Designation: D 5543 – 94 (Reapproved 1999)
e1
Standard Test Methods for
Low-Level Dissolved Oxygen in Water 1 This standard is issued under the fixed designation D 5543; the number immediately following the designation indicates the year of original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A superscript superscript epsilon epsilon (e) indicates an editorial change since the last revision or reapproval.
e1 NOTE—Footnotes were editorially removed in June 1999.
1. Scope Scope
D 3370 3370 Practi Practices ces for Sampli Sampling ng Water ater from from Closed Closed ConCon2 duits
1.1 These test methods methods cover the determination determination of low-level (<100µ g/L) dissolved oxygen in thermal-cycle steam condensate, sate, deaerated deaerated boiler feedwater feedwater,, boiler boiler water, water, and deaerated deaerated deionized water. The following test methods are included: Test Method A—Color Comparator Test Method Using Self-Filling Glass Ampoules Test Method B—Instrument Test Method Using Self-Filling Glass Ampoules
R an ange, ge, µg/L µg/L 0 to 100
Secti ection ons s 8 to 17
0 to 100
18 to 26
3. Terminology 3.1 Definitions—For definitions of terms used in these test methods, refer to Terminology D 1129. 4. Significanc Significancee and Use 4.1 Dissolved Dissolved oxygen is detrimen detrimental tal in certain certain boiler boiler and steam cycles because it may accelerate corrosion. Concentrations above 10 µg/L are unacceptable in many high-pressure boiler boiler systems. systems. The eff efficiency iciency of dissolved dissolved oxygen removal removal from boiler feedwater by chemical or mechanical means, or both, is determined by measuring the concentration before and after the process. The measurement is also made to check for air leakage into the boiler system. 4.2 The oxygen oxygen treat treatmen mentt metho method d for boiler boiler corros corrosion ion reduction requires injection of oxygen into the boiler feedwater ter. The The resu result ltin ing g oxyg oxygen en leve levell is moni monito tore red d for for cont contro roll purposes.
1.2 These These test test method methodss may be applic applicabl ablee to electr electroni oniccgrade, grade, pharmaceut pharmaceutical ical-grad -grade, e, and other high-puri high-purity ty waters, waters, although these were not addressed in the collaborative study. 1.3 Test Method A is a colorimetric procedure applicable applicable to dissolved oxygen in water in the range from 0 to 100 µg/L. 1.4 Test Method B is an instrumented instrumented colorimetr colorimetric ic proceprocedure applicable to dissolved oxygen in water in the range from 0 to 100 µg/L. 1.5 It is the user’s responsibi responsibility lity to ensure ensure the validity validity of these test methods for waters of untested matrices. 1.6 The values values stated in SI units are to be regarded regarded as the standard. standard d does does not purpor purportt to addre address ss all of the 1.7 This standar safe safety ty conc concer erns ns,, if any any, asso associ ciat ated ed with with its its use. use. It is the the responsibility of the user of this standard to establish appro priate safety and health practices and determine the applicability of regulatory limitations prior to use.
5. Reagents Reagents 5.1 This test method does does not require the preparation preparation of any reagents. All the necessary analytical reagents are provided by the manufacturer in sealed ampoules. Purity of Water — Unless 5.2 Purity Unless otherwise otherwise indicated, indicated, referreferences to water shall be understood to mean reagent water as defined by Type II of Specification D 1193.
2. Referenced Documents
6. Precauti Precautions ons
2.1 ASTM Standards: D 1066 Practice Practice for Sampling Steam Steam 2 D 1129 Terminology Terminology Relating to Water2 D 1192 1192 Specificat Specification ion for Equipment Equipment for Sampling Sampling Water and Steam in Closed Conduits 2 D 1193 1193 Specification for Reagent Water Water 2 D 2777 Practice for Determination Determination of Precision and Bias Bias of 2 Applicable Methods of Committee D-19 on Water
6.1 Users Users must must exerci exercise se cautio caution n by using using finger finger cots, cots, in accordanc accordancee with the manufactur manufacturer’s er’s instructio instructions, ns, when handling the mixing of sample and reagent in the glass ampoules. 7. Sampling Sampling 7.1 Samplin Sampling g is the most critic critical al part part of any dissol dissolved ved oxygen test. The sample stream must be completely leak-free, since even the smallest leak can elevate the oxygen level in the sample and cause large errors in the results. New or intermittently used sampling systems must be purged for a minimum of 4 h. Sample streams that are used routinely may require only a few minutes of purging. 7.2 Collec Collectt the sampl samples es in accord accordanc ancee with with Practi Practices ces D 1066 and D 3370 and Specification D 1192.
