Classification Extension

The classification of a hazardous area extends both above and below the floor if the hazardous atmosphere is present in both locations. The classification boundary does not stop at the floor but continues until the concentration of flammable gas or vapor falls below the threshold of the given Division or Zone.

Underground Extension

In the scenario you described, if the Class 1 Div. 2 area is located underground, then the classification will extend underground as long as the hazardous atmosphere continues to be present. The depth to which the classification extends will depend on the specific conditions and the layout of the underground space.

Determining the Extent

To determine the extent of the underground classification, you should follow these steps:1.

Identify the source of the flammable substance

Locate the equipment or process that is releasing the flammable substance.2.

Evaluate the ventilation and air flow

Determine the direction and rate of air movement to understand how the flammable vapors disperse.3.

Measure the concentration of flammable substance

Use appropriate gas detection instruments to measure the concentration of flammable vapors below the floor.4.

Consider the ignition sources

Identify any potential ignition sources in the underground area, such as electrical equipment or open flames.

Recommendations: Conduct a thorough risk assessment to identify and mitigate potential hazards in the underground Class 1 Div. 2 area. Install appropriate ventilation systems to control the accumulation of flammable vapors. Use explosion-proof electrical equipment and fixtures to prevent ignition sources. Ensure proper training and safety procedures for personnel working in the area.* Regularly monitor the concentration of flammable substances and adjust ventilation as necessary. Flag for review