1、Designation: D 6231 98 (Reapproved 2003)Standard Specification forHFC-125 (Pentafluoroethane, C2HF5)1This standard is issued under the fixed designation D 6231; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of last revis
2、ion. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon (e) indicates an editorial change since the last revision or reapproval.1. Scope1.1 This specification covers the requirements for HFC-125as a firefighting medium.1.2 This specification does not address the fire
3、fightingequipment or hardware that employs HFC-125 or the condi-tions of employing such equipment, for example, hand helds,fixed installations, etc.1.3 This specification does not address the storage ortransportation of HFC-125. Storage, handling, and transporta-tion issues are addressed in Practice
4、 D 6268.1.4 The following safety hazards caveat pertains to the testmethods portion, Section 6, of this specification. This standarddoes not purport to address all of the safety concerns, if any,associated with its use. It is the responsibility of the user of thisstandard to establish appropriate sa
5、fety and health practicesand determine the applicability of regulatory limitations priorto use. Specific hazards statements are given in 4.3.2. Referenced Documents2.1 ASTM Standards:2D 6268 Practice for Handling, Transportation, and Storageof HFC-125, Pentafluoroethane (C2HF5)2.2 ISO Standards:ISO
6、3363 Fluorinated Hydrocarbons for Industrial Use Determination of Acidity Titration Method3ISO 3427 Gaseous Halogenated Hydrocarbons (LiquefiedGases) Taking a Sample3ISO 5789 Fluorinated Hydrocarbons for Industrial Use Determination of Nonvolatile Residue32.3 CGA Standards:No. C-4 American National
7、Standard Method of MarkingPortable Compressed Gas Containers to Identify theMaterial Contained4No. P-1 Safe Handling of Compressed Gases in Containers42.4 U.S. Governmental Standards:Code of Federal Regulations (CFR) Title 49, Part 172.101,Tables of Hazardous Materials and Special Provisions5Code of
8、 Federal Regulations (CFR) Title 49, Parts 173.302and 173.304, Preparation and Packaging of Gases5Code of Federal Regulations (CFR) Title 49, Part 172Subpart D, Marking Requirements of Packaging forTransportation52.5 American Society of Refrigeration Engineers:ASRE Standard 34, Designation of Refrig
9、erants63. Terminology3.1 Definitions of Terms Specific to This Standard:3.1.1 halogenated hydrocarbon, nthe halogenated com-pound coding terminology system provides a convenientmeans to reference halogenated hydrocarbons (see ASRE 34).Halogenated hydrocarbons are saturated hydrocarbons inwhich one o
10、r more of the hydrogen atoms have been replacedby atoms of the halogen series: fluorine, chlorine, bromine, andiodine. It is convention to prefix the number with an abbrevia-tion of the compound:CFC = chlorofluorocarbonHCFC = hydrochlorofluorocarbonHFC = hydrofluorocarbonFC = fluorocarbonR = refrige
11、rant3.1.1.1 DiscussionBy definition, the rightmost digit ofthe numbering system is the number of fluorine atoms. Thesecond digit from the right is the number of hydrogen atomsplus one (+1). The third digit from the right is one less (-1) thannumber of carbon atoms in the compound (when this numberis
12、 zero (0) it is omitted from the number). Unaccounted forvalance requirements are assumed to be chlorine atoms. Whenthe compound contains bromine or iodine, the same rules applyexcept the letter “B” for bromine or “I” for iodine follows theparent compound designated number and the number of theatoms
13、 is placed after the letter.Example: C2HF55 R2125 5 HFC2125 (1)1This specification is under the jurisdiction of ASTM Committee D26 onHalogenated Organic Solvents and is the direct responsibility of SubcommitteeD26.09 on Halogenated Fire Extinguishants.Current edition approved Feb. 10, 1998. Publishe
14、d July 1998.2For referenced 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.3Available from American National Standards Insti
15、tute, 11 W. 42nd St., 13thFloor, New York, NY 10036.4Available from the Compressed Gas Association.5Available from Superintendent of Documents, U.S. Government PrintingOffice, Washington, DC 20036.6Available from American Society of Refrigeration Engineers, RefrigerationEngineering 65, 49 (1957).1Co
16、pyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.3.1.2 HFC-125, nthe compound pentafluoroethane;C2HF5.4. Material Requirements4.1 Type I:4.1.1 The nitrogen (N2) partial pressure shall be such thatthe safe working pressure of the receivin
17、g vessel is notexceeded. To prevent excessive pressure, the fill density of theHFC-125/nitrogen within the container should not exceed thatneeded to achieve complete filling of the container at themaximum expected storage temperature. For example, the U.S.DOT 4BA500 cylinder partial pressure shall n
