| 摘要 |
<p>PURPOSE:To prevent the contamination of an insulator regardless of pressure variation, by providing a hollow support insulator having an outer wall formed of a porous insulating material permitting gas to pass and a means for allowing seal gas to pass through the outer wall of said hollow support insulator. CONSTITUTION:The dust whirled up from a dust collection chamber 2 is adhered to the inside of a hollow support insulator 4' as it is. Because of this, when pressure is applied to an insulator chamber 1 from a seal gas introducing valve 10, the seal gas passes through the porous outer wall of the hollow support insulator 4' to leak to the inside of said insulator 4' and proper wind quantity is given by the seal gas to make it possible to prevent the adhesion of the dust whirled up. As mentioned above, by making the insulator itself porous, the adhesion of dust to the insulator can be directly prevented. Further, by properly selecting a porous insulator, the seal gas can be blown-in while definite pressure loss is held.</p> |
