1、Designation: D6897 09D6897 16Standard Test Method forVapor Pressure of Liquefied Petroleum Gases (LPG)(Expansion Method)1This standard is issued under the fixed designation D6897; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the
2、 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 use of automatic vapor pressure instruments to determine the vapor pressure of l
3、iquefiedpetroleum gas products at a temperature of 37.8C,37.8 C, vapor to liquid ratio of 0.5:1, and pressures from 200200 kPa to 1550kPa 1550 kPa on a sample volume of 3.33 mL.3.33 mL.1.2 This test method is applicable to the determination of vapor pressures of liquefied petroleum gas products at t
4、emperaturesfrom 37.837.8 C to 70C,70 C, vapor to liquid ratios of 0.1:1 to 4:1, and pressures up to 3500 kPa; 3500 kPa; however, theprecision of the test method (see Section 15) has only been determined for a vapor to liquid ratio of 0.5:1, at a temperature of37.8C,37.8 C, and a pressure range from
5、300300 kPa to 1500 kPa.1500 kPa.NOTE 1This test method is not intended to determine the true vapor pressure of LPG samples, but rather determine and report the vapor pressureof LPG at the 37.8C37.8 C temperature and 0.5:1 vapor to liquid ratio as the Test Method D1267 method.NOTE 2This test method i
6、s not a true vapor pressure method and will not measure the full contribution from any dissolved gases such as nitrogenor helium if they are present. The contribution of light gases to the measured vapor pressure is highly dependent on the test temperature, type of gas,and V/L ratio of the test.1.3
7、The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.1.3.1 ExceptionNon-SI units are included in parentheses for information only.1.4 This standard does not purport to address all of the safety concerns, if any, associated with its
8、 use. It is 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 warning statements, see Appendix X2.2. Referenced Documents2.1 ASTM Standards:2D1265 Practice for Sampli
9、ng Liquefied Petroleum (LP) Gases, Manual MethodD1267 Test Method for Gage Vapor Pressure of Liquefied Petroleum (LP) Gases (LP-Gas Method)D2892 Test Method for Distillation of Crude Petroleum (15-Theoretical Plate Column)D3700 Practice for Obtaining LPG Samples Using a Floating Piston CylinderD5191
10、 Test Method for Vapor Pressure of Petroleum Products (Mini Method)D6299 Practice for Applying Statistical Quality Assurance and Control Charting Techniques to Evaluate Analytical Measure-ment System Performance2.2 Energy Institute Standards:3IP 181 Sampling Petroleum Gases3. Terminology3.1 Definiti
11、ons:3.1.1 liquefied petroleum gases (LPG), nnarrow boiling range hydrocarbon mixtures, consisting mainly of propane orpropylene, or both (WarningWarningExtremelyExtremely flammable. Harmful if inhaled), butanes and butylenes, or both; in1 This test method is under the jurisdiction of ASTM Committee
12、D02 on Petroleum Products Products, Liquid Fuels, and Lubricants and is the direct responsibility ofSubcommittee D02.08 on Volatility.Current edition approved April 15, 2009July 15, 2016. Published May 2009 August 2016. Originally approved in 2003. Last previous edition approved in 20032009 asD68970
13、3a. DOI: 10.1520/D6897-09. 09. DOI: 10.1520/D6897-16.2 For 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 Summary page on the ASTM website.3 Availa
14、ble from Energy Institute, 61 New Cavendish St., London, WIG 7AR, U.K., http:/www.energyinst.org.uk.This 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 technicall
15、y possible to adequately depict all changes accurately, ASTM recommends 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.*A Summary of Changes section appears at the end of this stand
16、ardCopyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States1which the concentration of hydrocarbon compounds with boiling point greater than 0C0 C is less than 5 % by liquid volume,and whose vapor pressure at 37.8C (100F)37.8 C (100 F) is not
17、greater than 1550 kPa.1550 kPa.3.1.2 platinum resistance thermometer, ntemperature measuring device with platinum wire, whose electrical resistancechanges in relation to temperature.3.1.3 vapor-liquid ratio (V/L), nof a liquid, the ratio of the vapor volume to the liquid volume of specimen, in equil
18、ibrium,under specified conditions.3.2 Definitions of Terms Specific to This Standard:3.2.1 total vapor pressure (Ptot) , nthe absolute vapor pressure (relative to vacuum) exerted by the specimen at the specifiedtemperature and vapor-liquid ratio.3.2.2 true vapor pressure, nthe physical property of a