18、ot exceed 24.8bar at 21 C (360 psig at 70 F) for a 833 kg/m3(52 lb/ft3) filldensity. For this example, the safe working pressure of the4BA500 cylinder is not exceeded for temperatures below 54 C(130 F).4.1.2 HFC-125 shall conform to the requirements pre-scribed in Table 1 when tested by the appropri
19、ate test meth-od(s) listed in Section 6.4.1.3 When material analysis is required, by agreementbetween the purchaser and the supplier, the total pressure in theHFC-125 container, partial pressure of the nitrogen, the filldensity of the HFC-125 within the container, and the maximumsafe storage tempera
20、ture shall be part of the material analysis(certification). The pressure shall be reported in bar (preferred)or pound-force/in.2gage (psig). The fill density shall bereported in kg/m3at 21C (preferred) or lb/ft3at 70 F. Themaximum safe storage temperature of the HFC-125 shall bereported in C (prefer
21、red) or in F and shall conform to theapplicable regulations for the HFC-125 container design anduse.4.2 Type IIHFC-125 shall conform to the requirements ofType I as listed in 4.1 and shall contain no more than 1.5 % byvolume fixed gases in the vapor phase, expressed as air whentested by the appropri
22、ate test method(s) listed in Section 6.4.3 By agreement between the purchaser and the supplier,analysis may be required and limits established for elements orcompounds not specified in Table 1. (WarningExposure toconcentrations of HFC-125 in excess of 10 % by volume in airduring periods of elevated
23、adrenaline could produce cardiacarrhythmia in some personnel.)4.4 Unless otherwise specified, Type I is assumed.5. Sampling5.1 Samples of HFC-125 taken from the liquid phase, shallbe taken from filled containers in accordance with the methodspecified in ISO 3427. The sampling bottle shall be capable
24、 ofsafely resisting the vapor pressure of the sample at the highesttemperature that could be encountered.5.2 The HFC-125 selected in accordance with 5.1 shall betested for quality conformance in accordance with Section 6.The presence of one or more defects shall be cause forrejection.6. Test Methods
25、6.1 Purity:6.1.1 Determine the purity by gas chromatography in accor-dance with the technique described in 6.1.2-6.1.5 or anotheracceptable laboratory technique providing equivalent results.6.1.2 ApparatusThe following special apparatus is re-quired to determine the percent HFC-125.6.1.2.1 Gas Chrom
26、atograph, equipped with a thermal con-ductivity detector (TCD) and an integrator, 1-mV recorder, orother output device.6.1.2.2 Chromatographic Column, 6 ft length by18-in.outside diameter (OD) stainless steel tubing, packed with 80 to100 mesh PORAPAK Q or equivalent.NOTE 1Column is available prepack
27、ed from any chromatographicsupply vendor.6.1.2.3 Gas Sampling Valve, 1-mL volume or a volumesufficient to achieve proper separation and peak area for thespecified column.6.1.3 ReagentsThe carrier gas shall be a chromatographicgrade of helium. The column packing shall be 80 to 100 meshPORAPAK Q or eq
28、uivalent.6.1.4 Procedure:6.1.4.1 Install the column in the gas chromatograph and setthe oven temperature to 45 C, injection port to 175 C,detector clock to 200 C. The oven temperature is programmedto hold at 45 C for 2 min, then to rise 10 C/min, to amaximum of 150 C.6.1.4.2 Adjust the column helium
29、 flow to 20 mL/min.6.1.4.3 Adjust the detector voltage to the mid-range of thethermal conductivity detector (TCD) and allow the instrumentto equilibrate.6.1.4.4 Take a vapor sample from the liquid phase (invertedcylinder). Flush the sample loop and valve for approximately30 s.6.1.4.5 Rotate the samp
30、le valve to transfer the sample intothe chromatograph and note the time.6.1.4.6 Close the sample cylinder valve.6.1.4.7 Allow the sample to elute for approximately 15 min,attenuating as necessary to make the peak height a convenientsize. Under proper instrument settings, air (N2,O2) shouldelute afte
31、r about 0.4 min and HFC-125 should elute afterapproximately 5.7 min.6.1.5 Calculation:6.1.5.1 Calculate percent HFC-125 as follows:% HFC2125 5 AH100!/AT(2)where:AH= area of the HFC-125 peak (peak area x attenuation),andAT= sum all of the relevant peak areas excluding thenitrogen (air) peak (peak are
32、a x attenuation).Percent HFC-125 below that specified in Table 1 shallconstitute failure by this test method.TABLE 1 RequirementsProperty RequirementHFC-125 purity, mol/mol, min, % 99.0Acidity, ppm by mass, as HCI, max 3.0Water content, ppm by mass, max 10Nonvolatile residue, max, % by weight 0.08Su
33、spended matter or sediment none visibleD 6231 98 (2003)26.1.5.2 Calculate the percent nitrogen (air):%N2air!5 AN100!/AT1AN! (3)where:AN= area of the nitrogen (air) peak, andAT= sum of all the relevant peak areas including thenitrogen (air) peak.It is useful to calculate the percent nitrogen (air) to
34、 judge asafe fill density. This is the amount of nitrogen (air) in theliquid phase.6.2 AcidityVaporize a large sample in the presence ofdistilled water. Determine the acidity of the solution by theappropriate method specified in ISO 3363, titration in accor-dance with 6.2.1-6.2.3, a pH indicator, or
