Spectral method for determining the source of expanded vermiculite insulation in attics and walls

A method of identifying a source of a vermiculite sample in situ, comprising:

• providing a plurality of source area classes, the source area classes comprising Class 1, Class 2, Class 3, and Class 4;
• determining compositional field boundaries for each source area class, from spectral measurements of vermiculite materials of known origin, according to band depth ratios for absorption bands centered at 2.24 and 2.382 microns, each source area class having a range of 2.24/2.38-micron band depth ratios, the range of each source area class comprising:
• Class 1:
• 0.0000-0.0210,
• Class 2:
• 0.0210-0.2832,
• Class 3:
• 0.2832-0.4762,
• Class 4:
• 0.4762-2.5000;
• obtaining a plurality of near infrared reflectance spectral measurements at a plurality of locations within a sample of unknown origin;
• obtaining an average of the spectral measurements of the sample;
• calculating band depths of the averaged spectral measurements for absorption bands centered at wavelengths of 1.38, 1.40, 1.42, 2.24, 2.32, and 2.38 microns;
• calculating band depth ratios for the 1.38- and 2.32-micron absorption bands (1.38/2.32 ratio), the 2.24- and 2.38-micron absorption bands (2.24/2.38 ratio), and the 1.40- and 1.42-micron absorption bands (1.40/1.42 ratio);
• identifying the source of the sample by comparing the 2.24/2.38 ratio of the sample to the range of 2.24/2.38 ratios of each source area class to determine into which source area class the sample fits to arrive at a classification result;
• and
• representing the classification result to a user.

A method of identifying a source of a vermiculite sample in situ, comprising:

• providing a plurality of source area classes, the source area classes comprising Class 1, Class 2, Class 3, Class 4, and Class 5;
• determining compositional field boundaries for each source area class, from spectral measurements of vermiculite materials of known origin, according to band depth ratios for absorption bands centered at 1.38 and 2.32 microns, each source area class having a range of 1.38/2.32-micron band depth ratios, the range of each source area class comprising:
• Class 1:
• 0.0000-0.0005,
• Class 2:
• 0.0005-0.0106,
• Class 3:
• 0.0106-0.0418,
• Class 4:
• 0.0418-0.0657,
• Class 5:
• 0.0657-0.1200;
• generating a graph having an x-axis and a y-axis, where the x-axis=1.38/2.32-micron band depth ratio and the y-axis=1.40/1.42-micron band depth ratio;
• marking the boundaries of the source area classes on the graph;
• obtaining a plurality of near infrared reflectance spectral measurements at a plurality of locations within a sample of unknown origin;
• calculating a band depth ratio from the spectral measurements of the sample for an absorption band centered at wavelengths of 1.38 and 2.32 microns (1.38/2.32 ratio) and a band depth ratio for an absorption band centered at wavelengths of 1.40 and 1.42 microns (1.40/1.42 ratio);
• plotting a point on the graph of the 1.38/2.32 ratio relative to the 1.40/1.42 ratio of the sample;
• identifying the source of the sample by determining which source area class the plotted point falls under to arrive at a classification result;
• and
• testing for the presence of contaminants in the sample, said testing comprising:
• generating a contaminant curve on the graph, based upon the vermiculite materials having known origin, below which no contaminants are detectable,
• determining whether the sample contains contaminants based upon whether the plotted point lies above or below the contaminant curve, and
• determining a contamination level of the sample based upon a magnitude of the 1.40/1.42 ratio of the sample.

An apparatus for identifying a source of a vermiculite sample in situ, comprising:

• a portable computing device storing compositional field boundaries for each of a plurality of source area classes, the computing device determining the boundaries from spectral measurements of vermiculite materials of known origin, according to band depth ratios for absorption bands centered at 1.38 and 2.32 microns, each source area class having a range of 1.38/2.32-micron band depth ratios, the range of each source area class comprising:
• Class 1:
• 0.0000-0.0005,
• Class 2:
• 0.0005-0.0106,
• Class 3:
• 0.0106-0.0418,
• Class 4:
• 0.0418-0.0657,
• Class 5:
• 0.0657-0.1200;
• a portable spectrometer, with a light emitting contact probe, connected to the computing device, the spectrometer obtaining and averaging a plurality of near infrared reflectance spectral measurements at a plurality of locations within the sample, and providing the averaged spectral measurement to the portable computing device, wherein the portable computing device:
• calculates band depths of the averaged spectral measurements for absorption bands centered at wavelengths of 1.38, 1.40, 1.42, 2.24, 2.32, and 2.38 microns,
• calculates band depth ratios for the 1.38- and 2.32-micron absorption bands (1.38/2.32 ratio), the 2.24- and 2.38-micron absorption bands (2.24/2.38 ratio), and the 1.40- and 1.42-micron absorption bands (1.40/1.42 ratio),
• identifies the source of the sample by comparing the 1.38/2.32 ratio of the sample to the range of 1.38/2.32 ratios of each source area class to determine into which source area class the sample fits to arrive at a classification result;
• and
• a display connected to the portable computing device for displaying the classification result to a user.