A tube conveyor with a sensing device of an electromagnetically operating apparatus for the detection of foreign contents in the material stream of a tube conveyor, wherein the tube conveyor comprises: a non-metallic tube section, at least one coil (5, 6, 5'), an evaluation circuit with a ground point, and a metallic shielding case with two end plates which can be connected by means of tube flanges (3, 3') via an insulating layer, wherein - the non-metallic tube section in the conveying path of the tube conveyor is enclosed by the at least one coil (5, 6, 5') which is connected to the evaluation circuit to detect field changes caused by foreign contents in the stream of material being conveyed - wherein this non-metallic tube section is encompassed by the metallic shielding case which passes into continuing metallic transporting tubes of the tube conveyor, and - wherein the shielding case enclosing the non-metallic tube section and the coils (5, 6, 5') is electrically insulated from the continuing metallic transporting tubes for the material being conveyed, - the metallic tube flanges (3, 3') with a flat supporting surface are attached at the two end plates of the shielding case enclosing the coils (5, 6, 5') against the shielding case in an electrically insulating manner and with a thin layer of insulating material being placed intermediately, and - the shielding case thereby insulated is connected to the ground point of the evaluation circuit in an electrically conducting manner. a non-metallic tube section, at least one coil (5, 6, 5'), an evaluation circuit with a ground point, and a metallic shielding case with two end plates which can be connected by means of tube flanges (3, 3') via an insulating layer, wherein - the non-metallic tube section in the conveying path of the tube conveyor is enclosed by the at least one coil (5, 6, 5') which is connected to the evaluation circuit to detect field changes caused by foreign contents in the stream of material being conveyed - wherein this non-metallic tube section is encompassed by the metallic shielding case which passes into continuing metallic transporting tubes of the tube conveyor, and - wherein the shielding case enclosing the non-metallic tube section and the coils (5, 6, 5') is electrically insulated from the continuing metallic transporting tubes for the material being conveyed, - the metallic tube flanges (3, 3') with a flat supporting surface are attached at the two end plates of the shielding case enclosing the coils (5, 6, 5') against the shielding case in an electrically insulating manner and with a thin layer of insulating material being placed intermediately, and - the shielding case thereby insulated is connected to the ground point of the evaluation circuit in an electrically conducting manner. - the non-metallic tube section in the conveying path of the tube conveyor is enclosed by the at least one coil (5, 6, 5') which is connected to the evaluation circuit to detect field changes caused by foreign contents in the stream of material being conveyed - wherein this non-metallic tube section is encompassed by the metallic shielding case which passes into continuing metallic transporting tubes of the tube conveyor, and - wherein the shielding case enclosing the non-metallic tube section and the coils (5, 6, 5') is electrically insulated from the continuing metallic transporting tubes for the material being conveyed, - the metallic tube flanges (3, 3') with a flat supporting surface are attached at the two end plates of the shielding case enclosing the coils (5, 6, 5') against the shielding case in an electrically insulating manner and with a thin layer of insulating material being placed intermediately, and - the shielding case thereby insulated is connected to the ground point of the evaluation circuit in an electrically conducting manner.