Smoke Extraction, Regulation for Efficient Ventilation

In commercial premises and industrial buildings, one of the main requirements that must be followed is the smoke extraction. Being able to remove the pollution generated in work interiors, whether they are kitchens, factories, or other types of premises, is crucial for maintaining the health of employees and also for having clean air at all times. What does the regulation on smoke extraction tell us and how can we adapt to it?

The first thing to consider is the obligation, whose requirements will vary depending on the type of commercial or industrial activity. Although to guarantee the quality of indoor air, it will always be necessary to have a system that expels smoke to an outlet to the outside.

The smoke extraction regulation specifies the different air quality values to be extracted when contaminated with smoke, regardless of whether it is a building or a specific establishment. The air extraction flow in service premises must be 2 dm3/s per m2 of floor area, which applies to offices or establishments that do not regularly produce smoke.

In contrast, for areas affected by smoke, this regulation will be different, as these will be considered places with very high pollution levels, such as:

• Industrial kitchens or restaurant premises.
• Public or private parking lots.
• Clubs or smoking areas.
• Chemical laboratories.
• Industrial production zones.

All these premises are considered AE 4 zones, referring to extraction air with very high pollution levels. The best solution to eliminate smoke from these contaminated areas is through mechanical ventilation. To comply with the regulation, these mechanical solutions must meet the UNE-EN 1366-1 standard, which specifies that the extraction equipment must be fire-resistant and maintain integrity, insulation, and extraction capacity within a given time frame.

The Technical Building Code also has a lot to say and establishes that the complete system of smoke extractors must be fire-resistant for at least one hour. In the case of ventilation, the resistance must be equal or greater than that of the compartmentalization element through which the contaminated air will pass. This is specified this way so that, in case of fire, the ventilation ducts continue to extract the contaminated air coming from combustion without losing airtightness. It is important to emphasize that smoke can be more dangerous than fire in certain situations.

The shortest ducts in smoke extraction regulation

The design of the ventilation system for smoke extraction will be essential for the entire setup and may perhaps be the most important. What do we mean by design? Basically, it refers to the layout of the ducts through which the extracted smoke will travel.

The mechanical extraction systems are the most effective solution to eliminate smoke, and their efficiency is well-documented, but they are also very sensitive to the path that air or smoke takes in this case. The greater the distance, the less extraction efficiency.

This is why it would be essential to consider two important elements for a correct smoke extraction:

1. The suction device must be as close as possible to the smoke emission source. If it is a restaurant, it must be directly above the burners, and in industry, it should be located where controlled fire occurs.
2. Respecting the previous point, the smoke discharge location should be as close as possible. If the distance that ducts must cover is very long, head losses will occur, requiring more power. Worse still, in case of fire, more time will be needed to extract the contaminated air, putting the safety of the premises and its occupants at risk.

Another aspect to consider is that the installation for smoke extraction must be capable of encasing as much contaminated air as possible to operate efficiently in less time, in addition to utilizing inertia forces.

In this pursuit of the perfect design for smoke extraction, one can choose to frame the extraction nozzles. This way, the necessary air flow can be reduced while concentrating the extraction. To avoid potential leaks of contaminated air, it is also important to distribute the aspirated flow as uniformly as possible.

The regulation for smoke extraction also specifies in the UNE EN 1366-8: 2005 standard that the speed of the contaminated air transported must be sufficient to prevent particles suspended in the smoke from accumulating in the ducts. Head losses must be avoided according to the same standard, as well as excessive vibrations and annoying acoustic levels.