RVT offers both axial and centrifugal fans in a variety of sizes. Ducting is also available so that fresh air can be forced deep into basements and tunnels. Whether you need high pressure or high volume air flow; RVT has a ventilation solution for you.
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An Axial fan has its motor located in the middle of the fan casing, and the airflow passes around it. A centrifugal fan has its motor located to the side of the fan casing, with a ‘snail’ shaped impeller. Typically a centrifugal fan will provide less airflow but at higher pressure than an axial fan with the same size motor.
Axial fans are better for moving high volumes of air over short distances, whereas Centrifugal fans are better at maintaining high pressure over long duct runs. Despite a lower flow rate, centrifugal fans create a steadier flow, resulting in a significantly higher static efficiency. Centrifugal fans are also typically quieter than axial fans, and even with attenuators fitted are more compact. The best fan to use therefore depends on the requirements of the project.
For railway tunnels, centrifugal fans are often the preferred option as they can be situated outside the tunnel, ensuring that they do not get in the way or block access for vehicles and machinery. Centrifugal fans also maintain high pressure over long duct runs, so they can deliver clean air deep into long tunnels; however, we have also supplied large, high power axial fans, for several tunnel projects.
Typically, Centrifugal fans are the best fans to use for basement ventilation, because they are quiet, compact and perform well even when using long duct runs or duct runs with multiple bends (as is often required to be the case), however each project is unique and requires a specialist assessment.
In section 3 of the government guidance titled 'Transmission characteristics and principles of infection prevention and control', Public Health England explain that;
"A single air change is estimated to remove 63% of airborne contaminants, after 5 air changes less than 1% of airborne contamination is thought to remain".
The number of air changes required will depend on the environment you are working in and the activities you are conducting; however in more sensitive environments, Public Health England recommend 6 - 12 air changes.
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