Fabrication

IM DUCT SYSTEM FABRICATION

The construction of a IM pre-insulated duct generally follows a standard procedure regardless of the shape of the duct:

Cutting

All measurements refer to a duct’s internal dimension. This means the area of air passage or opening of the duct. All tracing and/or plotting is done on the internal side of the duct. Cutting 45° miter cuts are made along the edge of the duct, while “V” cuts or grooves of the same angle are made for folding of the panel into shape. Other special purpose angles can be made including 22.5°.

Gluing

The glue is contact adhesive and can be applied evenly to the cut surfaces with a glue spreader or a simple all-purpose paintbrush. The “V” grooves must be cleaned off of any PIR foam particles or dust. Generally, the curing period of the adhesive is between 10 to 20 minutes or when the glue is dry to the touch.

Folding

After the glue is cured, the sides are folded to each other and the duct is formed. When the outer sides of the duct are joined, use the internal surface of the cuts for aligning purposes. The rigid spatulas used to crease well the edges of the duct in the glued grooves.

Taping

The special double cured reinforcement aluminium tape is applied for the purpose of sealing PIR air duct material from the outside area, as a vapour barrier in the folded seams of the duct, to repair or cover any damages to the panel and for the aesthetic appearance of the duct. Before applying the tape, be sure that the surfaces are dry and clean. Ideally, the tape should be applied at temperatures above 10° C, it should not be applied when temperatures are below 0°C. The tape is applied only to the external seams of the duct where the sides of the panel were joined, tape. A soft spatula is used to brush along the surface of the tape and eliminate trapped air bubbles.

Flanging and Reinforcement

IM offers two types of flanging systems for joining ducts together: 1. Invisible Flange with hidden “H” bayonet in PVC The invisible flange is convenient in limited access areas and where the ducts are mounted insight and aesthetics are a priority. 2. Teeth Connector The “teeth connector” is designed for use with small ductwork and low air pressure systems. Duct reinforcement is required to protect against negative and positive pressure of systems based on two parameters: Duct size and total system pressure.

Sealing

After the duct has been assembled, all internal joints must be hermetically sealed with silicon. Apply a bead of silicon to all the joints and then using a radiuses tool or a wet finger run it along the length of the silicone to spread the sealant along the side of duct wall. Besides sealing the joints, the silicon also prevents any foam particles from entering the flow of air.
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