Standards Development

Scope

This document specifies requirements and recommendations for ultrasonic gas flowmeters (USMs) that measure the time of flight of ultrasonic signals to calculate the actual volumetric flow rate. These USMs are used for measuring flare and vent gas flows in closed conduits for emission monitoring and reporting purposes.

Although this document applies to USMs which are intended for single-phase homogeneous gases, these meters are designed for harsh conditions. This document covers meter models with meter bodies as well as meters with field-installed transducers.

This document addresses performance, calibration, and output characteristics of USMs under highly variable operating conditions typical of flaring and venting systems. Flare metering systems vary significantly in design and configuration; therefore, uniform system-level requirements cannot be applied within this document.

This document includes guidance on installation, diagnostics, and type testing options to enable regulatory compliance and environmental reporting. It does not establish requirements for conformity assessment schemes or systems. If conformity assesment is required by regulatory compliance, conformity with this document shall be evaluated by a third-party, in accordance with ISO/IEC 17000.

Any references to testing, evaluation, or documentation are intended solely to ensure repeatable and reproducible assessment of performance and do not mandate specific conformity assessment procedures or certification.

This is focusing on ultrasonic flow meter technology only – with a three staged approach:

a)       actual volumetric flow rate (primary measurement); this document;

b)       standard volumetric flow rate (primary measurement added with secondary quantities, e.g. T, P and Z); future revisions of this document.

c)        emissions in CO2 equivalent per hour (primary measurement with secondary quantities, added with tertiary measurement) in reference to ISO/DIS 25624 serie sfuture revisions of this document.