1
These test methods are under the jurisdiction of ASTM Committee D19 on Water and are the direct responsibility of Subcommittee D19.03 on Sampling of Water and Water-Formed Deposits, Surveillance of Water, and Flow Measurement of Water. Current edition approved Nov. 15, 1994. Published January 1995. 2 Annual Book of ASTM Standards Standards,, Vol 11.01.
Copyright © ASTM, 100 Barr Harbor Drive, West Conshohocken, PA 19428-2959, United States.
1
D 5543 7.3 Wit 7.3 ith h wa wate terr un unde derr pr pres essu sure re,, co conn nnec ectt a tu tube be of in iner ertt material to the inlet and extend the tube outlet to the bottom of the sample bottle or tube. Use stainless steel, Type 304 or 316, or glass tubing with short neoprene connections. Do not use copper tubing, long sections of neoprene tubing, or other types of elastomeric polymeric materials. If the water being sampled is abo above ve roo room m tem temper peratu ature, re, the sam sample ple lin linee sha shall ll con contai tain n a suitable cooling coil to cool it to approximate room temperature.
NOTE 1—Meas 1—Measure uremen ments ts of 0 to 100 µg/L of diss dissolve olved d oxyg oxygen en are unaffected by the presence of 2200 mg/L boron present as boric acid at pH 6 and above in the absence of hydrogen peroxide.
10.5 Benzoquinone, an oxidation oxidation product of hydroquinone, hydroquinone, interferes with this test method. One hundred micrograms per litre of benzoquinone may appear as 33 µg/L dissolved oxygen. 10.6 Reduc Reducing ing agents such as hydrazine hydrazine and sulfit sulfitee do not interfere at 5-mg/L (ppm) levels in the sample. 10.7 10. 7 Amp Ampoul oules es mus mustt be pro protec tected ted fro from m li light ght to pre preven ventt darkening darke ning.. Foll Follow ow the manuf manufactur acturer’s er’s stor storage age recom recommend mendaations. 10.8 Color comparator tubes tubes must be protected from from light to prevent fading. Follow the manufacturer’s storage recommendations.
TEST METHOD A—COLOR COMPARATOR TEST METHOD USING SELF-FILLING GLASS AMPOULES 8. Sco Scope pe 8.1 This test method covers the rapid, rapid, routine determination determination of diss dissolved olved oxygen in stea steam m conde condensate nsate,, deaer deaerated ated boiler feedwater, and deaerated deionized water. Color comparators allow the estimation of concentrations ranging from 0 to 100 µg/L (ppb) oxygen. 8.2 8. 2 This te test st me meth thod od wa wass te test sted ed in st stea eam m co cond nden ensa sate te,, deaerated boiler feedwater, and deaerated deionized water. It is the use user’s r’s res respon ponsib sibili ility ty to ens ensure ure the val validi idity ty of the tes testt method for waters of untested matrices.
11. Apparatus 11.1 Color Comparator , for 0, 2, 4, 6, 8, 12, 16, and 20 µg/L (ppb) of oxygen. 11.2 Color Comparator , for 0, 5, 10, 15, 20, 25, 30, and 40 µg/L (ppb) of oxygen. 11.3 Color Comparator , for 0, 10, 20, 30, 40, 60, 80, and 100 µg/L (ppb) of oxygen. 11.4 Sampling Tube. See Fig. 1.
