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UL 1581-2019 pdf free download
UL 1581-2019 pdf free download.Reference Standard for Electrical Wires , Cables and Flexible Cords.
490.1 GENERAL — Infrared Analysis is to be used to provide a method for the identification of PVC wire and cable compounds. Interpretation of infrared spectral transmittance is to be used to identify the composition of a compound by comparing the compound’s infrared spectra to the spectra of materials having known compositions.
490,2 The analysis is to be performed with a Fourier Transform Infrared (FTIR) Spectrophotometer and/or a Dispersive Infrared Spectrophotometer. The results are to be recorded as a plot of the percent transmittance of the infrared radiation through the sample versus the number of wavelengths in one centimeter [the reciprocal wavelength (cm’1) or ‘wavenumber”J of the radiation. Percent transmittance is to be expressed on the ordinate and wavenumber on the abscissa. The infrared spectra obtained by the methods described is to consist of a wavenumber range of at least 4000— 400 reciprocal cenhmeters.
490.3 SAMPLE PREPARATION / TEST PROCEDURE— The PVC compound is to be separated into solvent-soluble and solvent-insoluble fractions by use of a centrifuge and/or by filtration. Stabilized (peroxide-inhibited) tetrahydrofuran (THF) See 490.4, or other solvents with demonstrated comparable solubilities. are to be used. Stabilized (peroxide-inhibited) THF is the solvent of choice and centrifugation is the preferred fraction-separation method of choice. The solvents are to be readily evaporable by gentle heating and are not to react with the PVC material. The THF stabilizer/peroxide inhibitor component shall not be present in quantities detectable in the infrared spectra. Precautions are to be taken for the safe handling, storage, and disposal of each solvent employed.
490.4 PARTICULAR CAUTIONS WITH THF, AN ETHER— Tetrahydrofuran (THF) is indicated as a solvent in Infrared Spectroscopy, Section 490, Elemental Analysis, Section 492, and Gel Permeation Chromatography, Section 493 of this standard, and use of stabilized THF is specified. Unstabilized THF shall not be used. Stabilization of an ether inhibits the formation of peroxides, which are explosive when concentrated. Peroxides often concentrate as an ether is stored or exposed to air for a prolonged period; as an ether is distilled, heated to dryness. or otherwise evaporates; as heat/shock/friction are applied; and upon disposal in a manner in which incompatible materials are mixed.
490.5 The solvent-soluble compound fraction is to be cast on an optically transparent potassium bromide (KBr) crystal. The crystal is to be placed in an explosion-proof oven to evaporate the solvent, leaving a thin film of the soluble compound fraction on the KBr crystal. The crystal Is then to be placed directly into the sample holder of the instrument for recording the Infrared spectrum.
490.6 The insoluble portion is to be washed with additional solvent, centrifuged, and then decanted to remove the soluble compound components (resin, plasticizer, and the like). The insoluble portion is to be placed in an explosion-proof oven to evaporate the solvent. After drying, the insolubles are to be mixed with powdered spectroscopic-grade potassium bromide (KBr) and ground in a vibrating ball mill. A quantity of this mixture that produces a disk typically 1 mm thick and 1/2 inch or 12.7 mm in diameter is then to be placed in an evacuable die. The die is to be put under a vacuum and mechanical pressure of 10,000
— 15,000 lbflin2 or 69 — 103 MPa or 7 — 11 kgf/mm2 is to be applied. The pressed disk is to be removed from the die, put into a disk holder, and then placed directly into the sample holder of the instrument for recording the infrared spectrum.UL 1581-2019 pdf free download.
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