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 L.sub.M, having a pre-magnetization section L.sub.VM located within the magnetic field section L.sub.M and having a measuring device also located in the magnetic field section L.sub.M including a coil-shaped antenna (4) with the length L.sub.1 serving as a measuring antenna. At least one coil-shaped antenna (5) is provided in the pre-magnetization section L.sub.VM for generating a pulse or pulse sequence spoiling the magnetization of the medium in the direction of the magnetic field.

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 L.sub.M, having a pre-magnetization section L.sub.VM located within the magnetic field section L.sub.M and having a measuring device also located in the magnetic field section L.sub.M including a coil-shaped antenna (4) with the length L.sub.1 serving as a measuring antenna. At least one coil-shaped antenna (5) is provided in the pre-magnetization section L.sub.VM for generating a pulse or pulse sequence spoiling the magnetization of the medium in the direction of the magnetic field.

A method for operating a nuclear-magnetic flowmeter in which, when determining a velocity of the medium through a measuring tube, the dependency on properties or the state of a medium is at least reduced. The method exciting a first volume of the magnetized medium flowing at a first velocity within a first measuring section to nuclear-magnetic resonances and a first signal sequence is formed characterizing the nuclear-magnetic resonances of the medium in the first volume, and then, exciting a second volume of the magnetized medium flowing at a second velocity within the first measuring section is excited to nuclear-magnetic resonances and a second signal sequence is formed characterizing the nuclear-magnetic resonances of the medium in the second volume. A quotient sequence is determined from each of the first and second signal sequences, and the first velocity and/or the second velocity is/are determined using the quotient sequence.

A method for operating a nuclear-magnetic flowmeter in which, when determining a velocity of the medium through a measuring tube, the dependency on properties or the state of a medium is at least reduced. The method exciting a first volume of the magnetized medium flowing at a first velocity within a first measuring section to nuclear-magnetic resonances and a first signal sequence is formed characterizing the nuclear-magnetic resonances of the medium in the first volume, and then, exciting a second volume of the magnetized medium flowing at a second velocity within the first measuring section is excited to nuclear-magnetic resonances and a second signal sequence is formed characterizing the nuclear-magnetic resonances of the medium in the second volume. A quotient sequence is determined from each of the first and second signal sequences, and the first velocity and/or the second velocity is/are determined using the quotient sequence.

Flow measurement of hydrogen density, volumetric concentrations, and longitudinal relaxation times and transverse relaxation times have all n components in pairs different to each other. The method has the steps of: enclosing a mixture inside a probe volume and polarizing the mixture with a magnetic field; measuring the mixture enclosed inside the probe volume in terms of its longitudinal or transverse relaxation behaviour by means of pulsed electromagnetic waves at least n times with a different volumetric share of its components to measure at least n different relaxation curves; obtaining the relaxation times from the relaxation curves; obtaining the thermal equilibrium magnetizations M.sub.0 of the individual components from the relaxation curves; and correlating yielded thermal equilibrium magnetizations M.sub.0 of the individual components to calculate the hydrogen densities and the volumetric share of the components for each relaxation curve.

Flow measurement of hydrogen density, volumetric concentrations, and longitudinal relaxation times and transverse relaxation times have all n components in pairs different to each other. The method has the steps of: enclosing a mixture inside a probe volume and polarizing the mixture with a magnetic field; measuring the mixture enclosed inside the probe volume in terms of its longitudinal or transverse relaxation behaviour by means of pulsed electromagnetic waves at least n times with a different volumetric share of its components to measure at least n different relaxation curves; obtaining the relaxation times from the relaxation curves; obtaining the thermal equilibrium magnetizations M.sub.0 of the individual components from the relaxation curves; and correlating yielded thermal equilibrium magnetizations M.sub.0 of the individual components to calculate the hydrogen densities and the volumetric share of the components for each relaxation curve.

A method for operating a nuclear magnetic flowmeter in which the necessary time for determining a longitudinal relaxation time constant of the medium is reduced in comparison to the prior art by at least one nuclear-magnetic measuring process being carried out on a magnetized medium in the measuring tube. The at least one nuclear-magnetic measuring process includes an inversion pulse and acquisition sequences, each acquisition sequence beginning at a starting point in time in respect to the at least one nuclear-magnetic measuring process and has an activating pulse, a first waiting interval, a first refocusing pulse, an echo interval with a duration, a second refocusing pulse, a second waiting interval and a deactivating pulse. An echo signal is measured in the echo interval, and a longitudinal relaxation time constant of the medium is determined using the echo signals.

A method for operating a nuclear magnetic flowmeter in which the necessary time for determining a longitudinal relaxation time constant of the medium is reduced in comparison to the prior art by at least one nuclear-magnetic measuring process being carried out on a magnetized medium in the measuring tube. The at least one nuclear-magnetic measuring process includes an inversion pulse and acquisition sequences, each acquisition sequence beginning at a starting point in time in respect to the at least one nuclear-magnetic measuring process and has an activating pulse, a first waiting interval, a first refocusing pulse, an echo interval with a duration, a second refocusing pulse, a second waiting interval and a deactivating pulse. An echo signal is measured in the echo interval, and a longitudinal relaxation time constant of the medium is determined using the echo signals.

Method of determining a velocity profile of a fluid flowing through a conduit, the method including applying a saturation pulse on spins of magnetic field-sensitive nuclei in the fluid, measuring a signal of the fluid to determine position of the magnetic field-sensitive nuclei, the measurement carried out at a recovery time ‘TR’ and at a distance ‘d’ within the conduit, determining within the conduit a radial distance ‘r’ characterized by a local minimum in the measured signal, wherein the radial distance ‘r’ is measured from the center of the conduit, and determining a velocity profile of the fluid at the radial distance, based on the magnetic field-sensitive nuclei.

Method of determining a velocity profile of a fluid flowing through a conduit, the method including applying a saturation pulse on spins of magnetic field-sensitive nuclei in the fluid, measuring a signal of the fluid to determine position of the magnetic field-sensitive nuclei, the measurement carried out at a recovery time ‘TR’ and at a distance ‘d’ within the conduit, determining within the conduit a radial distance ‘r’ characterized by a local minimum in the measured signal, wherein the radial distance ‘r’ is measured from the center of the conduit, and determining a velocity profile of the fluid at the radial distance, based on the magnetic field-sensitive nuclei.