1、Designation: D5188 14Standard Test Method forVapor-Liquid Ratio Temperature Determination of Fuels(Evacuated Chamber and Piston Based Method)1This standard is issued under the fixed designation D5188; the number immediately following the designation indicates the year oforiginal adoption or, in the
2、case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon () indicates an editorial change since the last revision or reapproval.1. Scope*1.1 This test method covers the determination of the tem-perature at which the vapor formed
3、 from a selected volume ofvolatile petroleum product saturated with air at 0 C to 1 C(32 F to 34 F) produces a pressure of 101.3 kPa (oneatmosphere) against vacuum. This test method is applicable tosamples for which the determined temperature is between36 C and 80 C (97 F and 176 F) and the vapor-li
4、quid ratiois between 8 to 1 and 75 to 1.NOTE 1When the vapor-liquid ratio is 20:1, the result is intended tobe comparable to the results determined by Test Method D2533.NOTE 2This test method may also be applicable at pressures otherthan one atmosphere, but the stated precision may not apply.1.2 Thi
5、s test method is applicable to both gasoline andgasoline-oxygenate blends.1.2.1 Some gasoline-oxygenate blends may show a hazewhen cooled to 0 C to 1 C. If a haze is observed in 12.5,itshall be indicated in the reporting of results. The precision andbias statements for hazy samples have not been det
6、ermined(see Note 10).1.3 The values stated in SI units are to be regarded asstandard. The values given in parentheses are provided forinformation only.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
7、 standard to establish appro-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use. For specificwarnings, see 7.2 and 8.1.1.2. Referenced Documents2.1 ASTM Standards:2D2533 Test Method for Vapor-Liquid Ratio of Spark-Ignition Engine Fuels (Withdra
8、wn 2008)3D2892 Test Method for Distillation of Crude Petroleum(15-Theoretical Plate Column)D4057 Practice for Manual Sampling of Petroleum andPetroleum ProductsD6299 Practice for Applying Statistical Quality Assuranceand Control Charting Techniques to Evaluate AnalyticalMeasurement System Performanc
9、eD6708 Practice for Statistical Assessment and Improvementof Expected Agreement Between Two Test Methods thatPurport to Measure the Same Property of a Material3. Terminology3.1 Definitions of Terms Specific to This Standard:3.1.1 T(V/L = 20),nthe equilibrium temperature at whichthe partial pressure
10、of a sample under test conditions is equalto 101.3 kPa (14.69 psia) and the vapor-liquid ratio is 20.3.1.2 vapor-liquid ratio of a fuel, nthe ratio at a specifiedtemperature and pressure of the volume of vapor in equilibriumwith liquid to the volume of sample charged, as a liquid, at0 C (32 F).4. Su
11、mmary of Test Method4.1 A known volume of chilled, air-saturated sample isintroduced into an evacuated, thermostatically controlled testchamber of known volume or a test chamber with moveablepiston that expands the volume after sample introduction, theinternal volume of which is V/L+1 times of that
12、of the total testspecimen introduced into the chamber. The sample volume iscalculated to give the desired vapor-liquid ratio for the cham-ber volume in use. After injection, the chamber temperature isadjusted until a stable chamber pressure of 101.3 kPa (14.69psia) is achieved.5. Significance and Us
13、e5.1 The tendency of a fuel to vaporize in automotive enginefuel systems is indicated by the vapor-liquid ratio of the fuel.1This test method is under the jurisdiction of ASTM Committee D02 onPetroleum Products, Liquid Fuels, and Lubricants and is the direct responsibility ofSubcommittee D02.08 on V
14、olatility.Current edition approved Jan. 1, 2014. Published March 2014. Originallyapproved in 1991. Last previous edition approved in 2013 as D518813. DOI:10.1520/D5188-14.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Ann
15、ual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.3The last approved version of this historical standard is referenced onwww.astm.org.*A Summary of Changes section appears at the end of this standardCopyright ASTM International, 100 Barr Ha
16、rbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States15.2 Automotive fuel specifications generally include T(V/L = 20) limits to ensure products of suitable volatility perfor-mance. For high ambient temperatures, a fuel with a high valueof T(V/L = 20), indicating a fuel with a low
17、 tendency to vaporize,is generally specified; conversely for low ambienttemperatures, a fuel with a low value of T(V/L = 20)is specified.6. Apparatus6.1 Apparatus suitable for use shall employ a small volumetest chamber incorporating a transducer for pressure measure-ments and associated equipment f
