PD ISO/TR 12767:2007

Foreword
Introduction
1 Scope
2 Normative references
3 Terms and definitions
4 Symbols and abbreviated terms
5 Effect of errors on flowrate calculations
   5.1 General
   5.2 Quantifiable effect
6 Effects of deviations in construction
   6.1 Orifice-plate edge sharpness
   6.2 Thickness of orifice edge
   6.3 Condition of upstream and downstream faces of
        orifice plate
   6.4 Position of pressure tappings for an orifice
   6.5 Condition of pressure tappings
7 Effects of pipeline near the meter
   7.1 Pipe diameter
   7.2 Steps and taper sections
   7.3 Diameter of carrier ring
   7.4 Undersize joint rings
   7.5 Protruding welds
   7.6 Eccentricity
8 Effects of pipe layout
   8.1 General
   8.2 Discharge coefficient compensation
   8.3 Pressure tappings
   8.4 Devices for improving flow conditions
9 Operational deviations
   9.1 General
   9.2 Deformation of an orifice plate
   9.3 Deposition on the upstream face of an orifice plate
   9.4 Deposition in the meter tube
   9.5 Orifice-plate edge sharpness
   9.6 Deposition and increase of surface roughness in
        Venturi tubes
10 Pipe roughness
   10.1 General
   10.2 Upstream pipe
   10.3 Downstream pipe
   10.4 Reduction of roughness effects
   10.5 Maintenance
Bibliography

Provides guidance on estimating the flowrate when using pressure differential devices constructed or operated outside the scope of ISO 5167.

This Technical Report provides guidance on estimating the flowrate when using pressure differential devices constructed or operated outside the scope of ISO5167.

Additional tolerances or corrections cannot necessarily compensate for the effects of deviating from ISO5167 (all parts). The information is given, in the first place, to indicate the degree of care necessary in the manufacture, installation and maintenance of pressure differential devices by describing some of the effects of non-conformity to the requirements; and in the second place, to permit those users who cannot comply fully with the requirements to assess, however roughly, the magnitude and direction of the resulting error in flowrate.

Each variation dealt with is treated as though it were the only one present. Where more than one is known to exist, there may be unpredictable interactions and care has to be taken when combining the assessment of these errors. If there is a significant number of errors, means of eliminating some of them have to be considered. The variations included in this Technical Report are by no means complete and relate largely to examples with orifice plates. An example with Venturi tubes has been placed at the end of its section. There are, no doubt, many similar examples of installations not conforming to ISO5167 (all parts) for which no comparable data have been published. Such additional information from users, manufacturers and any others may be taken into account in future revisions of this Technical Report.