NQ corners combined with PQ flange profile are used for
building rectangular ventilation ducts. The standard NQ-20
duct flange corners piece is suitable for rectangular duct sections with the
long side up to ca. 800 mm.
For bigger sizes, the NQ-20L long corner is recommended.
If the short side of the rectangular duct section is less than 150 mm,
it is better to use the NQ-20K short corner. For larger ventilation ducts,
NQ-30 and NQ-40 corner are required.
