A sample to be measured is placed in a medium solution between two circular magnets to ensure that the sample to be measured is levitated in a set circular area between the two circular magnets, and a levitation position of the sample to be measured in the magnetic field is measured. The density of the sample is calculated according to formula (I): ${?}_s={?}_m+\frac{{?}_m-{?}_s}{g{?}_0}\left(B_r\frac{?B_z}{?r}+B_z\frac{?B_z}{?z}\right).$
Compared to the prior art, the method of the present disclosure provides a novel method for measuring a density of a substance, in which the involved device is easy to operate and has low cost, and the measurement results are easy to observe and have high accuracy.

Provided is a Coriolis flow sensor assembly that includes a fluid flow assembly, including a flow tube, wherein the fluid flow assembly is configured to provide a flow path through the flow tube. The flow tube has at least one region of increased stiffness, which may be a result of a structural support component coupled to the flow tube. In another embodiment, the increased stiffness is caused by integral properties of the flow tube.

A digital hydrometer and methods of digitally displaying a specific gravity measured by a hydrometer are provided. The digital hydrometer can comprise a base, a displacement vessel, an inductive distance sensor, an output circuit, and a hydrometer float. The displacement vessel and inductive distance sensor can be mounted in or on the base. The displacement vessel can hold a displacement fluid. The hydrometer float can float in the displacement fluid. The output circuit can be in electrical communication with the inductive distance sensor and comprise a digital display device configured to display a digital value that is commensurate with a change in impedance attributable to the proximity of a metallic object, in the hydrometer float, to the sensor or its inductor. The digital value can be a specific gravity of the displacement fluid.

A digital hydrometer and methods of digitally displaying a specific gravity measured by a hydrometer are provided. The digital hydrometer can comprise a base, a displacement vessel, an inductive distance sensor, an output circuit, and a hydrometer float. The displacement vessel and inductive distance sensor can be mounted in or on the base. The displacement vessel can hold a displacement fluid. The hydrometer float can float in the displacement fluid. The output circuit can be in electrical communication with the inductive distance sensor and comprise a digital display device configured to display a digital value that is commensurate with a change in impedance attributable to the proximity of a metallic object, in the hydrometer float, to the sensor or its inductor. The digital value can be a specific gravity of the displacement fluid.

A method of testing for a desired specific gravity of a liquid. The method including the use of a temperature calibration gauge and a hydrometer. The temperature calibration gauge has a thermo sensing end and a readout indicating the desired hydrometer reading at the current temperature of the liquid. The method includes the steps of contacting the thermo sensing end and the hydrometer with the liquid and comparing the readout of the temperature calibration gauge with the measurement indicated by the hydrometer.

A method of testing for a desired specific gravity of a liquid. The method including the use of a temperature calibration gauge and a hydrometer. The temperature calibration gauge has a thermo sensing end and a readout indicating the desired hydrometer reading at the current temperature of the liquid. The method includes the steps of contacting the thermo sensing end and the hydrometer with the liquid and comparing the readout of the temperature calibration gauge with the measurement indicated by the hydrometer.

A method of measuring liquid level in a tank. An electromechanical liquid level gauge (ESG) is provided including a processor, a displacer suspended on a wire from a grooved drum having a servo motor coupled thereto to rotate the drum for balancing the displacer. A change in liquid level causes a change in a counterforce to move the ESG out of balance. The processor monitors a torque sensor output, and controls movement of the motor using a programmed apparent weight (AW) setpoint to raise or lower the displacer based on an AW derived from the torque. An associated memory stores a density compensated fixed immersion depth level gauging algorithm. The algorithm implements obtaining a density reading for the liquid, continuously corrects an immersion depth of the displacer for changes in density to provide an essentially fixed immersion depth, and calculates the liquid level from the density reading and immersion depth.

A method of measuring liquid level in a tank. An electromechanical liquid level gauge (ESG) is provided including a processor, a displacer suspended on a wire from a grooved drum having a servo motor coupled thereto to rotate the drum for balancing the displacer. A change in liquid level causes a change in a counterforce to move the ESG out of balance. The processor monitors a torque sensor output, and controls movement of the motor using a programmed apparent weight (AW) setpoint to raise or lower the displacer based on an AW derived from the torque. An associated memory stores a density compensated fixed immersion depth level gauging algorithm. The algorithm implements obtaining a density reading for the liquid, continuously corrects an immersion depth of the displacer for changes in density to provide an essentially fixed immersion depth, and calculates the liquid level from the density reading and immersion depth.

A fluid monitoring apparatus for detecting which of a first fluid, a second fluid and a third fluid is present, the second fluid having a density less than the first fluid and the third fluid having a density less than the second fluid. The apparatus includes: a first float having a density less than that of the first fluid but greater than that of the second fluid; a second float having a density less than that of the second fluid but greater than that of the third fluid; and a sensor. The sensor is configured to detect the first float and the second float so that the position of the floats can be determined.

A fluid sensor including a guide, a float, a permanent magnet, and a magnetic angle sensor. In one example, the float is constrained at least in part by the guide to move along a vertical axis. The permanent magnet is mechanically coupled to the float. The magnetic angle sensor is configured to measure an angle of a magnetic field generated by the permanent magnet and is positioned such that movement of the float along the vertical axis varies the angle of the magnetic field generated by the permanent magnet through the magnetic angle sensor.