1、Designation: D5188 10Standard Test Method forVapor-Liquid Ratio Temperature Determination of Fuels(Evacuated Chamber Method)1This standard is issued under the fixed designation D5188; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision,
2、 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 from a selected
3、volume ofvolatile petroleum product saturated with air at 0 to 1C (32 to34F) produces a pressure of one atmosphere in an evacuatedchamber of fixed volume. This test method is applicable tosamples for which the determined temperature is between 36and 80C (97 and 176F) and the vapor-liquid ratio is be
4、tween8 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 This test method is
5、 applicable to both gasoline andgasoline-oxygenate blends.1.2.1 Some gasoline-oxygenate blends may show a hazewhen cooled to 0 to 1C. If a haze is observed in 11.5, it shallbe indicated in the reporting of results. The precision and biasstatements for hazy samples have not been determined (seeNote 1
6、0).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 standard to estab
7、lish 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 Fuels3D2892 Test Method for Dist
8、illation of Crude Petroleum(15-Theoretical Plate Column)D4057 Practice for Manual Sampling of Petroleum andPetroleum Products3. Terminology3.1 Definitions of Terms Specific to This Standard:3.1.1 T(V/L = 20), nthe equilibrium temperature at whichthe partial pressure of a sample under test conditions
9、 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, at 0C(32F).4. Summary of Test Method4.1 A known vol
10、ume of chilled, air-saturated sample isintroduced into an evacuated, thermostatically controlled testchamber of known volume. The sample volume is calculated togive the desired vapor-liquid ratio for the chamber volume inuse. After injection, the chamber temperature is adjusted untila stable chamber
11、 pressure of 101.3 kPa (14.69 psia) isachieved.5. Significance and Use5.1 The tendency of a fuel to vaporize in automotive enginefuel systems is indicated by the vapor-liquid ratio of the fuel.5.2 Automotive fuel specifications generally include T(V/L = 20) limits to ensure products of suitable vola
12、tility perfor-mance. For high ambient temperatures, a fuel with a high valueof T(V/L = 20), indicating a fuel with a low tendency to vaporize,is generally specified; conversely for low ambient tempera-tures, a fuel with a low value of T(V/L = 20)is specified.6. Apparatus6.1 Apparatus suitable for us
13、e shall employ a small volumetest chamber incorporating a transducer for pressure measure-ments and associated equipment for thermostatically control-ling the chamber temperature, evacuating the test chamber1This test method is under the jurisdiction of ASTM Committee D02 onPetroleum Products and Lu
14、bricants and is the direct responsibility of SubcommitteeD02.08 on Volatility.Current edition approved July 1, 2010. Published July 2010. Originally approvedin 1991. Last previous edition approved in 2009 as D518809. DOI: 10.1520/D5188-10.2For referenced ASTM standards, visit the ASTM website, www.a
15、stm.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.3Withdrawn. The last approved version of this historical standard is referencedon www.astm.org.1*A Summary of Changes sect
16、ion appears at the end of this standard.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.prior to sample introduction, and cleaning and purging thechamber following the test. Critical elements of the apparatusshall meet the following s
17、pecifications:6.1.1 Test Chamber, constructed of stainless steel or alumi-num, designed to contain between 5 and 50 mL of liquid plusvapor with a tolerance of 61 % of the nominal capacity.NOTE 3The test chamber volumes of the instruments used for the1991 cooperative test program to determine the pre
18、cision and biasstatements were between 5 and 15 mLof liquid plus vapor with a toleranceof 61 % of the nominal capacity.6.1.2 Pressure Transducer, minimum operational rangefrom 1 to 177 kPa (0 to 25.6 psia) with minimum resolution of0.1 kPa (0.01 psi) and minimum accuracy of 60.8 kPa (60.12psi). The
19、pressure measurement system shall include associ-ated electronics and readout devices to display the resultingpressure reading.6.1.3 Heater, thermostatically controlled heater capable ofmaintaining the test chamber within 0.1C of the set tempera-ture for a minimum of 5 min.NOTE 4The use of automated
20、 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 to 80C, minimum resolution of 0.1C(
21、0.2F) and minimum accuracy of 60.1C (60.2F).6.2 Vacuum Pump, capable of reducing the pressure in thetest chamber to less than 0.01 kPa (0.001 psia).6.3 Syringes, (if required for sample introduction), gas-tight, 1- to 20-mL capacity with minimum accuracy andprecision of 61%.6.4 Bath, iced water or a
22、ir, for chilling the samples andsyringe (if required) to between 0 and 1C (32 to 34F).6.5 Pressure Measuring Device, capable of measuring localstation pressure with an accuracy of 0.20 kPa (0.03 psi) orbetter, at the same elevation relative to sea level as theapparatus in the laboratory.6.5.1 When a
23、 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 device remains within the required accuracy specifiedin 6.5.6.6 McLeod Vacuu
24、m Gage or Calibrated Electronic VacuumMeasuring Device for Calibration, to cover at least the rangefrom 0.01 to 0.67 kPa (0.1 to 5 mm Hg). The calibration of theelectronic vacuum measuring device shall be regularly verifiedin accordance with the annex section on Vacuum Sensors(A6.3) of Test Method D
25、2892.7. 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 specifications are available. Lower purities can beused, provided it is first ascertained
26、 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, (WarningFlammable, health hazard.)8. Sampling8.1 General:8.1.1 Conduct bulk sampling to obt
27、ain 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 resulting changes in compositionis such as to require the utmost precaution and the
28、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 thesample is taken shall be 1 L (1 qt). It shall be 70 to 80 % filledwith sample.8.1.3 T
29、he 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 be affected. In the case ofreferee testing, the 1-L (1-qt) sample is mandatory.8.1.
