PRE-INSULATED AIR DUCT CONSTRUCTION GUIDELINE

1. PRE-INSULATED AIR DUCT CONSTRUCTION GUIDELINE

2 Duct PIR system is like no other insulated ductwork system. It is the most advanced and innovative system of pre-insulated air distribution ductwork available in China. The Duct System is proven to be innovative product that is easy to install and maintain providing a new perspective in the field of air distribution.

Duct PIR system is not only based on pre-insulated aluminum panels, but it also consists of accessories,machinery, tools and know-how necessary for the construction and installation in a masterly fashion. Duct PIR System has been developed and spread around the world. Its application has been gradually extended to all type of air distribution system such as industrial, commercial and civil.

Since the foundation in 2004, has been the constant leader in the production of rigid polyurethane and Polyiso (PIR) foam panels with aluminum faces. has been the pioneer of PIR panels with aluminum facing designed specifically to be used in the fabrication of ventilation ducts.

Based on the exceptional insulation properties of PIR aluminum foam panels and the simple fabrication and installation process, pre-insulated ductwork systems have been recognize by the HVAC industry as a significant innovative alternative to the classical sheet metal (GI) ductwork.

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

• Tracing    • Cutting    • Gluing     • Folding    • Taping      • Flanging and reinforcement if required      • Sealing

3 DUCTWORK FABRICATION

Tracing

Using an aluminum pencil which can be supplies outline of the duct shape can be scribed on the PIR panel. 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 paint brush. 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 supplied should then be used to crease well the edges of the duct in the glued grooves.

Taping

The special double cured reinforcement aluminium tape is available and is applied for the purpose of: sealing PIR foam material from the area, as a vapour barrier in the folded seams of the duct, to repair or cover any damages to the panel and for aesthetic appearance of the duct.

Before applying the tape, me 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, and not on the folded “V” grooves. Use a tape marker to scribe a reference line on the panel for applying the tape. A soft spatula is used to brush along the surface of the tape and eliminate trapped air bubbles.

Flanging and Reinforcement

two types of flanging systems for joining ducts together:

1. Invisible Flange with hidden “H” bayonet in PVC

2. Teeth Connector

The invisible flange is convenient in limited access areas and where the ducts are mounted in sight and aesthetics is a priority. 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 radiused 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.

The PIR panel is 1200 x 3 9 5 0mm in dimensions. The standard thickness is 20mm,+/- 1mm. (25, 30mm thickness are also available upon request).

• h=height, w=width, l=length

Refer to internal duct dimensions