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ASTM D 5128 : 2014

Superseded
Superseded

A superseded Standard is one, which is fully replaced by another Standard, which is a new edition of the same Standard.

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superseded

A superseded Standard is one, which is fully replaced by another Standard, which is a new edition of the same Standard.

Standard Test Method for On-Line pH Measurement of Water of Low Conductivity
Available format(s)

Hardcopy , PDF

Superseded date

12-10-2022

Language(s)

English

Published date

02-14-2014

1.1This test method covers the precise on-line determination of pH in water samples of conductivity lower than 100 μS/cm (see Table 1 and Table 2) over the pH range of 3 to 11 (see Fig. 1), under field operating conditions. pH measurements of water of low conductivity are problematic for conventional pH electrodes, methods, and related measurement apparatus.

TABLE 1 Calculated Conductivity and pH Values at 25°C of Low Concentrations of NaOH in Pure Water A
Note 1This table tabulates the theoretical conductivity and pH values of low levels of NaOH in pure water as calculated from available thermodynamic data.
Note 2To illustrate the high sensitivity of the sample pH at these low concentrations to contaminants, the last column lists errors that would result if the sample were contaminated with an additional 1 mg/L through sample or equipment handling errors.

Sample
Concentration,
mg/L

Sample
Conductivity,
μS/cm

Sample
pH

Δ pH Error from Additional 1 mg/L NaOH Contaminate

0.001

0.055

7.05

Δ 2.35

0.010

0.082

7.45

Δ 1.95

0.100

0.625

8.40

Δ 1.03

1.0

6.229

9.40

Δ 0.30

8.0

49.830

10.30

Δ 0.05

A Data courtesy of Ref (1).B This data developed from algorithms originally published in Ref (2).
B The boldface numbers in parentheses refer to a list of references at the end of this standard.
TABLE 2 Calculated Conductivity and pH Values at 25°C of Low Concentrations of HCl in Pure Water A
Note 1This table tabulates the theoretical conductivity and pH values of low levels of HCl in pure water as calculated from available thermodynamic data
Note 2To illustrate the high sensitivity of the sample pH at these low concentrations to contaminants, the last column lists errors that would result if the sample were contaminated with an additional 1 mg/L through sample or equipment handling errors.

Sample
Concentration,
mg/L

Sample
Conductivity,
μS/cm

Sample
pH

Δ pH Error from Additional 1 mg/L HCl Contaminate

0.001

0.060

6.94

Δ2.38

0.010

0.134

6.51

Δ 1.95

0.100

1.166

5.56

Δ 1.03

1.0

11.645

4.56

Δ 0.30

8.0

93.163

3.66

Δ 0.05

A Data courtesy of Ref (1). This data developed from algorithms originally published in Ref (2).
 Restrictions Imposed by the Conductivity pH Relationship
FIG. 1 Restrictions Imposed by the Conductivity pH Relationship

1.2This test method includes the procedures and equipment required for the continuous pH measurement of low conductivity water sample streams including the requirements for the control of sample stream pressure, flow rate, and temperature. For off-line pH measurements in low conductivity samples, refer to Test Method D5464.

1.3The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.

1.4This 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.

Committee
D 19
DocumentType
Test Method
Pages
11
PublisherName
American Society for Testing and Materials
Status
Superseded
SupersededBy
Supersedes

ASTM D 1193 : 2006 : R2018 Standard Specification for Reagent Water
ASTM E 2635 : 2014 Standard Practice for Water Conservation in Buildings Through In-Situ Water Reclamation
ASTM D 1293 : 2018 Standard Test Methods for pH of Water
ASTM D 5464 : 2016 Standard Test Method for pH Measurement of Water of Low Conductivity
ASTM D 6569 : 2014 Standard Test Method for On-Line Measurement of pH (Withdrawn 2023)
ASTM E 70 : 2019 Standard Test Method for pH of Aqueous Solutions With the Glass Electrode

