Describe Forced Air-ventilation Systems

The forced air will be directed to the immediate vicinity of each employee within the confined space. Ventilation must be provided until all employees exit the space.The method and ventilation equipment selected will be determined based upon the size of the confined space, the size of the entrance into the space, the gases present within the space, and the source of make-up air.If mechanical ventilation should fail during entry operations, all employees must immediately evacuate the space until ventilation is restored and retesting indicates acceptable entry conditions.Ventilation systems and electrical tools and equipment used in flammable atmospheres must be explosion-proof and appropriately rated for the hazard. Each employee must leave the space immediately; The space must be evaluated to determine how the hazardous atmosphere developed; and, Measures must be implemented to protect employees from the hazardous atmosphere before any subsequent entry takes place