30、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)deter-mination. If a second determination is necessary, obtain a newsample.8.1.5 Protect samples from excessive temperature prior totest
31、ing. 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 TemperatureCool the sample container andcontents in an iced bath or refrigerator to between 0 and
32、 1C(32 to 34F) prior to opening the sample container. Ensuresufficient time to reach this temperature by direct measurementof the temperature of a similar liquid in a like container placedin the cooling bath at the same time as the sample.8.3 Verification of Sample Container Filling:8.3.1 With the s
33、ample at a temperature of 0 to 1C, take thecontainer from the cooling bath or refrigerator and wipe drywith absorbent material. If the container is not transparent,4Reagent Chemicals, American Chemical Society Specifications, AmericanChemical Society, Washington, DC. For Suggestions on the testing o
34、f reagents notlisted by the American Chemical Society, see Annual Standards for LaboratoryChemicals, BDH Ltd., Poole, Dorset, U.K., and the United States Pharmacopeiaand National Formulary, U.S. Pharmacopeial Convention, Inc. (USPC), Rockville,MD.D5188 102unseal it and using a suitable gage, confirm
35、 that the samplevolume equals 70 to 80 % of the container capacity (see Note5). If the sample is contained in a transparent glass container,verify that the container is 70 to 80 % full by suitable means(see Note 5).8.3.2 Discard the sample if the container is filled to less than70 % by volume of the
36、 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 the container once it has been withdrawn.NOTE 5For non-transparent containers, one way to confir
37、m 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 material that it shows wettingafter being immersed and withdrawn from the sample. To confirm thesample volu
38、me, 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 orby comparing the sample container to a like container which has the 70and 80 % levels clearly mark
39、ed, 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:8.4.1 Transparent Container OnlySince 8.3.1 does notrequire that the sample container be opened to verify
40、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 With the sample again at a temperature of 0 to 1C,take the container from the cooling bath or refrigerato
41、r, wipe itdry with an absorbent material, remove the cap momentarily,taking care that no water enters, reseal and shake vigorously.Return it to the bath or refrigerator for a minimum of 2 min.9. Preparation of Apparatus9.1 Prepare the instrument for operation in accordance withthe manufacturers inst
42、ructions.9.2 Clean and dry the test chamber to avoid contaminationof the test sample.9.3 Prior to sample introduction, visually determine fromthe instrument display that the test chamber pressure is stableand does not exceed 0.1 kPa (0.01 psia). If the pressure is notstable or exceeds this value, ch
43、eck that the chamber containsno volatile materials from a previous sample, the seals aresatisfactory, the calibration of the transducer is correct, and theapparatus does not leak.9.4 If a syringe is used for introduction of the sample, chillthe syringe to between 0 and 1.0C (32 to 34F) in arefrigera
44、tor or ice bath before drawing in the sample. Thesyringe must be kept completely dry during this cooling. Placethe clean and dry syringe in a water tight plastic bag and placethe sealed bag in the ice bath or refrigerator maintained at 0 to1.0C (32 to 34F).9.5 Prior to introduction of the test speci
45、men, set thetemperature of the test chamber to close to the expected result,if known; or 40C (104F), if unknown.10. Calibration10.1 Perform a calibration check of the pressure transduceras indicated by the performance check (see 10.3). The calibra-tion of the transducer is accomplished using two ref
46、erencepoints, 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 sensiti
47、ve 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 measuring device to the vacuum source in line with thetest chamber. Apply vacuum to the test chamber. When thevacuum measuring d
48、evice registers a pressure less than 0.1 kPa(0.8 mm Hg) adjust the indicator to zero or to the actualreading on the vacuum measuring device as dictated by theinstrument design or manufacturers instructions.10.1.2 Open the test chamber to the atmosphere and observethe indicator reading. If the pressu
49、re reading is not equal to theambient barometric pressure, adjust the indicator span controluntil the appropriate reading is observed. Ensure that theinstrument is set to display the total pressure and not acalculated or corrected value.10.1.3 Repeat 10.1.1 and 10.1.2 until the zero and baromet-ric pressure read correctly without further adjustments.10.2 Calibrate the platinum resistance thermometer andindicator used to monitor the temperature of the test chamberat least every six months against a National Institute ofStandards and Technology
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