PSI Explained: Ventilation System Design

Similar to the Relief System Design and Design Basis, Title 8 CCR §5189(d)(3)(A)(5) and Title 29 CFR §1910.119(d)(3)(i)(E) require that the owner of a PSM chemical process prepare documentation describing the design of the ventilation systems associated with the process. With regard to ammonia refrigeration machinery room ventilation, we have written about the current ventilation system requirements extensively in a previous blog post. It is not sufficient, however, to simply document the current ventilation requirements. Rather, documentation must be prepared that describes the “as-built” design of the existing ventilation system(s). Ideally, this documentation will include:

• Functional description of the ventilation system – Description of fan control, alarm signals, normal vs. emergency ventilation, etc.
• Fan specifications – Airflow, static pressure, motor type, blade material
• Room characteristics – Dimensions, volume, make-up air dampers
• Design basis – Code or standard to which the ventilation system was designed