1、Designation: E 1786 02Standard Test Method forDetermination of Low Levels of Water in Liquid Chlorine byOn-Line Infrared Spectrophotometry1This standard is issued under the fixed designation E 1786; the number immediately following the designation indicates the year oforiginal adoption or, in the ca
2、se of revision, the year of last revision. 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 test method is designed for the on-line determina-tion of the content of water in li
3、quid chlorine in the concen-tration range of 0.5 to 15 mg/kg (ppm).1.2 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 establish appro-priate safety and health practices and determine the ap
4、plica-bility of regulatory limitations prior to use. Specific hazardsstatements are given in Section 7 and Note 2.2. Referenced Documents2.1 ASTM Standards:D 1193 Specifications for Reagent Water2E 806 Test Method for Carbon Tetrachloride and Chloro-form in Liquid Chlorine by Direct Injection (Gas C
5、hroma-tography Procedure)32.2 Federal Standards:449 CFR 173 Code of Federal Regulations Title 49 Trans-portation: Shippers General Requirements for Shipmentsand Packaging, including the following sections:173.304 Charging of Cylinders with Liquefied CompressedGas173.314 Requirements for Compressed G
6、ases in Tank Cars173.315 Compressed Gases in Cargo Tanks and PortableTank Containers2.3 Other Document:5Chlorine Institute Pamphlet No. 77Sampling LiquidChlorine3. Summary of Test Method3.1 Liquid chlorine continuously flows through a specialinfrared cell where it is maintained as a liquid under its
7、 ownpressure. A process infrared spectrometer scans from 400 to4400 wavenumbers of the infrared transmission spectrum ofliquid chlorine. This spectrum then is ratioed to one obtainedfrom the nitrogen-filled infrared cell previously. The ratioedspectrum is converted to absorbance, and the net absorba
8、nce ofwater band at 1596 wavenumbers, relative to a reference at1663 wavenumbers, is determined.3.2 The amount of water corresponding to this net absor-bance is determined from a calibration curve prepared from theinfrared absorbencies of standards which contain concentra-tions of water in liquid ch
9、lorine. These standards are preparedfrom manual samples of liquid chlorine in tantalum cylinders.Sample from each cylinder is introduced into a calibrationinfrared cell and maintained as a liquid under its own pressure.4. Significance and Use4.1 Trace amounts of water may be detrimental to the use o
10、fchlorine in some applications. The amount of water in thechlorine must be known to prevent problems during its use.5. Apparatus5.1 Process Infrared Spectrometer, capable of measure-ments in the 1600 wavenumber region. An FTIR with fourwavenumber resolution is the instrument of choice, but disper-si
11、ve instruments also may be used to achieve similar results.5.2 Special Infrared Calibration Cell (Fig. 1), as used forcalibration. Neither cell size nor pathlength are critical to theanalysis, but sensitivity and limit of detection are dependent onpathlength. The concentration range reported in the
12、Section 1 isachievable with a 60-mm pathlength cell constructed with thefollowing: Figs. 2-75.2.1 Hastelloy C and 316 Stainless Steel Stock, suitable formachining,65.2.2 Silver Chloride Windows, 0.5 cm 3 2.5 cm,7and5.2.3 Perfluoroelastomer Sheet, 0.030 in thickness.85.3 Ball Valves, Monel914-in. val
13、ve with pipe and14-in.tube ends.1This test method is under the jurisdiction of ASTM Committee E15 onIndustrial and Specialty Chemicalsand is the direct responsibility of SubcommitteeE15.02 on Product Standards.Current edition approved March 10, 2002. Published May 2002. Originallypublished as E 1786
14、 - 96. Last previous edition E 1786 - 96.2Annual Book of ASTM Standards, Vol 11.01.3Annual Book of ASTM Standards, Vol 15.05.4Code of Federal Regulations, available from U.S. Government Printing Office,Washington, DC 20402.5Available from The Chlorine Institute, Inc., 2001 L St. NW, Washington, DC20
