Round spiral perforated ducts are available in diameters from 80 to 630 mm; from diameter 250 mm they are provided corrugations/exterior grooves for better tightness and rigidity under negative pressure. Shape, structure and size of holes” RV 5x8 (round holes 5 mm in staggered row pattern, space between holes: 8 mm).
Perforated spiral ducts can be used in duct silencer production and for diffuser construction.
