How Air Blowers Work: The Principle
Effectively, the kinetic energy of the impeller is transferred to the air. Pressure builds up as the volume of the airstream increases inside the housing. The air is then discharged from the housing towards a defined point.
This targeted channelling of the air is what differentiates an air blower from a simple fan. Air blowers, designed in as part of an air knife system, will create a balanced airflow – reducing wasteful over-generation of excess volume and pressure.
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why Specifying The Right Type Of Air Blower Is So Important
Air blowers may look and sound simple enough at headline level. But it’s very important to specify the correct type for your application – otherwise you risk compromising blower performance and/or paying for more energy than you need.
These are the various types of air blower, based on their impeller design:
• forward curved centrifugal
• backward curved centrifugal
• backward inclined aerofoil
• axial fans.
And here are the advantages of each type…
Forward Curved Centrifugal Air Blowers
Centrifugal air blowers can move high volumes of air at low pressure – making them up to 90% cheaper than compressed air. Here’s how and why…
The air velocity (in metres/second) in a blower is fixed. But the mass flow rate (the number of kilograms of air passing a defined point per second) is not fixed. Centrifugal air blowers operate at lower pressure because they can use less air to create the required high-velocity airstream.
Lower pressure equals lower energy bills – for the same (or better) performance.
The impellers in forward curved centrifugal air blowers look a lot like hamster wheels. And as risible as that may sound, it’s probably the best visual description. It’s not one you’re likely to forget.
These are some of the most common air blowers – delivering medium levels of pressure from a medium level of power. The impellers can be either left- or right-handed to suit the application.
Which is better? Left- or right-handed? It depends on the application and where it is most advantageous for the motor to sit in relation to the discharge.
View our range of forward curved centrifugal fans. Our catalogue features more than 550 fans to meet the requirements of a broad spectrum of industrial applications.
backward Curved Centrifugal Air Blowers
Backward -curved blades flick the air – rather than cut it. So size-for-size, they deliver higher volumes of air at lower pressure. This means greater performance for less power (should the application demand it). Centrifugal? ‘Centri-frugal’ more like.
They’re not just more energy-efficient, they’re also quieter. So you’ll find them used in a lot of air conditioning systems and for data centre cooling. Some were also used to help create special effects in Walking With Dinosaurs – The Arena Spectacular, based on the BBC’s multi-award-winning TV mini-series.
View our range of backward curved centrifugal air blowers. Direct mounting of the impellers and low motor speeds deliver high-pressure performance with minimal noise levels.
BACKWARD INCLINED AEROFOIL BLOWERS
Backward inclined aerofoil blowers such as the belt-driven EP10A have a different type of impeller. The rotor in this type of blower is much flatter, making them more compact.
But don’t underestimate their small size – they’re designed to blast out medium volumes of air at high pressure. The EP10A in particular has state of the art impeller design and superior belt technology, creating less friction. The belt’s tension is lower too – putting less load on the bearings so they last longer.
You’ll find EP10A blowers in our LNL (Low Noise Level) fully enclosed air knife systems and our EL partially enclosed air knives.
RADIAL AIR BLOWERS
These are very tough blowers. They’re particularly recommended for marine/offshore applications or hot/cold environments. They’re not quite ‘fit and forget’ but they are very hard-working blowers.
The impeller blades radiate from the centre to the outside edge like the paddles on an old Mississippi steamboat. These blades are usually sandwiched between protective layers – resulting in greater strength and more efficient air movement.
ACI’s range of radial fans offers flow rates of up to 212,000 m³/hr (360,000CFM) and pressures up to 300 Mbar (120 In.Swg).
AXIAL AIR BLOWERS
The impellers on these high-volume, low-pressure units look like desk fans. They’re best suited to cooling large volumes of air cost-effectively.
You’ll find them in wind tunnels and some HVAC systems (not big ducted systems, though because they’re low-pressure fans). They’re also good for destratification in buildings – mixing air to help stop stratified layers of heat becoming trapped near the ceiling.
ACI offers Euroventilatori axial fans with flow rates of up to 75,000 m3/hr (44,143 CFM) and static pressures up to 3 In.Swg (75 mmWG).
Why It Pays To Get Expert Technical Advice
- The type and size of the impeller – the shape, angle and configuration of the blades. Larger diameter impellers create more pressure; wider (deeper) impellers give greater airflow.
- The distance between the impeller and the cut-off point (the location where the air begins to exit the housing). This is crucial to performance.
- How much heat the air blower gives off (due to the higher pressure of the air) – the temperature differential can range from 3°C to 20°C.
- Where will the air blowers be used – what is the climate like? How hot/cold is it? At what altitude will the blowers be used? (Thinner air is harder to move).
- Configuration of multiple blowers – will they be used in series (stacked) or parallel (side by side)? Stacking fans in series creates more pressure.
Furthermore, there is the issue of how the blowers are wired in. A blower is not a pump – so if you get it wrong, you’ll only get around 60% of the performance at best.
Our field engineers occasionally come across blowers that have been mis-wired in a three-phase supply – significantly affecting their airflow output.
See How ACI Air Blowers Solve Technical Challenges
50+ years of technical expertise and experience.
World-class solutions – US (Maine) subsidiary. Distributors, agents and partners in 40+ countries.
Performance guaranteed – all standard and custom systems will perform as tested and specified. Guaranteed results and savings.
Advanced quieter air blowers that take up less space.
UK designed and manufactured equipment.
Thousands of happy customers across the world.
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