Flexible Ducting vs Rigid Ducting

Flexible vs. Rigid Ducting

Flexible vs. Rigid Ducting

 

Ducting, or ductwork, refers to any system of pipes or tubing used in extraction, ventilation, heating and air conditioning systems to conduct air – and also to carry away waste particles (such as dust, metal swarf, wood particles etc). Ducting is made from a wide variety of materials and is available in different types for different purposes, and to suit various regulatory requirements. Therefore, selecting the right type is essential for your system to operate efficiently and safely.

Fortunately, all the varieties of ducting can be boiled down into two main categories: flexible ducting and rigid ducting. In this article, we look at each category in turn, with advantages, disadvantages and suggested applications for each.

1) Flexible Ducting – pros, cons and applications

Flexible ducting uses a highly versatile, accordion-like design with flexible ridges that can be compacted and manipulated in almost any direction. Flexible ductwork is ideal for use in small spaces, cabinets and non-standard layouts, and has a wide range of applications. Flexible ducting can be made from PVC, silicone, rubber, PU polyurethane, and even aluminium, and is available in insulated and non-insulated versions.

Advantages

There are several reasons to choose flexible ducting:

  • Very flexible – this type of ducting is ideal for installation in tight and confined spaces, such as cabinets, ventilation and wall cavities etc.
  • Flexible ducting is easier and quicker to install than rigid ductwork, and it is easier to make adjustments to the ducting after installation.
  • Transparent ductwork is available, which is useful to identify blockages in the flex duct.
  • The flexibility of the material makes flexible ducting ideal for short duct runs.
  • Can be used to connect outlets and vents to rigid ductwork systems.
  • Easy to use as a temporary ducting system, while waiting for the installation of a more permanent, rigid system.

Disadvantages

  • Flexibility and convenience comes at the cost of durability. Flexible ducting, in general, is not as strong as its rigid counterpart, and is prone to punctures and leaks. These can impede the efficiency of the extraction system and lead to downtime, so care must be taken to regularly check for blockages and other signs of damaged ductwork.
  • Most flexible ducting is only suitable for internal mounting.
  • Flexible ductwork can be noisier than rigid ducting.

Applications

Flexible ductwork is available in different diameters and lengths, but the main difference between the types of flexible ducting is the material. As some materials are better suited to certain applications than others, the material is the place to start when choosing the right type of ducting. The table below lets you quickly identify the type of flexible ducting you need, based on the application and sector.

Ducting Material Application Industry
PU / HD PU polyurethane Dust and dry particle extraction Woodworking/processing
Aluminium (non-insulated) Ventilation, heating and air transfer Heating/ventilation/air conditioning (HVAC)
Aluminium (insulated) Warm or cold air transfer Heating and refrigeration systems, cold rooms, air conditioning
Silicone Hot air transfer Heating systems, welding, automotive manufacturing
Thermal resistant coating Fume and exhaust extraction Welding, manufacturing, power generation, waste processing
Antistatic coating Organic dust and animal waste extraction Food preparation/processing, agriculture, pharmaceutical manufacturing
Chemical-resistant rubber Caustic fume extraction Chemical processing, plastics, petrochemicals etc.

 

Rigid Ducting – pros, cons and applications

Rigid ducts, or spiral ducts, are metal pipes used in permanent ventilation, heating and air conditioning systems, as well as large-scale dust and exhaust extraction plant. Rigid ductwork is versatile and can be adapted to a wide variety of purposes and building layouts. It is also more heavy duty than its flexible counterpart. However, the size and strength of rigid ducting makes it less suitable for tight spaces and smaller applications – and also increases cost and installation time. Rigid ducting is usually made from metal – such as stainless steel, or galvanised carbon steel – but for some non-corrosive applications, PVC plastic and polypropylene ductwork can be used.

Advantages

  • Rigid ducting is built to last – and therefore usually forms part of the infrastructure of a building. Once installed, a durable rigid ductwork system requires minimal maintenance beyond periodic inspections, and is not prone to faults.
  • Rigid ductwork is suitable for all applications, including hot and cold air transfer, exhaust fumes and particle extraction.
  • Rigid ducts are durable and provide excellent lifetime value for money.
  • Lower airflow resistance leads to greater efficiency and capacity than flexible ductwork.
  • Weather resistant and suitable for external mounting.

Disadvantages:

  • Installation must be carefully planned and can be lengthy and complex – so must be conducted by a suitably qualified professional. Seek third party support if you don’t have the skills in house.
  • The weight of metal rigid ductwork – especially for larger sizes and lengths – requires more extensive mounting infrastructure than flexible ducting.
  • The metal fabrication, combined with higher time and labour costs, make rigid ducting a more expensive choice.

 

Applications:

Rigid ducting can be used for almost all fume, air and particle transfer applications, so it is less important to select the right type of material, although in some sectors you’ll need a hygienic or food safe material. The table below shows how the main processes are applicable to different industries:

Process Industry / application
Air transfer Air conditioning, heating, ventilation, cooling etc.
Dust extraction All processing and manufacturing industries dealing with wood, stone, metals, plastics, organic by-products etc.
Hygienic dust extraction Stainless steel ducting is required for ductwork in the food, drink, dairy, electronics and pharmaceutical sectors.
Fume / exhaust extraction Welding, ceramics, chemical processing, automotive manufacturing, plastics etc.
Sawdust, trim, and large particle extraction Wood working, furniture manufacturing, timber yards, building supplies, paper, cardboard and packaging manufacturing.
Toxic vapour extraction Chemical processing, oil & gas, power generation.

 

Flexible and rigid ducting from Dust Spares

Rigid and flexible ducting are frequently used side by side within the same system. The difference is in function – with flexible ducting providing versatile and short term solutions for compact extraction machinery, and rigid ducting being more of an infrastructure investment.

At Dust Spares, we stock an extensive range of both flexible ducting and rigid ductwork for sale, at competitive prices and with fast delivery. If you’re unsure of what you need, our knowledgeable and experienced team can help you find the best and most cost effective solution, so please give us a call today for free advice.

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