct mass lossmeasurement.6.3 For the gas-saturation method, the results can be re-ported in terms of the partial pressure for each component ofthe mixture that is identified and quantified through thetrapping procedure. However, unless the pure
23、componentvapor pressures and the vapor/liquid activity coefficients of thecontaminants are known, the results cannot be interpreted anymore clearly. If the activity coefficient of the major constituentis defined as one ( = 1), the indicated partial pressure andanalytical purity data can be converted
24、 to a pure componentvapor pressure.7. Gas-Saturation Procedure7.1 The test sample can be (1) coated onto clean silica sand,glass beads, or other suitable inert support from solution; priorto data measurement, the solvent must be completely removedby application of heat and flow (2) in solid state, p
25、ossibly usinga method similar to the previous one or by melting the solid tomaximize surface area prior to data measurement; or (3) a neatliquid. If using a coated-support procedure, the thickness of thecoating must be sufficient to ensure that surface energy effectswill not impact vapor pressure or
26、 vaporization rate. Followingvolatilization the surface must remain completely coated withthe test compound.7.2 Coat the support prior to column loading, to ensure thesupport is properly coated. Use sufficient quantity of materialon the support to maintain gas saturation for the duration of thetest.
27、7.3 Put the support into a suitable saturator container. Thedimensions of the column and gas velocity through the columnshould allow complete saturation of the carrier gas andnegligible back diffusion.7.4 Connect the principal and back-up traps to the columndischarge line downstream from the saturat
28、or column. Use theback-up trap to check for breakthrough of the compound fromthe principal trap. For an example of such a system, see Fig. 1.7.5 Surround the saturator column and traps by a thermo-stated chamber controlled at the test temperature within60.05C.7.6 If test material is detected in the
29、second trap, break-through has occurred and the measured vapor pressure will betoo low. To eliminate breakthrough, take one or both of thefollowing steps:7.6.1 Increase trapping efficiency by using more efficienttraps, such as a larger higher capacity or a different type of trap.7.6.2 Decrease the q
30、uantity of material trapped by decreas-ing the flow rate of carrier gas or reduce the sampling period.7.7 After temperature equilibration, the carrier gas contactsthe specimen and the sorbent (or cold) traps and exits from thethermostated chamber. The thermostatically-controlled cham-ber should util
31、ize liquid baths to facilitate heat transfer. Liquid(for example, ethylene-glycol-water or oil) baths are suggestedbecause of the difficulty in controlling temperatures in accor-dance with the tight specifications required (7) using air baths.Variations in the ambient temperature in facilities desig
32、ned forhazardous chemical work make this a critical requirement.5“Reagent Chemicals,American Chemical Society Specifications,”Am. Chemi-cal Soc., Washington, DC. For suggestions on the testing of reagents not listed bytheAmerican Chemical Society, see “Reagent Chemicals and Standards,” by JosephRosi
33、n, D. Van Nostrand Co., Inc., New York, NY, and the “United StatesPharmacopeia.”TABLE 1 Gas-Saturation Procedure Results Obtained During anInterlaboratory EvaluationTestCompoundTempera-ture, CMeanVaporPres-sures,kPaStandardDevia-tion Esti-mate, SrASquareRoot,SRBPrecisionEstimate,SRCNaphthalene 25 1.
