Active Standard ASTM E645 | Developed by Subcommittee: E35.15
Book of Standards Volume: 11.05
Historical (view previous versions of standard)
Significance and Use
5.1 This practice determines potentially effective microbicides for use in cooling water systems using cooling water and deposits/biofilm obtained from the field. The addition of deposits/biofilms addresses the need to include the major source of microorganisms in cooling water systems. Even with this addition, laboratory results may not be totally predictive of microbicidal effectiveness in the field. This is because conditions in the field affecting microbicide effectiveness are difficult to mimic in the laboratory. These conditions that affect microbicide efficacy include blow-down rate, addition of makeup water, water hardness, hydrocarbon leaks, pH, sediment loading, dissolved solids, microbes in slime (biofilms), and deposits (salts, iron minerals, organics, and so forth) on surfaces. An additional factor is the difficulty in enumerating all microbes in the water due to the lack of adequate recovery media. Guidelines that address formation of and testing for surface-attached microbes (biofilms) may be found in Guide E1427, while a guideline for unconventional measurement of microbes is found in Guide E1326.
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.
2. Referenced Documents (purchase separately) The documents listed below are referenced within the subject standard but are not provided as part of the standard.
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 Nonconventional Microbiological Tests Used for Enumerating Bacteria
E1427 Guide for Selecting Test Methods to Determine the Effectiveness of Antimicrobial Agents and Other Chemicals for the Prevention, Inactivation and Removal of Biofilm
ICS Number Code 65.100.99 (Other pesticides and agrochemicals)