Ductwork installation guide - screws usage


Catalog excerpts

Ductwork installation guide - screws usage - 1

Alnor Knowlegde Base Using screws to install ventilation ducts Lap screws have a broad possible application in the assembly of ventilation ducts, both round and 
 square ones.
 Screw types
 Screws are mostly divided by head type. Alnor product offer consists of screw types: “7” socket head, Phillips head and PAMHEAD. 
 Which screws to choose – it depends on personal preference of the fitter and tools available. 
 However, for ventilation ducts we recommend screws with flat head bottom.
 Illustration no. 1
 Lap screws with 
 assembly ends Screws have different lengths which allows to match the thickness of the joined surfaces. Alnor offers screws between 9 and 25 mm in length. Screws can be easily used with special wrench and screw driver heads.
 Screws can be used in installations using both round and square ducts. 
 When installing round ducts, it is required to match the amount of screws to duct diameter. See table 1 for suggested amounts. 
 Illustration no. 2
 Installation of the EQRS/EQVS suspension system on a round duct 
 Table 1 - number of screws per duct diameter

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Ductwork installation guide - screws usage - 2

Alnor Knowlegde Base Illustration no. 3
 Installation order for screws on a round duct The key factor is the order of installing the screws - they should be screwed in crosswise. Improper order of screw spacing creates folds which cause leakage. Screws should be installed 10 mm away from the duct edge. This is particularly important when using fittings with washers, which offer class “D” tightness according to Eurovent. 
 Illustration no. 3 shows an improper installation order and a proper screw spacing.
 Installing ducts with screws is recommended for installations with class A and B...

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Ductwork installation guide - screws usage - 3

Alnor Knowlegde Base sion is used for suspending round ducts. The suspension is attached to the duct surface by screws. L and Z suspensions are used for quick installation of square ventilation ducts, especially with threaded rods and self-threading screws.
 Self-threading screws also allow for joining square ducts - even at the construction site. Contractors Illustration no. 5 
 Installation of a frame on a square duct who do not know the exact duct length may purchase ducts with loose frame on one end, this allows to cut the duct down to desired length and use the screws to attach the...

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Ductwork installation guide - screws usage - 4

Alnor Knowlegde Base Illustration no. 7
 Installing a wall mounted air intake using screws Screws are also used for making own components of the ventilation system - both round and square ones. They facilitate easy and fast coupling of side profiles and tongues to create the final product wall mounted air intakes or multiblade dampers. 
 Lap screws are perfect for installing PVC damper mechanisms. They allow for quick and easy joining of the plastic mandrel with the revolving damper surface. 
 Different types of accessories are used to mount ventilation systems. Without a doubt,...

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