Three-Stage Gas Check for Confined Spaces
Before entering a confined space, it’s vital to confirm that the atmosphere is safe from top to bottom. In this episode, we walk through the three-stage gas check, the essential procedure that ensures every layer of your space is tested for potential hazards before entry. Watch the full video:
The Core Principle: Layered Testing for Hidden Risks
A confined space atmosphere isn’t uniform, gases can settle at different levels. A single test at the entry point isn’t enough. The three-stage gas check ensures that lighter, mid-level, and heavier-than-air gases are all detected and managed before work begins.
This process not only identifies immediate hazards but also prevents exposure to undetected gases that could accumulate at the base of the space.
Key Steps for a Safe Three-Stage Gas Check
- Pre-check around the sealed lid: Use your gas monitor to scan for escaping gases before opening.
- Crack and test: Slightly open the lid and test for lighter gases for 1–2 minutes.
- Initial deep test: Lower your monitor to the bottom to check for heavier gases before starting the formal check.
- Ventilation: Allow 15–20 minutes for the space to vent before full entry testing.
- Top → Middle → Bottom testing:
- Test the top for lighter gases (e.g. methane).
- Test the middle for gases like carbon monoxide.
- Test the bottom for heavier gases (e.g. hydrogen sulfide, carbon dioxide).
- Record all readings: Log results on your entry control sheet or gas log before entry.
Expert Insight: Why Process Matters
We reinforce that good confined space practice is about consistency, not shortcuts. Following the three-stage method gives your team confidence that every atmospheric layer is checked, recorded, and controlled reducing risks and ensuring compliance with confined space entry regulations.
Watch the Full Video
Watch: Three-Stage Gas Check↗︎
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