9. Summ Summary ary of Test Test Method
12. Reag Reagents ents and Materials Materials
9.1 9. 1 Th Thee ti tip p of a pa part rtia iall lly y ev evac acua uate ted d se seal aled ed am ampo poul ulee is broken whi broken while le sub submer merged ged in a flow flowing ing wat water er sam sample ple.. The sample sam ple is dra drawn wn int into o the amp ampoul oulee whe where re it rea reacts cts ins instan tantataneousl neo usly y wit with h the oxy oxygen gen-se -sensi nsitiv tivee ind indica icator tor to pro produc ducee a reddis red dish h vio violet let col color or who whose se int intens ensity ity is pro propor portio tional nal to the 3 concentration of dissolved oxygen.
12.1 Seal Sealed, ed, evacu evacuated ated glass ampo ampoules ules containing containing oxygensensitive indicator. 13. Sampl Sampling ing 13.1 Atta Attach ch the feedwater feedwater sourc sourcee to the plastic sampling sampling tube as described in 7.3. Clamps may be attached to the tube to hold it vertical, or it can be attached to a vertical rod or pipe above a sink, drain, or bucket.
10. Interference Interferencess 10.1 Color Color,, turbi turbidity dity,, and oxidi oxidizing zing impu impuriti rities es inte interfer rferee in this test method to yield high results. If the sample is colored or tur turbid bid or con contai tains ns oxi oxidiz dizing ing im impur puriti ities, es, the amo amount unt of interference that may be contributed by such effects must be determined independently prior to using this test method. 10.2 10. 2 Eas Easil ily y red reduce uced d met metal al ion ionss may interfer interferee in thi thiss tes testt method to cause high results. For example, 100 µg/L (ppb) Cu +2 may appear as 5 µg/L (ppb) dissolved oxygen, and 100 µg/L Fe+3 may appear as 7 µg/L dissolved oxygen. However, less than 50 µg/L Cu +2 or Fe+3 cause less than 1-µg/L interference. 10.3 Hydro Hydrogen gen peroxide peroxide alone in conce concentra ntration tionss up to 200 µg/L does not affect the measurement of 1.5 µg/L of dissolved oxygen. Above 200 µg/L hydrogen peroxide, there is a positive positive interference of 3.3 µg/L dissolved oxygen per 100 µg/L excess over 200 µg/L hydrogen peroxide. 10.4 The following following inter interfere ferences nces occur in the presence presence of 2200 mg/L boron present as boric acid: ( 1) at pH levels below pH 6, recovery can be as low as 80 %; ( 2) added hydrogen peroxi per oxide de at a con concen centra tratio tion n of 0.1 mg/ mg/L L yie yields lds a pos positi itive ve interf int erfere erence nce of 10 µg/ µg/L L dis dissol solved ved oxy oxygen gen;; and ( 3) add added ed hydrogen peroxide in a concentration range from 0.5 to 650 mg/L yields a positive interference of 20 to 25 µg/L.
14. Calibration and Standardization 14.1 No calibration calibration is required. required.
3
Spokes, G. N., Dissolved Oxygen in Water Measurement and Standardization , EPRI PWR Plant Chemists’ Meeting, San Diego, CA, Nov. 17–20, 1992. Copies obtainable from CHEMetrics Inc., Route 28, Calverton, VA 22016.
FIG. 1 Sampling Tube for Use with Ampoules to Measure Dissolved Dissolved Oxygen in a Flowing Flowing Water Water Sample
2
D 5543 NOTE 2—The 2—The col color or com compar parato atorr stan standar dards ds are pre precal calibr ibrate ated d by the manufacturer for measurement of dissolved oxygen in water.
the comparator label. Estimate the concentration to within a half color standard interval.
14.2 A disso dissolvedlved-oxyge oxygen-inn-in-water water standard may be gener gener-ated by following the procedures given in Appendix X1.
16. Calc Calculati ulation on
15. Proc Procedur eduree
16.1 16. 1 The dissolve dissolved d oxy oxygen gen content content of the sample sample is the value obtained in 15.4. Use the average of the two resulting values if two ampoules are used.
