Pulses

Among many other materials, flour and starch are a combustible material. Industrial fans within our ATEX compliant lines can handle material and reduce the risk of explosive atmospheres. Within many manufacturing units, a pneumatic conveyor, utilising a stream of clean air, is used to transport raw materials such as grains, sugar, flour and granular materials. Storage areas, in addition, require humidity and temperature control and at the end of the production line a high-pressure fan acting as a vacuum for the packaging may also be required.

Drying

Used to reduce the water volume within some food, in addition to facilitating the drying of washed fruits and vegetables, industrial fans such as the ER or EQ range of cased axial fans make a significant contribution. The use of industrial fans in the dehydration of certain fruits, vegetables and meats is also widely used to prevent the growth of bacteria.

The extraction of corrosive fumes should be done with chemical/corrosion resistant fans. Polypropylene is the standard material which can withstand the nature of the chemical gases that pass through the scroll and the impellers. In this instance, the motor should be kept out of the airstream to ensure long lifespan and also to prevent the overheating of the motorised components. The duct work that is attached to the industrial fan should also carry the same level of protection against corrosion as the fan scroll and impeller itself. In smaller storage units, where the materials are non-corrosive and ventilation is more general, an axial fan can be used for ventilation. This should be certified for use in ATEX applications, where in these instances the motor that is held within the airstream can withstand the nature of the gases, fumes or mists.

It is worth noting that flammable gases are denser than air so they can accumulate at floor level. For this reason, the ventilation system should be set up to ensure that these low level, potentially hazardous, gases can be extracted effectively.

An air handling unit is a factory-made case assembly consisting of a fan or fans and other necessary equipment to perform one or more of the functions of circulating, cleaning, heating, cooling, humidifying, dehumidifying and mixing air. The air handler is normally constructed around a framing system with metal infill panels to suit the configuration of the components.

The AHU is used to control the following:

• Temperature
• Humidity
• Air Cleanliness

There are commonly two types of air handling unit: Draw-Through or Blow-Through.

In the Draw-Through type, the fan pulls the air through a plenham box, filters and cooling coil before discharging it from the fan outlet to the space to be conditioned or to the ducting network. The design can be vertical or horizontal. In this case, the section before the fan has negative pressure.

In the Blow-Through type, the fan blows the air through a plenham box, filters and cooling coil before discharging it to the space being conditioned or the ducting system. In this case, the section after the fan has positive pressure.

AHU Fan Selection

In air handling units, centrifugal fans are used to circulate air to various parts of the building. Fan selection will depend on the air volume (measured in m³/h) and the static pressure (measured in Pascals Pa) required of the system. Usually the designer of the system will use a specialised software to do this selection.

In order to reduce the effect of vibration on the panel, the motor and the fan are usually installed with anti vibration mounts, except when the drive assembly is external to the fan casing.

The use of variable air volume (VAV) systems is becoming more popular as within these systems the volume of the air being discharged can be varied depending on the load condition. If the load is high, the fan speed will be higher and if the load is lower, the speed of the fan will be lower. The speed of the fan is varied using a frequency inverter instead of a conventional motor. A whole range of fan speed, from super low to super high, can now be utilised with a frequency converter based on the load conditions required. A greater focus on the development in EC technology has enabled better use of energy and is in line with the move to more energy efficient products (ERP).

Requirement of AHU Systems

Ventilation system requirements are not always the same. In many applications all that is required is a straightforward exchange of air, whereas in other applications the requirements can vary according to the temperature, humidity and purity of the air. Noise is also a significant factor to consider when choosing AHU fan components.

Moduflow Fans can supply components for efficient air movement within air handling units, including backward-curved impellers, EC motorised impellers within their centrifugal fans and belt driven options, where required.