Fire and Explosion

Fire and Explosion

Fire and explosion: Incidents involving serious bodily injury sustained by workers – fire, chemical discharge or explosion are daily hazards in industries. The danger of damage from explosive material is a serious concern facing construction workers, along with those who work in our local mines and mills, as well as manufacturing plant employees and those involved in transporting hazardous materials.

Avoiding fires, knowing the basic principles of prevention, detection and extinction, as well as the evacuation of buildings, are social duties of the first order. The level of risk must be evaluated in every workplace and also here the intervention of the prevention delegates is necessary.

The employer, taking into account the size and activity of the company, as well as the possible presence of people in the workplace, must analyze possible emergency preparedness and adopt the necessary measures in terms of first aid, fire watch training and evacuation of the workers.

Fire and Explosion
Fire and Explosion

Designating for this purpose the personnel in charge of putting these measures into practice and periodically checking, where appropriate, their correct operation. The aforementioned personnel must have the necessary training, be sufficient in number and have the appropriate material, depending on the aforementioned circumstances.

The risk assessment must take into account the activity, relating the substances and materials, the usual tasks and possible exceptional tasks that may increase the risk of fire and explosion. Regarding substances and materials, their intrinsic characteristics must be analyzed, as well as the quantities and methods of handling, transport and storage.

Fire and explosion factors

All companies must organize fire and explosion prevention through occupational risk prevention regulations and local and regional regulations. The risk factors of fire and explosion that can cause Work Accidents can be classified, depending on their origin, into three large groups:

  1. Factors of a structural nature,
  2. Factors linked to the facilities and factors linked to the machines, equipment and
  3. Substances used,

Some material agents in combination with certain accident production mechanisms can cause serious damage if there is an uncontrolled release of the energy they generate fire and explosion are part of these highly bloody mechanisms.

What is the difference between fire and explosion?

Fire is a chain chemical reaction between the oxidation of a fuel (liquid, solid or gaseous product) by an oxidizer (typically oxygen from the air) and heat. This phenomenon is summarized in the “fire triangle”. The three components of the fire triangle are:

  • Power source: flame, heat, spark, electric discharge, etc.
  • Oxidizing: mainly the oxygen present in the air,
  • Combustible: solid compound, liquid, or a mixture of flammable vapours.

Most common causes: According to statistics, about 90% of industrial fires are caused by 11 ignition sources:

  1. Electrical fires 19%
  2. Rubbing and friction 14%
  3. Mechanical sparks 12%
  4. Smoking and matches 8%
  5. Spontaneous ignition 7% •
  6. Hot surfaces 7% •
  7. Combustion sparks 6%
  8. Open flames 5%
  9. Welding and cutting 4%
  10. Overheated materials 3%
  11. Static electricity 2%

An explosion is a simultaneous, sudden, and often violent release of heat, light, and sound energy. Explosions are generally associated with human activity, with natural or unintentional explosions being less common. The sources of explosions generally fall into two categories:

  • Mechanical (moving shock), electromagnetic (lightning) or pneumatic (pressure and gas).
  • Chemical reactions, fast kinetics.

An explosion consisting of a sudden release of energy results in an increase in the local kinetic energy of the molecules near the centre of the explosion. This causes temperature differences and therefore expansion. This expansion is the cause of pressure or expansion waves in the surrounding environment where the explosion occurred.

What is the cause of fire and explosion?

Below, for the informational purpose of reducing risks, we are going to mention the 4 main causes that cause the fire and explosion:

Flammable and combustible materials

These are materials, “combustible” and “flammable” are synonymous. These would be two words with the same meaning since both allude to what ‘burns easily’. Flammables have a lower flash point than combustibles. The flash point defines the degree of risk of the liquid or solid igniting.

According to OSHA, a Flammable liquid is any liquid having a flashpoint at or below 199.4 °F (93 °C). Flammable liquids are divided into four categories as follows: 1. Category 1 shall include liquids having flashpoints below 73.4 °F (23 °C) and having a boiling point at or below 95 °F (35 °C).

The difference between one and the other is that the flammable material gives off flames immediately (flammable comes from flame, ‘flame’); on the other hand, what is fuel takes a little longer; Thus, they are combustible, for example, gasoline and alcohol; on the other hand, plastic, wood, paper, cardboard, etc. are combustible.

In general terms, NFPA 30 (Flammable and Combustible Liquids Code) defines flammable liquids as those having a flash point below 37.8oC (<100°F), and combustible liquids as those with a flash point equal to or greater than 37.8oC (100°F – 140°F and higher).

Combustible dust

It is often overlooked, but it is highly dangerous and highly deadly. Combustible dust is a major cause of fire and explosion in many of the food manufacturing, lumber, chemical, metallurgical, pharmaceutical, and many other industries.

Fire and Explosion
Fire and Explosion

The reason includes almost everything mentioned, since the products involved in these processes generate a large amount of dust as residue in the environment, having a great potential to be combustible. When dust particles of combustible materials disseminated through the air appear in a certain concentration and with a certain size, an explosion can occur.

