ASTM D6504-11(2016)e1
(Practice)Standard Practice for On-Line Determination of Cation Conductivity in High Purity Water
Standard Practice for On-Line Determination of Cation Conductivity in High Purity Water
SIGNIFICANCE AND USE
5.1 Cation conductivity provides one of the most sensitive and dependable on-line means of detecting anionic contamination in the boiler/steam cycle, such as chlorides, sulfates, nitrates, bicarbonates, and organic acids, such as formic and acetic.
5.2 High sensitivity is provided by intentionally eliminating the pH adjusting treatment chemical(s), for example, ammonia and amines, from the sample and converting remaining salt contaminants into their acid forms which are approximately three times as conductive.
5.3 Guidelines on cation conductivity limits for various cycle chemistry and boiler types have been established by EPRI (2-4) and by ASME (5 and 6).
5.4 The sample effluent from the cation exchange column also may be used, and in some cases is preferred, for ion chromatography or other anion measurements.
SCOPE
1.1 This practice describes continuous sample conditioning by hydrogen ion exchange and measurement by electrolytic conductivity. It is commonly known as cation conductivity measurement in the power industry although it is actually an indication of anion contamination in high purity water samples. Measurements are typically in a range less than 1 μS/cm.
1.2 The actual conductivity measurements are made using Test Method D5391.
1.3 This practice does not provide for separate determination of dissolved carbon dioxide. Refer to Test Method D4519.
1.4 The values stated in SI units are to be regarded as standard. The values given in parentheses are mathematical conversions to inch-pound units that are provided for information only and are not considered standard.
1.5 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
Relations
Standards Content (Sample)
This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the
Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
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Designation: D6504 − 11 (Reapproved 2016)
Standard Practice for
On-Line Determination of Cation Conductivity in High Purity
Water
This standard is issued under the fixed designation D6504; 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.
ε NOTE—Editorial corrections were made throughout in February 2016.
1. Scope D1193 Specification for Reagent Water
D3370 Practices for Sampling Water from Closed Conduits
1.1 This practice describes continuous sample conditioning
D3864 Guide for On-Line Monitoring Systems for Water
by hydrogen ion exchange and measurement by electrolytic
Analysis
conductivity. It is commonly known as cation conductivity
D4519 Test Method for On-Line Determination of Anions
measurement in the power industry although it is actually an
and Carbon Dioxide in High Purity Water by Cation
indicationofanioncontaminationinhighpuritywatersamples.
Exchange and Degassed Cation Conductivity
Measurements are typically in a range less than 1 µS/cm.
D5391 Test Method for Electrical Conductivity and Resis-
1.2 The actual conductivity measurements are made using
tivity of a Flowing High Purity Water Sample
Test Method D5391.
D5540 Practice for Flow Control and Temperature Control
1.3 This practice does not provide for separate determina- for On-Line Water Sampling and Analysis
tion of dissolved carbon dioxide. Refer to Test Method D4519.
3. Terminology
1.4 The values stated in SI units are to be regarded as
3.1 Definitions—For definitions of terms used in this
standard. The values given in parentheses are mathematical
practice, refer to Test Methods D1125, Terminology D1129,
conversions to inch-pound units that are provided for informa-
and Guide D3864.
tion only and are not considered standard.
3.2 Definitions of Terms Specific to This Standard:
1.5 This standard does not purport to address all of the
3.2.1 cation conductivity, n—the parameter obtained by
safety concerns, if any, associated with its use. It is the
conditioning a sample by passing it through a hydrogen form
responsibility of the user of this standard to establish appro-
cation ion exchange resin column and then measuring its
priate safety and health practices and determine the applica-
electrolytic conductivity, on-line.
bility of regulatory limitations prior to use.
3.2.2 specific conductivity, n—direct electrolytic conductiv-
2. Referenced Documents
ity measurement of a power plant sample, usually dominated
by treatment chemicals, such as ammonia or amines.
2.1 ASTM Standards:
D1066 Practice for Sampling Steam
4. Summary of Practice
D1125 Test Methods for Electrical Conductivity and Resis-
4.1 The sample is passed continuously through a small
tivity of Water
cation exchange column in the hydrogen form, which ex-
D1129 Terminology Relating to Water
+
changes all cations for H . In this process, pH adjusting
treatment chemicals, such as ammonia and amines are re-
This practice is under the jurisdiction ofASTM Committee D19 on Water and
moved.
is the direct responsibility of Subcommittee D19.03 on Sampling Water and
4.2 Measurement is made continuously on the conditioned
Water-Formed Deposits, Analysis of Water for Power Generation and Process Use,
On-Line Water Analysis, and Surveillance of Water.
sample with a process high purity conductivity analyzer/
Current edition approved Feb. 15, 2016. Published March 2016. Originally
transmitter.
approved in 1999. Last previous edition approved in 2011 as D6504 – 11. DOI:
10.1520/D6504-11R16E01.
