ASTM D1498-14

Standard Test Method for Oxidation-Reduction Potential of Water

ABSTRACT
This test method covers the apparatus and procedure for the electrometric measurement of oxidation-reduction potential (ORP) in water. The test method described has been designed for the routine and process measurement of oxidation-reduction potential. ORP is defined as the electromotive force between a noble metal electrode and a reference electrode when immersed in a solution.� The ORP electrodes are inert and measure the ratio of the activities of the oxidized to the reduced species present. In addition, the ORP electrodes reliably measure ORP in nearly all aqueous solutions and in general are not subject to solution interference from color, turbidity, colloidal matter, and suspended matter. The apparatus to be used in the measurement of ORP includes: pH meter, reference electrode, oxidation-reduction electrode and electrode assembly. Materials necessary in the procedure for ORP measurement include chemical reagents, aqua regia, water, buffer standard salts, phthalate reference buffer solution, phosphate reference buffer solution, chromic acid cleaning solution, detergent, nitric acid, redox standard solution or ferrous-ferric reference solution, and redox reference quinhydrone solutions.
SCOPE
1.1 This test method covers the apparatus and procedure for the electrometric measurement of oxidation-reduction potential (ORP) in water. It does not deal with the manner in which the solutions are prepared, the theoretical interpretation of the oxidation-reduction potential, or the establishment of a standard oxidation-reduction potential for any given system. The test method described has been designed for the routine and process measurement of oxidation-reduction potential.  
1.2 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.  
1.3 This standard does not purport to address all of the safety concerns, 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.

General Information

• Status: Historical
• Publication Date: 14-Feb-2014
• ICS: 13.060.60 - Examination of physical properties of water
• 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

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: D1498 − 14
Standard Test Method for
1
Oxidation-Reduction Potential of Water
This standard is issued under the fixed designation D1498; 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 (´) indicates an editorial change since the last revision or reapproval.
1. Scope 3.2.1.1 Discussion—This oxidation-reduction potential
(ORP) is related to the solution composition by:
1.1 This test method covers the apparatus and procedure for
theelectrometricmeasurementofoxidation-reductionpotential RT
o
E 5 E 12.3 log A /A
@ #
m ox red
(ORP) in water. It does not deal with the manner in which the nF
solutions are prepared, the theoretical interpretation of the
where:
oxidation-reduction potential, or the establishment of a stan-
E = ORP,
m
dard oxidation-reduction potential for any given system. The
o
E = constant that depends on the choice of refer-
test method described has been designed for the routine and
ence electrodes,
process measurement of oxidation-reduction potential.
F = Faraday constant,
1.2 The values stated in SI units are to be regarded as
R = gas constant,
standard. No other units of measurement are included in this T = absolute temperature, °C + 273.15,
standard. n = number of electrons involved in process
reaction, and
1.3 This standard does not purport to address all of the
A and A = activities of the reactants in the process.
ox red
safety concerns, if any, associated with its use. It is the
responsibility of the user of this standard to establish appro-
4. Summary of Test Method
priate safety and health practices and determine the applica-
4.1 This is a test method designed to measure the ORP
bility of regulatory limitations prior to use.
which is defined as the electromotive force between a noble
2. Referenced Documents
metal electrode and a reference electrode when immersed in a
2 solution. The test method describes the equipment available to
2.1 ASTM Standards:
make the measurement, the standardization of the equipment
D1129 Terminology Relating to Water
and the procedure to measure ORP. The ORP electrodes are
D1193 Specification for Reagent Water
inert and measure the ratio of the activities of the oxidized to
D2777 Practice for Determination of Precision and Bias of
the reduced species present.
Applicable Test Methods of Committee D19 on Water
D3370 Practices for Sampling Water from Closed Conduits
5. Significance and Use
3. Terminology
5.1 Various applications include monitoring the
chlorination/dechlorination process of water, recognition of
3.1 Definitions—For definitions of terms used in this test
oxidants/reductants present in wastewater, monitoring the
method, refer to Terminology D1129.
cyclechemistryinpowerplants,andcontrollingtheprocessing
3.2 Definitions of Terms Specific to This Standard:
of cyanide and chrome waste in metal plating baths.
3.2.1 oxidation-reduction potential, n—the electromotive
5.2 ThemeasurementofORPhasbeenfoundtobeusefulin
force, E , developed between a noble metal electrode and a
m
the evaluation of soils, for evaluating treatment design data at
standard reference electrode.
sites contaminated with certain chemicals, and in evaluating
solid wastes.
1
This test method is under the jurisdiction of ASTM Committee D19 on Water
and is the direct responsibility of Subcommittee D19.03 on Sampling Water and
6. Interferences
Water-Formed Deposits, Analysis of Water for Power Generation and Process Use,
On-Line Water Analysis, and Surveillance of Water.
6.1 The ORP electrodes reliably measure ORP in nearly all
Current edition approved Feb. 15, 2014. Published March 2014. Originally
aqueous solutions and in general are not subject to solution
approved in 1957. Last previous edition approved in 2008 as D1498 – 08. DOI:
interference from color, turbidity, colloidal matter, and sus-
10.1520/D1498-14.
2
For referenced ASTM standards, visit the ASTM website, www.astm.org, or pended matter.
contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM
6.2 The ORP of an aqueous solution is sensitive to change
Standards volume information, refer to the standard’s Document Summary page on
the ASTM website. in temperature of the solution, but temperature correction is
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
1

