Abstract: Provided is a magnetic material concentration measuring device including: a bobbin having an outer circumference around which an exciting coil, an output coil, and a further exciting coil are wound; an eccentric hole formed in the bobbin; a rotor that is rotatably fitted in the eccentric hole about an eccentric axis line; a first cutout part that forms a first flow passage on one end side in an eccentric axis line direction of the rotor; a second cutout part that forms a second flow passage whose angle is shifted in a rotor rotation direction with respect to the first cutout part, on another end side in the eccentric axis line direction of the rotor; and a communication passage that connects the first flow passage and the second flow passage.

Abstract: Provided is a magnetic material concentration measuring device including: a bobbin having an outer circumference around which an exciting coil, an output coil, and a further exciting coil are wound; an eccentric hole formed in the bobbin; a rotor that is rotatably fitted in the eccentric hole about an eccentric axis line; a first cutout part that forms a first flow passage on one end side in an eccentric axis line direction of the rotor; a second cutout part that forms a second flow passage whose angle is shifted in a rotor rotation direction with respect to the first cutout part, on another end side in the eccentric axis line direction of the rotor; and a communication passage that connects the first flow passage and the second flow passage.

Abstract: A device for measuring a concentration of magnetic material has exciting coils 11a and an output coil 11b which generates exciting voltage when alternating current flows through the exciting coils 11a. Measurement means 6 is provided to measure variation in phase difference between voltages of the exciting and output coils 11a and 11b, so that a concentration of magnetic material is measured with high accuracy from variation in phase difference when a test object is caused to approach the exciting coil 11a or/and the output coil 11b. A minute concentration of magnetic material in the fluid is continuously measured.

Abstract: A device for measuring a concentration of magnetic material has exciting coils 11a and an output coil 11b which generates exciting voltage when alternating current flows through the exciting coils 11a. Measurement means 6 is provided to measure variation in phase difference between voltages of the exciting and output coils 11a and 11b, so that a concentration of magnetic material is measured with high accuracy from variation in phase difference when a test object is caused to approach the exciting coil 11a or/and the output coil 11b. A minute concentration of magnetic material in the fluid is continuously measured.