LEL & Explosive Atmospheres

Overview

LEL & Explosive Atmospheres should be managed through a planned system of work: identify the task-specific hazards, eliminate exposure where practical, use engineered or collective controls before relying on PPE, verify critical safeguards before starting, and stop the task when controls are missing or conditions change. This guide applies those principles specifically to monitoring and controlling flammable atmospheres before introducing ignition sources.

Main Hazards

• • Flammable vapor or gas concentration entering an ignitable range
• • Detector limitations, sensor poisoning or wrong calibration gas
• • Oxygen deficiency or enrichment
• • Toxic or flammable atmosphere
• • Engulfment, entrapment or difficult rescue

Essential Controls

1. 1Confirm the monitor is suitable for the expected gas/vapor and environmental conditions.
2. 2Stop ignition-source work whenever readings exceed the approved limit or trend upward unexpectedly.
3. 3Identify permit-space hazards and isolate connected energy, process and material sources.
4. 4Test the atmosphere with suitable calibrated instruments before and during entry as required.
5. 5Provide ventilation, communication, attendant coverage and controlled entry authorization.
6. 6Prepare non-entry or entry rescue arrangements appropriate to the space and hazards.

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