Generally, these types of explosions are not easy to contain at all. In a typical incident in these environments, a small fire will break out when combustible material comes into contact with an ignition source. This can lead to a dust explosion, possibly starting a fire. However, this small initial explosion is not the real problem. What is critical is what happens afterwards.

If a sufficient amount of accumulated dust is found in the area, the primary explosion will cause that dust to become airborne. That cloud of dust can then ignite, causing a secondary explosion that can be many times larger and more dangerous than the initial explosion itself.

This second explosion, in turn, generates new shock waves that again stir up dust from other areas, causing new explosions and so on, giving rise to a very similar chain reaction. In certain cases these successive explosions could have the potential to destroy entire facilities, causing immense damage and deaths.

While you probably won’t be able to completely remove dust, you can ensure it doesn’t build up to a dangerous level simply by following a regular cleaning process. It is always advisable to implement safety procedures in this type of industry, especially when operating machines and equipment.

Additionally, work should be done on the possible causes that generate an ignition. Special consideration or prohibition of hot operations such as welding, cutting, and polishing, among others, without first having taken all safety precautions.

Have electrical installations and equipment been approved by current standards for this type of environment? For further details, we recommend taking into account the NFPA 652 standard “Standard on the fundamentals of combustible dust”

Hot work

Hot work is another of the main causes of industrial fire and explosion that cross all industries regardless of size and sector. Generally, this type of incident is associated with welding and torch cutting, but many other activities must be taken into account.

This is because sparks and molten material, which often reach temperatures above 600°C, are often ejected at high speed, impacting potentially combustible materials. Hot work is also considered to be the main culprit for fires in combustible dust environments, as sparks generated from the work can easily ignite dust in the surrounding area.

In an accident in North Carolina, USA, three welding contractors were badly burned when sparks ignited wood dust in the silo where they were doing repair work. An investigation found several problems that triggered the incident, the silo had not been properly prepared and cleaned of dust residues before the work began, the permit and documentation to carry out the hot work had not been issued, and additionally no they had a fire prevention and protection plan.

Like combustible dust incidents, hot work accidents can be prevented by following proper safety procedures. Reducing and avoiding all possible tasks that involve hot work, since often this is not the only possible solution to carry out the tasks, first evaluate possible alternatives.

Train personnel on the hazards associated with hot work, site-specific hazards, proper policies and procedures, and use of safety equipment. Employing a written permit system for all hot work projects, even when permits are not required, is a best practice to reduce potential risk situations. Gas testing results of lower explosive limit should be zero before hot work and checked periodically.

Flammable liquids and gases

This type of fire and explosion usually occurs in chemical plants and depending on the characteristics and volume, they can be disastrous.

We can cite as an example that in 2010 the explosion of the Middletown power plant, USA, which was attributed to a leak of flammable gases, causing the death of six people and injuring more than fifty. In this particular case, the subsequent investigation revealed a large number of violations of safety protocols, many of which were considered by OSHA (Occupational Safety and Health Administration) as “intentional”.

Fire and Explosion
Fire and Explosion

The company received a fine of more than 16 million dollars as a sanction for the irregularities and the lack of compliance with the required security standards.

How to prevent flammable liquid and gas fire and explosion

Certainly, whenever flammable liquids and gases are being worked on or handled, there will be some associated hazards, but all available safety precautions must be taken to mitigate these hazards.

  • They must be known and work on raising awareness of possible dangers. An important component of prevention is simply knowing the safety information for each liquid in your facility.
  • Provide appropriate personal protective equipment. This is imperative in all categories of fire hazards, especially where liquids and gases are involved.
  • Proceed with proper storage of flammable liquids ensuring that all hazardous materials are stored by local procedures and regulations and/or in compliance with OSHA recommendations.
  • Control all sources of ignition. Except when you are intentionally heating flammable materials as part of a controlled industrial process, you should keep all sources of ignition as far away as possible or tend to avoid them.

Equipment and machinery

In the industrial environment, the use of equipment and machinery is very common and part of the operation of many processes. The case of operating with defective equipment and without adequate maintenance is one of the most relevant causes that give rise to fire and explosion in industries.

Heating equipment, metal-mechanical carrying processes, and hot work are often the biggest problems in these environments, particularly furnaces that are not installed, operated, and/or maintained properly. Also, any mechanical equipment can become a fire hazard due to friction between moving parts. This risk can be reduced to virtually zero simply by following manufacturers’ recommended cleaning and maintenance procedures.

It may surprise us, but even seemingly harmless equipment can become dangerous under certain circumstances. In many cases, these teams considered the least likely end up becoming the biggest problem. This is because many companies tend not to recognize or perceive the risk potential and therefore do not take the necessary precautions.

The lesson here might be that when you think about safety in a plant, don’t forget everyday, commonly used equipment.

Preventing fire and explosion due to Equipment and Machinery 

Strategies to prevent fires due to equipment and machinery problems fall into three main categories:

  1. Awareness
  2. Cleaning and
  3. Maintenance


You cannot avoid risks that we do not know exist. Provide safety awareness training so that all staff and visitors at industrial facilities know and understand what potential hazards to watch for and what to do if they encounter one.


