ASTM D5173-1997(2007) Standard Test Method for On-Line Monitoring of Carbon Compounds in Water by Chemical Oxidation by UV Light Oxidation by Both or by High Temperature Combustion.pdf

《ASTM D5173-1997(2007) Standard Test Method for On-Line Monitoring of Carbon Compounds in Water by Chemical Oxidation by UV Light Oxidation by Both or by High Temperature Combustion.pdf》由会员分享，可在线阅读，更多相关《ASTM D5173-1997(2007) Standard Test Method for On-Line Monitoring of Carbon Compounds in Water by Chemical Oxidation by UV Light Oxidation by Both or by High Temperature Combustion.pdf（5页珍藏版）》请在麦多课文档分享上搜索。

1、Designation: D 5173 97 (Reapproved 2007)Standard Test Method forOn-Line Monitoring of Carbon Compounds in Water byChemical Oxidation, by UV Light Oxidation, by Both, or byHigh Temperature Combustion Followed by Gas PhaseNDIR or by Electrolytic Conductivity1This standard is issued under the fixed des

2、ignation D 5173; the number immediately following the designation indicates the year oforiginal adoption or, in the case 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 revisi

3、on or reapproval.1. Scope1.1 This test method covers the selection, establishment,and application of monitoring systems for carbon and carboncompounds by continual sampling or continuous flow-through,automatic analysis, and recording or otherwise signaling ofoutput data. The system chosen will depen

4、d on the purpose forwhich it is intended (for example, regulatory compliance,process monitoring, or to alert the user to adverse trends) andon the type of water to be monitored (low purity or high purity,with or without suspended particulates, purgeable organics, orinorganic carbon). If it is to be

5、used for regulatory compliance,the test method published or referenced in the regulationsshould be used in conjunction with this test method and otherASTM test methods. The test method covers carbon concen-trations of 10 g/L to 5000 mg/L.1.2 The values stated in SI units are to be regarded as thesta

6、ndard.1.3 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 regulatory limitations prior to use. For spec

7、ific hazardstatements, see Section 9.2. Referenced Documents2.1 ASTM Standards:2D 1129 Terminology Relating to WaterD 1193 Specification for Reagent WaterD 2777 Practice for Determination of Precision and Bias ofApplicable Test Methods of Committee D19 on WaterD 3370 Practices for Sampling Water fro

8、m Closed ConduitsD 3694 Practices for Preparation of Sample Containers andfor Preservation of Organic ConstituentsD 3864 Guide for Continual On-Line Monitoring Systemsfor Water AnalysisD 4453 Practice for Handling of Ultra-Pure Water SamplesD 4779 Test Method for Total, Organic, and InorganicCarbon

9、in High Purity Water by Ultraviolet (UV) orPersulfate Oxidation, or Both, and Infrared Detection3D 4839 Test Method for Total Carbon and Organic Carbonin Water by Ultraviolet, or Persulfate Oxidation, or Both,and Infrared Detection3. Terminology3.1 DefinitionsFor definitions of terms used in this te

10、stmethod, refer to Terminology D 1129 and Guide D 3864.4. Summary of Test Method4.1 A representative sample of a water stream, or the waterstream itself flows into a reaction chamber where all or someof the dissolved organic carbon is oxidized to carbon dioxideby either of two means: (1) a chemical

11、oxidant, an energysource such as ultraviolet (UV) radiation, or both, or (2) hightemperature combustion. This carbon dioxide is subsequentlymeasured in the gas phase by a non-dispersive infrareddetector, or is measured in solution by means of electrolyticconductivity. Interference may occur from the

12、 latter method ifthe water sample has a high conductivity.4.2 If there are suspended solids in the water stream, it isadvisable to filter them out to prevent accumulation andpossible blockage in the analyzer. The instrument will thenmeasure dissolved carbon plus any particulate carbon thatpasses the

13、 filter. This parameter is usually called dissolvedcarbon.4.3 If there is inorganic carbon present in the water (in theform of carbonate, bicarbonate, or carbon dioxide), it will alsobe detected as carbon dioxide. If inorganic carbon is notremoved before analysis, the monitor will report total carbo

14、n.1This test method is under the jurisdiction of ASTM Committee D19 on Waterand is the direct responsibility of Subcommittee D19.03 on Sampling Water andWater-Formed Deposits, Analysis of Water for Power Generation and Process Use,On-Line Water Analysis, and Surveillance of WaterCurrent edition appr

15、oved June 15, 2007. Published July 2007. Originallyapproved in 1991. Last previous edition approved in 2001 as D 5173 97 (2001).2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards volume informatio

16、n, refer to the standards Document Summary page onthe ASTM website.3Withdrawn.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.4.4 Inorganic carbon is removed from the water stream byacidifying and sparging the sample. This process ma

