Patent ID: 7148678

Claim:
A ferrous magnetic taggant system for monitoring a ratio of at least two components being combined in a mixture, comprising: a first sensor for generating a first sense signal representing an amount of ferrous taggant particles per unit volume of a first component flowing adjacent said first sensor; a second sensor for generating a second sense signal representing an amount of ferrous taggant particles per unit volume of a mixture of the first component and a ferrous taggant particle free second component flowing adjacent said second sensor; a control means responsive to said first and second sense signals for calculating a ratio of the volumes of the first and second components in the mixture, and wherein at least one of said first and second sensors has a generally tubular body with a central passage through which material flows, an inner sense coil extending about a circumference of said passage, a drive coil extending about a circumference of said inner sense coil, and an outer sense coil extending about a circumference of said drive coil; and a master for calibrating said first and second sensors, said first and second sensors each having a passage through which material flows, said master having a body with a smaller diameter end sized to fit into said passages and a larger diameter end sized for use as a handle, said body further having a core formed from a filler material and a predetermined percentage of the ferrous taggant particles.