1.Overview
In modern food processing plants and industrial buildings, ducting systems play a critical role in maintaining temperature control, air quality, and hygienic conditions. These systems, comprising metal or plastic pipes, ensure efficient air management by transporting cooled or heated air between various zones. While passive ducts lack moving parts, active ducts include fans to facilitate airflow, especially in controlled environments such as food factories and HVAC-equipped manufacturing units.
A well-designed duct system is integral to any HVAC installation in commercial food facilities. It promotes:
- Contaminant removal
- Temperature regulation
- Energy efficiency
- Compliance with food safety standards
For consultants in food manufacturing, optimizing duct design minimizes energy loss, controls airborne particles, and ensures compliance with industry-grade hygiene regulations.
Flexible Ducts
Flexible ducts (or flex ducts) are widely used in HVAC applications due to their:
- Plastic inner liner with metal helix coil support
- Fiberglass insulation
- Ideal for tight or complex spaces in food manufacturing zones
However, improper installation—sagging, tearing, or kinking—can cause air leakage and reduced efficiency. Food industry consultants emphasize the importance of secure and precise installation.
Fabric Ducts
Used increasingly in food and beverage industries, fabric ducts offer:
- Uniform airflow
- Anti-bacterial and flame-retardant properties
- Condensation control
- Lightweight and quick installation
Their non-corrosive polyester materials prevent microbial growth, making them ideal for food technology consulting projects focused on GMP compliance.
Further, we shall discuss how textile ducting systems are better than tradition steel ducting systems.
Rigid Ducts
Sheet Metal Ducts
- (a) Galvanized Steel Ducts: Known for durability, rust resistance, and mold prevention. Cost-effective when used in round form.
- (b) Aluminum Ducts: Preferred for cleanrooms and dryer vents, offering lightweight structure and corrosion resistance.
Fiberglass Ductwork
- Best for underground or low-pressure systems
- Reduces HVAC noise
- Not ideal for ventilation in food plants due to maintenance difficulty and potential fiberglass particle release
Fiberboard Ductwork
- Constructed from bonded fiberglass
- Cost-effective for cooling and heating
- Rough internal surface may hinder airflow
- Prone to deterioration if not installed or maintained properly
(a)-Galvanized Ducting
- Galvanized ducts are a perfect fit for sustainable buildings, sheet metal ductwork like galvanized steel is created from recycled materials and is easy to plan.
- Glavanized ducts have a number of advantages like; Sturdiness, non-combustible and non-porous, and due to this reason, sheet metal ducts restrict the growth of mold.
- This material is used to make duct material for most air handling systems due to its higher strength, durability, rust resistance, easy availability, and can be easily changed to a new shape.
- Round galvanized ducts are recommended for the maximum air-carrying capacity rather than rectangular ducts and they have lower installation costs which may result in substantial cost savings.
- A disadvantage of galvanized type ducts is that they are more likely to leak air where seams or two sections are joined.
(b)-Aluminium ducts
- Aluminium ducts are the most common type of ducts. They are usually used for cleanroom applications.
- These ducts are very light in weight and very easy to install.
- These ducts have a resistance to corrosion from moisture but the basic cost per pound is more than the galvanized steel.
- The ductwork can either be flexible or rigid and sometimes fiberglass insulation is added for better thermal control.
- The flexible form is used because of aluminum’s ability to stretch; a flexible aluminum duct can be bent hundreds of times and still maintain an air-tight cavity. Insulated forms of both of these can be used to minimize the transfer of heat between the contents and the environment, making HVAC systems more efficient.
- Aluminium ducts have limited characteristics of aluminum ductwork including their low strength, cost of material, thermal expansion, and weldability. Aluminum ducts also are used with home dryer systems; as aluminum doesn’t rust, this type of duct is perfect for removing warm, moist air.
Fiberglass ductwork
- Fiberglass ductwork is used in low-pressure systems.
- Sheet metal ducts frequently use fiberglass insulation, which has a metal foil and acts as a vapor barrier. To prevent the formation of condensation, insulation is been provided by this line.
- These types of ducts are insulated as part of their construction, and they are majorly used as underground duct systems. Further applications of these types of ducts are their resistance to corrosion, strength, and ease of modification.
- Fiberglass duct board provides excellent sound attenuation, reducing sounds created by an HVAC system, which is ideal for commercial buildings.
- Major disadvantage of Fiberglass ducts is that over time, the liner can deteriorate and expose building occupants to fiberglass particles. But to prevent this from happening, most of the sheet metal ducts are lined with fiberglass on the outside of the duct.
- Also, in addition, these ducts are quite tough to clean and that’s a challenging process as well as the cleaning process can damage the inner lining. Molds and bacteria too can contaminate these ducts.
- Further limiting characteristics includes the cost, weight, range of chemical and physical properties, and brittleness.
Fiberboard ductwork
- Fiberboard ducts come under the type of rigid artwork, which is constructed of fiberglass and stands bonded by resin.
- The outer surface of the board is covered with foil, which acts as a barrier between air and moisture. The inner surface of the fiberboard will be in contact with the airflow which would not be as smooth as metal and is rough which can affect the airflow and efficiency.
- These types of ducts are often used for heating and cooling ducts but this is never recommended when the requirement is for ventilation ducts.
- One of the major disadvantages of this type of ductwork is that fiberboard is inherently insulating. It is airtight, contingent on the care taken in constructing the sections, and cutting and sealing the joints.
- An unnoticed crack or damage in the bonded fiberglass over time can lead to erosion of the glass fibers, creating a durability issue and compromising the insulation value of the duct.
Semi-rigid ducts
These are preferred in heavy-duty industrial settings, including:
- Chemical plant ventilation
- Food factory exhaust systems
- Offer zero-leakage, anti-static, and anti-bacterial lining
- Allow switching between round and oval formats without compromising airflow
3. Efficient ductwork
o achieve optimal air handling in food industry factories, ensure:
- Airtight sealing and proper sizing
- Balanced airflow (supply vs return)
- Minimized temperature loss
- Energy efficiency, reducing operational costs
Proper ducting design and maintenance are essential for consultants and contractors working in food plant projects, ensuring comfort, compliance, and cost control.
4. Conclusion
Whether it’s a fabric duct for hygienic airflow in a dairy plant or a semi-rigid duct in a chemical processing unit, selecting the right duct type is vital. For food industry consultants, engineers, and project managers, understanding the technical and operational nuances of each system can significantly enhance energy efficiency, air quality, and compliance with food safety standards.
5. Reference
1. https://www.techtarget.com/searchdatacenter/definition/ducting-data-center-cooling
2. https://www.accessdoorsandpanels.com/blog/different-types-of-duct-systems/
3. https://www.therma.com/types-of-ductwork/
4. https://www.ducting.com/semi-rigid-ducting/
5. https://www.euroair-sea.com/en/resources/news/what-is-textile-ducting-a-beginners-guide-to-the-future-of-hvac-design/
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