15、036-4919.6Available from Collins Instrument Company, Inc., P.O. Drawer 938, Angleton,TX 77516-0938.7Available from Harshaw Chemical Company, 6801 Cochran Road, Solon, OH44139.8Available from E.I. DuPont de Nemours and Company, Wilmington, DE 19898.9Available from International Nickel Company and has
16、 been found satisfactoryfor this purpose.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.5.4 Needle Valves, Nickel or Monel914-in. valve with pipeand14-in. tube ends.5.5 Sample Cylinder Assembly (Fig. 8), consisting of:5.5.1 Sample C
17、ylinder, nickel, Monel,9or tantalum, 400 to1000-mL capacity, double-ended, with valves at each end,specially cleaned. Cylinders with both valves at one end andwith a dip tube on one valve have been found to be satisfactory.Another option is to construct special cylinders containing aseptum fitting o
18、n one end.NOTE 1A procedure for cleaning cylinders and valves, for use withliquid chlorine, is given in Test Method E 806, Appendix X2 .5.5.2 One Needle and One Ball Valve, nickel body, havingpacking resistant to liquid chlorine.10If nickel valves are notavailable, monel valves may be used.5.5.3 Sep
19、tum, inserted into a14-in. nut.5.5.4 Glove Bag or Dry Box, purged with dry nitrogen (lessthan 5 ppm water vapor).5.5.5 Fittings, for transferring chlorine from one cylinder toanother.5.5.6 One0to10L Syringe and One 0 to 25 L Syringe,26 gage needle.5.5.7 Dewar Flask, of sufficient size to hold a cyli
20、ndersurrounded by dry ice and methylene chloride. The Dewarflask should be supported by a wooden holder for safetypurposes.5.5.8 Hygrometer, capable of measuring moisture as low as5 ppm in glove bag or dry box.5.6 Silicone Rubber Septa.5.7 Mechanical Shaker.5.8 Drying Oven.5.9 Special Infrared Proce
21、ss Cell (Fig. 9) for on-line analy-sis of water in liquid chlorine. Neither cell size nor path lengthis critical to the analysis, but sensitivity and limit of detectionare dependent on pathlength. The concentration range reportedin the scope is achievable with a 60-mm pathlength cellconstructed with
22、:5.9.1 Hastelloy C and 316 Stainless Steel Stock, suitable formachining.65.9.2 Silver Chloride Windows, two, 25-mm diameter by2-mm thick and two 25-mm diameter by 4-mm thick.710Packing made from tTEFLON, tVITON, or tKEL-F has been foundsatisfactory for this purpose.FIG. 1 Infrared Cell (Drawing Not
23、to Scale)FIG. 2 Pipe AdapterFIG. 3 Air Cap DetailE 178625.9.3 Eight Viton O-rings, Size 027.6. Reagents6.1 Purity of WaterUnless otherwise indicated, watermeans Type II or III reagent water conforming to SpecificationD 1993.6.2 Chlorine, liquid with less than 5 ppm water.6.3 Methylene Chloride (CH2C
24、l2).116.4 Dry Ice (CO2).6.5 Dry Nitrogen (5 ppm water), to purge glove bag or drybox and test equipment.7. Hazards7.1 Safety Precautions:7.1.1 Chlorine is a corrosive and toxic material. Use awell-ventilated fume hood to house all test equipment, exceptthe infrared spectrophotometer, when this mater
25、ial is analyzedin the laboratory.7.1.2 Persons who are thoroughly familiar with the handlingof chlorine should perform this analysis. An experiencedperson should not work alone. The analyst must be provided11This reagent is used for cooling purposes only.FIG. 4 Body DetailFIG. 5 Gasket DetailFIG. 6
26、Insert DetailFIG. 7 Flange DetailE 17863with adequate eye protection (chemical goggles are recom-mended) and an approved chlorine respirator. Splashes ofliquid chlorine destroy clothing, and if such clothing is next tothe skin, will produce irritation and burns.7.1.3 When sampling and working with c
27、hlorine out ofdoors, warn people downwind from such operations of thepossible release of chlorine.7.1.4 Dispose of excess chlorine in an environmentally safeand acceptable manner. If chlorine cannot be disposed of in achlorine consuming process, provide a chlorine absorptionsystem. When the analysis
28、 and sampling regimen requires aninitial purging of chlorine from a container, the purged chlorineshould be similarly handled. Avoid purging to the atmosphere.7.1.5 In the event chlorine is inhaled, use first aid immedi-ately.8. Sampling for Calibration Standards8.1 Carefully choose sampling points.
