High solar-thermal conversion and low heat loss Stable advanced coating up to 380 centigrade Long time warranty to 15 years High level vacuum ensure operation under cold weather Data sheet of solar water heater Material borosilicate glass 3.3 Structure all glass coaxial double-layer tubes Material of coating aln/ain-ss/cu Absorptance 0.94 to 0.96 Emittance 0.04 to 0.06 Vacuum les than 5f-10-4pa Stagnation temperature 270 to 300 centigrade Heat-loss coefficient less than 0.6w/ +o *fª) Bearing hailstone ability hailstone diameter ª¬25mm Pressure-endure ability 1mpa Carton packing standard