4.3 Temperature conditioning of the sample and specialized
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
compensation of the measurement are used to minimize
contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
temperature effects on the performance of the ion exchange
Standards volume information, refer to the standard’s Document Summary page on
the ASTM website. resin and the measurement.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
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D6504 − 11 (2016)
4.4 Few studies have been published on the performance of desirable to obtain a cation conductivity measurement with
cation conductivity measurement but one collaborative effort carbon dioxide removed (see Test Method D4519.)
provides some background (1).
6.5 Carbondioxidemayalsobeaspiratedasacomponentof
air, into the sample line through loose fittings in the exchange
5. Significance and Use
column,flowmeter,valves,etc.Thisisnotrepresentativeofthe
5.1 Cation conductivity provides one of the most sensitive
actual sampling point and produces positive errors.
and dependable on-line means of detecting anionic contamina-
6.6 Incompletely regenerated or inadequately rinsed resin
tion in the boiler/steam cycle, such as chlorides, sulfates,
will release trace ionic impurities that produce positive errors.
nitrates, bicarbonates, and organic acids, such as formic and
The use of fresh resin completely in the hydrogen form and
acetic.
thoroughlyrinsedisrecommended.Anexhaustedresincolumn
5.2 High sensitivity is provided by intentionally eliminating
will have the same effect but with more rapidly increasing
the pH adjusting treatment chemical(s), for example, ammonia
errors.
and amines, from the sample and converting remaining salt
6.7 Fouled resin can leach conductive components even
contaminants into their acid forms which are approximately
with an absolutely pure influent sample. Fresh resin is recom-
three times as conductive.
mended.
5.3 Guidelines on cation conductivity limits for various
6.8 Some cation resins contain leachables which can raise
cycle chemistry and boiler types have been established by
background conductivity and reduce sensitivity to sample
EPRI (2-4) and by ASME (5 and 6).
impurities. Extensive rinsing usually is required.Acontinuous
5.4 The sample effluent from the cation exchange column
rinsingschemeisgiveninSectionX1.2.Somesuccessalsohas
also may be used, and in some cases is preferred, for ion
been achieved with a hydrochloric acid (1 + 4) pre-rinse.
chromatography or other anion measurements.
6.9 For interferences with basic high purity conductivity
measurements, refer to Test Method D5391.
6. Interferences
6.1 Some weakly ionized cations may not be completely
7. Apparatus
exchanged by the resin. This will produce positive or negative
errors in the measurement depending on the sample composi- 7.1 Cation Exchange Column:
tion. These errors can reduce sensitivity to corrosive contami- 7.1.1 The cation exchange column shall have an inside
nants. diameter of less than 60 mm (2.4 in.) and produce a flow
velocity greater than 300 mm/min (1 ft/min) at the sample flow
6.2 Temperature effects on the cation resin may alter its
rate (see Appendix X1). The column shall have end screens to
equilibrium properties. Control sample temperature within the
distribute flow across the cross-section of the column and to
resin manufacturers’ temperature limits to obtain consistent
prevent resin beads and fines from escaping. The column may
results.
be piped for upward or downward flow. Upward flow provides
6.3 Thelargetemperatureeffectsofhighpurityconductivity
automatic purging of air at startup which is helpful in cycling
measurement must be minimized by sample conditioning and
plants. However, the resin must be packed full to prevent
temperature compensation. Although sample temperature may
fluidizing and channeling. Downward flow eliminates the
be controlled closely, it may be significantly influenced by the
possibility of fluidizing but requires the means to vent air from
ambient temperature as it passes through the column, tubing
the column at startup. Care must be exercised to eliminate all
and flow chamber. The temperature coefficient of pure water is
air pockets which could cause channeling. The column should
near 5 % of measurement per °C at 25°C, which can contribute
be constructed of nonleaching material, such as polycarbonate
substantial errors if not compensated properly. Temperature
or polypropylene. Materials, such as polyvinylchloride, may
compensation must be appropriate for the unique acidic com-
leachchloridesandarenotrecommended.Flexibletubingused
position of cation conductivity samples. Conventional high
tomakeconnectionstothecolumnshouldhaveminimallength
purity temperature compensation for neutral mineral contami-
and diameter to minimize the amount of leaching and air
nants is not suitable for this application (7 and 8). The user is
(carbon dioxide) permeation.
cautioned that the accuracy of algorithms for cation conduc-
7.1.2 The resin shall be a sulfonated styrene-divinylbenzene
tivity compensation may vary widely. The u
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