18、or thermostatically control-ling the chamber temperature, evacuating the test chamberprior to sample introduction, or expanding the volume aftersample introduction by a moveable piston, and cleaning andpurging the chamber following the test. Critical elements of theapparatus shall meet the following
19、 specifications:6.1.1 Test Chamber, constructed of stainless steel oraluminum, designed to contain between 5 mL and 50 mL ofliquid plus vapor with a tolerance of 61 % of the nominalcapacity.NOTE 3The test chamber volumes of the instruments used for the1991 cooperative test program to determine the p
20、recision and biasstatements were between 5 mL and 15 mL of liquid plus vapor with atolerance of 61 % of the nominal capacity.6.1.2 Pressure Transducer, minimum operational rangefrom 1 kPa to 177 kPa (0 psia to 25.6 psia) with minimumresolution of 0.1 kPa (0.01 psi) and minimum accuracy of60.8 kPa (6
21、0.12 psi). The pressure measurement system shallinclude associated electronics and readout devices to displaythe resulting pressure reading.6.1.3 Heater, thermostatically controlled heater capable ofmaintaining the test chamber within 0.1 C of the set tempera-ture for a minimum of 5 minutes.NOTE 4Th
22、e use of automated instruments that automatically adjustthe temperature, after sample injection, to give a pressure of 101.3 kPa(14.69 psia) is allowed.6.1.4 Platinum Resistance Thermometer, used to measurethe temperature of the test chamber, having a minimumtemperature range of 36 C to 80 C, minimu
23、m resolution of0.1 C (0.2 F) and minimum accuracy of 60.1 C (60.2 F).6.2 Vacuum Pump, (when required to produce the vacuum),capable of reducing the pressure in the test chamber to less than0.01 kPa (0.001 psia).6.3 Syringes, (if required for sample introduction), gas-tight, 1 mL to 20 mL capacity wi
24、th minimum accuracy andprecision of 61%.6.4 Bath, iced water or air, for chilling the samples andsyringe (if required) to between 0 C and 1 C (32 F to 34 F).6.5 Pressure Measuring Device, capable of measuring localstation pressure with an accuracy of 0.20 kPa (0.03 psi) orbetter, at the same elevati
25、on relative to sea level as theapparatus in the laboratory.6.5.1 When a mercury manometer is not used as thepressure measuring device, the calibration of the pressuremeasuring device employed shall be periodically checked(with traceability to a nationally recognized standard) to ensurethat the devic
26、e remains within the required accuracy specifiedin 6.5.6.6 McLeod Vacuum Gage or Calibrated Electronic VacuumMeasuring Device for Calibration, to cover at least the rangefrom 0.01 kPa to 0.67 kPa (0.1 mm Hg to 5 mm Hg). Thecalibration of the electronic vacuum measuring device shall beregularly verif
27、ied in accordance with the annex section onVacuum Sensors (A6.3) of Test Method D2892.7. Reagents and Materials7.1 Purity of ReagentsUnless otherwise indicated, allreagents shall conform to the specifications of the Committeeon Analytical Reagents of the American Chemical Society4where such specific
28、ations are available. Lower purities can beused, provided it is first ascertained that the reagent is ofsufficient purity to permit its use without lessening the accu-racy of the determination. Reagents used for performancechecks (see 10.3) shall be of at least 99 % purity.7.2 n -pentane, (WarningFl
29、ammable, health hazard.)8. Sampling8.1 General:8.1.1 Conduct bulk sampling to obtain the laboratorysamples in accordance with Practice D4057 except forgasoline-oxygenate blends where water displacement is notused. The extreme sensitivity of T(V/L)measurements to lossesthrough evaporation and the res
30、ulting changes in compositionis such as to require the utmost precaution and the mostmeticulous care in the handling of samples. (WarningExtremely flammable, harmful if inhaled or ingested. Skinirritant on repeated contact. Aspiration hazard.)8.1.2 The size of the sample container from which thesamp
31、le is taken shall be 1 L (1 qt). It shall be 70 % to 80 %filled with sample.8.1.3 The precision statement will be derived using samplesin 1 L (1 qt) containers. However, samples taken in containersof other sizes as prescribed in Practice D4057 can be used if itis recognized that the precision could
32、be affected. In the case ofreferee testing, the 1 L (1 qt) sample is mandatory.8.1.4 Perform the T(V/L)determination on the first testspecimen withdrawn from the sample container. Do not use theremaining sample in the container for a second T(V/L)determi-nation. If a second determination is necessar
33、y, obtain a newsample.8.1.5 Protect samples from excessive temperature prior totesting. This can be accomplished by storage in an appropriateice bath or refrigerator.8.1.6 Do not test samples stored in leaky containers. Discardand obtain a new sample if leaks are detected.8.2 Sampling TemperatureCoo
34、l the sample container andcontents in an iced bath or refrigerator to between 0 C and4Reagent Chemicals, American Chemical Society Specifications, AmericanChemical Society, Washington, DC. For Suggestions on the testing of reagents notlisted by the American Chemical Society, see Annual Standards for
