ASTM D5462-02

Standard Test Method for On-Line Measurement of Low-Level Dissolved Oxygen in Water

SIGNIFICANCE AND USE
DO may be either a corrosive or passivating agent in boiler/steam cycles and is therefore controlled to specific concentrations that are low relative to environmental and wastewater treatment samples. Out-of-specification DO concentrations may cause corrosion in boiler systems, which leads to corrosion fatigue and corrosion products—all detrimental to the life and efficient operation of a power unit. The efficiency of DO removal from boiler feedwater by mechanical or chemical means, or both, may be monitored by continuously measuring the DO concentration before and after the removal process with on-line instrumentation. DO measurement is also a check for air leakage into the boiler water cycle.
Guidelines for feedwater to high-pressure boilers with all volatile treatment generally require a feedwater DO concentration below 5 μg/L (3).
Boiler feedwater with oxygenated treatment is maintained in a range of 50 to 300 μg/L DO (4).
In microelectronics production, DO can be detrimental in some manufacturing processes, for example, causing undesirable oxidation on silicon wafers.
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.

General Information

• Status: Historical
• Publication Date: 09-Jun-2002
• ICS: 13.060.50 - Examination of water for chemical substances
• Technical Committee: D19 - Water
• Drafting Committee: D19.03 - Sampling Water and Water-Formed Deposits, Analysis of Water for Power Generation and Process Use, On-Line Water Analysis, and Surveillance of Water

Relations

• Replaces: ASTM D5462-01 - Standard Test Method for On-Line Measurement of Low-Level Dissolved Oxygen in Water
• Effective Date: 10-Jun-2002
• Replaced By: ASTM D5462-08 - Standard Test Method for On-Line Measurement of Low-Level Dissolved Oxygen in Water
• Effective Date: 01-May-2008
• Referred By: ASTM D5127-13(2018) - Standard Guide for Ultra-Pure Water Used in the Electronics and Semiconductor Industries
• Effective Date: 10-Jun-2002

Standards Content (Sample)

NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.
Contact ASTM International (www.astm.org) for the latest information
Designation:D5462–02
Standard Test Method for
On-Line Measurement of Low-Level Dissolved Oxygen in
1
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 3.2.2 equilibrium-type probes—modified polarographic
sensing probes that have a negligible influx of oxygen through
1.1 This test method covers the on-line determination of
the membrane except during changes of sample DO concen-
dissolved oxygen (DO) in water samples primarily in ranges
tration. Oxygen consumption and regeneration balance each
from 0 to 500 µg/L(ppb), although higher ranges may be used
otherwithintheprobesunderstableconditions,andthenetflux
for calibration. On-line instrumentation is used for continuous
through the membrane is insignificant.
measurements of DO in samples that are brought through
3.2.3 galvanic systems—sensing probes and measuring in-
sample lines and conditioned from high-temperature and high-
struments that develop an electrical current from two elec-
pressure sources when necessary.
trodes inside the probe from which the final measurement is
1.2 This standard does not purport to address all of the
derived.
safety concerns, if any, associated with its use. It is the
3.2.4 partial pressure (of oxygen)—the volume fraction of
responsibility of the user of this standard to establish appro-
oxygen multiplied by the total pressure.The partial pressure of
priate safety and health practices and determine the applica-
oxygenistheactualparameterdetectedbyDOprobes,whether
bilityofregulatorylimitationspriortouse.Forspecifichazards
in air or dissolved in water.
statements, see 6.5.
3.2.5 polarographic systems—sensing probes and measur-
2. Referenced Documents ing instruments that include circuitry to control the operating
voltage of the system, usually using a third (reference) elec-
2.1 ASTM Standards:
2
trode in the probe.
D 1066 Practice for Sampling Steam
2
D 1129 Terminology Relating to Water
4. Summary of Test Method
D 1192 Specification for Equipment for Sampling Water
2
4.1 Dissolved oxygen is measured by means of an electro-
and Steam in Closed Conduits
2 chemical cell separated from the sample by a gas-permeable
D 1193 Specification for Reagent Water
membrane. Behind the membrane and inside the probe, elec-
D 2777 Practice for Determination of Precision and Bias of
2 trodes immersed in an electrolyte develop an electrical current
Applicable Methods of Committee D-19 on Water
proportional to the oxygen partial pressure of the sample.
D 3370 Practices for Sampling Water from Closed Con-
2 4.2 The partial pressure signal is temperature compensated
duits
automatically to account for variations with temperature of the
D 3864 PracticeforContinualOn-LineMonitoringSystems
2 following: oxygen solubility in water; electrochemical cell
for Water Analysis
output; and, when necessary, diffusion rate of oxygen through
3. Terminology the membrane. This yields a direct readout in concentration of
µg/L (ppb) or mg/L (ppm).
3.1 Definitions—For definitions of terms used in this test
4.3 Diffusion-type probes rely on a continuous diffusion of
method, refer to Terminology D 1129.
oxygen through the membrane. Immediately inside the mem-
3.2 Definitions of Terms Specific to This Standard:
brane, oxygen is reduced at the noble metal cathode, usually
3.2.1 diffusion-type probes—galvanic or polarographic sen-
platinum or gold. An electrical current is developed that is
sors that depend on the continuous influx of oxygen through
directly proportional to the arrival rate of oxygen molecules at
the membrane to develop the measurement signal.
the cathode, which is in turn dependent on the diffusion rate
through the membrane. The less noble anode, usually silver or
1
This test method is under the jurisdiction of ASTM Committee D19 on Water
lead, completes the circuit and is oxidized in proportion to the
and is the direct responsibility of Subcommittee D19.03 on Sampling of Water and
current flow.At steady state, the resulting current signal is then
Water-Formed Deposits, Surveillance of Water, and Flow Measurement of Water.
proportional to the oxygen partial pressure of the sample.
Current edition approved June 10, 2002. Published August 2002. Originally
published as D 5462 – 93. Last previous edition D 5462 – 93 (01).
2
Annual Book of ASTM Standards, Vol 11.01.
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D5462–02
Thorough descriptions of diffusion-type probes
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