BS ISO 7194:2008

Foreword
Introduction
1 Scope
2 Normative references
3 Symbols
4 Principle
5 Choice of measuring plane
6 Devices for improving flow conditions
7 Measurement of local velocities
8 Determination of mean flow velocity
9 Accuracy of flow-rate estimation
Annex A (normative) - Detection and removal of regular
        pressure fluctuations
Annex B (normative) - Damping of manometers
Annex C (normative) - Calculation of Pitot static tube
        locations for method B
Annex D (normative) - Corrections to be applied when a
        Pitot static tube is used
Annex E (normative) - Corrections to be applied when a
        current-meter is used
Annex F (normative) - Errors due to non-axisymmetrical
        velocity distribution
Bibliography

Describes velocity-area methods for measuring flow in swirling or asymmetric flow conditions in circular ducts by means of current-meters or Pitot static tubes.

This International Standard specifies velocity-area methods for measuring flow in swirling or asymmetric flow conditions in circular ducts by means of current-meters or Pitot static tubes.

It specifies the measurements required, the precautions to be taken, the corrections to apply, and describes the additional uncertainties which are introduced when a measurement in asymmetric or swirling flow has to be made.

Only flows with a negligible radial component are considered, however. Furthermore, it is not possible to make a measurement in accordance with this International Standard if, at any point in the measuring cross-section, the local velocity makes an angle of greater than 40° with the axis of the duct, or where the index of asymmetry Y (defined in AnnexF) is greater than 0,15.

This International Standard deals only with instruments for measuring local velocity as defined in ISO3354 and ISO3966. If Pitot static tubes are used, this International Standard applies only to flows where the Mach number corresponding to local velocities does not exceed 0,25.