... 5. Bracket: premium cold roll bracket stainless steel screw 6. Vacuum tube: 3.3 high borosilicate glass (47/58mm) 7. ... is 0.05 to 0.075 (80± 5) 9. Vacuum tightness is P ≤ 5.0 x 0.0001Pa 10. ... . Type: 16, 18, 20, 24, 26, 28 , 30and36 tubes 14. Capacity: 130 to 300L 15. Characteristics: 1.Best angle ... dispose of scale, bacteria and prevent electricity7.Environmental friendly vacuum tubes solar water heater