... axial structure Glass material High borosilicate 3.3 glass External pipe diam eter and thickness Φ=47±0.7mm &=1. ... 47±0.7mm &=1.6mm, Φ=58±0.7mm &=1.6mm Pipe length 800mm, 1200mm, 1500mm, 1600mm, 1800mm, 1900mm, 2000mm, 2100mm ... 0.96(AM1.5) Emission ratio εh=0.04~0.06(80±5) Vacuum tightness P≤5.0X10-3Pa Idle ... or manifold, when it works, cold water flows down into the vacuum tube, and there it is heated ...