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Confined Space Ventilation

Confined Space Ventilation

Posted by Dr. David J. Silver, B.S., M.S. Ph.D., CIH on Mar 21st 2019

Sending workers into a confined space can be tragic if the hazards are not tallied correctly. Ventilation can be one of the key components in keeping confined space entrants safe. 


First, is it a confined space? Identify all of your confined spaces, identify chemical, biological, and physical hazards in the space and then take steps to assure safety for all entrants. Safety depends on the following the OSHA Confined Space Regulation 29CFR1910.146 “Permit Required Confined Spaces.”


Ventilation, an aspect of a confined space program, is used to stabilize the environment, making it relatively safe for entrants to occupy the space and work. A blower with ducting delivers air to a confined space of a volume and changes air with the outside to drive down toxic atmospheres, also delivers lifesaving oxygen, and keeps explosive gases at bay. This is termed positive pressure displacement and depending on the locality, 5-10 air changes per hour are typically recommended.


Ventilation will not protect entrants from other hazards like engulfment, mixer blades, or high voltage, so the appropriate hazard control must be implemented. An IDLH atmosphere may be supplemented with emergency respirators with air supply for quick egress. Rescue devices like a tripod and wench to pull an entrant to safety or other devices may be used.

Constant monitoring of a ventilated atmosphere will assure a safe environment. Alarms at pre-set levels will allow both the attendant and entrants quickly move out of the confined space until the issue is resolved. The ventilator must remain operational during the time the entrants are occupying the space and must quickly leave if the ventilator becomes compromised.


Allegro blowers can be purchased through EGas Depot. We offer Allegro high output compact axial blowers designed for easy use and storage. Available as complete units with ducting, they are super quiet, in safety oranges and come complete with a handy storage case. Other blowers are also available such as axial, centrifugal or venture. Visit EGas Depot at www.egasdepot.com

GAS FINDER - Enter 1 to 6 gases