Sizing low-pressure industrial suction systems

When designing an industrial suction or ventilation installation, the choice of thickness, material and duct type is often made out of habit: whatever was done on the previous project gets repeated. Yet every application has its own operating conditions, and these are what should drive the design.

 

 

Below you will find 5 questions that will help you optimise the system from the outset.

 

1. What is the real working pressure?

It is the starting point that is most often taken for granted. Standard fans and filters on the market work at a maximum of -0.07 bar (-7,000 Pa). Knowing the actual fan data and the pressure losses along the duct layout makes it possible to tailor the design to what the system needs, rather than to what has always been done “just in case”.

 

 

What can a low-pressure installation withstand? Test data

In both an external laboratory and our own in-house laboratory, we have tested our ROS DUCTING galvanised steel products, joined with a Hybrid Pull-ring with a profiled EPDM gasket, in diameters from Ø80 to Ø400 mm. The results:

 

- Positive pressure (blowing): resistance up to 0.5 bar (50,000 Pa).

 

- Negative pressure (suction): resistance up to -0.1 bar (-10,000 Pa).

 

 

In suction, the assembly exceeds by around 40% the pressure at which standard fans and filters usually operate (-0.07 bar). In other words, for this range of applications the system offers a safety margin based on measured data, not on assumptions.

 

 

2. What is being conveyed?

Capturing fine dust is not the same as capturing abrasive particles, welding fumes or humid air. The nature of the material being conveyed determines the duct material, the internal finish and the points that need the most attention, such as elbows and changes of direction. Knowing it helps avoid blanket oversizing, and also makes it possible to plan ahead for the reinforcements that are genuinely needed at specific points.

 

3. What environment will it operate in?

Here, the deciding factor is usually corrosion resistance:

 

- Galvanised steel: a suitable solution for most industrial applications in dry, non-aggressive environments.

 

- AISI 304 stainless steel: recommended for the food and pharmaceutical industries, where hygiene and ease of cleaning are essential.

 

- AISI 316 stainless steel: designed for saline or acidic environments and coastal areas, with greater corrosion resistance.

 

 

4. How much will the installation change?

 

A plant is often not a closed project: it expands, machinery is rearranged, new extraction points are added. Designing with the evolution of the process in mind, using a modular and scalable system, avoids having to rebuild parts of the installation every time the plant changes.

 

 

5. What does the technical office need to design and document it?

The efficiency of an installation is also decided on screen. Having the 2D and 3D CAD library of ducts and fittings reduces engineering hours, avoids redrawing standard elements and allows the layout to be validated before it reaches site.

 

Decisions you can defend

 

Answering these 5 questions leaves the design backed by data: real pressure, the nature of the material conveyed, the working environment, the need for modularity and test results. This way, every choice can be explained with solid arguments to management or to a client. Optimising is not about reducing for the sake of it, but about being able to justify why each element is the right one.

 

How ROS Ducting supports you

 

We manufacture ducts and fittings in galvanised and stainless steel, using laser cutting and welding, ready to install without last-minute adjustments on site. We have designed our modular system for low-pressure applications and make our CAD library available to designers and engineering firms.

 

Are you defining an industrial suction or ventilation installation? Contact us and we will help you find the most suitable solution for your application.