| 摘要 |
1,254,024. Drying glass fibre strands. PPG INDUSTRIES Inc. 1 Aug., 1969 [2 Aug., 1968; 2 June, 1960], No. 38655/69. Heading F4G. Glass fibre strands are dried on packages 26 in a vacuum chamber 32 at reduced pressure and elevated temperature. Initially the packages 26, mounted on rack 31 having air float supports, or on truck 34 having roller support, are heated at atmospheric pressure by steam heated pipes 46 for twenty to thirty minutes, after which the pressure is reduced by vacuum pump 38 during a similar time. A vacuum pressure measuring device 50 is provided and the degree of pressure rise in chamber 32 as measured by 50 when the pump 38 is switched off, gives a measure of the remaining moisture in the packages, so that the drying can be terminated when a desired moisture level is attained. Uniformity of drying through the package is achieved by this method. The vacuum is approximately 27 inches of mercury below atmospheric. Temperatures in the range 150-270‹ F. are used. |
