Calculation rules for quantities of ventilation pipes
1. Sheet steel air duct
(1) The air duct is calculated based on the expanded area according to
different specifications, and the area occupied by inspection hole,
measuring hole, air supply outlet and air suction outlet on the duct is
(2) When calculating the length of the air duct, the length of the
center line indicated in the drawing shall prevail, including the length
of elbow, tee, reducer, round place and other pipe fittings, but shall
not include the length of the location of ventilation components (such
as air valve, air outlet, etc.). The diameter and perimeter of the air
duct shall be expanded according to the dimensions indicated in the
drawing. However, the joint and flanging amount of undercut air duct
shall not be calculated in the developed area.
(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 and measuring holes are
calculated in units of different types and specifications.