Confined Space Ventilation Strategies
Construction and general industry · Ver en español
Talking points
- Forced-air ventilation (positive pressure) pushes fresh air into the space and displaces hazardous atmospheres out. The air supply must come from a clean source — not near vehicle exhaust or other contaminants.
- Direct the ventilation duct to the bottom of the space when displacing gases heavier than air (H₂S, CO₂). Direct it to the top when displacing gases lighter than air (methane).
- The duct length and diameter affect airflow. Long duct runs reduce the volume of air delivered. Use the shortest duct length practical and a blower sized for the space volume.
- Ventilation must run continuously during the entire entry — not just before entry. Turning off ventilation during work allows hazardous atmospheres to re-accumulate.
- Continuous atmospheric monitoring verifies that ventilation is working. If readings climb despite ventilation, increase airflow or evacuate and reassess.
Ask the crew
Is our ventilation blower pulling air from a clean source — and is the duct directing air to the right level of the space?
Standards this talk is built on
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