초록 ▼

In the preferred and illustrated embodiments hereof, a method and apparatus for conducting NMR moisture measurements is set forth. In various forms, hydrogen transient NMR signal peak amplitude values indicative of total hydrogen concentration of the tested material space. The hydrogen concentration

In the preferred and illustrated embodiments hereof, a method and apparatus for conducting NMR moisture measurements is set forth. In various forms, hydrogen transient NMR signal peak amplitude values indicative of total hydrogen concentration of the tested material space. The hydrogen concentration is converted by a constant into water concentration. In one embodiment, a comparison is made between the NMR peak voltage of the unknown material and the NMR peak voltage from a standard sample having a specified water content to obtain a calibration for determining moisture content as a weight percentage in the tested specimen. If the densities of the two samples vary, the weights of each are necessary for accurate measurements. An alternative procedure involves determining moisture and material from the hydrogen in the water and in the material itself. In this procedure, the spin-spin relaxation T2 for the moisture is preferably more than three times longer than the T2 for the hydrogen in the solid or substrate hygroscopic material. Subsequently, two separate measurements can be obtained at separate times and their proportion is related to the percent water. An alternate procedure is used when the T2 of the water varies as a function of the percentage of water. In that instance, the values proportional to the total hydrogen in the sample and to the hydrogen in the water must be obtained at the same time so that the ratio is proportional to the percent water independent of the variations in T2. In the last two procedures, weight measurement is not required.

대표청구항 ▼

A method of measuring moisture in a flowing material which moisture is subject to different bonding mechanisms as a function of percent water concentration comprising the steps of: (a) in a flowing material subject to interrogation, obtaining by a transient response a NMR response indicative of the

A method of measuring moisture in a flowing material which moisture is subject to different bonding mechanisms as a function of percent water concentration comprising the steps of: (a) in a flowing material subject to interrogation, obtaining by a transient response a NMR response indicative of the total hydrogen population in an NMR detection volume for the flowing material; (b) plotting the transient NMR response as a function of time after interrogation; (c) extending selected portions of the plotted NMR response to an intercept at time equals zero to obtain intercept values A and B, the portions being selected to define at least two straight line segments; (d) determining K and M from the slope of the straight line portions of the plotted NMR response where K and M are characteristic for different water binding mechanisms in the flowing material; and (e) determining with the intercept values a moisture relationship for different water binding mechanisms given by Ae-kt+Be-mt.