【国外标准】 Standard Guide for Intercomparing Permeation Tubes to Establish Traceability

5.1 The accuracy of air pollution measurements is directly dependent upon accurate calibrations.5.2 Such measurements gain accuracy and can be intercompared when the measurement procedures are traceable to national measurement standards.5.3 This guide describes procedures for enhancing the accuracy of air pollution measurements which may be specified by those organizations requiring traceability to national standards.1.1 This guide covers two procedures for establishing the permeation rate of a permeation tube and defining the uncertainty of the rate by comparison to National Institute of Standards and Technology's Standard Reference Materials (SRM).1.2 Procedure A consists of a direct comparison of the permeation rate of the device undergoing calibration with that of an SRM.1.3 Procedure B consists of a gravimetric calibration process in which a certified permeation tube is used as a quality control for the measurements.1.4 Both procedures are limited to the case where a suitable certified permeation device is available.1.5 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.1.6 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. (See 8.2 on Safety Precautions.)1.7 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.