Abstract: A nuclear magnetic flowmeter (1) for determining the flow of a medium flowing through a measuring tube (2), having a magnetic field generator (3) having permanent magnets for generating a magnetic field interfusing the medium over a magnetic field section LM, having a pre-magnetization section LM located within the magnetic field section LM and having a measuring device also located in the magnetic field section LM including a coil-shaped antenna (4) with the length L1 serving as a measuring antenna. At least one coil-shaped antenna (5) is provided in the pre-magnetization section LVM for generating a pulse or pulse sequence spoiling the magnetization of the medium in the direction of the magnetic field.

Abstract: A method for operating a nuclear magnetic flowmeter having a measuring device for determining the flow of the medium through the measuring tube, the measuring device having a magnetic field generator for generating a magnetic field permeating the medium and the measuring tube and for carrying out nuclear magnetic measurements of measuring volumes that are adjustable in position and size in the magnetic field. The nuclear magnetic measurements involve adjusting the size of the measuring volume, positioning the measuring volume, generating excitation signals for exciting the medium, transmitting excitation signals into the measuring volume and measuring echo signals caused by the excitation signals. Deposits on the inner wall of the measuring tube are determined from echo signals of all nuclear magnetic measurements assigned to the position of the measuring volume of the respective nuclear magnetic measurement and at least one abrupt change in the echo signals detected.

Abstract: A flowmeter for determining the flow of a multi-phase medium through a measuring tube has a first and a second measuring device, one of which operates on a tomographic measuring principle and one of uses a measuring principle based on nuclear magnetic resonance. The first measuring device operates in a different manner from the second measuring device, e.g., using a measuring device operating on the measuring principle of pre-magnetization contrast measurement and having a pre-magnetization section with a constant magnetic field. The magnetic field has at least one component perpendicular to the direction of flow of the multi-phase medium and is generated by using magnetic field generating elements, which are arranged around the measuring tube. Additionally, an assembly for exciting nuclear spin by a RF excitation pulse or a RF excitation pulse sequence is part of the measuring device.