Types of ventilation
Natural Ventilation
Natural ventilation is that which is obtained through natural techniques, without using any mechanical device. Some of these techniques are the use of temperature differences between two points (chimney effect), pressure differences (Venturi effect) and the speed and pressure of the wind over a hole.
Forced Ventilation
Forced ventilation is that which is carried out through the artificial creation, by mechanical means (extractors, fans, air handling units or other powered elements), of depressions or overpressures in air distribution ducts or areas of the building.
Cross Ventilation
Cross ventilation is one in which the air crosses from the farthest end to the opposite end of the room to be ventilated, taking or sweeping away all the contaminating particles in its path. These systems can generally be applied in greenhouses, warehouses, factories, etc.; itself, where it is desired that all contaminated air be effectively extracted. It is very important to consider places where contaminated air is being generated when applying cross ventilation so that the contaminants are on the side close to the extraction; In this way, we are able to remove the contaminants immediately, instead of transporting them from one side of the premises to the other.
Semi-cross ventilation
In semi-cross ventilation, a slightly shorter path is sought through which an air sweep can be created and the contaminated air carried away, removing it as soon as possible. Generally, for this type of ventilation, exhaust fans are placed along the entire length of the ridge of a gable roof. With this, it is possible to sweep all the contaminants towards the center of the industrial warehouse and remove them in a more effective way. This is an effective way to extract heat, odors or contaminants that are being generated in many places in the facility. It is very important not to cause an air short circuit. These types of errors are caused when the extraction is placed very close to the air injection; Therefore, the injected air is being extracted immediately, achieving low efficiency in air renewal.
Selective Ventilation
Selective ventilation is a bioclimatic building design strategy proposed by Givoni, when the humidity content of the air is low and if strategies such as cross ventilation are applied, the building would have hygrothermal discomfort. This is because a current of air with low moisture content on the skin produces its drying with consequent discomfort. In these cases, selective ventilation takes advantage of the difference in enthalpy between day and night air, favoring the cooling of the interior spaces of buildings. This implies that during the day the ventilation of the premises will be minimal and they must be shady (shaded), reducing the incidence of direct and diffuse solar radiation as much as possible. By doing this, you can keep the premises cool.
Infiltration Ventilation
Infiltration ventilation is one in which the entry of air from outside is produced by phenomena that are not being controlled but that are not taken as ventilation itself. We are talking about, for example, the grilles on the walls or the cracks in doors and windows.
Depression Ventilation
Depression ventilation is one in which the air is renewed through the use of devices placed for this purpose, as occurs with air conditioners in which hot air is extracted and replaced by cold air. In this type of system, a difference in the pressure of the atmosphere is created which causes the air inside to be expelled and replaced by fresh air from outside.
Layered Ventilation
In layer ventilation, the portion of the room where the people, animals, processes or elements to be ventilated are considered. This concept is applied when the height of the enclosure is calculated and considerably reduces the volume of air required; Consequently, it produces savings in ventilation equipment, obtaining equal results. Generally, it can be applied in industrial warehouses where the height exceeds 4.5 meters. This means that it can be adjusted to almost any case, since the standard average height of industrial warehouses is 6 to 7 meters; Therefore, in some ventilation systems it is highly recommended to only carry out the calculations in the layer where people are located. An example of this: if you have an industrial warehouse 14 meters high and people live only in the first 2 meters of height, we can add a couple of meters to ensure a good ventilation result and avoid the need to do a project with a height of 14 meters, which would practically result in an excessive amount of ventilation equipment and would increase costs more than 200 percent.
General and Environmental Ventilation
General and ambient ventilation consists of ventilating an entire area through an air extraction and injection system. In the central part of both systems, a current or sweep of air is created. This type of ventilation is done using the volume of the room and multiplying it by a specific number of air changes per hour. In general ventilation systems, hourly air changes are used to determine the final flow rate required to extract and supply air.
Localized and Punctual Ventilation
In this case, a very specific area is being ventilated. Some of the most common examples are:.
• Industrial hoods: generally, they can be involved in the galvanizing process where different types of highly toxic vapors are emanated. In the industry there are many processes during which vapors, fumes, gases, odors and mists are emanated that have to be captured with this equipment.
• Kitchen hoods: are located everywhere, economical kitchens, restaurants, residences, industrial canteens, etc. Its operation is based on capturing vapors, odors and grease mists that are emanated when cooking, ensuring that the premises are free of all these contaminants, as well as the diner area.
• Horizontal Laminar Flow Pickups: Commonly handled in locations where vertical extraction cannot be performed or the dust particles are heavier and easier to suck horizontally, such as in polishing, grinding, sanding, dense dusts, and more. The metalworking industry, among many, is one of the places that most frequently handle them due to their fundraising needs.
• Polluted air intakes: designed based on each particular situation. They can be of very varied shapes; Among them, there are suction nozzles, suction flutes, crescents, etc. Each one can be used in specific cases of contaminant release; Subsequently, they are all connected to the trunk air extraction system where the contaminant passes through a bank of filters, cyclones and scrubbers, achieving adequate air purification.
• Dry or wet air extraction cabins: they can be for various types of contaminants that are emanated in different processes, such as varnishing, painting, mixing of acids, emanation of toxic gases, etc. The total flow rate required can be obtained by multiplying the section through which the contaminant is not expected to cross by the air velocity required to capture the contaminant. In air extraction or purification cabins, the required flow rate is calculated by means of an adequate capture speed, which will drag the contaminated particle to the filtration or purification point, and subsequently to the outside.