15.1 Inser Insertt the ampou ampoule le into the samp sampling ling device, device, with the pointed end down. Allow the sample to flow at least 5 min. A15-m A15 -min in wai waitt tim timee may be nec necess essary ary to ach achiev ievee the best accuracy for samples with below 20 µg/L of dissolved oxygen. 15.2 15 .2 Gently Gently pr pres esss th thee am ampo poul ulee to towa ward rd th thee wa wall ll of th thee sampling tube to snap off the tip, and remove thc ampoule, keeping the tip down, immediately after filling is complete. 15.3 Using a protective rubber rubber finger cot, place a finger finger over the bro broken ken tip tip.. Caution: glass glass ma may y be sh shar arp. p. In Inve vert rt th thee ampoule several times to mix the contents, allowing the bubble to travel from end to end each time. Wipe all liquid from the exterior of the ampoule.
17. Prec Precisio ision n and Bias
4
17.1 The overall 17.1 overall pre precis cision ion and bias of thi thiss tes testt met method hod cannot be determined by round-robin testing because of the instability of shipping solutions. 17.2 17. 2 Thi Thiss tes testt met method hod was eva evalua luated ted for sin single gle-op -opera erator tor precision preci sion by eight laborator laboratories, ies, with a total of 15 operators operators running a total of 200 samples in triplicate. The collaborative test te st da data ta we were re ob obta tain ined ed on th thee sa samp mple less av avai aila labl blee at th thee laboratory site locations. These data may not apply for other matrices. 17.2.1 The single-operator single-operator precision, precision, S , of this test method was found to be dependent on the ampoule type and to be partly par tly dep depend endent ent on the dis dissol solved ved oxy oxygen gen con conten tentt of the sample. The data are summarized in the tables that follow. 17.2.1.1 The data in the following table table were obtained using 0 to 20-µg/L (ppb) range ampoules and comparators. 5 A total of 66 samples samples was mea measur sured ed in triplica triplicate te by a tot total al of 15 operators in 8 laboratories:
NOTE 3—A small bubble of inert gas will remain in the ampoule to facilitate mixing. NOTE 4—Due to the possibility of air leaking in during this step, it is advisable to run tests in duplicate. It should be noted, however, that some variation in observed concentrations may be due to changes in system conditions.
o
15.4 Use the col 15.4 color or com compar parato atorr as ill illust ustrat rated ed in Fig Fig.. 2 to determine the level of dissolved oxygen in the sample. Place the ampoule in the center (empty) tube of the comparator, with the flat end downward. Direct the top of the comparator toward a source of bright, white light while viewing from the bottom. Hold the comparator in a nearly horizontal position, and rotate it until the color standard below thc ampoule shows the closest match. Complete this color matching procedure in less than 30 s after snapping the tip in the sample.
R ang ange, e, µg µg/L /L (p (pp pb) S o
0 to 0. 0.9 9 0.20
1 to 4.9 1.6
5 to 9.9 2.5
10 to 14 14.9 .9 1.4
15 to 20 3.2
17.2.1.2 The data in the following table table were obtained using 0 to 40-µg/L (ppb) range ampoules and comparators. 6 A total of 78 samples samples was mea measur sured ed in triplica triplicate te by a tot total al of 14 operators in 7 laboratories: Range, Rang e, µg µg/L /L (p (ppb pb)) 0 to 1. 1.9 9 S 0.15 o
NOTE 5—The color intensity may continue to increase after the rapid initial init ial colo colorr rea reactio ction. n. Howe However ver,, it is the initial color rea reacti ction on tha thatt is complete within 30 s, and to which the system calibrations apply.
2 to 9. 9.9 9 1.4
10 to 19 19.9 .9 2.8
20 to 29 29.9 .9 2.7
30 to 40 2.2
17.2.1.3 The data in the following table table were obtained using 0 to 100-ppb range ampoules and comparators. 7 A total of 56 samples was measured in triplicate by a total of 10 operators in 6 laboratories.