17、y alsoremove purgeable organic compounds.4.5 Suspended elemental carbon will not be oxidized bylow-temperature methods.5. Significance and Use5.1 Accurate measurement of organic carbon in water at lowand very low levels is of particular interest to the electronic,pharmaceutical, and steam power gene

18、ration industries.5.2 Elevated levels of organics in raw water tend to degradeion exchange resin capacity. Elevated levels of organics in highpurity water tend to support biological growth and, in somecases, are directly detrimental to the processes that require highpurity water.5.3 In the case of s

19、team power generation, naturally occur-ring organics can become degraded to CO2and low molecularweight organic acids that, in turn, are corrosive to the processequipment. Their effect on conductivity may also cause waterchemistry operating parameters to be exceeded, calling forplant shutdown.5.4 In

20、process water in other industries, organic carbon cansignify in-leakage of substances through damaged piping andcomponents, or an unacceptable level of product loss.5.5 In wastewater treatment, organic carbon measurementof influent and in-process water can help adjust optimizetreatment schemes. Meas

21、urement of organic carbon at dis-charge may contribute to regulatory compliance.6. Interferences6.1 If inorganic carbon (dissolved CO2and ions in equilib-rium with it) is present, it will give a false positive to anorganic carbon measurement. Ion exchange resins used forhigh purity water production

22、typically strip CO2from thewater, so this interferent is absent from such water unless thewater stream comes in contact with the atmosphere prior toanalysis.6.2 If electrolytic conductivity is used for the measurementof CO2, other conductive species in solution will cause apositive interference unle

23、ss their background conductivity ismeasured and deducted.6.3 Particulates suspended in the water stream may causeblockage in the monitor over a period of time, and may also behard to oxidize. If problems are anticipated, the water streamshould be appropriately filtered upstream of the monitor. Thepa

24、rameter measured in the filtered water will be dissolvedorganic carbon (DOC).6.4 Non-dispersive infrared detectors tuned to CO2absor-bance are also sensitive to water vapor, which may thereforegive a positive interference unless removed.7. Apparatus7.1 Figs. 1-4 show in block diagram form several de

25、signs ofon-line total organic carbon (TOC) analyzers that have beensuccessfully introduced.8. Reagents and Materials8.1 Purity of ReagentsReagent grade chemicals shall beused in all tests. Unless otherwise indicated, all reagents shouldconform to the specifications of the Committee on AnalyticalReag

26、ents of the American Chemical Society.4Other gradesmay be used, provided it is first ascertained that the reagent isof sufficient purity to permit its use without decreasing theaccuracy of the determinations.8.2 Purity of Water:8.2.1 Unless otherwise stated, references to reagent watershall be under

27、stood to mean that conforming to SpecificationD 1193, Type II. The carbon content of this water should bemeasured regularly by a suitably sensitive test method, such asTest Method D 4779. It will typically be less than 0.2 mg/Lcarbon.8.2.2 Water as free as possible of organics is desirable whenestab

28、lishing the test method blank at carbon levels of less than1 mg/L. Absolutely carbon-free water is not obtainable inordinary circumstances. However, a working approximation tothis goal is the solution contained in the reaction vessel ofcarbon analyzers that UV-irradiate and sparge an acidifiedpersul

29、fate solution. Alternatively, water that has been acidified,mixed with persulfate to a final concentration of 2 % w/v,heated or exposed to ultraviolet radiation, or both, for at leastan hour, then thoroughly sparged, may be used.8.3 Amber glass bottles should be used to store reagentwater, organic-f

30、ree water, and standard solutions. The bottlesshould be dedicated to their respective types of solution.4Reagent Chemicals, American Chemical Society Specifications , AmericanChemical Society, Washington, DC. For suggestions on the testing of reagents notlisted by the American Chemical Society, see

31、Analar Standards for LaboratoryChemicals, BDH Ltd., Poole, Dorset, U.K., and the United States Pharmacopeiaand National Formulary, U.S. Pharmacopeial Convention, Inc. (USPC), Rockville,MD.NOTE 1The unit employs available water system pressure to rinse theline and test chamber, followed by a downstre

32、am valve closure thatisolates the sample. Subsequent irradiation with intense UV light breaksdown organic compounds in the water, with the liberated carbon formingcarbon dioxide in solution as carbonic acid. By monitoring the change insample conductivity, corrected for temperature, the TOC concentra

33、tion iscalculated and displayed.FIG. 1 Low Temperature UnitD 5173 97 (2007)2Practices D 3370, D 3694, and D 4453 address handling ofwater samples. While the most rigorous method of cleaningglassware is described below, Practice D 4453 has alternativeprocedures not involving Cr(VI).8.3.1 Clean bottle

