Item name: Normal solar vacuum tubeStructure: All-glass double-tube co-axial structure47mm*1.5m/58mm*1.8mGlass material: High borosilicate 3.3 glassExternal pipe diameter and thickness:dia.=47±0.7mm &=1.6mm, ida.=58±0.7mm &=1.6mmInternal pipe diameter and thickness:dia.=37±0.7mm &=1.6mm, ida.=47±0.7mm &=1.6mmPipe Length: 1500mm/1800mmAbsorptive coating property: Structure: AL/AL-ALN(H)-ALN(L)/ALNSediment method: Single target magnertron sputterig platingSpecific absorption: as=0.90~0.93(am1.5)Emission ratio:0.05~0.075(80±5)Vacuum tightness: P�5.0*1000PaIdle sunning property parameters: Y=220~260m2/KWSolar irradiation for obtaining a preset water temperature:H�4.7MJ/m2(dia.58) H=4.1~4.4MJ/m2H�3.7MJ/m2(dia.47) H=3.1~3.4MJ/m2Average heat loss coeffieient: ult=0.6~0.7W/(m2)