15.4.1 Fin 15.4.1 Find d the ana analyt lytica icall res result ult fro from m the con concen centra tratio tion n value of the closest matching color standard as designated on
Range, Rang e, µg µg/L /L (p (ppb pb)) S o
0 to 4. 4.9 9 0.95
5 to 19 19.9 .9 1.1
20 to 39 39.9 .9 40 to 59 59.9 .9 60 to 10 100 0 1.4 5.3 2.9
17.3 Eight independen independentt labor laborator atories ies (and a tota totall of fifteen operators) participated in this study. Precision testing for this test method conforms to Practice D 2777. TEST METHOD B—INSTRUMENT TEST METHOD USING SELF-FILLING GLASS AMPOULES 18. Scope 18.1 This test method covers covers the rapid routine determination determination of dissolved dissolved oxygen in stea steam m conde condensat nsate, e, deaer deaerated ated boiler
4 Supporting Suppo rting data have been filed at ASTM Headquarters. Headquarters. Request RR:D1 RR:D1991153. 5 CHEMet CHE Metrics rics Cata Catalog log No. K7511 K7511 kits or R75 R7511 11 ampoule ampoule with a C75 C7511 11 comparator. 6 CHEMetrics Catalog No. K7540 kits or R7540 ampoule with C7540 comparator. 7 CHEMet CHE Metrics rics Catalog Catalog No. K7599 K7599 kit kitss or R75 R7540 40 or R75 R7599 99 ampoule ampoule with a C7599 comparator.
FIG. 2 Use of the Comparator—Test Method A
3
D 5543 23. Sampl Sampling ing
feedwater,, and deaer feedwater deaerated ated deion deionized ized water water.. This inst instrume rumental ntal test method provides a digital presentation of dissolved oxygen concentrations ranging from 0 to 100 µg/L (ppb). 18.2 18. 2 Thi Thiss tes testt me metho thod d was tes tested ted on ste steam am con conden densat sate, e, deaerated boiler feedwater, and deaerated deionized water. It is the use user’s r’s res respon ponsib sibili ility ty to ens ensure ure the val validi idity ty of the tes testt method for waters of untested matrices.
23.1 Atta Attach ch the feedwater feedwater sourc sourcee to the plastic sampling sampling tube in accordance with 7.3. Clamps may be attached to the tube to hold it vertical, or it can be attached to a vertical rod or pipe above a sink, drain, or bucket. 24. Calibration and Standardization 24.1 No calibrati calibration on is required. required. A cali calibrat bration ion check ampoule ampoule is provided by the manufacturer. 24.2 A diss dissolved olved-oxyg -oxygen-i en-in-wat n-water er stan standard dard may be gener gener-ated by following the procedures given in Appendix X1.
19. Summ Summary ary of Test Test Method 19.1 19. 1 The tip of a par partia tially lly evacuate evacuated d sea sealed led ampoule ampoule is broken whi broken while le sub submer merged ged in a flow flowing ing wat water er sam sample ple.. The sample sam ple is dra drawn wn int into o the amp ampoul oulee whe where re it rea reacts cts ins instan tantataneously with oxygen-sensitive indicator to produce a reddish violet color whose intensity is proportional to the concentration of dissolved oxygen. 19.2 19 .2 The am ampo poul ulee is th then en pl plac aced ed in a bi bich chro roma mati tic, c, microprocessor-controlled microprocessor -controlled spectrophotometer instrument that is designed specially for measurement of the absorbance of the oxygen-sensitive indicator chromophore at 555 nm and referenced at 660 nm. 19.3 A digital readout readout of the determinati determination on is pres presented ented in micrograms per litre (parts per billion) oxygen.
