ASTM D5128 - 14 - Standard Test Method for On-Line pH Measurement of Water of Low Conductivity

ASTM D5128 - 14

Standard Test Method for On-Line pH Measurement of Water of Low Conductivity

Status : Current   Published : January 2014

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1.1 This 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.

[This table has been removed.]

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.

[This table has been removed.]

A Data courtesy of Ref (1). This data developed from algorithms originally published in Ref (2).

[This image has been removed.]


FIG. 1 Restrictions Imposed by the Conductivity pH Relationship

1.2 This 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.

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

1.4  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.




Standard NumberASTM D5128 - 14
TitleStandard Test Method for On-Line pH Measurement of Water of Low Conductivity
StatusCurrent
Publication Date01 January 2014
Normative References(Required to achieve compliance to this standard)No other standards are normatively referenced
Informative References(Provided for Information)No other standards are informatively referenced
Descriptors High purity, Low conductivity, On-line, PH, Calculated pH
ICS13.060.50
71.040.50
PublisherASTM
FormatA4
DeliveryYes
Pages12
File Size0 KB
Price£45.00


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