A factory ductwork upgrade is rarely prompted by one obvious failure. More often, extraction gradually becomes less effective: dust settles around work areas, fumes hang for longer, operators complain about draughts or odours, and the fan seems to run constantly without producing the result it once did. Replacing a fan alone may not solve any of this if the duct system is undersized, leaking, poorly routed or restricted by years of alterations.
For factory and workshop operators, the right upgrade starts with the process being extracted, not the catalogue size of a duct or fan. The aim is to capture contaminants close to the source, move them through a properly designed duct run and discharge or filter them in a controlled way. Every part of that route affects the next.
Signs a factory ductwork upgrade is due
Visible damage is an easy reason to act. Crushed spiral pipe, loose joints, corroded sections and makeshift repairs all reduce the reliability of an extraction system. However, sound-looking ductwork can still be the cause of poor performance.
A common issue is that a factory has changed while its extraction layout has not. A new machine may have been added to an existing branch, a bench moved further from its hood, or several workstations connected to a system designed for fewer points of extraction. The available airflow is then divided across more demand. One area may appear acceptable while another receives too little capture.
Frequent blockages are another warning sign. Dust build-up, debris caught at sharp bends and restrictions at reducers can raise resistance through the system. This puts more demand on the fan and can make cleaning harder. Where deposits are recurring, simply replacing the affected duct section does not address the underlying cause. The duct route, velocity and point of collection all need review.
Noise also deserves attention. Whistling at joints, rattling duct sections and excessive air noise can indicate air leaks, loose fittings or a layout that forces air through narrow sections and abrupt direction changes. Some noise will always be present in industrial extraction, but it should not be treated as an unavoidable feature of a poorly arranged installation.
Start with capture, then design the duct run
The most costly mistake in a ductwork project is to concentrate on the fan at the end of the system. Extraction is only effective if contaminants are captured where they are produced. A hood, canopy, enclosure or machine connection that sits too far from the source can allow dust or fumes into the working area before the ductwork has a chance to remove them.
Once the capture point is correct, the duct route should preserve as much useful airflow as possible. Shorter, more direct runs generally create less resistance than long routes with unnecessary bends. That does not mean the shortest route is automatically the best route. Access for cleaning, future maintenance, machine movement and safe positioning of the discharge all matter.
Sharp changes in direction and improvised connections tend to create problems. Proper elbows, spigots, reducers and branches provide a more controlled route than taped joints or mismatched components. The diameter must also suit the required airflow and the equipment being connected. Reducing a duct simply because it is easier to route can restrict the whole system.
A good design accounts for all connected points, including those that may operate at the same time. It also considers whether the system needs to accommodate a later expansion. Allowing for future machinery can be sensible, although oversizing every part of a system without a clear basis can create its own capture and control issues. This is a specification decision, not a rule of thumb.
Fan selection follows the system resistance
An extraction fan must overcome the resistance created by the hood, filters or separators, duct length, bends, branches, silencers and terminal components. Two systems with the same nominal duct diameter can require very different fan duties because their layouts are different.
This is why replacing an existing fan with a larger unit can be a poor-value response to weak extraction. A more powerful fan may increase energy use and noise while leaks, blockages or poor capture remain. Conversely, after an efficient ductwork redesign, the appropriate fan selection may be more straightforward because unnecessary resistance has been removed.
Speed control can be useful where demand changes during the day, but it is not a substitute for correct design. Reducing fan speed may save energy when fewer stations are operating; it must not reduce airflow below what the process needs. An authorised S&P fan and controller combination should be selected against the actual duty rather than chosen on motor size alone.
Duct material, joints and access matter
Factory ductwork faces practical conditions that are often tougher than they first appear. Abrasion, vibration, heat, moisture, cleaning regimes and airborne contaminants all influence the suitable material and construction. The correct choice depends on the process and the environment, so there is no universal thickness or finish that suits every site.
Where stainless steel is required for a particular application, grade and thickness should be specified against the working conditions rather than selected by appearance. For context, 430-grade stainless steel is a practical standard material for many fabricated canopy products, while 304-grade is available for applications needing greater corrosion resistance. That comparison should not be used to assume that one material is right for all factory ductwork. The extraction duty comes first.
Joint quality is equally important. Leaking connections waste extracted air and can deposit contaminants in roof voids, plant spaces or other areas where they are difficult to identify and clean. Properly matched duct fittings and secure joints make installation more predictable and simplify future alterations.
Access is often neglected at the quotation stage. A duct route may fit on a drawing but be difficult to inspect, clean or repair once machinery, cable trays and services are in place. Include access requirements early, especially where the extracted material can settle inside the system. Planned access costs less than dismantling a section during a production stoppage.
Use the right standard for the application
For industrial ductwork, DW144 is the relevant UK industry standard commonly used for sheet metal ductwork manufacture and installation. It provides a useful baseline for construction quality, fittings and workmanship. A system built with suitable components and clear installation requirements is easier for contractors and facilities teams to assess than a collection of unverified parts.
DW172 applies specifically to kitchen ventilation. It is highly relevant where a commercial kitchen canopy and associated extract system are being specified, but it should not be presented as the design standard for every factory extraction project. This distinction matters when sites have mixed operations, such as an on-site catering kitchen alongside workshop areas.
Compliance is wider than the duct itself. Employers must consider the substances generated by the process, worker exposure, inspection and maintenance duties, and any relevant fire or process safety requirements. Where combustible dust, hazardous fumes or specialised process emissions are involved, the system should be assessed by a suitably competent specialist before equipment is ordered. Generic ducting is not a safe substitute for application-specific design.
Plan installation around production, not just delivery
The least disruptive upgrade is normally phased. Measure the route, confirm connection sizes, identify supports, check access and agree which areas can be isolated without stopping the entire operation. This avoids the familiar situation where a new duct section arrives but cannot be installed because an existing cable run, machine guard or structural member was missed during the survey.
For straightforward replacements, standard spiral duct, elbows, spigots, reducers and vent components can keep lead times and cost under control. Bespoke fabrication is more appropriate where the route has unusual dimensions, a transition must meet existing plant precisely, or an awkward space demands a made-to-measure section. Standard is often the economical answer, but custom work is worthwhile when it prevents poor fitment or unnecessary site modification.
CanopyMan manufactures ventilation and stainless steel products in Birmingham and can supply both standard ducting components and made-to-order fabrication for projects across England and Wales. The useful starting point is a clear brief: process type, existing equipment, connection sizes, route dimensions, access constraints and the outcome the upgrade must achieve.
A factory extraction system should support the way people actually work, not merely satisfy a drawing. If the duct route improves capture, remains accessible and matches the fan to the real resistance of the system, the upgrade has a far better chance of delivering cleaner, more reliable working conditions over the long term.