ESDU 12003 provides an overview of the techniques available to practising engineers for measuring fluid pressure and flow rate, and of the range of instruments that can be selected for specific internal flow applications. The criteria for measurement accuracy, including uncertainty, external influences, and calibration, are covered. Based on the relative merits of the different techniques, guidance is then given on the selection of an appropriate measurement technique, and, where appropriate, on the construction, installation, calibration, and use of a measuring instrument.

ESDU 12003 covers pressure measurement in stationary and moving fluids, and volume flow and mass flow measurements. Measurements in incompressible and compressible fluids are discussed. The flows considered are, in the first instance, considered steady and single phase. Advice, with appropriate warnings, is given where techniques and instruments are also suitable for unsteady or multiphase flows.

ESDU 12003 provides comprehensive references to further information, including cases where the described techniques do not cover some other possible requirements for measurements of pressure and flow in internal flow applications.