Standard ISO 5167

Calibration Precision

Secondary instruments convert the pressure drop generated by these primary devices into volumetric flow rate readings. The relationship between mass flow and pressure differential follows specific discharge coefficient formulas provided within the text. Errors arise when upstream flow disturbances deviate from the idealized conditions assumed during laboratory testing.

Proper maintenance of the pressure sensing lines prevents signal drift caused by fluid traps or condensation.

Installation Constraint

Piping geometry dictates the magnitude of measurement uncertainty for these metering systems. Designers must account for the proximity of valves, bends, or fittings to the primary element to avoid skewed velocity distributions. Sufficient upstream length allows the fluid to stabilize, while shorter runs introduce systematic bias into the pressure drop reading.

Technical personnel mitigate these deviations by installing flow conditioners when available space precludes the use of standard straight runs.

Measurement Limit

Compliance with these protocols establishes a common framework for industrial fluid accounting. Variations in fluid density, viscosity, or pipe diameter change the discharge coefficient and require recalculation based on the governing formulas. Small deviations in the edge sharpness of an orifice plate alter the flow contraction ratio and degrade measurement fidelity over time.

Mechanical wear of the throat or plate face remains the primary factor in long term performance degradation.