OHS Code Explanation Guide

Published Date: July 01, 2009
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Part 36 Mining

Section 731 Fammable gas levels

Through the four subsections, safe working limits for atmospheres containing flammable gases are clearly described to ensure safe operation of the mine. The manager must take appropriate corrective actions once the related limits are exceeded. These actions are clearly described in this section and cannot be altered.

Subsection 731(1)

As gas levels rise there is a critical level at which workers must be evacuated from any area. This is set at a level where the concentration of flammable gas exceeds 40 percent of its lower explosive limit (LEL). This level is consistent with established practices in many jurisdictions around the world.

Subsection 731(2)

Automatic shutdown of electrical power is ensured on equipment where 25 percent of the LEL is exceeded. This level is consistent with established practices in many jurisdictions around the world.

Subsections 731(3) and 731(4)

These subsections prohibit blasting and the use of diesel equipment where gas concentrations exceed 20 percent of their LEL.

Subsection 731(5)

A properly designed gas bleeder system collects ventilation discharged from gobs, typically containing coal dust and methane gas. The level of gas in any bleeder roadway must be controlled to be less than 40 percent of the LEL. The underground coal mine manager must ensure that appropriate corrective actions are taken if  the related limits are exceeded.