... / Painted metal2) Material of collector frame: aluminum alloy3) Coil material: copper 4) Water capacity: 150L, 200L,300L, 450L,5) Pressure: 0.6MPa6 ... resistance of vacuum tube: 25mm8) Tube standards: 15, 18,30,36,45tubes with 58mm diameter and 1.8m length solar water heater (split design, bear ...