19、 given liquid which specifies the maximum pressure at which a vaporphase can coexist with the liquid phase at a given equilibrium temperature condition.3.2.3 vapor pressure of LPG, nthe total pressure corrected relative to normal barometric pressure.3.3 Abbreviations:3.3.1 LPGliquefied petroleum gas
20、3.3.2 V/Lvapor liquid ratio4. Summary of Test Method4.1 Employing a measuring chamber with a built-in piston, the chamber is rinsed three times with a portion of sample, whichis then discarded. A sample of defined volume is drawn from a pressurized sampling system into the temperature-controlledcham
21、ber at 5C5 C by moving the piston to the filling position. After sealing the chamber, the volume is expanded by movingthe piston until the final volume produces the desired vapor to liquid ratio of 0.5:1. The temperature of the measuring chamber isthen regulated to the test temperature of interest,
22、such as 37.8C.37.8 C.4.2 The observed total pressure at equilibrium is corrected relative to 101.3 kPa 101.3 kPa and reported as the LPG vaporpressure at the selected test temperature.5. Significance and Use5.1 Information on the vapor pressures of liquefied petroleum gas is pertinent to selection o
23、f properly designed storage vessels,shipping containers, and customer utilization equipment to ensure safe handling of these products.5.2 Determination of the vapor pressure of liquefied petroleum gas is important for safety reasons to ensure that the maximumoperating design pressures of storage, ha
24、ndling, and fuel systems will not be exceeded under normal operating temperatureconditions.5.3 For liquefied petroleum gases, vapor pressure can be considered a semi-quantitative measure of the amount of the mostvolatile material present in the product.5.4 This test method uses a small sample volume
25、 and excludes any manual handling of a measuring chamber under highpressure.6. Apparatus6.1 Vapor Pressure Apparatus4The type of apparatus suitable for this test method employs a small volume, cylindricallyshaped measuring chamber with associated equipment to control the chamber temperature within t
26、he range of 55 C to 70C.70 C.The measuring chamber shall contain a movable piston with a maximum dead volume of less than 1 % of the total volume at thelowest position to allow sample introduction into the measuring chamber and expansion to the desired vapor-liquid ratio. A staticabsolute pressure t
27、ransducer shall be incorporated in the piston. The measuring chamber shall contain an inlet/outlet valvecombination for sample introduction and expulsion. The piston and the valve combination shall be at the same temperature as themeasuring chamber to avoid any condensation or excessive evaporation.
28、6.1.1 The test chamber shall be designed to contain a total of 5 mL 5 mL of liquid and vapor and be capable of maintaininga vapor-liquid ratio of 0.5:1 with a maximum deviation of 0.02.NOTE 3The test chamber employed by the instruments used in generating the precision and bias statements were constr
29、ucted of nickel-platedaluminum and stainless steel.NOTE 4Test chambers exceeding a 5 mL 5 mL capacity can be used, but the precision and bias statements (see Section 15) are not known to apply.6.1.2 Electronic temperature control shall be used to maintain the measuring chamber at the prescribed temp
30、erature within60.1C60.1 C for the duration of the vapor pressure measurement.4 The sole source of supply of the apparatus known to the committee at this time is Grabner Instruments,A-1220 Vienna, Dr. Otto Neurathgasse 1,Austria. If you are awareof alternative suppliers, please provide this informati
31、on toASTM International Headquarters.Your comments will receive careful consideration at a meeting of the responsibletechnical committee,1 which you may attend.D6897 1626.1.3 The pressure transducer shall have a range of 00 kPa to 3500 kPa 3500 kPa with a minimum resolution of 1 kPa. 1 kPa.The minim
32、um accuracy shall be 61 kPa 61 kPa for pressures up to 700 kPa, 62 kPa 700 kPa, 62 kPa for pressures up to 1750kPa, and 64 kPa 1750 kPa, and 64 kPa for pressures up to 3500 kPa.3500 kPa.6.1.4 A platinum resistance thermometer, or equivalent, shall be used for measuring the temperature of the test ch
33、amber. Theminimum temperature range of the measuring device shall be from 00 C to 80C80 C with a resolution of 0.1C0.1 C and aminimum accuracy of 60.1C.60.1 C.6.2 Vacuum Pump for Calibration , capable of reducing the pressure in the measuring chamber to less than 0.01 kPa 0.01 kPaabsolute.6.3 McLeod
34、 Vacuum Gage or Calibrated Electronic Vacuum Measuring Device for Calibration, to cover at least the range from0.01 to 0.67 kPa (0.1 to 5 mm 0.01 kPa to 0.67 kPa (0.1 mm to 5 mm Hg). The calibration of the electronic vacuum measuringdevice shall be regularly verified in accordance with A6.3 of Test
