vacuum tube made of high borosilicate 3.3 glass and has an all glass double-tube co-axial structure. vacuum tubeThe evacuated tubes are ... 92.The tubes exist different diameters: Φ47, Φ58,Φ70 -800mm, 1200mm, 1500mm, 1600mm,1800mm, 1900mm, 2000mm, 2100mm.The rate of vacuum between the ... pipes is below 5*10-3Pa which is the best rate currently available for evacuated tubes. The ...