ISO 16911-1:2013

Overview

ISO 16911-1:2013 - Stationary source emissions - Manual reference method - defines a standardized, manual procedure for periodic determination of axial velocity and volume flow rate of gases in ducts and stacks. Applicable to circular and rectangular ducts (measurement locations per EN 15259), the standard establishes methodology, quality requirements and reporting rules for flow measurements used in emissions monitoring, regulatory compliance and calibration of automated measuring systems.

Key topics and technical requirements

• Measurement principle: Uses point velocity measurements to derive flow profiles and mean velocity; also covers alternative methods (tracer gas dilution, transit-time tracer, energy-consumption calculation).
• Measurement elements: Defines the measurement plane, measurement lines/points, and procedures for selecting sampling locations and number of points to characterize velocity profiles.
• Instrumentation: Describes common techniques and instruments such as Pitot tubes (differential-pressure), vane anemometers, tracer gas systems and time-of-flight instruments (annexes provide normative/ informative details).
• Metrological traceability: All flow measurements must have demonstrable traceability to national or international primary standards.
• Performance & uncertainty: Users must demonstrate method performance meets or exceeds ISO 16911-1 criteria. The overall expanded uncertainty (k=2, 95% confidence) must be determined and reported; uncertainties for the defined methods typically range from 1% to 10% at 20 m/s.
• Quality assurance: Site survey, pre- and post-measurement checks, quality control and calibration procedures are specified to ensure reliable results.
• Documentation: Requires an uncertainty budget, measurement report and validation where alternative methods are used.

Applications and who uses it

ISO 16911-1:2013 is used by:

• Environmental/stack testing engineers and accredited laboratories performing periodic stack/duct flow measurements.
• Plant operators and environmental managers for emissions reporting and permitting compliance.
• Regulatory authorities reviewing flow measurement data submitted for compliance.
• Teams calibrating or validating automated measuring systems (AMS) - see ISO 16911-2 for permanent AMS guidance.

Practical uses include flow rate determination for pollutant emission calculations, calibration of continuous flow monitors, verification of combustion efficiency calculations, and providing traceable data for regulatory reporting.

Related standards

• EN 15259 - Requirements for measurement sections and sites (measurement location criteria).
• ISO 16911-2 - Automated measuring systems (part 2).
• CEN/TS 14793 - Principles for demonstrating equivalence of alternative methods.
• ISO/IEC Guide 98-3 (GUM) and ISO 20988 - Guidance on uncertainty evaluation.

Keywords: ISO 16911-1:2013, stationary source emissions, velocity and volume flow rate, stack emissions, Pitot tube, tracer gas, uncertainty, metrological traceability, EN 15259.