Thermo Scientific APEX 100 User Manual page 278

Product Phase Angle
The APEX measures magnetic field changes and derives reactive and resistive
components. A "clean" product changes both components proportionately and this
proportionality allows the APEX to discriminate between product characteristic and
metal. When metal is present, the ratio of resistive to reactive components is not
constant.
When the APEX learns the product, it converts the ratio between reactive and resistive
components to a phase angle. Once this angle is known, a clean product passing
through the aperture can be largely ignored.
As a general rule, the following phase angles are representative of the following types of
contaminants and non-contaminated products.
Degrees Contaminant or non-contaminated product
+ 130 Metallic (ferrous) contaminants, such as iron.
+ 90 Dry, non-conductive products, such as grains and cereals.
+ 65 Non-ferrous metallic contaminants, such as copper.
+ 20–30 Metallic contaminants, such as stainless steel.
0 Wet, conductive products, such as fresh meats and breads.
Page 278 Thermo Scientific APEX User's Guide