---------------------- Page: 1 ----------------------
D1498 − 14
TABLE 1 National Institute of Standards and Technology (NIST)
rarely done due to its minimal effect and complex reactions.
Materials for Reference Buffer Solutions
Temperature corrections are usually applied only when it is
NIST Standard
desired to relate the ORP to the activity of a
...

This document is not an ASTM standard and is intended only to provide the user of an ASTM standard an indication of what changes have been made to the previous version. Because
it may not be technically possible to adequately depict all changes accurately, ASTM recommends that users consult prior editions as appropriate. In all cases only the current version
of the standard as published by ASTM is to be considered the official document.
Designation: D1498 − 08 D1498 − 14
Standard Test Method for
1
Oxidation-Reduction Potential of Water
This standard is issued under the fixed designation D1498; 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 (´) indicates an editorial change since the last revision or reapproval.
1. Scope
1.1 This test method covers the apparatus and procedure for the electrometric measurement of oxidation-reduction potential
(ORP) in water. It does not deal with the manner in which the solutions are prepared, the theoretical interpretation of the
oxidation-reduction potential, or the establishment of a standard oxidation-reduction potential for any given system. The test
method described has been designed for the routine and process measurement of oxidation-reduction potential.
1.2 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.
1.3 This standard does not purport to address all of the safety concerns, 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.
2. Referenced Documents
2
2.1 ASTM Standards:
D1129 Terminology Relating to Water
D1193 Specification for Reagent Water
D2777 Practice for Determination of Precision and Bias of Applicable Test Methods of Committee D19 on Water
D3370 Practices for Sampling Water from Closed Conduits
3. Terminology
3.1 Definitions of Terms Specific to This Standard:
3.1.1 oxidation-reduction potential—the electromotive force, E , developed between a noble metal electrode and a standard
m
reference electrode. This oxidation-reduction potential (ORP) is related to the solution composition by:
RT
o
E 5 E 12.3 log@A /A #
m ox red
nF
where:
E = ORP,
m
o
E = constant that depends on the choice of reference electrodes,
F = Faraday constant,
R = gas constant,
T = absolute temperature, °C + 273.15,
n = number of electrons involved in process reaction, and
A and A = activities of the reactants in the process.
ox red
3.1 Definitions—For definitions of other items terms used in this test method, refer to Terminology D1129.
3.2 Definitions of Terms Specific to This Standard:
3.2.1 oxidation-reduction potential, n—the electromotive force, E , developed between a noble metal electrode and a standard
m
reference electrode.
1
This test method is under the jurisdiction of ASTM Committee D19 on Water and is the direct responsibility of Subcommittee D19.03 on Sampling Water and
Water-Formed Deposits, Analysis of Water for Power Generation and Process Use, On-Line Water Analysis, and Surveillance of Water.
Current edition approved May 1, 2008Feb. 15, 2014. Published May 2008March 2014. Originally approved in 1957. Last previous edition approved in 20072008 as
D1498 – 07.D1498 – 08. DOI: 10.1520/D1498-08.10.1520/D1498-14.
2
For referenced ASTM standards, visit the ASTM website, www.astm.org, or contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM Standards
volume information, refer to the standard’s Document Summary page on the ASTM website.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
1

---------------------- Page: 1 ----------------------
D1498 − 14
3.2.1.1 Discussion—
This oxidation-reduction potential (ORP) is related to the solution composition by:
RT
o
E 5 E 12.3 log@A /A #
m ox red
nF
where:
E = ORP,
m
o
E = constant that depends on the choice of reference electrodes,
F = Faraday constant,
R = gas constant,
T = absolute temperature, °C + 273.15,
n = number of electrons involved in process reaction, and
A and A = activities of the reactants in the process.
ox red
4. Summary of Test Method
4.1 This is a test method designed to measure the ORP which is defined as the electromotive force between a noble metal
electrode and a reference electrode when immersed in a solution. The test method describes the equipment available to make the
measurement, the standardization of the equipment and the procedure to measure ORP. The ORP electrodes are inert and measure
the ratio of the activities of the oxidized to the reduced species present.
5. Significance and Use
5.1 Various applications include monitoring the chlordination/dechlorinationchlorination/dechlorination process of water,
recgoniti
...