25. Proc Procedur eduree 25.1 Foll Follow ow the proc procedure edure in accordance accordance with 15.1 through 15.3. 25.2 Foll Follow ow the manu manufactu facturer’s rer’s procedure proceduress to turn on and “zero” the measuring instrument. With the instrument in the“ ready” condition, place an ampoule in the instrument as shown in Fig. 3, and close the door firmly. Press the “run” button, and read rea d and rec record ord the dig digita itally lly dis displa played yed dis dissol solved ved oxy oxygen gen concentration. 26. Prec Precisio ision n and Bias
20. Interference Interferencess
4
26.1 The overall 26.1 overall pre precis cision ion and bias of thi thiss tes testt met method hod cannot be determined by round-robin testing because of the inability of shipped solutions. 8 26.2 26. 2 Thi Thiss tes testt met method hod was eva evalua luated ted for sin single gle-op -opera erator tor precision by 6 laboratories, with a total of 11 operators running a total of 93 samples in triplicate. These collaborative test data were obtained on the samples available at the laboratory site locations. These data may not apply for other matrices.
20.1 Interferences are in accordance with 10.1 through through 10.5. 21. Appa Apparatus ratus Bichromatic tic Instrum Instrument ent , micropr 21.1 Bichroma microprocessor ocessor-contro -controlled, lled, for measuring from 0.0 to 100 µg/L dissolved oxygen. 21.2 Sampling Tube. See Fig. 1.
22. Reag Reagents ents and Materials Materials 22.1 Seale Sealed, d, evac evacuated uated glass ampoules ampoules conta containing ining oxygensensitive indicator indicator..
8
CHEMetrics CHEMet rics OXYGE OXYGEN N DCR instrument with CHEMet CHEMetrics rics ampou ampoules les Catalog No. R7540 or R7599.
FIG. 3 Placement of Ampoule into Digital Instrument for Dissolved Oxygen Measurement
4
D 5543 26.2.1 The single-operator single-operator precision, precision, S , of this test method was fou found nd to be par partly tly dependen dependentt on the dissolve dissolved d oxy oxygen gen content of the sample. The data were obtained using a 0 to 100-µg/L (ppb) range instrument with ampoule. 8 The data are summarized in the following table:
operators) participated in this study. Precision testing for this test method conforms to Practice D 2777.
o
Range, Rang e, µg µg/L /L (p (ppb pb)) S o
0 to 4. 4.9 9 0.40
5 to 19 19.9 .9 4.2
20 to 39 39.9 .9 3.1
40 to 59 59.9 .9 3.1
27. Keyw Keywords ords 27.1 ampoules; bichromatic bichromatic instrument; boiler; boiler feedwater; col water; colori orimet metric ric ana analys lysis; is; dis dissol solved ved oxy oxygen gen;; oxy oxygen gen;; oxygen-sensitive indicator; steam; steam condensate
60 to 10 100 0 3.9
26.3 26. 3 Six ind indepe epende ndent nt lab labora orator tories ies (an (and d a tot total al of ele eleven ven
APPENDIX (Nonmandatory Information) X1. ESTABLISH ESTABLISHMENT MENT OF DISSOLVED OXYGEN IN WATER WATER STANDARDS
X1.2.8 Loose-Fitting Plastic Cap . X1.2.9 Fritted Bubbler . 10 X1.2.10 Thermometer , accurate to 0.2°C. 10 X1.2.11 Barometer . 10
X1.1 Dissolved oxygen-in-water oxygen-in-water standards may be made by bubbling bubbl ing oxyge oxygen-in n-in-nitr -nitrogen ogen gas mixt mixtures ures throu through gh a water sample. The apparatus and procedures described in this appendix permit the inexpensive and easy establishment of dissolved oxygen-in oxyge n-in-wate -waterr stand standards ards of good quali quality ty.. These stan standards dards may be used to check the accuracy of the self-filling ampoules, comparators, and instrument of Test Methods A and B.
