1、Designation: E 1786 08Standard 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. Scope*1.1 This test method is designed for the on-line determina-tion of the content of water in l
3、iquid chlorine in the concen-tration range of 0.5 to 15 mg/kg (ppm).1.2 The values stated in SI units are to be regarded as thestandard. The values given in parentheses are for informationonly.1.3 Review the current Material Safety Data Sheets (MSDS)for detailed information concerning toxicity, firs
4、t aid proce-dures, and safety precautions.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 establish appro-priate safety and health practices and determine the applica-bility of regulator
5、y limitations prior to use. Specific hazardsstatements are given in Section 7 and Note 3.2. Referenced Documents2.1 ASTM Standards:2D 1193 Specification for Reagent WaterE 806 Test Method for Carbon Tetrachloride and Chloro-form in Liquid Chlorine by Direct Injection (Gas Chro-matographic Procedure)
6、2.2 Federal Standards:349 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 Gases in Tank Cars173.315 C
7、ompressed Gases in Cargo Tanks and PortableTank Containers2.3 Other Document:4Chlorine Institute Pamphlet No. 77 Sampling LiquidChlorine3. Summary of Test Method3.1 Liquid chlorine continuously flows through a specialinfrared cell where it is maintained as a liquid under its ownpressure. A process i
8、nfrared 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 absorbance ofwater band at 1596
9、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 chlorine. These standards a
10、re 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 ofchlorine in some applica
11、tions. 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-sive instruments also may b
12、e 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 Section 1 isachievable wi
13、th a 60-mm pathlength cell constructed with thefollowing: Figs. 2-75.2.1 Hastelloy C and 316 Stainless Steel Stock, suitable formachining,1This test method is under the jurisdiction of ASTM Committee E15 onIndustrial and Specialty Chemicals and is the direct responsibility of SubcommitteeE15.02 on P
14、roduct Standards.Current edition approved April 1, 2008. Published May 2008. Originallyapproved in 1996. Last previous edition approved in 2002 as E 1786 - 02.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of
15、ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.3Code of Federal Regulations, available from U.S. Government Printing Office,Washington, DC 20402.4Available from The Chlorine Institute, Inc., 2001 L St. NW, Washington, DC20036-4919.1*A Summary of Cha
16、nges section appears at the end of this standard.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.5.2.2 Silver Chloride Windows, 0.5 cm 3 2.5 cm, and5.2.3 Perfluoroelastomer Sheet, 0.762 mm (0.030 in.) thick-ness.5.3 Ball Valves, Monel
17、 6.35 mm (14-in.) valve with pipe and6.35 mm (14-in.) tube ends.FIG. 1 Infrared Cell (Drawing Not to Scale)FIG. 2 Pipe AdapterFIG. 3 Air Cap DetailFIG. 4 Body DetailE17860825.4 Needle Valves, Nickel or Monel 6.35 mm (14-in.) valvewith pipe and 6.35 mm (14-in.) tube ends.5.5 Sample Cylinder Assembly
18、(Fig. 8), consisting of:5.5.1 Sample Cylinder, nickel, Monel, or 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
19、cylinders containing aseptum fitting on 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. If nickel valves are notavailabl
20、e, monel valves may be used.5.5.3 Septum, inserted into a 6.35 mm (14-in.)-in. nut.5.5.4 Glove Bag or Dry Box, purged with dry nitrogen (lessthan 5 mg/kg (ppm) water vapor).5.5.5 Fittings, for transferring chlorine from one cylinder toanother.5.5.6 One 0 to 10 L Syringe and One 0 to 25 L Syringe,26
21、gage needle.5.5.7 Dewar Flask, of sufficient size to hold a cylindersurrounded 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 mg/kg (ppm) in glove bag or dry box.5.6 Silicone Rubbe
22、r Septa.5.7 Mechanical Shaker.5.8 Drying Oven.5.9 Special Infrared Process 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 reporte
23、din the scope is achievable with a 60-mm pathlength cellconstructed with:5.9.1 Hastelloy C and 316 Stainless Steel Stock, suitable formachining.5.9.2 Silver Chloride Windows, two, 25-mm diameter by2-mm thick and two 25-mm diameter by 4-mm thick.5.9.3 Eight Viton O-rings, Size 027.6. Reagents6.1 Puri
