Ventilation – Atmospheric Testing
General Guidelines: Ventilate the space for a minimum of 30 minutes, up to 60 minutes, and test again. Ventilation of the space is determined by:
Continuous mechanical/forced air ventilation must be provided as long as Entrants are in the space.
Ventilation equipment (forced air and/or exhaust) should be directed to the immediate vicinity of each entrant within the confined space.
If mechanical ventilation equipment should fail during entry operations, all employees must immediately evacuate the space until equipment is restored/replaced, and retesting indicates acceptable entry conditions.