ASTM E645-18

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Designation: E645 − 13 E645 − 18
Standard Practice for
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Evaluation of Microbicides Used in Cooling Water Systems
This standard is issued under the fixed designation E645; 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 Scope*
1.1 This practice outlines a procedure for evaluating the efficacy of microbicides (algicides, bactericides, and fungicides) that
will be used for controlling microbial growth in cooling water systems. The microbicides will be evaluated using simulated or real
cooling tower water against (1) microbes from cooling water, (2) microbes in microbiological deposits (biofilms) from operating
cooling systems, or (3) microorganisms known to contaminate cooling water systems, or a combination thereof. This practice
should be performed by individuals familiar with microbiological techniques.
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 safety, health, and healthenvironmental practices and determine the
applicability of regulatory limitations prior to use.
1.4 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.
2. Referenced Documents
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2.1 ASTM Standards:
D3731 Practices for Measurement of Chlorophyll Content of Algae in Surface Waters
D4012 Test Method for Adenosine Triphosphate (ATP) Content of Microorganisms in Water
D4412 Test Methods for Sulfate-Reducing Bacteria in Water and Water-Formed Deposits
E1054 Test Methods for Evaluation of Inactivators of Antimicrobial Agents
E1326 Guide for Evaluating Non-culture Microbiological Tests
E1427 Guide for Selecting Test Methods to Determine the Effectiveness of Antimicrobial Agents and Other Chemicals for the
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Prevention, Inactivation and Removal of Biofilm (Withdrawn 2009)
E2756 Terminology Relating to Antimicrobial and Antiviral Agents
3. Terminology
3.1 For definitions of terms used in this practice, see Terminology E2756.
3.2 Definitions of Terms Specific to This Standard:
3.2.1 algicide, n—a chemical agent that kills algae; unicellular or filamentous chlorophyll-containing plants.
3.2.2 bactericide, n—a physical or chemical agent that kills bacteria, but not necessarily bacterial spores.
3.2.3 biofilm, n—a dynamic, self-organized accumulation of microorganisms and environmental by-products immobilized on a
substrate and embedded in an organic polymer matrix.
3.2.4 cooling system, n—equipment and coolant used for the removal of heat from processes, equipment, or both.
3.2.4.1 Discussion—
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This practice is under the jurisdiction of ASTM Committee E35 on Pesticides, Antimicrobials, and Alternative Control Agents and is the direct responsibility of
Subcommittee E35.15 on Antimicrobial Agents.
Current edition approved April 1, 2013Oct. 1, 2018. Published May 2013October 2018. Originally approved in 1978. Last previous edition approved in 20072013 as
E645 – 07.E645 – 13. DOI: 10.1520/E0645-13.10.1520/E0645-18.
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volume information, refer to the standard’s Document Summary page on the ASTM website.
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The last approved version of this historical standard is referenced on www.astm.org.
*A Summary of Changes section appears at the end of this standard
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E645 − 18
The most common medium used for removal or transfer of heat is water. The heated water then can be discharged into a receiving
body (once through cooling system) or it can be cooled and reused (recirculating cooling system).
3.2.5 cooling tower, n—a structure used to dissipate heat in open recirculating cooling systems.
3.2.6 cooling water, n—any water-
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