The influence of flow admixtures to the electromagnetic flow meter accuracy

Abstract

The measurement error appears in an electromagnetic flow meter when the flow has admixtures with magnetic and/or electric properties different from the fluid. The particle shape approximates the ellipsoid. The reasons of error appeared inside and outside of the particles in the active zone of the flow meter with any canal form and turbulent flow investigated. The investigation is performed by analogy among electrostatic, magnetic, and electric current fields. Expressions for error depending on volume concentration, permeability, electric conductivity of particles, and different ellipsoid axes lengths are presented. The expressions of the error are obtained assuming that particles are oriented in various directions concerning the flow direction. Magnetic particles with the considerable value of electric conductivity are dangerous in particular. The extra measurement error depends on particle shape in this case especially. The measurement error increases if the particle shape differs from the sphere. The complementary measurement error can exceed some hundred times the volume concentration of particles if the ratio between the longest and shortest axes of the ellipsoid exceeds 10. The error is proportional to the second power of admixtures volume concentration when particles are nonmagnetic. When admixtures are nonmagnetic and nonconductive, the measurement error does not depend on the particle’s shape.