| 摘要 |
PURPOSE:To shorten a measuring time, by a method wherein the air-tight closure part of an arrester is formed in each hermetically sealed lid and connected to a vacuum pump through each pipe drawn out from each hermetically closed lid while a differential pressure sensor is interposed between pipes to detect the change in the pressure in each lid. CONSTITUTION:Hermetically closed lid 1a are arranged so as to respectively cover the air-tight closure parts provided to the upper and lower end parts of an arrester 3 and the open peripheral edge 15 of each lid 1a is applied to the surface of a porcelain tube 3a through a gasket 17. The lids 1a are evacuated by a vacuum pump through pipes 6, 6a connected to both lids 1a and one lid 1a is set a master while the other lid 1a is subjected to air-tightness test by the air leak tester (abbreviated in the drawing) interposed between both pipes 6, 6a. By this mechanism, the volume of each air-tight part can be reduced and, therefore, measuring accuracy can be also enhanced. |