Keep your equipment and machinery clean as well as the area around it. Equipment, especially electrical equipment that is covered in dirt or grease is a great risk. By keeping your equipment and machinery clean, you will increase your chances of not having enough fuel available in the event of a fire and lessen the impact.

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Follow the manufacturer’s recommended maintenance procedures for all equipment and machinery. In addition to reducing the risk of fire by preventing overheating, regular maintenance will also keep your equipment running in top condition.

Electrical Fire hazards

Electricity has long been recognized as a serious workplace hazard, and electrical fire and explosion are one of the top five causes of fire and explosion in industrial plants. Anywhere there is electrical wiring, there is also an electrical fire hazard.

Here is a list of specific electrical risks:

  • High-voltage.
  • Damaged tools and equipment.
  • Improper wiring and overloaded circuits.
  • Exposed electrical parts.
  • Improper grounding.
  • Damaged insulation.
  • Wet conditions.

The damage caused by these fires can escalate quickly. Any of the above hazards can cause a spark or arc, which can serve as an ignition source for combustible dust, as well as flammable liquids, gases, and almost any accumulated material.

How to prevent electrical fire and explosion incidents

As with the previous hazards, the key to preventing electrical fires is awareness and prevention.  For more information on electrical safety, you can refer to   NFPA 70, National Electrical Code and Electrical safety hazard

Fire and explosion prevention

Fire and explosion safety is a matter of establishing policies and procedures, and then ensuring and verifying that they are properly implemented throughout your facility.

Here are some recommendations for incorporating fire and explosion safety into operations from the start.

Fire and Explosion
Fire and Explosion

Carry out a risk analysis

A dust hazard analysis is the primary component of   NFPA 652, Standard on the Fundamentals of Combustible Dust provided that the materials handled and processed have been identified as combustible and/or explosive. When conducting a materials and process assessment, an analysis of the hazards posed by these materials and processes should be taken as a comprehensive risk management plan.

But do not consider this as a single key point, a risk analysis of all facilities must be carried out to find out exactly where the greatest risks lie and what you can do to mitigate them, as it is also important to carry out this analysis regularly, especially, every time you install new equipment or make changes to your production processes.

Establish fire and emergency prevention procedures

Make sure you have policies and procedures that go from the minimum to the maximum condition. From smoking in dangerous environments to having personal protective equipment and having an emergency evacuation plan.

Ensure that all personnel have knowledge of and easy access to these documents at all times. Implement fire safety training programs. We have mentioned training several times because it is very important.

Consult the safety data sheet (SDS) for each hazardous material, as it includes specific details on spill cleanup procedures, acceptable firefighting equipment, and first aid instructions. If you are not sure what protocols and procedures to include in your emergency plan, there are many sources you can turn to or contact, including your local fire.

Training program

Training could cover:

  • Spill Response Procedures
  • Proper use and handling procedures, including storage and transfer of materials
  • Adequate ventilation systems
  • Area limitations and restrictions, including no smoking and open flame rules
  • Cleaning procedures, including equipment maintenance
  • The use of fire extinguishers
  • Emergency protocols, including an evacuation plan

Duty of employers to protect workers from fire and explosion hazards in the workplace

The industrial use of chemicals, as well as the need for flame or heat and the requirement for flammable materials, all contribute to the hazards workers face from a potential explosion or fire. Consequently, the Occupational Safety and Health Administration (OSHA) oversees employers’ compliance with a series of regulations designed to protect against fire and explosion on the job.

The legal duties here not only involve the employer’s general duty of care towards workers at work, but the regulations go into detail about these dangerous situations, with duties including:

  • Employer’s legal duty for the fire prevention and protection program. The employer shall be responsible for developing and maintaining an effective workplace fire prevention and protection program during all phases of construction, repair, alteration, or demolition work. The employer shall ensure the availability of the fire protection and extinguishing equipment required by 29 CFR 1926 subpart F
  • Duty of the employer to supervise the handling and use of explosives. The employer will permit only authorized and qualified persons to handle and use explosives. Smoking, firearms, matches, open flame lamps, and other fires, flame-producing devices, or heat and sparks shall be prohibited in or near explosive chargers or while explosives are being handled, transported, or used.
  • No person shall be permitted to handle or use explosives while under the influence of intoxicating liquor, narcotics, or other dangerous drugs.  Unused explosives will be stored in a lockable magazine, not available to unauthorized persons to handle them. The employer shall maintain an inventory and usage log of all explosives. The appropriate authorities will be notified of any loss, theft, or unauthorized entry 29 CFR 1926.900.


Although this type of event implies a danger for the personnel and the economy of the companies, it also generates a bad image in the market and potential clients, putting their future at risk. The following are fire statistics published by the NFPA (National Fire Protection Association) only in the USA from 2011 to 2015.

According to more basic data provided by the NFPA, each year:

  • Annual average of over 37,910 fires in industrial environments.
  • Average of 16 fatalities and 273 injuries
  • $1.2 billion in property damage

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