X1.3 Caut Cautions ions X1.3.1 Use fresh water in a clea clean n system. To To obtain good results with this technique, use fresh water daily, and clean the gradua gra duate te reg regula ularl rly y wit with h a dil dilute ute hyp hypoch ochlor lorite ite sol soluti ution on to prevent biological growth. Rinse thoroughly. X1.3.2 X1. 3.2 Kee Keep p the sys system tem at atm atmosp ospher heric ic pre pressu ssure. re. Do not permit pressure to build up in the graduate by, for example, puttin put ting g tap tapee or wax over openings openings in the cap. The sys system tem pressure and hence dissolved oxygen content will increase by approximately 1 % for each 4 in. (102 mm) of water pressure (1.0 (1 .00 0 kP kPa) a) th that at is ap appl plie ied. d. Th Thee hi high gh ga gass flo flow w (2 (20 0 mL mL/s /s)) mainta mai ntains ins a sli slight ght pos positi itive ve pre pressu ssure re in the gra gradua duate te tha thatt is sufficient to prevent the ingress of atmospheric air. X1.3.3 Avoid allowing allowing bubbl bubbled ed gas to accu accumula mulate te aroun around d the tip of the ampoule. Occasional agitation and tapping of the snapper on the bottom of the graduate can dislodge bubbles and prevent their occurrence near the ampoule tip. One millilitre of gas mixture typically typically contains contains more than 30 time timess as much oxygen as 1 mL of water in oxygen equilibrium. The reaction of oxygen with Rhodazine D is irreversible so that bubbles of gas asp aspira irated ted acc accide identa ntally lly int into o the amp ampoul oulee can lea lead d to an erroneous (high) determination. X1.3.4 Do not use oxyge oxygen n scav scavenger enger chemicals chemicals.. Oxyge Oxygen n scavenger chemicals prevent the achievement of equilibrium of oxygen and pure water, and the Henry’s law (Eq 1) will not apply.
X1.1.1 The dissolved dissolved oxyge oxygen n conce concentra ntration tion attained attained is determined by Henry’s law: 9 C ~ µg / L! 5 X ~P 2 P w!exp T ! / T T% (X1.1) $16.9775 2 ~ 5268.95 2 1004170/ T
The gas pressure is P (bar), the fraction of oxygen is X , and the absolute temperature is T kelvins. P (bar) is the water vapor pressure given by the following: w
P w 5 exp $11.857 2 ~ 3840.7 1 216961/ T T ! / T T%
(X1.2)
1-mm Hg press pressure ure is equiv equivalen alentt to 0.001333 bar (0.13 (0.1333 33 kPa). X1.1.2 X1. 1.2 Ambient Ambient air pre pressu ssure re may be mea measur sured ed wit with h an accuratel accur ately y cali calibrate brated d barom barometer eter.. It may also be deter determine mined d from fro m the bar barome ometri tricc pre pressu ssure re rec record orded ed by a loc local al wea weathe therr station or airport, with a correction for the altitude difference between the laboratory and the weather station. X1.2 Appa Apparatus ratus X1.2.1 Graduate, cylindrical, 100 mL. 10 X1.2.2 Aluminum Ampoule Snapper , 10 in. (254 mm). X1.2.3 Square Plastic Tip Breaker . X1.2.4 Gas Flow Meter , equipped with needle valve, 0 to 2.5 L/mi L/min. n.10 X1.2.5 Compressed Gas Cylinder , containing 200 ft (5.66 m) certified oxygen in nitrogen gas mixture(s) with pressure regulator adjustable to give 20 to 30 psi (140 to 210 kPa). 11 X1.2.6 Nylon Tubing, 3-m length, 1 ⁄ 4-in. (6.35-mm) diameter.10 X1.2.7 Buret Stand and Clamps. 10
X1.4 Proc Procedur eduree X1.4.1 Assem Assemble ble the apparatus apparatus as shown in Fig. X1.1, with a the therm rmome ometer ter in pla place ce of the 1010-in. in. (25 (254-m 4-mm) m) alu alumin minum um snapper. Clamp the graduate vertical and fill to 100-mL mark with deionized or distilled water. Ensure that the fritted bubbler is approximately 2 cm from the bottom of the graduate. X1.4.2 X1. 4.2 Est Establ ablish ish a gas flow of 15 to 25 mL/s. Sparge Sparge the wate wa terr in th thee gr grad adua uate te fo forr 20 to 30 mi min n pr prio iorr to ma maki king ng measureme meas urements. nts. Measu Measure re the water temperature. temperature. Remove the thermometer.
