【国外标准】 Standard Practices for Sampling Water from Flowing Process Streams

5.1 The goal of sampling is to obtain for analysis a portion of the main body of water that is representative. The most critical factors necessary to achieve this are points of sampling, and materials selection, system design, time of sampling, frequency of sampling, and proper procedures to maintain the integrity of the sample prior to analysis.5.2 Homogeneity of the process to be sampled is frequently lacking, necessitating multiple-point sampling. If it is impractical to utilize a most-representative sampling point, it may be practical to determine and understand interrelationships so that results obtained at a minimum number of points may be used to characterize the system.5.3 Samples collected from a single point in a system are always recognized as being non-representative to some degree. For this reason, total representativeness of samples cannot be a prerequisite to the selection of a sampling point. The degree of representativeness of the sample shall be assessed and the assessment made a part of the permanent record. This will prevent an artificial degree of accuracy from being assigned to the data derived from tests on the sample.5.4 The samples shall be of sufficient volume and shall be taken frequently enough to permit reproducibility of testing requisite for the desired objective, as required by the method of analysis to be used.5.5 Laboratories or facilities conducting water sampling should be in compliance with Guide D3856.1.1 These practices cover the equipment and methods for sampling water from closed conduits such as process streams at power stations for chemical, physical, microbiological, and radiological analyses. It does not cover specialized equipment required for and unique to a specific test or method of analysis. The following are included:  Sections   Practice A—Grab Samples 9 – 17Practice B—Composite Samples 18 – 23Practice C—On-Line Sampling 24 – 291.2 For information on specialized sampling equipment, tests or methods of analysis, reference should be made to Volumes 11.01 and 11.02 of the Annual Book of ASTM Standards, relating to water.1.3 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.1.4 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, health, and environmental practices and determine the applicability of regulatory limitations prior to use. For specific hazards statements, see 8.3 and 13.4.1.5 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.