34、3 1020.31 0.39 0.5035 3.5 1020.55 1.23 1.35Benzaldehyde 25 1.8 1010.31 1.24 1.2835 2.8 1010.33 1.12 1.17Aniline 25 7.9 1021.9 3.8 4.335 1.5 1010.25 0.28 0.382-Nitrophenol 25 1.2 1020.33 0.41 0.5335 3.2 1020.53 1.57 1.66Benzoic Acid 25 1.5 1040.32 1.69 1.7235 5.7 1042.3 5.2 5.7Phenanthrene 25 1.6 105
35、0.36 0.46 0.5835 4.7 1052.41 2.39 2.422,4-Dinitrotoluene 25 7.1 1051.9 6.3 6.635 2.3 1041.0 3.2 3.4Anthracene 25 6.0 1063.7 13.8 14.335 1.1 1050.23 2.29 2.30Dibutylphthalate 25 6.8 1064.4 8.8 9.835 2.0 1050.49 2.28 2.33p,p-DDT 25 1.7 1070.55 1.66 1.7535 5.7 10711.1 4.7 12.1ASris the estimated standa
36、rd deviation within laboratories, that is, an average ofthe repeatability found in the separate laboratories.BSRis the square root of the component of variance between laboratories.CSRis the between-laboratory estimate of precision.E1194 1727.8 Measure the flow rate of the effluent carrier gas at th
37、eadiabatic saturation temperature using a calibrated mass flowmeter bubble meter or other, nonhumidifying devices consid-ered suitable. Check the flow rate frequently during theprocedure to ensure that the total volume of carrier gas isaccurately measured. Use the flow rate to calculate the amountof
38、 gas that has passed through the specimen and sorbent ortrap. (volume/time) (time) = volume or (mass/time) (time) =mass).7.9 Measure the pressure at the outlet of the saturator.Determination of the saturator operating pressure is criticalbecause it will always be above ambient pressure due to apress
39、ure drop through the system. Measure either by includinga pressure gage between the saturator and traps or by deter-mining the pressure drop across the particular trapping systemused in a separate experiment for each flow rate.7.10 Calculate the test specimen vapor pressure (which is itspartial pres
40、sure in the gas stream) from the total gas volume(corrected to the volume at the temperature at the saturator) andthe mass of specimen vaporized.7.11 Record the ambient pressure frequently during the testto ensure an accurate saturator pressure value. Laboratories areseldom at normal atmospheric pre
41、ssure, and this fact is oftenoverlooked.7.12 Determine the time required for collecting the quantityof test specimen necessary for analysis in preliminary runs orby estimates based on experience. Before calculating the vaporpressure at a given temperature, carry out preliminary runs todetermine the
42、flow rate that will completely saturate the carriergas with sample vapor. To check, determine whether anotherflow rate at the same system temperature gives a differentcalculated vapor pressure.7.13 Measure the desorption efficiency for every combina-tion of sample, sorbent, and solvent used. To dete
43、rmine thedesorption efficiency, inject a known mass of sample onto asorbent. Then desorb and analyze it for the recovered mass.7.14 For each combination of sample, sorbent and solventused, make triplicate determinations at each of three concen-trations. Desorption efficiency may vary with the concen
44、trationof the actual sample and it is important to measure theefficiency at or near the concentration of the sample under gassaturation test procedure conditions. It is usually necessary tointerpolate between two measured efficiencies.7.15 If the test specimen vapor pressure is very low, checkand ma
45、ke sure significant amounts of the test specimen are notlost on the surface of the apparatus. This is checked by amaterial compatibility test prior to loading the sorbent into thetraps or saturation column. If the tested chemical has asignificant affinity for the traps or saturation column material
46、ofconstruction, select and test an alternative material of construc-tion.7.16 When testing elevated temperature conditions, it isnecessary that the system is operating at a uniform tempera-ture. Contaminant condensation on cold spots will give lowvapor pressure values.7.17 The choice of the analytic
47、al method, trap, and desorp-tion solvent depends upon the nature of the test specimen andthe temperature conditions of interest.FIG. 1 Configuration of Analytical ApparatusE1194 1737.18 Advantages of this test method when used with ananalysis specific for the compound of interest are:7.18.1 Minor im
48、purities are not likely to interfere witheither the test protocol or the accuracy of the vapor pressureresults, and the effects of impurities on the indicated vaporpressure can be corrected for in the final calculation.7.18.2 Pressures of two or more compounds may be ob-tained simultaneously, provid
49、ing the compounds do not havesignificant vapor/liquid activity interaction.7.18.3 If the analytical method chosen is preceded by aseparation step such as GC, the sample purity correction maybe possible.8. Alternative Procedures8.1 Although the procedures stated in Section 7 are pre-ferred for vapor pressure measurement at ambienttemperatures, many laboratories have employed other success-ful methods. If an alternative is chosen, determine the vaporpressure in triplicate at each of three te
