Fire Tetrahedron

The fire triangle is a simple model used to describe the three essential elements required for a fire to occur and sustain itself. The three elements are heat, fuel, and oxygen. The fire tetrahedron is an expanded model of the fire triangle, which includes a fourth element, the chemical reaction.

Table of content:
1. Fire Tetrahedron
2. Heat
3. Fuel
4. Oxygen
5. Chemical Reaction
6. Related Standards and Codes

Fire Tetrahedron

Further research over the years revealed a fourth necessary component of fire, the chemical chain reaction. The Fire Triangle was consequently transformed to the Fire Tetrahedron. Put it simply, a Tetrahedron is a solid pyramid with four plane faces (from the Greek words ''tesseris edres''), each one representative of the four necessary elements.

In short, a fire begins by an external ignition source which is usually in the form of a flame or spark. With its turn, the external ignition source heats the fuel under the presence of oxygen. As both fuel and oxygen are heated, molecular activity increases. If properly heated, a self-sustaining chemical reaction is developed. The consequent chemical reaction will then escalate at a point where the external ignition source is no longer necessary for the propagation of the fire.

Once ignition has occurred, it will continue until:
- all the available fuel has been consumed or
- the fuel and/or oxygen is removed or
- the temperature is reduced by cooling or
- the number of excited molecules is reduced and the chain reaction is broken

Although simplistic in nature, presented diagrams are in fact a good example of how to actually extinguish a fire in the real world. For example, we can create a barrier using foam in order to reduce/eliminate the ''fueling'' of fire and therefore deprive the fire from one of its necessary elements (oxygen). By applying water, we can also reduce the temperature below the ignition temperature. Finally, by using a Halon extinguisher, we can create an inert gas barrier which will interfere with the chemical chain reaction.

Related Standards and Codes

There are various international standards referring to fire protection. Most widely used standards and codes fire nowadays are National Fire Protection Association (NFPA) standards. However, reference can also be made to other US standards (like ANSI standards or Code of Federal Regulation (CFR) standards) or European standards (ISO and DIN standards). Leading commercial insurance companies have also developed standards of their own codes for fire (for example Factory Mutual) and their requirements may sometimes be stricter than those of international standards of fire.

Here are some of the important standards and codes of fire related to fire safety:

National Fire Protection Association (NFPA) Codes:

The NFPA develops and maintains various codes and standards for fire related to fire safety. The NFPA's standards are widely used in the United States and around the world. The following NFPA codes are particularly relevant to the fire tetrahedron:

The American National Standards Institute (ANSI):

ANSI is a non-profit organization that sets voluntary consensus standards for a wide range of products and services. ANSI standards are developed through a process that involves input from a variety of stakeholders, including manufacturers, users, and government agencies. Some of the most common ANSI standards and codes for fire protection include:

The Code of Federal Regulation (CFR):

CFR is a set of regulations issued by the U.S. government that govern a variety of activities, including fire protection. The CFR is divided into 50 titles, each of which covers a different subject area. The title that covers fire protection is Title 29, Labor. Some of the most common CFR standards and codes for fire protection include:

The International Organization for Standardization (ISO)

ISO is an international organization that develops and publishes standards for a wide range of products and services. ISO standards are developed through a process that involves input from a variety of stakeholders, including manufacturers, users, and government agencies. Some of the most common ISO standards and codes for fire protection include:

Occupational Safety and Health Administration (OSHA) Standards:

It's important to note that fire safety standards and codes can vary by region and country. The ones mentioned above are widely recognized and used, but local regulations and standards should always be consulted to ensure compliance with specific requirements in a particular jurisdiction.