Vacuum Tube - Borosilicate Glass, 1500mm/1800mm Length, 58mm Outer Diameter, 47mm Inner Diameter | Superior Insulation With Advanced Solar Radiation Absorption And Minimal Reflection Properties

We are offering our customers a wide range of Vacuum Tubes. Each evacuated tube consist of two glass tubes made from extremely strong borosilicate glass The outer tube is transparent allowing light rays to pass through with minimal reflection, The inner tube is coated with a special selective coating (AL-N/AL) which features excellent solar radiation absorption and minimal reflection properties, The top of the two tubes are fused together and the air contained in the space between the two layer of glass is pumped out while exposing the tube to high temperatures, This "evacuation " of the gasses form a vacuum, which is an important factor in the performance of the evacuated tubes Please.
Why a vacuum?As you would know if you have used a glass lined Thermos flask, a vacuum is an excellent insulator, This is important because once the evacuated tube absorbs the radiation from the sun and converts it to heat, we don't want to lose it!The vacuum helps to achieve this, The insulation properties are so good that while the inside of the tube may be 150A C / 304oF, the outer tube is cold to touch, This means that evacuated tube water heaters can perform well even in cold weather when flat plate collectors perform poorly due to heat loss (during high Delta-T conditions)

Evacuated tube basic specifications
Length(nominal) 1500mm/1800mm
Outer tube diameter 58mm
Inner tube diameter 47mm
Glass thickness 1.6mm
Thermal expansion 3.3*10-6A C
Material Borosilicate Glass3.3