In Mexico, an average of 1,100 people die every year due to fire burns, that is why it is essential to take measures to prevent this. One of the best ways to prevent fires is through fire protection systems.
What is a fire protection system?
A fire protection system is the measures and safety plan that any building must have to know how to act and minimize the effects of fire in case there is a fire in the place.
Fires can cause great human and material losses, as well as affect the building structures and generate air pollution. To avoid these losses it is necessary to have a fire protection system.
This system must take into account factors such as: air conditioning installations, ventilation, plumbing, lighting, etc.
In Mexico, the standard that regulates fire equipment and systems is the NMX-S-066-SCFI-2015 and the NOM-002-STPS-2010 standard mentions the safety and fire protection conditions in workplaces.
classification of fire protection systems
Active protection:
These are the set of equipment and systems that warn of a fire and are associated with taking action.
Among the systems included in active protection are: smoke extraction, temperature control, fire extinguishers, smoke detectors, evacuation, etc.
Passive protection:
These are the set of means and measures that prevent the spread of fire and contain the fire in the area where the fire was caused. The function of passive protection is to protect the building structure and facilitate the evacuation of people.
Among the systems included in the passive protection are:
- Fire doors
- Signaling
- Fireproofing of materials
- Among others.
Stages of a fire protection system
All stages of the fire system work simultaneously and have the same objective: to safeguard life and property within a building.
- Detection: The first stage that a fire protection system must fulfill is to be able to locate the area where the fire started in the shortest possible time, in order to alert and clear the area safely. Fire detection will determine how the fire will be controlled, because if it is detected quickly, the risk of loss decreases. The necessary elements for this stage are: push buttons, alarms and fire detectors.
- Prevention: The prevention stage focuses on controlling the fire and preventing its spread to the rest of the building. This stage mainly includes passive protection systems.
- Suppression: The suppression stage is responsible for extinguishing the fire during the first minutes of its generation in order to safeguard lives, the building and goods. The most commonly used equipment for this purpose are water sprinklers, clean agents or foam, as well as fire extinguishers.
Fire protection systems: General principles of fire
Fires are one of the most serious risks to human dwellings and workplaces. The consequences caused by a fire will be material losses of family, social or business property. However, the most serious and painful because they are irreparable losses are the loss of human lives and the ecological damage caused by this type of incident.
Fires will probably never cease to occur, but it is possible to significantly reduce the dimensions of the damage caused by any type of fire by means of appropriate actions to increase fire protection.
In order to know how to prevent and protect ourselves from fires, it is essential to know the factors necessary for a fire to start and how they develop.
Fire
Fire is a chemical reaction of combustion, based on phenomena of rapid oxidation of a combustible substance generating heat (exothermic reaction) and other substances (gases, liquids or solids), it is accompanied by light and incandescence.
Triangle of Fire
Fire cannot exist without the simultaneous conjunction of three elements: The fuel (burning material), the comburent (oxygen in the air) and the activation energy (mechanical sparks, welds, electrical faults, etc.) If any of these elements is missing, combustion is not possible (oxidation reaction between a fuel and a comburent, initiated by an activation energy). Each of these elements is presented as sides of a triangle, called the fire triangle, which is the representation of a flameless or incandescent combustion.
Fire classification
Fires can be classified as follows:
Flammability Limit
It is required the combination of air and fuel that when mixed in a certain proportion can have a range of flammability and explosiveness. That is to say, it is required a percentage of fuel and air that when mixed can be flammable or explosive, so there is a lower limit (LEL) and an upper explosive limit (UEL). Outside these ranges the air-fuel mixture does not burn.
The following table shows the mixing limits for different substances.
Flash point temperature
Es la temperatura mínima requerida para que una sustancia (solida, liquida o gaseosa) puedan inflamarse, por ejemplo el combustible Diesel su temperatura de inflamación es de 52°C, contrasta con el punto de inflamación de la gasolina que es de -30 °C, es claro, la diferencia en el cuidado que debemos tener al manipular o almacenar ambas sustancias. La temperatura de inflamación siempre deberá ser considerada para la prevención de incendios al momento de manipular distintas sustancias.
