Calculation rules for quantities of ventilation ducts
1. Sheet steel air duct
(1) The air duct shall be calculated based on the developed area
according to different specifications, and the area of inspection hole,
measuring hole, air supply outlet, air suction outlet, etc. on the duct
shall not be deducted.
(2) When calculating the length of the air duct, the length of the
center line in the drawing shall prevail, including the length of pipe
fittings such as elbows, tees, reducer pipes and round places, but not
including the length of the location of ventilation components (such as
air valves, air vents, etc.). The diameter and perimeter of the air duct
shall be expanded according to the dimensions in the drawing. However,
the joint and flanging amount of the undercut air duct shall not be
calculated within the developed area.
（3）风管导流叶检查井钢模具 隔离墩模具 隔离墩钢模具 流水槽模具 U型槽模具 螺杆启闭机 卷扬式启闭机 铜雕佛像 片按叶片的面积计算。
(3) The air duct guide vane is calculated according to the area of the vane.
(4) Air duct accessories (except for flexible joints, which are
calculated by square meters), inspection holes, measuring holes, etc.
are calculated in units of pieces according to different types and