The following are my tips to ensure PRCS are properly ventilated when necessary. Far too often, ventilation is nothing more than a “nice effort,” which can lead to disastrous results. So, in my time in safety at petrochemical and semiconductor facilities, the safety team managed the ventilation equipment (blowers and flexible ductwork). Still, the entry supervisor was responsible for the proper setup, and they were trained annually on this skill.
When a Confined Space needs to be ventilated due to heat or an atmospheric hazard (even a potential atmospheric hazard), the ventilation must meet the following requirements:
Forced Air Ventilation is the only type of ventilation allowed without consulting with the EHS team regarding other means (e.g., negative flow/vacuum).
NOTE: Some work inside a CS may ALSO require local exhaust ventilation (LEV), such as welding work that could generate a hazardous atmosphere.
All ventilation for a confined space will be forced air ventilation, provided by a blower specifically APPROVED and PROVIDED by the EHS Department for this specific purpose.
NOTE: CS Ventilation Blowers may NOT be used for other purposes. ALL blowers will be “rated” for the location they will be used (e.g., Class 1, Class 2, Div1, or Div 2 HAZLOC).
The EHS Department will maintain and issue CS Ventilation fans and flexible ductwork to entry supervisors upon their request.
The Entry Supervisor is responsible for obtaining the size of the space (in Cubic Feet) and the distance from the entry portal to the end/bottom/top of the space. This information will be provided to an EHS Team Member, who will then provide a CS fan properly sized for the space to be ventilated and the length of flexible ductwork needed to ventilate the space properly.
The EHS Team Member will utilize the Ventilation Straight-Edge tool to ensure the CFM capacity of the blower will provide an exchange rate of 7 per hour. (See Appendix XXX)
The EHS Team Member will issue ample length of flexible ductwork to ensure the space is adequately ventilated.
The Entry Supervisor MUST set up the ventilation blower and duct work to use the forced air to move the hazardous atmosphere OUT OF the space. For example, if the hazardous atmosphere is at the bottom of the space, then the forced air must be introduced at the top of the space, forcing the hazardous atmosphere out to the bottom of the space. And vice versa.
NOTE: there must be an opening for the discharge of air from the space. The entry and ventilation discharge portals should be the ONLY openings in the space. This discharge opening should be at least 3” or larger in diameter.
WARNING! Be aware of where this hazardous atmosphere is discharging to, as it may create a hazardous atmosphere outside the space. This may require the exhausted air to be ducted, using flexible duct work, to a “safe location”.
The Entry Supervisor is required to “Lockout” the power source (electrical or pneumatic) in the ON position to prevent the fan from losing power during entry. This is to be part of the Energy Isolation Control Plan. Loss of ventilation MUST sound an alarm to alert entrants to EXIT the space.
The forced air ventilation MUST be set up with no more than two (2) 90-degree bends or three (3) 45-degree bends in the flexible ductwork between the blower and the space.
If the air exiting the space needs to be ducted to a safe location, then the exit ductwork may not have more than two (2) bends greater than 20 degrees.