35、Method D2892.6.4 Pressure Measuring Device for Calibration, capable of measuring local station pressure with an accuracy and a resolutionof 0.1 kPa (1 mm 0.1 kPa (1 mm Hg) or better, at the same elevation relative to sea level as the apparatus in the laboratory.NOTE 5This test method does not give f
36、ull details of instruments suitable for carrying out this test. Details on the installation, operation, andmaintenance of each instrument may be found in the manufacturers manual.7. Reagents and Materials7.1 Purity of ReagentsUse chemicals of at least 99 % purity for quality control checks. Commonly
37、 used quality control checkmaterials are propane, butane, and pentane (see Section 11). Unless otherwise indicated, it is intended that all reagents conformto the specifications of the Committee on Analytical Reagents of the American Chemical Society5 where such specifications areavailable. Lower pu
38、rities can be used, provided it is first ascertained that the reagent is of sufficient purity to permit its use withoutlessening the accuracy of the determination.NOTE 6The chemicals in this section are suggested for quality control procedures (see Section 11) and are not used for instrument calibra
39、tion.7.2 Cleaning SolventsUse noncorrosive solvents capable of cleaning the measuring chamber, the valves, and the inlet andoutlet tubes. A commonly used solvent is acetone. (WarningWarningPropane,propane, butane, pentane, and acetone areflammable and health hazards.)8. Sampling and Sample Introduct
40、ion8.1 Samples shall be obtained and stored in accordance with Practice D1265, or IP 181, unless the test samples can be takendirectly from the source of the material to be tested. Use a container of not less than 100 mL100 mLin size and filled at least 70 %with sample up to a maximum fill density a
41、s specified in regulations, which is typically no more than 80 %. Consult the specifiedregulations for more details.8.2 Any method of coupling the vapor pressure apparatus to the sample source can be employed. Tubing, 33 mm to 7 mm 7 mmin diameter, of suitable-working pressure, and made of material
42、corrosion-resistant to the products being sampled, is satisfactoryfor this purpose. A flexible transparent polyperfluoroalkoxyethylene (PFA) tubing greatly facilitates the purging and samplingoperations.8.3 Practice D1265 cylinders shall be equilibrated above the sample cell temperature of 5C5 C to
43、ensure sufficient samplecylinder pressure to fill the sample cell entirely. Practice D3700 cylinders shall be maintained at a pressure above the vaporpressure of the LPG at 5C5 C (approximately 655 kPa 655 kPa for special duty propane and approximately 175 kPa 175 kPa forcommercial butanes).9. Prepa
44、ration of Apparatus9.1 Prepare the instrument for operation in accordance with the manufacturers instructions. Since LPG is discharged at theoutlet of the apparatus, connect a tubing to the outlet and lead the other end of the tubing to a safe exhaust system or a gas recoverysystem to protect the en
45、vironment from LPG.9.2 If contaminated, clean the measuring chamber with a solvent. Acetone has been used successfully. Cleaning is performedby drawing the solvent into the chamber by the integrated piston and expelling the solvent into a waste container.10. Calibration10.1 Pressure Transducer:10.1.
46、1 Check the calibration of the transducer when needed as indicated from the quality control checks performed accordingto Section 11. The calibration of the transducer is checked using two reference points, zero pressure (that is, 0.1 kPa) 0.1 kPa)and the ambient barometric pressure.5 Reagent Chemica
47、ls, American Chemical Society Specifications, American Chemical Society, Washington, DC. For Suggestions on the testing of reagents not listed bythe American Chemical Society, see Annual Standards for Laboratory Chemicals, BDH Ltd., Poole, Dorset, U.K., and the United States Pharmacopeia and Nationa
48、lFormulary, U.S. Pharmacopeial Convention, Inc. (USPC), Rockville, MD.D6897 16310.1.2 Connect a McLeod gage or a calibrated electronic vacuum-measuring device to the vacuum source in line with themeasuring chamber (Note 7). Apply vacuum to the measuring chamber. When the vacuum measuring device regi
49、sters a pressureless than 0.1 kPa (0.8 mm 0.1 kPa (0.8 mm Hg), adjust the transducer control to zero or to the actual reading on the vacuummeasuring device as dictated by the instrument design or manufacturers instructions.NOTE 7Refer toAnnexA6.3 of Test Method D2892 for further details concerning the calibration of electronic vacuum measuring devices and propermaintenance of McLeod gages.10.1.3 Open the measuring chamber of the apparatus to atmospheric pressure and observe the corresponding pressure value ofthe tran
