Ventilation Designs
Ventilation design techniques are based on two principal processes; extraction and input. Each of these is governed by good design principles, covering performance, effectiveness, energy consumption and treatment. Simple applications often use wall extraction Nylair fans or their derivative Extractair roof extraction units. These simple axial flow fans offer high air movements at low energy requirements simply passing air from the production area to the outside.
Simply extracting air takes away the warm or humid or contaminated air, but it is important to remember that for air to be extracted, it must be possible to enable replacement air into the area. Ignoring this means the area will operate under a negative condition and draw air in through any opening, doorway or gap in the building fabric. In food industries like breakfast cereal, that is understandably unacceptable as it is likely to cause the ingress of airborne pollution and insects: not great in your breakfast bowl! However, these high food hygiene standards apply equally to the food packaging industries such as carton and corrugated manufacturing but also to can making for food and beverage products.
Within the ventilation design, the positioning of both the extraction and air input points can have a substantial influence on the performance of the system. Air movement can create as many 'draught' problems for any operators as it benefits the working environment. Positioning extraction points as close as practicable to the contaminant source, often reduces the amount of extraction required and prevents the contaminant having an effect over a broader area. Air input points should then be positioned to ensure a spread or air movement, rather than a localised condition.
Air input systems often require some form of treatment, starting with filtration to ensure a level of cleanliness to the air. However, a balance on cost, maintenance cleanliness level is a major consideration. Generally speaking, the greater the level of filtration selected, then the higher the capital, operating and maintenance costs will be and probably the frequency of maintenance, as any filters collect the dust and pollution and the higher the efficiency the more they will collect.
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