Document N2kND6r9V03eX4peRvzKgVGkD
SETTEMBER4. 1911
A8BES108 WIRKS - UL 11 b
17
11.5 The impregnating compound ihuli retain its initial qualities during the life of the wire and shall not develop any damaging chemical action within itself or with any other component of the finished wire.
11.6 ThcTinsulation on a specimen of finished conductor ft to be inspected visually to determine whether or not it complies with the requirements in paragraphs 11.1--11.5 with respect to general construction. The thickness of the insulation is to be determined in accordance with paragraph 15.4.
11.7 The insulation, after removal of uny exterior material other than asbestos, shall comply with the requirements in paragraphs 23.1,23.1A-- 23.IF, 23.2, 25.1-25.4, and 27.2-27.5.
Prrj>h 11.7 iviw4 Septembtr 4, 1981
Asbestos Content
11.8 STRAIGHT ASBESTOS - If reinforcing glass-fiber threads arc not employed, Class A asbestos, after the impregnating compounds have been removed from the insulation, shall contain not less than 80 percent by weight of asbestos.
11.9 To obtain representative material for
the test, the asbestos is to be removed from a
3--4-ft or 900--1200-mm length of conductor
and cut into short sections about 1/8 inch or
S mm in length. Reinforcing cotton threads and
cotton binder threads are not to be removed
even if such threads serve as an identifying marker.
These pieces arc to be well mixed and the impreg
nating compounds are then to be removed with
an organic solvent.
'
*11.10 A specimen of the asbestos (with the impregnating compounds removed) weighing ap proximately 5 gm is to be dried to a constant weight Wj in a weighed crudble at a temperature of 1105C (2S09F), ignited in an electric furnace at a temperature of 80020C (1472 S6F) for 60 minutes, cooled to room tempera ture in a desiccator, and then weighed again W,,. The percentage of asbestos in the specimen is then to be calculated bv means of the formula
in which X is the percentage of asbestos, Wj is the weight of the. dried specimen before ignition, W2 is tlie weight after ignition and drying, and 0.86 is a multiplying factor reflecting the fact that chrysotilc asbestos usually contains about 14 percent water of crystallization.
11.11' If the asbestos insulation is known to have more or less than 14 percent of water crystal lization, the factor 0.86 in the formula in para graph 11.10 is to be adjusted accordingly.
11.12 ASBESTOS AND GLASS - If reinforcing
glass-fiber threads are employed, Class A asbestos tape, after the impregnating compounds have been removed from the insulation, shall not contain less than 30 percent by weight of asbestos.
11.13 Insulation consisting of asbestos end glass shall not show a Joss in weight of more than SO percent after ignition at a temperature that eliminates all combustible material and water of crystallization in the asbestos.
11.14 Specimens of the insulation are to be prepared and ignited ns indicated in paragraphs 11.9 and 11.10. After ignition, the weight W2 is not to be less than 70 percent of Wj.
11.15 insulation consisting of asbestos and glass shall not contain more than 9 percent by weight of carbon (corresponding to a maximum content of 20 percent by weight of combustible material).
11.16 Tin* carbon content is to be determined from insulation from which the impregnating compounds have been removed as indicated in paragraph 11.9. A sample weighing approxi mately 1 gm is to lie dried to constant weight at 1105#C (2S09F) and then ignited Sn a stream of oxygen at 90020C (165236F). The evolved carbon dioxide is to be absorbed in an acceptable medium, and the carbon content is to be calculated from the increase in weight of the medium.
*Replaces page 17 doted June I, J9S1 # COPYRIGHT 7676,-1801 UNDERWRITERS I.ABORATORIGS INC.
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