35、 LaboratoryChemicals, BDH Ltd., Poole, Dorset, U.K., and the United States Pharmacopeiaand National Formulary, U.S. Pharmacopeial Convention, Inc. (USPC), Rockville,MD.D5188 1421 C (32 F to 34 F) prior to opening the sample container.Ensure sufficient time to reach this temperature by directmeasurem
36、ent of the temperature of a similar liquid in a likecontainer placed in the cooling bath at the same time as thesample.8.3 Verification of Sample Container Filling:8.3.1 With the sample at a temperature of 0 C to 1 C, takethe container from the cooling bath or refrigerator and wipe drywith absorbent
37、 material. If the container is not transparent,unseal it and using a suitable gage, confirm that the samplevolume equals 70 % to 80 % of the container capacity (seeNote 5). If the sample is contained in a transparent glasscontainer, verify that the container is 70 % to 80 % full bysuitable means (se
38、e Note 5).8.3.2 Discard the sample if the container is filled to less than70 % by volume of the container capacity.8.3.3 If the container is filled to more than 80 % by volume,pour out enough sample to bring the container contents towithin the 70 % to 80 % by volume range. Do not return anysample to
39、 the container once it has been withdrawn.NOTE 5For non-transparent containers, one way to confirm that thesample volume equals 70 % to 80 % of the container capacity is to use adipstick that has been pre-marked to indicate the 70 % and 80 % containercapacities. The dipstick should be of such materi
40、al that it shows wettingafter being immersed and withdrawn from the sample. To confirm thesample volume, insert the dipstick into the sample container so that ittouches the bottom of the container at a perpendicular angle, beforeremoving the dipstick. For transparent containers, using a marked ruler
41、 orby comparing the sample container to a like container which has the 70 %and 80 % levels clearly marked, has been found suitable.8.3.4 Reseal the container, if necessary, and return thesample container to the cooling bath or refrigerator.8.4 Air Saturation of the Sample in the Sample Container:8.4
42、.1 Transparent Container OnlySince 8.3.1 does notrequire that the sample container be opened to verify thesample capacity, it is necessary to unseal the cap momentarilybefore resealing it, so that samples in transparent containers aretreated the same as samples in non-transparent containers.8.4.2 Wi
43、th the sample again at a temperature of 0 C to1 C, take the container from the cooling bath or refrigerator,wipe it dry with an absorbent material, remove the capmomentarily, taking care that no water enters, reseal and shakevigorously. Return it to the bath or refrigerator for a minimumof 2 minutes
44、.9. Preparation of Apparatus9.1 Prepare the instrument for operation in accordance withthe manufacturers instructions.9.2 Clean and dry, or rinse the test chamber to avoidcontamination of the test sample.9.3 When a vacuum pump is used for evacuation prior tosample introduction, visually determine fr
45、om the instrumentdisplay that the test chamber pressure is stable and does notexceed 0.1 kPa (0.01 psia). If the pressure is not stable orexceeds this value, check that the chamber contains no volatilematerials from a previous sample, the seals are satisfactory, thecalibration of the transducer is c
46、orrect, and the apparatus doesnot leak.9.4 If a syringe is used for introduction of the samplespecimen, chill the syringe to between 0 C and 1.0 C (32 Fto 34 F) such as in a refrigerator or ice bath before drawing inthe sample specimen. Water contamination of the syringereservoir during this cooling
47、 procedure shall be avoided. Oneway to achieve this is by sealing the outlet of the syringe duringthe cooling process.9.5 When a vacuum pump is used for evacuation prior tointroduction of the test specimen, set the temperature of the testchamber to close to the expected result, if known; or 40 C(104
48、 F), if unknown.9.6 When a moveable piston is used for evacuation, set thetemperature of the test chamber to close to 20 C (68 F) priorto introduction of the test specimen.10. Calibration10.1 Perform a calibration check of the pressure transduceras indicated by the performance check (see 10.3). The
49、calibra-tion of the transducer is accomplished using two referencepoints, zero pressure, and ambient barometric pressure.NOTE 6Calibration frequency of the pressure transducer may varywith instrument type and frequency of use. A calibration check of thepressure transducer at least once every six months is recommended.NOTE 7Pressure transducers can be sensitive to working temperature.Calibration should be performed at the test chamber temperature mostfrequently used.10.1.1 Connect a McLeod gage or a calibrated electronicvacuum meas
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