Draft summary

This document specifies a method for periodic determination of the axial velocity and volume flow rate of gas within emissions ducts and stacks. It is applicable for use in circular or rectangular ducts with measurement locations meeting the requirements of ISO 15259. Minimum and maximum duct sizes are driven by practical considerations of the measurement devices described within this document. This document requires all flow measurements to have demonstrable metrological traceability to national or international primary standards. This document applies to a range of monitoring objectives with different uncertainty requirements, ranging from very stringent (Emission Trading Schemes and calibration of automated flow measuring systems) to less demanding (support of isokinetic sampling). The level of quality control within this document is determined by the uncertainty requirements of the monitoring objective. Monitoring objectives are grouped based on the required quality control. The document specifies which requirements and performance characteristics apply to specified measurement objectives and application areas. The methods specified in this document can be used as a standard reference method, if the user demonstrates that the performance characteristics of the methods are equal to or better than the performance criteria specified in this document and that the expanded uncertainty of the measurement results obtained by the methods, expressed with a level of confidence of 95 %, is determined and reported. The results for each method defined in this document have different uncertainties within a range of 1 % to 10 % at flow velocities of 20 m/s. Other methods can be used provided that the user can demonstrate equivalence, e.g. based on the principles of EN 14793[11].