29、 Ensure that theFIG. 8 Sample Cylinder AssemblyFIG. 9 Special Infrared Process CellE 17864sample point is associated with flowing chlorine and is not neara “dead leg” where the concentrations of impurities in thechlorine will never change because the chlorine never moves.If sampling through secondar
30、y piping, purge that piping wellwith nitrogen or dry air before being blocked in. Otherwise,temperature variations can result in water vapor condensinginside the piping to contaminate the chlorine sample when it isgrabbed.8.1.1 Finally, perform sampling at a sample point represen-tative of the chlor
31、ine needing to be analyzed; that is, samplepure chlorine after all purification steps, drying steps, and soforth, to ensure that the analytical results are meaningful.8.1.1.1 Sampling from tank cars, barges, storage tanks, andlarge cylinders presents unique problems. Each facility, how-ever, must be
32、 capable of delivering a liquid sample (not gas).Acceptable samples can be obtained by sampling in accordancewith the Chlorine Institute Pamphlet No. 77.8.2 Collect samples from these facilities in the samplecylinder assembly listed in 6.5. Follow proper and safesampling techniques. The cylinder mus
33、t contain at least 75 %by volume of liquid chlorine (less than 25 % vapor space).NOTE 2Do not allow the cylinder to become liquid-full. Tare thecylinder, fill with water, and reweigh to determine the weight of water inthe cylinder. Multiply this weight by 1.56 (the assumed specific gravity ofliquid
34、chlorine) and by 0.75 to obtain the weight of chlorine to fill thecylinder 75 % full. For example, the cylinder holds 1000 g of water (1000mL, assuming a specific gravity of 1.0). The filled cylinder will hold 1560g of chlorine, and at 75 % of capacity, it will contain 1170 g of chlorine.8.3 Thoroug
35、hly dry the sample cylinders by placing them inan oven at 105C for at least6horpreferably overnight. Theunheated dip tubes are placed in a desiccator. Valves also areplaced in the oven but not as a part of the cylinder (packingsare resistant to this temperature). After this treatment, thecylinders a
36、re cooled with plant air or N2having 5 ppmmoisture. The valves are removed, placed in a desiccator witha suitable drying agent, and cooled to room temperature.9. Preparation of Standards for Calibration9.1 Obtain four clean, evacuated sample cylinders. Use onlycylinders that have been properly press
37、ure-tested. Equip threewith a ball valve and a needle valve, label these Cylinders No.2 through No. 4, and record weight to the nearest gram. Equipthe fourth cylinder with two needle valves, weigh to the nearestgram, record, and label No. 1. Once it contains chlorine, it willbe used to purge the inf
38、rared cell before standards are loaded.Use caps on all valves. If dip tubes are used, attach the dip tubeto the needle valve. Check the hygrometer to make sure theatmosphere in the glove bag or dry box contains 5 ppmmoisture before performing any transfers of chlorine.9.2 Load the four cylinders wit
39、h liquid chlorine. The liquidchlorine should contain less than 5 ppm water. All cylindersmust contain at least 75 % by volume of liquid chlorine (lessthan 25 % vapor space). All cylinders should be weighed to thenearest gram and recorded to determine the weight of chlorinein each cylinder (Note 2).
40、Place the filled cylinders into theglove bag or dry box inside the hood. Place all fittings, toolsand equipment, including the purged infrared cell, in the glovebag or dry box. Wait until the hygrometer in the glove bag ordry box is reading 5 ppm moisture before proceeding.9.3 Remove the cap on Valv
41、e A of Cylinder No. 1 and blowwith N2to remove any trapped moisture. Do this each time aconnection is made. Then connect the cylinder and the specialinfrared cell to the filling apparatus (Fig. 8) in such a way thatthe liquid chlorine will flow into the cell and the valves on allparts of the apparat
42、us are closed prior to filling the cell. For thefollowing operations, refer to 7.4 on venting chlorine.9.4 Open Valve F and then Valve A. Flush the fillingapparatus by partially opening Valve B for a few s and thenclosing it. Leave Valve A open.9.4.1 Open Valves E and C. Flush the cell by partiallyo
43、pening Valve D and observing flow, then close Valve C andthen Valve D.9.5 Fill the infrared cell by opening Valve C and observe thefilling of the cell windows. Close Valve C and empty the cellby opening Valve D. Close Valve D.9.6 Fill and empty the cell once more, as described above.9.6.1 Close Valv
44、e A and open Valve B, to purge the fillingapparatus, then close.9.7 Remove the cylinder. Connect Cylinder No. 2 to thefilling apparatus after blowing Valve A with N2. Make sure thatthe cylinder is connected to the apparatus in such a way that theliquid chlorine will flow into the cell and that the v
45、alves on allparts of the apparatus are closed prior to attempting to fill thecell. For the following operations, refer to 7.4 on ventingchlorine. Repeat 9.4-9.6.9.8 Fill the cell by opening Valve C. Close Valve C andinvert the cell to ensure complete filling of the cell window andthen close Valve A.
46、9.9 Vent the residual chlorine from the filling apparatus byopening Valve B and then open Valve C a little and dump asmall amount of chlorine from the inverted cell, then quicklyclose. The cell window should have about15 vapor space wheninverted. Then close Valves B and E.9.10 Allow the cell to come
47、 to ambient temperature. Beforeremoving the cell from the filling apparatus, check again foradequate vapor space in the inverted cell window. If no vaporspace is seen, open Valve B and quickly open, and close ValveC a little to dump some more chlorine. Make sure that no morethan15to14 of the cell wi
48、ndow is vapor space when the cell isinverted. Remove Cylinder No. 1 and No. 2 and record theirweights.9.11 Place the infrared cell in the spectrometer and scan intransmission mode from 400 to 4400 wavenumbers at4-wavenumber resolution. Ratio this spectrum to a spectrumtaken of the infrared cell fill
49、ed with nitrogen. Convert theratioed transmission spectrum to absorbance, and measure thenet absorbance of the band at 1596 wavenumber relative to areference at 1663 wavenumbers.9.12 Repeat the operations above (9.4-9.11, omit 9.6.1) withchlorine Cylinders No. 3 and No. 4.9.13 Low concentrations of water will be present in eachcylinder prior to introduction of additional water via a microli-tre syringe. Infrared absorbance spectra of the three cylindersof liquid chlorine obtained at the same time should agreewithin 20 %. For example, absorbance of water at 1596 cm-1less the
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