9 Deriv De rived ed by J. M. Ha Hale le fro from m B. B. Benson Benson an and d D. Kr Krau ause, se, Jr. Jr.,, Limnol. Oceanogr., Vol 25, 1980, p. 662. Oceanogr., 10 Obtainable Obtain able from variou variouss laborat laboratory ory supply houses houses.. 11 Obtainable Obtain able from variou variouss compres compressed sed gas suppl suppliers. iers.
5
D 5543 down in the 10-in. (254-mm) aluminum snapper, and slowly lower the snapper assembly through the access hole in the cap to the bottom bottom of the graduate graduate.. Ens Ensure ure that the gas bub bubble ble stream does not pass immediately over the ampoule tip. Wait for 2 to 3 min and squeeze the syringe-like plunger of the snapper gently, thereby breaking the ampoule tip. Pause for a few seconds to allow the ampoule to fill with sample. Remove the sna snappe pperr ass assemb embly ly fro from m the gra gradua duate, te, and rem remove ove the ampoule ampou le from the asse assembly mbly.. Compl Complete ete the quant quantificat ification ion of diss di ssol olve ved d ox oxyg ygen en by Tes estt Me Meth thod od A or B wi with thin in 30 s of snapping the tip. X1.4.4 For 0 to 20-µg/L range ampoules, insert insert the ampoule tip down through the access hole in the cap and lower it to the bottom of the graduate. Wait 2 or 3 min, and use the edge of the square tip snapper at the bottom as a fulcrum against which to snap the tip. Pause until filling is complete. Then withdraw and quantitate the determination by Test Method A. X1.4.5 Calcu Calculate late the oxygen content content of the wate waterr using the formulae of Eq X1.1 and Eq X1.2. The oxygen-in-nitrogen gas mixtures (ppm by volume) that will generate particular dissolved oxygen in water concentrations at 760-mm Hg (101.3 kPa) pressure are presented in Table X1.1.
Dissolved Oxygen Standard Parts List Part A B C D E F G H I J
Description Entry Cap 10 in. Aluminum Snapper 1 / 4 in. Nylon Connection Tubing Flow Meter 100 mL Measuring Cyclinder Ampoule Bubbler Connection Line Tip Beaker Chip Gas Mixture In Bubbler
TABLE TABLE X1.1 Oxygen-in-Nitrogen Mixtures ppm (by Volume) Volume) Required to Generate µg/L (ppb) Dissolved Oxygen Standards at 760-mm 760-mm Hg (101.3 kPa) in Distilled Distilled Water
FIG. X1.1 Dissolved Oxygen Standard
X1.4.3 (Whe (When n usin using g ultr ultra-low a-low range 0 to 20-µg/L oxygen oxygen ampoules, skip to X1.4.4.) Place the self-filling ampoule tip
µg/L DO
15°C
2O°C
25°C
30°C
10 20 30 40 60 80 100
208 415 623 831 1246 1661 2077
230 461 691 921 1382 1843 2303
253 507 760 1014 1521 2028 2534
277 554 831 1108 1662 2216 2770
The American Society for Testing Testing and Materials takes no position respecting the validity of any patent rights asserted in connection with any item mentioned in this standard. Users of this standard are expressly advised that determination of the validity of any such patent rights, and the risk of infringement of such rights, are entirely their own responsibility. This standard is subject to revision at any time by the responsible technical committee and must be reviewed every five years and if not revised, either reapproved or withdrawn. Your comments are invited either for revision of this standard or for additional standards and should be addressed to ASTM Headquarters. Your comments will receive careful consideration at a meeting of the responsible technical committee, which you may attend. If you feel that your comments have not received a fair hearing you should make your views known to the ASTM Committee on Standards, at the address shown below. This standard is copyrighted by ASTM, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, Conshohocken, PA19428-2959, United States. Individual reprints (single or multiple copies) of this standard may be obtained by contacting ASTM at the above address or at 610-832-9585 (phone), 610-832-9555 (fax), or
[email protected] (e-mail); or through the ASTM website (www.astm.org).
6
