Industrial Ventilation Systems

What problem it solves

In a production area, air is a variable you cannot see from the outside, yet it affects every stage of production. When temperature, humidity, dust and gas concentration are not controlled, the result does not arrive as a single complaint: in summer nobody can work next to the machines, in winter heat escapes every time the doors open, electronic boards fail early in dusty areas, and condensation starts on surfaces when humidity is left unchecked.

Industrial ventilation makes these variables measurable and brings them under control. The basic logic is simple: calculate how much air enters the space, how much leaves it and through which points it travels. The hard part is getting that calculation right. Insufficient airflow does not solve the problem; excessive airflow increases both the energy bill and the noise, and multiplies the heating load in winter.

The second, often overlooked topic is air balance. If air is exhausted from a space, it has to be replaced with fresh air in a controlled way. Extraction systems installed without a planned fresh air inlet create negative pressure; air is drawn in irregularly through door gaps, window edges and flue openings. The result: doors that are hard to open, disturbed flue draught and cold draughts in winter.

Applications

• Machine manufacturing and metalworking shops
• Plastic injection moulding and extrusion lines
• Textile production and dye houses
• Warehouses and logistics centres
• Packaging and printing plants
• Assembly lines and quality control areas

System components

Fresh air units

Units that filter the outside air brought into the space and heat or cool it where needed. The filter class is chosen according to the sensitivity of the space: G4 for coarse dust, F7 and above for cleaner environments. Filter selection is not arbitrary; a higher filter class means more pressure drop, and fan selection must account for it.

Exhaust fans

Roof, wall or in-line types. The choice depends on the temperature of the exhaust air, its particle and gas load, the total pressure drop in the duct system and the noise limit. If hot process air is to be exhausted, the temperature class of the fan casing and motor is checked separately.

Ductwork

Fabricated from galvanised sheet as rectangular or spiral round duct. The duct cross-section is sized so that the air velocity stays within an acceptable range. A small section increases velocity, pressure drop and noise; an oversized duct increases material and installation cost.

Dampers and grilles

They balance airflow between zones. During commissioning the airflow through each grille is measured and the dampers are set according to that measurement. When this step is skipped, the system is correct on paper but unbalanced on site.

The calculations that drive the design

The air change rate alone is not a sufficient criterion. In an area with a high heat load, even a high air change rate may not bring the temperature down; in that case the process heat has to be captured at source or a cooled solution is needed.

Points to watch

Noise. If fans are selected only by airflow and pressure, the sound level becomes a surprise. Silencers and flexible connections on lines close to work areas should be planned at the design stage.

Maintenance access. Filter doors, fan motors and dampers must be within reach. A filter that cannot be reached does not get changed; a filter that is not changed clogs, and the system loses efficiency over time.

Fire and smoke scenario. Where ductwork passes through fire compartments, fire dampers are required. This is a difficult and costly item to add later.

Energy recovery. In systems running at high airflow all year round, recovering heat from the exhaust air lowers operating costs significantly. The payback period can be calculated from operating hours and climate data.

Commissioning and handover

After installation, the system is handed over with measurements: grille airflows, duct velocities, fan current values and room sound levels are recorded. These measurements prove that the system works as designed and serve as the reference for comparison if a problem arises later.

Upgrading an existing system

Not every job is a new installation. Most facilities already have a ventilation system, but it is either undersized or no longer matches the need because production has changed. In that case, the first step is to measure the existing system.

The measurements look at how many m³/h the fans actually deliver, the air velocity in the ducts, the difference between grille airflows and design values, the differential pressure across the filters and the current drawn by the fan motors. These four measurements often explain on their own why the system falls short.

A common picture: the fan was selected correctly, but duct branches added over the years increased the pressure drop and shifted the operating point on the fan curve. Here, enlarging the duct section or correcting the branch balance is cheaper and more lasting than buying a new fan. The opposite also happens: the fan was undersized from the start and no improvement to the ducts will be enough.

In upgrade projects it is usually possible to work without stopping production. Ducts are prepared in the workshop, and installation is split across shift changes and planned shutdowns.

What drives the cost

The cost of a ventilation project does not depend on a single item. The deciding factors, in order, are:

1. Total airflow. Fans, duct sections and filter area depend directly on airflow.
2. Length and complexity of the duct system. The number of bends, reducers and branches increases both material and installation time.
3. Roof or wall penetrations. Penetrations that require structural work are a separate item.
4. Heating or cooling requirement. If the fresh air has to be conditioned, the cost rises significantly.
5. Electrics and automation. Control panel, cabling, speed controllers and sensors.
6. Height and access. In high-ceiling areas, the need for platforms and cranes extends installation time.

During the site survey each of these items is seen on site; the quote is built on measurements and counts, not estimates.

Common mistakes

Just installing a fan. An extractor fitted without ductwork and fresh air balance makes noise but does not renew the room air.

Putting the extraction point in the wrong place. Hot air rises, heavy dust settles. If the extraction point works against the natural movement of the air to be removed, efficiency drops.

Keeping duct velocity high. A narrow duct looks cheap; the result is high pressure drop, excess energy consumption and whistling noise.

Handover without measurement. In a system handed over without commissioning measurements, the source of a later complaint cannot be identified.