CHARLIE McDONOUGH, CJM Solutions, is an independent consultant in the area of industrial and process water treatment. He has been a member of ASTM Committee D19 on Water since 1986, and is currently the chairman of subcommittee D19.03. He received the Max Hecht Award in 2002 and the ASTM Award of Merit in 2007.
Subcommittee D19.03 on Water Sampling (and Much More)
Subcommittee D19.03, as it exists today, is the result of the merger of two subcommittees. The older of these dates back to the early years of Committee D19 on Water and was one of the first four subcommittees formed. The second was formed in 1976 to focus on industrial and power plant water, which included high purity water, process water, water-formed deposits and solvent systems for removing such deposits.
In January 1999, Committee D19 voted to merge the two subcommittees, both of which had benefited for many years from the support of members whose interests were similar. The name of the new subcommittee was changed to 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 to reflect its new responsibilities.
Membership of the Subcommittee
Today, with 65 active members who participate in the standardization process, D19.03 is a diverse representation of industries and interests (see Figure 1). There are members from general industry, utilities, government agencies, and of course the instrument and equipment manufacturers who are the subcommittee’s source of technology. It is also useful to look at the members from the perspective of classification. The diversity of these voting interests can be seen in Figure 2.
At the time of the merger in 1999, each of the subcommittees was responsible for 22 standards, which gave the new subcommittee responsibility for 44 standards. Since that time, a few obsolete standards have been withdrawn and new ones added. See Table 1 for a historical perspective of the 46 current standards.
The subcommittee is responsible for 28 test methods, 17 practices and one guide. Of these, only 18 deal with water as we commonly encounter it in nature and in industry. In nine standards, the matrix is high purity water, seven standards deal with water-formed deposits, and seven others with steam. In five of the standards, the matrix is a metal coupon or system component that is used to measure the tendency for corrosion or deposition within a system or to measure the quantity of deposit already present. See Table 2 for a breakdown of D19.03 standards by sample matrix.
Of the 28 standards, 23 are methods for determining the concentration of an analyte in either water or in a solid matrix. The remaining five standards do not measure the concentration of an analyte at all, but they do make measurements and produce values and therefore are methods. We will get back to them in a bit.
Fifteen of the methods under the jurisdiction of D19.03 involve the on-line monitoring of a variety of parameters including pH, conductivity, oxygen, silica, sodium by specific ion electrode, dissolved and particulate metals by X-ray fluorescence, anions and carbon dioxide by conductivity anions by ion chromatography, and turbidity. One method for the on-line determination of deposit forming impurities in steam provides four techniques including gravimetric, electrical conductivity, sodium tracer and silica.
There are three methods that present a variety of techniques for measuring total organic carbon. D 5544, Test Method for On-Line Measurement of Residue After Evaporation of High-Purity Water, measures the µg/l and sub-µg/l level of the residue after evaporation of high purity water. See Table 3 for a complete list of the on-line standard methods.
There are eight methods under the jurisdiction of the subcommittee that utilize grab samples, and they are largely of interest to the control of water used in the power and process industries. Among these are standard methods for the determination of pH, conductivity, dissolved oxygen and hydrazine. Methods that are specific to monitoring the quality of high purity water include low level sodium in high purity water by graphite furnace, low level silica by flameless AA, trace anions by ion chromatography, and the measurement of pH in water of low conductivity. A complete list of the grab sample methods is given in Table 4.
Monitoring the Effects of Water
There are 28 standards; of these, 15 are on-line methods and eight are grab sample methods. That leaves five methods that do produce values and do make measurements, but do not determine the concentration of an analyte.
One of these methods measures the corrosivity of water in the absence of heat transfer, while a second measures the corrosion and fouling tendency of cooling water under heat transfer conditions. These methods are typically applied by the plant operators to monitor cooling water in power plants, manufacturing plants and oil refineries. The remaining three methods on this list were developed for the operators of power plants to assist with the measurement of accumulated deposits on the steam generator tubes, and to measure the corrosivity and efficacy of solvent systems developed to remove the deposits. They are important to the operators of steam generators in both the power and manufacturing sectors as they do battle with the energy-robbing effects of accumulated deposits. See Table 5 for a complete list of the test methods that deal with corrosion, fouling and chemical cleaning.
