Axial flow fan

What are axial fans?

Axial fans are a type of fan that creates airflow through a fan wheel that rotates around an axis and moves the air parallel to the axis.
Axial fans can also be called propeller fans and are usually delivered as a complete unit consisting of fan wheel, motor and cover.
Typically axial fans are direct driven with the impeller mounted on the motor shaft. There are also other designs such as e.g. belt-driven or with shaft bearing and coupling.

The axial fan’s strength is to transport large volume flows at low pressures. At higher pressures, a centrifugal fan may be a better choice.
To reach higher pressures with axial fans, these can be connected in series.

Usually, the efficiency of an axial fan is comparatively lower than that of a centrifugal fan. But by using guide rails, diffusers and other accessories, an axial fan can reach the same or higher efficiency.
The flow of axial fans can be regulated with vane or damper or speed regulation.

In order to choose the right axial fan, one should start from the area of ​​use, how the fan is to be controlled and whether there are any special requirements.
Contact us at FläktComp for support.

Where are axial fans used?

Axial fans are suitable in many different systems and can, for example, be used as supply air fans for ventilation or evacuation fans in case of fire or in industry and process.
An axial fan is a good fan choice for large volume flows, such as e.g. dryers in the paper industry, mine ventilation or arenas, etc.
Depending on requirements, the design of axial fans can be completely adapted to the customer’s needs.
Correctly dimensioned, an axial fan provides problem-free operation and high performance for many years.

Design

The construction and design of an axial fan is a function of casing length, fan diameter (inner diameter), casing thickness, motor/junction box design and accessories.
All our axial fans can be delivered as standard with 3 to 20 mm cover thickness in a diameter from 250 to 3550 mm.
It is the application and location that determine the design of the fan. For example, 3 to 4 mm is used in normal industrial installations, 3 to 6 mm below deck on ships, and 8 to 20 mm above deck or in heavy industrial applications.

The specifications of the installation determine the design.
The following provides some guidelines.

Normal design (Long case)

For many applications (industry or shipbuilding) designs A and G (GT for jet fans) are used. The designs have a long case that completely encloses the engine, with an external junction box.
Design A has a service access to allow for easier service.
A special case of the G design (GT for jet fans) is the GD (GDT) design, which has an inlet cone instead of a free inlet flange.

Normal design (Short case)

For many ventilation applications, a small fan is mounted in a duct system.
Models D and W (DD and WD with inlet cone for free inlet) are our solution for these applications.
They have a short fan shroud with the motor partially outside the shroud.

Swing-out fan

In some installations, it is important to be able to frequently access the impeller or the motor without dismantling the entire system, e.g. in applications with a large service requirement.
For this type of application we recommend our design B or W, WD.
By mounting the fan wheel and motor on a fold-out door, all types of service and maintenance can be easily carried out, without the fan having to be dismantled.

Free suction fans

In applications with free-suction fans, fans with inlets adapted for this should be chosen, e.g. with inlet cone. We recommend our models DD or E.

Reversible fans

In principle, all fans are reversible, although with greatly reduced performance.
Our fan models marked R (e.g. GDR) with special fan wheels are almost completely reversible, i.e. almost without loss of performance.

Fans with external motor

For systems where the motor should not or cannot be placed in the air flow, we offer the designs S (motor on the fan shaft) and T (motor on its own foundation).
Both solutions drive the impeller via a belt drive.

Impeller

Our fan wheels are equipped with aerodynamically designed blades that have high efficiency and good sound performance.
Of course, the electric motors are normally mounted symmetrically, without feet that can disturb the flow. The fan wheels are equipped with blades that can be adjusted during standstill, a great advantage if, for example, the duct system is modified.
The aerodynamically shaped impellers are made of corrosion-resistant cast aluminum alloy and its light weight ensures long life for motor bearings.

Description of single step wheels

Our standard range of impellers consists of four main types: N. M, X and Y with 6, 8 or 12 blades. By using guide vanes with 5 or 15 blades, a high efficiency at high pressures can be achieved.

1 – Fan wheels for low pressures (P6 and P8)

This type with 6 or 8 profiled blades is characterized by high efficiency (up to 85%) and very good sound behavior.

2 – Fan wheels for low pressures (N6 and N8)

This type with 6 or 8 profiled blades is characterized by high efficiency (up to 85%) and very good sound behavior.

3 – Medium pressure impellers (M8 and X8)

To still achieve a high efficiency (up to 80%) with larger air volumes and higher pressures, we often use M8 or X8 impellers.

4 – Fan wheels for high pressures (Y8 and Y12)

These impellers in combination with 15-blade guide vanes provide very high pressures (for axial fans) while maintaining a good overall efficiency.

5 – Reversible impellers (PR6 and PR8)

These impeller designs allow almost 100% reversibility of airflow, without major performance losses.

6 – Reversible impellers (NR6 and MR8)

These impeller designs allow almost 100% reversibility of airflow, without major performance losses.

Design

ELTA has worked with axial fans for over 40 years and has a wide range of standardized axial fans.
ELTAS axial fans are available in over 160 different standard designs, which means that there is always a suitable fan for your particular application.

ELTA’s standard covers for axial fans are either long covers; where the entire length of the impeller and motor assembly is enclosed or short-cased; where the engine body protrudes outside the cover.

Long coat

Axial long hood (LG) fans have built-in industry standard mounting flanges. This enables easy assembly and disassembly in ventilation ducts.
The centrally mounted motor is connected to an IP55 protected, duct mounted junction box mounted on the outside of the fan housing, with a flexible weather resistant cable.

Card cover

Short shroud (SC) axial fans have built-in industry standard mounting flanges.
This fan design allows the rear of the platform-mounted motor to protrude beyond the flange.
For even easier cable installation, an external duct-mounted junction box is available on request.
This design is used to advantage in OEM applications or in applications with limited space.

Impellers

High efficiency flow-profiled wheels, fitted with adjustable blades made of high-quality cast aluminum, GRP or carbon-loaded composite. ELTA’s impellers come factory-set to meet your specific flow requirements.
ELTA’s flow-optimized wheels and profiled vane blades provide 7% higher efficiency, which reduces total energy consumption. This is a very economical method of moving large volumes of air at low to medium pressures.