34、s with chromic acid, rinse several timeswith water, and dry overnight at 400C in a muffle furnace.8.3.2 Rinse the TFE-fluorocarbon-lined closures severaltimes with water, then allow to soak in water overnight. Rinsethese closures again with water before use.8.3.3 Put the closures loosely on the bott

35、les while the latterare still warm. When the bottles have cooled to room tempera-ture, tighten the closure.8.3.4 Follow the cleaning procedure in 8.3.1 through 8.3.3before each re-use of the bottles.8.4 Gas SupplyUse a gas free of CO2and organic matter,of a purity as specified by the equipment manuf

36、acturer. Oxygenis recommended.8.5 Organic Carbon Solution, Standard:8.5.1 Prepare high-concentration calibration standards(2000 mg/L carbon) using a water-soluble, stable compound.This stock solution can then be further diluted to a concentra-tion suitable for the method used. (See 8.5 of Test Metho

37、dD 4779.)NOTE 1This unit is designed to continually measure TOC in a watersample. The sample flows into a sample overflow chamber and out todrain. Every 5.5 min, acid and sample are aspirated into the carbonateremoval system. The inorganic carbon in the combined acid/sample issparged with nitrogen g

38、as. A fixed volume of sparged inorganic “carbon-free” sample is then injected into the reaction chamber heated at 900C.The organics in the sample are oxidized to carbon dioxide. The carrier gasflows continuously through the reaction chamber, carrying the CO2through a gas-liquid separator into the in

39、frared analyzer. The concentra-tion of CO2measured is directly correlated to the carbon concentration inthe sample.FIG. 2 High Temperature UnitNOTE 1OperationThe water sample is pumped continuously to theconductivity block where the inlet conductivity is measured to establishthe baseline. The sample

40、 then flows to the UV reaction chamber where theorganics are oxidized to form organic acids, as described in the followingformula:organics + O2+ UV light rCOOHAs the organics oxidize to organic acids, the conductivity of the sampleincreases. Next, the sample flows through the outlet conductivity det

41、ector,and then to drain. The electronics continuously compare the temperature-corrected conductivity readings from the inlet and outlet detectors, andderive the organic content of the sample in micrograms/litre that is shownon a digital display.FIG. 3 Low Temperature UnitContinuous Flow for High-Pur

42、ityWaterNOTE 1This TOC analysis unit uses ultraviolet-promoted persulfateoxidation combined with infrared detection to continuously determine theconcentration of organics in water. Sample flows continuously into theanalyzer through a sample bypass, either by means of process pressure, oran optional

43、sample pump. A side stream for analysis is continuouslypumped at a constant rate and acidified with a sodium persulfate/phosphoric acid solution, that reacts with any inorganic carbon to formCO2. The acidified sample is then sparged with carrier gas (N2or O2)toremove the CO2. Passing through a liqui

44、d/gas separator, the CO2isvented, and the liquid flows to the reaction chamber, where it is exposedto ultraviolet light. The UV radiation catalyzes the persulfate oxidation ofthe remaining organic carbon to CO2. The CO2-laden carrier gas is passedthrough a permeation dryer to remove moisture, and th

45、en through theNDIR detector, that measures the CO2. The electronics linearize and scalethe IR detector signal to equate to milligrams/litre organics, displayed onthe digital read-out.FIG. 4 Low Temperature UV-Persulfate UnitContinuous FlowD 5173 97 (2007)38.5.2 The compound used for calibration shou

46、ld be assimilar as possible to the compound(s) expected to be presentin the water to be analyzed.9. Hazards9.1 Give full consideration to safe disposal of the analyzersspent samples and reagents (especially chromic acid), andcleaning solutions.9.2 Provide pressure relief valves, if applicable, to pr

47、otectboth the analyzer and monitoring system.9.3 Take precautions when using cylinders containing gasesor liquids under pressure:9.3.1 Gas cylinders must be handled by trained personnelonly.9.3.2 Fasten gas cylinders to a rigid structure.9.3.3 Take special safety precautions when using or storingcom

48、bustible or toxic gases to ensure that the system is safe andfree of leaks.10. Technical Considerations10.1 Carefully define the measurement objective for themonitoring system before specifying the apparatus. Considersuch factors as the expected total level of carbon; whethersignificant inorganic ca

49、rbon is likely to be present; whetherthere are significant levels of purgeable organic compounds inthe stream; whether there are particulates in the water; how fastthe system must respond to a change in carbon concentration inthe stream; how accurate the result must be to meet internal andexternal requirements; and how readily the monitors calibra-tion and performance can be checked.10.2 If the monitoring system is intended primarily todetermine compliance with regulatory standards, the accuracy,precision, frequency of sampling, and response time may bedictated by