capillary tube

This is a review article and it presents the flowrate characteristics of throttle elements used for measuring diagrams of transducers of fluids parameters. The review includes a wide range of research on the characteristics of incompressible and compressible fluids, Newtonian and Non-Newtonian fluids at the conditions of laminar, transient and turbulent flow through the channels of different cross-sections. The article considers equations for macroscopic flows. The theoretical equations for calculating the pressure drop for fluid flow in microchannels are presented.

The possibility of application of glass capillary tubes (CTs) as sensors of small and micro flowrates of gases was justified. The accuracy of a number of CTs flowrate equations was analyzed on the basis of experimental studies of CTs flowrate characteristics. It was shown that CTs can be applied as primary devices of small and micro flowrates of gases without individual calibration.