Feature
DUCT SHAPE Ducting can be manufactured in round , square , rectangular or oval shapes and each style has advantages and disadvantages . Round duct shape is the most efficient as they offer the least resistance in conveying moving air and also require less material compared to square or rectangular ducts for the same volume of air handled . Although this style also has several other advantages , the biggest challenge is that they require more space for installation .
Square and rectangular ducts generally have a better suitability to the various conditions of a building design . They are able to be installed in ceiling voids , into walls , under or between floors , and they are notably easier to install .
DESIGN CONSIDERATIONS AND GOOD ENGINEERING PRACTICES Air distribution to any space is required to primarily maintain space conditions and minimise noise factors . Ducting can be manufactured to meet almost any dimensions , so is essentially limited by each manufacturer ’ s capacity . In South Africa , producers are able to create products from as small as 70mm x 70mm to as large as 5000mm x 2000mm .
Some guidelines when designing ducting systems that can be considered in order to optimise objectives follow .
Extracted from SANS 1238:2005 .
Low pressure duct metal thickness .
• Design should provide proper control of air flow as well as appropriate stability .
• The design will ultimately be determined by each site as well as the site conditions .
• Availability of space to work with and well as aesthetics if applicable will be high up on the list .
• Trunk- & -branch configurations with shorter runs generally work best .
www . refrigerationandaircon . co . za RACA Journal I October 2022 31