ASTM D 1129 : 2003 Standard Terminology Relating to Water
ASTM D 3864 : 2006 Standard Guide for Continual On-Line Monitoring Systems for Water Analysis
ASTM D 1129 : 2013 Standard Terminology Relating to Water
ASTM D 1129 : 2013 : R2020 Standard Terminology Relating to Water
ASTM D 2777 : 2012 Standard Practice for Determination of Precision and Bias of Applicable Test Methods of Committee D19 on Water
ASTM D 1193 : 1977 : R1983 : EDT 1 Standard Specification for Reagent Water
ASTM D 5464 : 2011 Standard Test Method for pH Measurement of Water of Low Conductivity
ASTM D 1129 : 2006 Standard Terminology Relating to Water
ASTM D 4453 : 2002 Standard Practice for Handling of Ultra-Pure Water Samples
ASTM D 2777 : 2003 Standard Practice for Determination of Precision and Bias of Applicable Methods of Committee D-19 on Water
ASTM D 2777 : 2021 Standard Practice for Determination of Precision and Bias of Applicable Test Methods of Committee D19 on Water
ASTM D 2777 : 2013 Standard Practice for Determination of Precision and Bias of Applicable Test Methods of Committee D19 on Water
ASTM D 2777 : 1998 Standard Practice for Determination of Precision and Bias of Applicable Methods of Committee D-19 on Water
ASTM D 1129 : 1999 : REV A Standard Terminology Relating to Water
ASTM D 1129 : 2006 : REV A Standard Terminology Relating to Water
ASTM D 1193 : 2006 : R2011 Standard Specification for Reagent Water
ASTM D 1129 : 2003 : REV A Standard Terminology Relating to Water
ASTM D 1129 : 2002 Standard Terminology Relating to Water
ASTM D 1293 : 1999 Standard Test Methods for pH of Water
ASTM D 4453 : 1991 : R1997 Standard Practice for Handling of Ultra-Pure Water Samples
ASTM D 1193 : 1991 Standard Specification for Reagent Water
ASTM D 1293 : 1999 : R2005 Standard Test Methods for pH of Water
ASTM D 1129 : 2004 Standard Terminology Relating to Water
ASTM D 2777 : 2008 Standard Practice for Determination of Precision and Bias of Applicable Test Methods of Committee D19 on Water
ASTM D 1293 : 2018 Standard Test Methods for pH of Water
ASTM D 2777 : 2006 Standard Practice for Determination of Precision and Bias of Applicable Test Methods of Committee D19 on Water
ASTM D 1129 : 2002 : REV A Standard Terminology Relating to Water
ASTM D 4453 : 2017 Standard Practice for Handling of High Purity Water Samples
ASTM D 3864 : 2012 Standard Guide for On-Line Monitoring Systems for Water Analysis
ASTM D 1193 : 1970 Standard Specification For Reagent Water
ASTM D 1193 : 2006 Standard Specification for Reagent Water
ASTM D 4453 : 2002 : R2006 Standard Practice for Handling of Ultra-Pure Water Samples
ASTM D 5464 : 2007 Standard Test Method for pH Measurement of Water of Low Conductivity
ASTM D 1293 : 2012 Standard Test Methods for pH of Water
ASTM D 1193 : 1999 Standard Specification for Reagent Water
ASTM D 1129 : 2010 Standard Terminology Relating to Water
ASTM D 4453 : 2011 Standard Practice for Handling of High Purity Water Samples
ASTM D 1129 : 2006 : REV A : EDT 1 Standard Terminology Relating to Water
ASTM D 1129 : 2001 Standard Terminology Relating to Water
ASTM D 1129 : 2004 : EDT 1 Standard Terminology Relating to Water
ASTM D 5464 : 1993 : R2001 Standard Test Methods for pH Measurement of Water of Low Conductivity
ASTM D 5464 : 2016 Standard Test Method for pH Measurement of Water of Low Conductivity
ASTM D 1193 : 2006 : R2018 Standard Specification for Reagent Water
ASTM D 2777 : 2008 : EDT 1 Standard Practice for Determination of Precision and Bias of Applicable Test Methods of Committee D19 on Water
ASTM D 3864 : 1996 : R2000 Standard Guide for Continual On-Line Monitoring Systems for Water Analysis
ASTM D 1293 : 1984 : R1990 Standard Test Methods for pH of Water
ASTM D 4453 : 2016 Standard Practice for Handling of High Purity Water Samples

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