ASTM D5462-01
(Test Method)Standard Test Method for On-Line Measurement of Low-Level Dissolved Oxygen in Water
Standard Test Method for On-Line Measurement of Low-Level Dissolved Oxygen in Water
SCOPE
1.1 This test method covers the on-line determination of dissolved oxygen (DO) in water samples primarily in ranges from 0 to 500 µg/L (ppb), although higher ranges may be used for calibration. On-line instrumentation is used for continuous measurements of DO in samples that are brought through sample lines and conditioned from high-temperature and high-pressure sources when necessary.
1.2 This standard does not purport to address all of the safety problems, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use. For specific hazards statements, see 6.5.
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Standards Content (Sample)
Designation: D 5462 – 01
Standard Test Method for
On-Line Measurement of Low-Level Dissolved Oxygen in
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Water
This standard is issued under the fixed designation D 5462; 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 epsilon (e) indicates an editorial change since the last revision or reapproval.
1. Scope the membrane except during changes of sample DO concen-
tration. Oxygen consumption and regeneration balance each
1.1 This test method covers the on-line determination of
other within the probes under stable conditions, and the net flux
dissolved oxygen (DO) in water samples primarily in ranges
through the membrane is insignificant.
from 0 to 500 μg/L (ppb), although higher ranges may be used
3.2.3 galvanic systems—sensing probes and measuring in-
for calibration. On-line instrumentation is used for continuous
struments that develop an electrical current from two elec-
measurements of DO in samples that are brought through
trodes inside the probe from which the final measurement is
sample lines and conditioned from high-temperature and high-
derived.
pressure sources when necessary.
3.2.4 partial pressure (of oxygen)—the volume fraction of
1.2 This standard does not purport to address all of the
oxygen multiplied by the total pressure. The partial pressure of
safety concerns, if any, associated with its use. It is the
oxygen is the actual parameter detected by DO probes, whether
responsibility of the user of this standard to establish appro-
in air or dissolved in water.
priate safety and health practices and determine the applica-
3.2.5 polarographic systems—sensing probes and measur-
bility of regulatory limitations prior to use. For specific hazards
ing instruments that include circuitry to control the operating
statements, see 6.5.
voltage of the system, usually using a third (reference) elec-
2. Referenced Documents
trode in the probe.
2.1 ASTM Standards:
4. Summary of Test Method
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D 1066 Practice for Sampling Steam
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4.1 Dissolved oxygen is measured by means of an electro-
D 1129 Terminology Relating to Water
chemical cell separated from the sample by a gas-permeable
D 1192 Specification for Equipment for Sampling Water
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membrane. Behind the membrane and inside the probe, elec-
and Steam in Closed Conduits
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trodes immersed in an electrolyte develop an electrical current
D 1193 Specification for Reagent Water
proportional to the oxygen partial pressure of the sample.
D 2777 Practice for Determination of Precision and Bias of
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4.2 The partial pressure signal is temperature compensated
Applicable Methods of Committee D-19 on Water
automatically to account for variations with temperature of the
D 3370 Practices for Sampling Water from Closed Con-
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following: oxygen solubility in water; electrochemical cell
duits
output; and, when necessary, diffusion rate of oxygen through
D 3864 Practice for Continual On-Line Monitoring Systems
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the membrane. This yields a direct readout in concentration of
for Water Analysis
μg/L (ppb) or mg/L (ppm).
3. Terminology
4.3 Diffusion-type probes rely on a continuous diffusion of
oxygen through the membrane. Immediately inside the mem-
3.1 Definitions—For definitions of terms used in this test
brane, oxygen is reduced at the noble metal cathode, usually
method, refer to Terminology D 1129.
platinum or gold. An electrical current is developed that is
3.2 Definitions of Terms Specific to This Standard:
directly proportional to the arrival rate of oxygen molecules at
3.2.1 diffusion-type probes—galvanic or polarographic sen-
the cathode, which is in turn dependent on the diffusion rate
sors that depend on the continuous influx of oxygen through
through the membrane. The less noble anode, usually silver or
the membrane to develop the measurement signal.
lead, completes the circuit and is oxidized in proportion to the
3.2.2 equilibrium-type probes—modified polarographic
current flow. At steady state, the resulting current signal is then
sensing probes that have a negligible influx of oxygen through
proportional to the oxygen partial pressure of the sample.
Thorough descriptions of diffusion-type probes are given by
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This test method is under the jurisdiction of ASTM Committee D19 on Water
Hitchman (1) and Fatt (2).
and is 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 June 10, 2001. Published August 2001. Originally
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published as D 5462–93. Last previous edition D 5462–93 (01). The boldface numbers in parentheses refer to the list of references at the end of
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Annual Book of ASTM Standards, Vol 11.01. this test method.
Copyright © ASTM, 100 Barr Harbor Drive, West Conshohocken, PA 19428-2959, United States.
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D 5462
4.4 Equilib
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