Types of industrial extractors. Specific uses and characteristics

The ventilation of an industrial premises consists of the replacement of the inadequate indoor air due to its lack of purity, presence of contaminants, inadequate temperature or excessive humidity with better characteristic external air. When it comes to ventilating an industrial building, the location of the ventilation devices and the industrial extractors must be taken into account.

Different ventilation systems: industrial extractors

• If the ventilation is to be carried out through the roof, the conditions of tightness must be preserved, so that the industrial extractors will incorporate special devices to comply with this requirement. If there is an air inlet, it will have a cover element to prevent rainwater from entering. In the case of using a roof extractor, it will be equipped with a discharge nozzle that also acts against the wind as well as a flap that prevents water from entering.

• When the ventilation devices are located in the main or rear facades, air can be extracted directly from the interior of the building or through a false ceiling if it is part of the interior enclosures. The space enclosed between the roof and the false ceiling acts as a depression chamber that facilitates the uniform extraction of air through the grilles placed on its surface. In the case that these wall devices act by blowing air into the interior of the building, it puts it in a state of overpressure. Ventilation through the roof can also be done using a rigid or flexible duct arranged at the top of the building running the entire length inside the roof. In this case, the duct must have openings of increasing section to ensure a uniform ventilation flow.

• If the propulsion or extraction is carried out through the side enclosures, the total flow must be divided among several ventilation devices to evenly distribute the flow of air. The supply grilles have air inlet deflectors to prevent the entry of rainwater into the system. The same function is served by the shutters housed in the extractors.

Ventilation control

Due to the different ventilation needs in winter and summer, it will be necessary to supply the maximum flow needed in summer while simultaneously significantly reducing this flow in winter. This same variation in the air flow pushed and extracted will have to be foreseen on a daily basis when the temperature variations inside exceed predetermined values. This regulation of the flow can be done by manual operation of the fans, acting on the number of operating fans or by "all or nothing" automatic regulation, varying the rotation speed of the devices. The latter system is the most reliable. A timer is used for its operation that connects or stops the devices at intervals of time pre-established according to the seasons of the year or according to the environmental conditions to be obtained.

At any moment, whether due to a sudden drop in temperature (for example, due to the effect of a storm) or a significant rise, the automatic system will react immediately by ordering the fans to operate, providing the necessary ventilation conditions, and will return to the initial conditions once the disturbing effect has disappeared.