It is the minimum temperature required for a substance (solid, liquid or gaseous) to ignite, for example, diesel fuel has a flash point of 52°C, in contrast to the flash point of gasoline which is -30°C, it is clear the difference in the care we must take when handling or storing both substances. The flash point should always be considered for fire prevention when handling different substances.
Minimum ignition energy
The minimum energy required to start a fire within a combustible substance – air. This energy required is different for all substances and can range from a small spark to high temperatures that produce self-ignition of the substances. This is what usually happens to oils when they are heated to excess, exceeding 300ºC, and self-ignite without the need for a spark or direct fire. Therefore, controlling heat sources is one of the best ways to prevent fires.
The above can be summarized as follows:
Fire is a process of rapid oxidation between a fuel and oxygen in the air that releases energy in the form of heat and light.
A combination of three factors is required for fire to start: fuel, air and energy.
It is not the solid or liquid substances that ignite, it is the mixture of combustible vapors and air at certain combination percentages and temperatures that actually ignite.
Solid and liquid substances at certain temperatures evaporate into the air causing fire hazard conditions.
Fire Tetrahedron
Once a fire starts, it can spread or it can self-extinguish, this will depend on another factor called “chain reaction” that intervenes in a decisive way and causes the fire, this additional factor forms the “fire tetrahedron” concept introduced by Walter Haessler in 1961 after several tests carried out by Arthur Guise.
When the amount of gases produced is sufficient and we have the necessary concentration of comburent, the fire is self-sustaining as it generates more heat which produces more gases and so on. A self-sustained reaction is produced, like a domino effect and in this way the fire spreads producing a fire.
Fire cases
Case 1. In the following video we can observe a case of fire caused by a highly flammable substance with minimum ignition energy, in this case a spark produced by static electrical energy.
The video shows an activity of pouring a highly flammable substance from the manufacturer’s metal containment vessel into a plastic process vessel.
- The activity should be performed in a special cubicle that has walls that can contain the fire if it occurs and chemical extinguishers.
- It should be considered that the friction of a fluid or cleaning wipes on a plastic surface tends to produce static electrical energy that accumulates on the surface of the containers, so the use of antistatic mats and grounded clamps that prevent the accumulation of static electrical energy should be considered.
- The worker does not have the required personal protective equipment according to the risk of the activity performed.
Case 2. In the following video we can observe a case of a vegetable oil fire that was overheated to the point of self-ignition.
The video shows vegetable oil in which fire is produced by overheating, it is clear that the worker does not know how to extinguish it properly and causes it to spread.
- Hot oils should be disposed of in covered metal containment containers; it is a mistake to dispose of them directly on the sink.
- Water should never be used to extinguish a fire in a container with hot oil. When water is used, it vaporizes quickly, creating an emulsion between the oil and the water vapor that escapes into the air, producing a combustible mixture of vapor, air and oil that ignites quickly.
- A fire in a container with hot oil should be extinguished by suffocation by covering it with a metal lid or a wet towel.
Understanding the basic principles of fire will help us to prevent and know how to act in case of possible fires.
Alher Sem, Your best option in fire protection systems
When installing a fire protection system it is essential that it complies with the regulations and that they are constantly maintained to ensure the proper functioning and minimize any risk in case of fire.
That is why in Alher Sem we make sure that the fire fighting installations are carried out in the most proper way, our installations consist of:
- Conceptual, basic and detailed design.
- Hydraulic installations of steel and blazemaster and storage tanks.
- Installations of detection, alarm and extinction systems.
- Installations and start-up of pumping equipment and machine room.
- All our procedures are strictly elaborated under the NFPA, which will assure in its totality the effectiveness of the fire fighting installations.
Alher Sem is a company with more than 15 years of experience that offers Engineering and Multi-technical solutions in the Industrial, Commercial and Service Sectors. Conformed with a team of expert professionals in the subject. To know more about Alher Sem click here.
Sources: Protección Civil CDMX, NFPA, Manual de Protección Contra Incendios Ed. MAPFRE 2001, Fundamentos de la Lucha Contra Incendios Ed. Richard Hall y Barbara Adams.
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