EN ISO 16911-1:2013

Foreword
Introduction
1 Scope
2 Normative references
3 Terms and definitions
4 Symbols and abbreviated terms
5 Principle
6 Selection of monitoring approach
7 Measuring equipment
8 Performance characteristics and requirements
9 Measurement procedure
10 Calculation of results
11 Establishment of the uncertainty of results
12 Evaluation of the method
Annex A (normative) - Measurement of velocity
        using differential pressure based techniques
Annex B (normative) - Vane anemometer
Annex C (normative) - Tracer gas dilution method
        determination of volume flow rate and
        average velocity
Annex D (normative) - Transit time tracer gas
        method determination of average velocity
Annex E (normative) - Calculation of flue gas
        volume flow rate from energy consumption
Annex F (informative) - Example of uncertainty
        budget established for velocity and volume
        flow rate measurements by Pitot tube
Annex G (informative) - Description of validation
        studies
Annex H (informative) - Differential pressure
        measurement
Annex I (informative) - The use of time of flight
        measurement instruments based on modulated
        laser light
Annex J (informative) - Relationship between this
        International Standard and the essential
        requirements of EU Directives
Bibliography

ISO 16911-1:2013 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 EN 15259. Minimum and maximum duct sizes are driven by practical considerations of the measurement devices described within ISO 16911-1:2013.ISO 16911-1:2013 requires all flow measurements to have demonstrable metrological traceability to national or international primary standards.To be used as a standard reference method, the user is required to demonstrate that the performance characteristics of the method are equal to or better than the performance criteria defined in ISO 16911-1:2013 and that the overall uncertainty of the method, expressed with a level of confidence of 95 %, is determined and reported. The results for each method defined in ISO 16911-1:2013 have different uncertainties within a range of 1 % to 10 % at flow velocities of 20 m/s.Methods further to these can be used provided that the user can demonstrate equivalence, based on the principles of CEN/TS 14793.