Sampling Water and Sample Handling
Of the 17 standard practices, seven deal with sampling and the handling and conditioning of samples (see Table 6). Several of these are among those most frequently referenced by other ASTM standards, because they establish practices that are applicable to most other standards, i.e., sampling and sample handling. One of these deals with the practice of sampling steam, another with sampling water from closed conduits, and a third establishes the techniques that are necessary for effectively handling ultra-pure water samples.
Taking samples for continual or on-line analysis places special requirements on the analyst that are addressed by two standards. One of these is D 3864, Guide for Continual On-Line Monitoring Systems for Water Analysis; the other is D 5540, Practice for Flow Control and Temperature Control for On-Line Water Sampling and Analysis. Both of these standards are applicable to all on-line methods; however, another practice (D 6301, Practice for the Collection of Samples of Filterable and Nonfilterable Matter in Water) was developed to address the unique requirements of a single on-line standard, D 6502, Standard Test Method for On-Line Measurement of Low Level Particulate and Dissolved Metals in Water by X-Ray Fluorescence (XRF).
Five of Subcommittee D19.03’s practices cover a wide range of topics dealing specifically with water-formed deposits. Sampling water- formed deposits is addressed by D 887, Practices for Sampling Water-Formed Deposits, while three practices deal with the use of a variety of techniques for analyzing them. Finally, there is D 933, Practice for Reporting Results of Examination and Analysis of Water-Formed Deposits.
A number of practices have been developed to aide in the monitoring and control of industrial systems. There are practices that cover such topics as the measurement of cation conductivity, the assessment of the tendency of industrial boiler waters to cause embrittlement, the estimation of chlorine demand, the running of coagulation-flocculation jar tests, and even performing pressure in an in-line coagulation-flocculation-filtration test.
One of the standards, D 1498, Practice for Oxidation-Reduction Potential of Water, is listed as a practice, but is currently being balloted as a test method. To make this change the members of the subcommittee who were present at the January 2006 meeting in Cocoa Beach, Fla., conducted a laboratory study. The data developed and the changes to D 1498 will have been balloted by the time this issue of SN goes to press.
At the time of this writing, D19.03 is responsible for a total of 46 standards, five of which have been developed since the merger, and three standards are currently in development. Four of the newest standards are methods and one is a practice. All of them use on-line techniques to address the needs of a variety of industries to monitor and control operationally important parameters.
D 6502, Test Method for On-Line Measurement of Low Level Particulate and Dissolved Metals in Water by X-Ray Fluorescence, is widely used by the power industry, and is especially important to the nuclear power industry for measuring corrosion product transport. D 6504, Practice for On-Line Determination of Cation Conductivity in High Purity Water, is probably the single most widely used technique to monitor water quality all around the steam cycle. Samples of steam, condensate and feedwater are routinely condensed where necessary and cooled as required to use this technique. Cation conductivity is used as part of the water quality monitoring package in virtually every power plant where steam pressures exceed 600 psi (41.3 bar), and in many power plants operating at lower pressures.
D 6569, Test Method for On-Line Measurement of pH, is useful for every industry that monitors water anywhere in the plant, from the inlet to the outfall and all points in between. D 6698, Test Method for On-Line Measurement of Turbidity Below 5 NTU in Water, was developed as a collaborative effort because of an EPA mandate regarding the monitoring of potable water produced by filtration. The task group that developed this standard included representatives from a number of instrument manufacturers, standards manufacturers and end users, including a major municipal water department as well as the EPA. D 7126, Test Method for On-Line Colorimetric Measurement of Silica, was developed for the monitoring of silica in industrial systems.
There are currently three standards in development:
• On-line measurement of turbidity above 2 NTU;
• On-line measurement of dissolved ozone in water; and
• On-line measurement of TOC in high purity water by conductivity detection.
You can expect to see the work product of these task groups as ballot items on future subcommittee and main ballots. These task groups are scheduled to meet in June in Norfolk, Va. All are invited to come and contribute to these efforts. Subcommittee D19.03 and Subcommittee D19.11 live on. Come and join us. //