35、 another acceptablelaboratory technique providing equivalent results.Sodium Hydroxide Titration6.2.1 Reagents:6.2.1.1 Sodium Hydroxide, 0.01 N solution, standardizedagainst reagent grade potassium acid phthalate.6.2.1.2 Methyl Red Indicator, 0.1 % solution.6.2.2 ProcedurePlace distilled water-crushe
36、d ice slurry ina 250mL Erlenmeyer flask. Sparge 50 g of the HFC-1257intothe slurry. Loosely stopper the flask and swirl the flask gentlyfrom time to time until the ice is completely melted. Add 1drop of methyl red indicator, swirl, and if a reddish colorremains, titrate to a yellow endpoint with 0.0
37、1 N sodiumhydroxide solution. Run a crushed ice distilled water blank (noHFC-125) along with the sample.6.2.3 CalculationCalculate parts per million acid halides,as HCI, as follows:acid halides, ppm 5A2B! 3 N NaOH 3 0.03645 3 106weight of sample, g(4)where:A = NaOH for sample, mLB = NaOH for blank,
38、mLN = normality of the NaOH solution,NaOH = sodium hydroxide, and0.0365 3 106= factor to express result as ppm HCI (hy-drogen chloride).Acid halides in excess of that specified in Table 1 shallconstitute failure by this test method.6.3 Water ContentTest HFC-125 for water content. Thestandard method
39、shall be by Karl Fischer method. The analysismay be conducted by the phosphorous pentoxide method,infrared absoption, electronic moisture analysis, piezoelectricanalyzer, or another acceptable laboratory technique. Watercontent greater than specified in Table 1 shall constitute failureby this test m
40、ethod.6.4 Nonvolatile ResidueDetermine the nonvolatile resi-due in accordance with the method specified in ISO 5789 oranother accepted laboratory technique providing equivalentresults. Determine suspended matter or sediment (6.6) whileperforming this analysis.6.5 Fixed Gases in the Vapor PhaseTest H
41、FC-125 for thepresence of air in the vapor phase by gas chromatography oranother accepted laboratory technique providing equivalentresults.6.5.1 Gas Chromatography:HFC-125 may be tested for the concentration of air in thevapor phase by gas chromatography. A concentration of air inexcess of 1.5 % by
42、volume shall constitute failure by this testmethod.6.5.2 Procedure IFollow the procedure as outlined in 6.1(purity) except the sample is taken from the vapor space of thecontainer. This will be an area, volume % result. Air (N2,O2)will elute after about 0.4 min.6.5.3 Procedure II:6.5.3.1 ApparatusTh
43、e following special apparatus is re-quired to determine the percent fixed gases in HFC-125:6.5.3.2 Gas Chromatograph, equipped with a thermal con-ductivity detector (TCD) and an integrator, 1-mV recorder, orother output device.6.5.3.3 Chromatographic Column, 9-m length by 3.175 mmoutside diameter (2
44、9.5 ft by18 in.) stainless steel tubing,packed with 30 to 60 mesh 13X molecular sieve. This columnis available prepacked from any chromatographic supplyvendor.6.5.3.4 Gas Sampling Valve, 1-mL volume or a volumesufficient to achieve proper separation and peak area for thespecified column.6.5.4 Reagen
45、tsThe carrier gas shall be a chromatographicgrade of helium. The column packing shall be 30 to 60 mesh13X molecular sieve. Calibration gas shall be 0.8 % to 2 % N2and 0.2 % to 1 % O2in helium. This gas is available fromspecialty gas suppliers.6.5.5 Procedure:6.5.5.1 Install the column in the gas chr
46、omatograph and setthe oven temperature to 100 C, injection port to 200 C,detector block to 200 C. The oven temperature is programmedto hold at 100 C for 11 min, then to rise 35 C/min, to amaximum of 190 C, and hold for 30 min.6.5.5.2 Adjust the column helium flow to 15 mL/min.6.5.5.3 Adjust the dete
47、ctor voltage to the mid-range of thethermal conductivity detector (TCD) and allow the instrumentto equilibrate.6.5.5.4 Take the sample from the vapor phase. Flush thesample loop and valve for approximately 30 s at a flow rate of20 mL/min.6.5.5.5 Rotate the sample valve to transfer the sample intothe
48、 chromatograph and note the time.6.5.5.6 Close the sample cylinder valve.6.5.5.7 Allow the sample to elute for approximately 42 min,attenuating as necessary to make the peak height a convenientsize. Under proper instrument settings, the oxygen will elute atabout 2 min and nitrogen will elute at abou
49、t 3 min.6.5.6 Calculation:6.5.6.1 CalibrationCalibration factors are determined byanalyzing the Standard Gas as outlined in 6.5.5 and calculatingas follows:FN5 %N2in Std Gas/ AN(5)FO5 %O2in Std Gas/ AO7FE-25y is the registered trademark for HFC-125 manufactured by E.I. duPontde Nemours Company, Wilmington, DE.D 6231 98 (2003)3where:AN= area of the nitrogen peak,AO= area of the oxygen peak,FN= nitrogen factor, andFO= oxygen factor.6.5.6.2 Calculate the concentrations in the sample as fol-lows:%N25 AN! FN! (6)%O25 AO! FO!% NAG
