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Class O Air Duct


  • Complete air-tight duct systems!
  • Simple on-site assembly!
  • No parts fabrication required on the job!
  • Standard range of accessories available to permit speedy installation.
  • Clean efficient fast installation!
  • Greater airflow Life time durability.
  • Choice of materials; Aluminium and Stainless Steel for Flexible duct.
  • QUALITY job at low cost!

Machine made round metallic duct systems such as METAL FLEX for air handling and ventilation applications are being preferred to conventional duct systems world wide. Round ducts have high strength to weight ratio and this invariably means lower cost per ton of air conditioning or per m3 flow of air.

Near zero permeability of round metallic ducts has earned them a class 0 (Zero) Fire Hazard rating. Being machine made, no fabrication on site is required. METAL FLEX ducts can be supplied in any convenient lengths, thereby reducing the number ofjoints for a given layout. Field jointing can be carried out using readily available jointing kits. Availability of standard accessories and fittings permits fast installation on site. Low weight per unit length of these ducts allows larger hanger spacings upto 1 0' (3.00 m.) centres. The strength of round ducts makes them the preferred shape for underground or concealed applications.

However, the most outstanding feature of the round duct system is the use of flexible metallic ducts. It eliminates the need for fabricated bends. Their installation is simple and cumbersome alignment of flanges is totally avoided. Metal Flex flexible metallic ducts are ideally suited for applications where the space is limited and where other design considerations limit the available head space. These ducts can literally "snake!' through cramped spaces, recesses and corners, thus making climate control possible in difficult layouts; a job which would have looked hitherto impossible using conventional ducting. Features such as these make METAL FLEX flexible metallic ducts an air handling system designer's delight. The pressure drop data of round metallic ducts compares favourably with data for alternative systems. The ducts can be conveniently insulated using conventional materials such as glass wool.



  • Class O fire hazard classification permits installation in return plenum ceilings or other areas where the use of class I air duct would contribute to smoke and flame spread in the event of fire.
  • All metal construction permits duct to be installed within walls, wall chases or ceilings where inaccessibility necessitates a duct with a life expectancy of the building.
  • Near Zero Permeability and Leakage reduces energy loss by delivering dried, moistened, cooled or heated air to the terminal without un- expected transmission loss.
  • Assured attainment of designed air-flow. METAL FLEX will not droop between six foot supports, and can be installed with severe bends that do not cause bunch-up, ovaling and restriction at every turn. A round ball can be rolled through METAL FLEX turns. Also METAL FLEX is pulled open to the desired length and can be recompressed where too long providing shortest point to point air flow.

No limitation to installed Length.


CONSTRUCTION : Type IOOA& 140 A special aluminium alloy prevents corrosion and metal fatigue. Close tolerance machine fabrication produces a continuous lock-seam that permits duct to be compressed, pulled open, bent and rebent without developing leakage.


Static Pressure 3" to 10" diameters 12" to 18" diameters 12" (300mm.) WC. Positive & Negative
8" (200mm.) W.C. Positive & Negative
Maximum Velocity 5000 f.p.m. \ (25 m/sec.)
Temperature Range -1 to 435 0F \ (-73 0C to 224 0C)
Permeance Near Zero

No limitation to installed length

Physical Characterstics

Typical Installation

Some Application

  • Kitchen Venting
  • Bathroom Venting
  • Furnace Venting
  • Clother Drier Venting