24、ty of WaterUnless otherwise indicated, watermeans Type II or III reagent water conforming to SpecificationD 1193.6.2 Chlorine, liquid with less than 5 mg/kg (ppm) water.6.3 Methylene Chloride (CH2Cl2).NOTE 2This reagent is used for cooling purposes only.6.4 Dry Ice (CO2).6.5 Dry Nitrogen (5 mg/kg (p
25、pm) water), to purge glovebag or dry box 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 material is analyzedin the laboratory.7.1.2 Perso
26、ns who are thoroughly familiar with the handlingof chlorine should perform this analysis. An experiencedperson should not work alone. The analyst must be providedFIG. 5 Gasket DetailFIG. 6 Insert DetailFIG. 7 Flange DetailE1786083with adequate eye protection (chemical goggles are recom-mended) and a
27、n 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 chlorine out ofdoors, warn people downwind from such operations of thepossible release of chlorine.7.1.4 Dispos
28、e 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 and sampling regimen requires aninitial purging of chlorine from a container, the purged chlorineshould be si
29、milarly handled. Avoid purging to the atmosphere.FIG. 8 Sample Cylinder AssemblyFIG. 9 Special Infrared Process CellE17860847.1.5 In the event chlorine is inhaled, use first aid immedi-ately.8. Sampling for Calibration Standards8.1 Carefully choose sampling points. Ensure that thesample point is ass
30、ociated 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 secondary piping, purge that piping wellwith nitrogen or dry air before being blocked in. Otherwise,temperature varia
31、tions 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 chlorine needing to be analyzed; that is, samplepure chlorine after all purification steps, drying steps, and sofo
32、rth, 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 capable of delivering a liquid sample (not gas).Acceptable samples can be obtained by sampling in accordance
33、with the Chlorine Institute Pamphlet No. 77. (See 49 CFR 173,including Parts 173.304, 173.314, and 173.315.)8.2 Collect samples from these facilities in the samplecylinder assembly listed in 6.5. Follow proper and safesampling techniques. The cylinder must contain at least 75 %by volume of liquid ch
34、lorine (less than 25 % vapor space).NOTE 3Do 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 chlorine) and by 0.75 to obtain the weight of
35、 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 Thoroughly dry the sample cylinders by placing them
36、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 are cooled with plant air or N2having 5 mg/kg(
37、ppm) moisture. The valves are removed, placed in a desiccatorwith a 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 pressure-tested. Equip threewith a ball va
38、lve 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 infrared cell before standards are loade
39、d.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 mg/kg(ppm) moisture before performing any transfers of chlorine.9.2 Load the four cylinders with liquid chlorine. The liquid
40、chlorine should contain less than 5 mg/kg (ppm) water. Allcylinders must contain at least 75 % by volume of liquidchlorine (less than 25 % vapor space). All cylinders should beweighed to the nearest gram and recorded to determine theweight of chlorine in each cylinder (Note 3). Place the filledcylin
41、ders into the glove bag or dry box inside the hood. Placeall fittings, tools and equipment, including the purged infraredcell, in the glove bag or dry box. Wait until the hygrometer inthe glove bag or dry box is reading 5 mg/kg (ppm) moisturebefore proceeding.9.3 Remove the cap on Valve A of Cylinde
42、r 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 apparatus are closed
43、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 partiallyopening Valve D
44、 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 Valve A and open V
45、alve B, to purge the fillingapparatus, then close.9.7 Remove the cylinder. Connect Cylinder No. 2 to thefilling apparatus after blowing ValveAwith 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 valves on allpart
46、s 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.9.9 Vent the res
47、idual 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 to ambient temp
48、erature. 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 morethan15 to14 of the cell window is vapor s
49、pace when the cellis inverted. 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 filled 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.E17860859.13 Lo
