Workplace accidents remain a major challenge for many industries, with the potential to cause significant damage to property and even human life. In fact, there is a direct correlation between accident rates and the tools used. However, a significant number of companies and workers are still unaware of how to work safely and what tools to use in hazardous environments.

Today we will learn about explosive atmospheres (ATEX) and how to work in them. This is also the first article in a series about the importance of safety tools in industry .

I. What is an explosive environment?
II. Classification of gas groups based on flammability
III. Classification of environments with fire and explosion risks
IV. Notes for safe working in environments with risk of fire and explosion

I. What is an explosive environment?

Simply put, an explosive atmosphere is a mixture of flammable substances (in the form of gases, vapours, mists or dusts) with air which, when ignited, will result in a combustion process that spreads throughout the unburned mixture.

However, an explosive environment does not spontaneously combust, but requires certain conditions. In other words, there must be a large enough mixture of air and combustibles to create an explosive environment. There must be a certain minimum and maximum percentage of air (oxygen), beyond which combustion will not occur and is not considered an explosive environment.

Although an explosive atmosphere is a combination of a flammable substance with air in the form of a gas, vapour, mist or dust, this does not mean that liquids are not involved in this hazard. There are some liquids that can easily create an explosive atmosphere if the right conditions are met to cause a fire, and liquids can also create vapors on their surfaces. When these vapors mix with air, they can form an explosive atmosphere.

II. Classification of gas groups based on flammability

Not all gases or dusts have the same properties. Depending on their properties, each will have a different flammability limit. Gases are divided into four main groups based on their ignition temperature:

• Group I: For example, methane gas
• Group IIA: (Acetone, benzene, gasoline): Has a flash point higher than 0.18 mJ
• Group IIB: (Coal gas): Has a flash point from 0.06 to 0.18 mJ
• Group IIC: (Hydrogen, acetylene): Has a flash point below 0.06 mJ

Obviously, the gases with the lowest flammability limit are the most dangerous, because even a small spark can ignite and burn.

III. Classification of environments with fire and explosion risks

Many governments have introduced laws and standards to improve working conditions. The European Union has led the way in this initiative by adopting the ATEX Directive 1999/92/EC, which sets out the requirements for safe work in hazardous environments.

The EN 1127 standard referred to in the above regulation divides hazardous areas into three categories based on the level of risk:

• Zone 0/20 : Danger is present for a long time or frequently (more than 1000 hours/year)
• Zone 1/21 : Infrequent hazard occurrence (10 to 1000 hours/year)
• Zone 2/22 : Hazards occur rarely or are short-lived (0.1 to 10 hours/year)

In addition, the standard also points out that tools, especially those made of steel, are a potential source of ignition. In potentially explosive environments, depending on the type of gas, even a small spark can lead to serious consequences.

Below are the rules for using tools in these areas:

• Zone 0 (gas) and 20 (dust): Prohibit the use of any tools that can create sparks (not just steel tools).
• Zones 1 and 2 (gas): Steel tools may be used provided that:
  • Class A: Does not produce sparks during normal use (e.g. wrenches, screwdrivers).
  • Type B: To be used only if there is no explosive atmosphere in the workplace.
  • With group IIC gases (hydrogen, ethylene oxide, carbon monoxide), it is not allowed to use tools made of steel.
• Zones 21 and 22 (dust):
  • Tools made of grade A steel are permitted.
  • Class B tools shall only be used if there is separation between the work place and the explosive atmosphere.
  • Dust should be removed regularly, and the workplace should be kept sufficiently humid to prevent dust from being stirred up.

IV. Notes for safe working in environments with risk of fire and explosion

ATEX Regulation 1999/92/EC states that all sources of ignition must be eliminated or, if this is not possible, reduced to a minimum. If the work area has been classified as hazardous, all necessary measures must be taken to eliminate or reduce the source of ignition and to limit the consequences if an explosion occurs.

Among them, mechanical tools are ranked among the top agents because of the frequency of use in industries. Therefore, using safe tools that meet standards and ensure quality is something that every business and individual needs to pay attention to.

Which tools are safe in potentially explosive environments? This will be the topic of the next article in this series. Or you can contact PHU THAI TECH , the leading distributor of high-end hand tools in Vietnam. Here, we have the highest quality tools and the most experienced people, ready to provide customers with reasonable, safe solutions while still ensuring the best performance.