Hazardous locations: the game rules – Part 1

A bit of history

Coal mines were among the first sites considered hazardous due to the following phenomena:

1. Possible presence of methane—a flammable gas—in underground tunnels, especially when there are gas clouds.
2. Coal dust—a combustible dust—that is continually generated in tunnels and accumulates on the ground and surfaces.

In the past, numerous ignition sources were present almost continuously during mining activities; these could include mechanical sparks from tunnelling equipment or open flames such as lighting systems like oil lamps. The sadly famous “firedamp explosions”, which are serial deflagrations, could start as soon as a pocket of methane gas was reached and ignited by an ignitions source. The first blast is powerful enough to suspend the dust accumulated in the drifts and form dense, highly concentrated clouds. Fine explosive combustible dusts then ignite, causing a second explosion (Read our blog article about combustible dust). The fireball spreads along the drifts until the fuel source is exhausted. Workers don’t stand a chance during these catastrophic underground events.

Initial control solutions

Fairly reasonable control solutions in terms of occupational health and safety standards have been implemented over time to prevent the risk of explosion. One of the first measures to be put in place was to employ “front-line miners”, whose role was to lead the way and ignite gas with a flame at the end of a long rod. Then, underground mine operators started using ponies. Later, more acceptable control and prevention solutions emerged, marking the beginning of risk management for hazardous locations:

• Risk identification
• Prevention of the formation of explosive gas atmospheres (methane) using underground ventilation (dilution)
• Prevention of ignition by installing sealed enclosures around electric motors
• Protection of certain open-flame components like portable lamps; one of the oldest “safety lighting” processes (1760) consists of wire mesh (a kind of close-meshed screen) that prevents the spreading of flame from the inside to the outside of the lamp^[1].

Where are hazardous locations?

Today, like coal mines, many other industries must face the potential of hazardous locations, such as the petrochemical industry, from mining and storing flammable materials to distribution. The risks associated with the formation of explosive atmospheres, both with gases and dust, can also be found in:

• Chemical facilities (e.g., fabrication of rubber, plastics, paints, lacquers and varnishes).
• Pharmaceutical, metallurgical and food processing plants.
• Cement plants.
• The wood industry and pulp and paper plants.

What regulation applies in Canada?

In Canada, the regulation of hazardous locations falls under the jurisdiction of the provinces and territories. The regulatory bodies in each province are responsible for adopting the Canadian Electrical Code (CEC).

The control of hazardous locations can also be the responsibility of municipal authorities, as in Manitoba (e.g., Winnipeg), Alberta (e.g., Calgary) and British Columbia (e.g., Victoria).

In some Canadian regions where at-risk industries, like petrochemicals, are present, such as Alberta, the concept of hazardous locations is implemented in provincial occupational health and safety regulations.

To learn more, please read the second part of this blog article.

[1] According to the https://museumcrush.org/a-visual-history-of-the-miners-safety-lamp/ website, many other inventions marked the evolution of portable safety lamps for lighting