St. Louis Children’s Hospital 6th Floor OR HVAC Pressurization

St. Louis, Missouri

Health Care
  • Year Completed: 
  • Project Team: 
    • Eric Utterson, Principal
    • Ryan Corrigan, Project Manager
    • Drew Flanakin, Project Engineer

Following a decade of hospital expansions and renovations, the hospital determined that the air balance on the 6th Floor operating suite was not performing satisfactorily.  Pressure control was changing depending on factors outside the OR and were not predicable.  8760 Engineering was hired initially to prepare a test and balance specification for the suite.  In the process of preparing this document, it became apparent that pressurization problems were affected by HVAC systems outside the 6th floor and that further analysis and testing were required to solve the problem.

During our analysis phase, we found that the exhaust path common to many of the air handling units in the building was incapable of moving sufficient air resulting is the inability to exhaust properly in the 6th floor and in other areas of the building.  Pressure drops and airflows were measured throughout the exhaust system in an effort to diagnose cause of the restriction.  Additionally, data loggers were setup to measure airflow rate on several air handling systems for the purpose of identifying that variable volume operation was significant enough to affect pressurization on the 6th floor where numerous exhaust paths were pressure dependent.

Following our analysis, we completed a design that installed 10 foot by 10 foot turning vanes in a portion of the exhaust system that was experiencing significant pressure drops, installed airflow measuring stations on all uncontrolled exhaust flows from the OR HVAC system and identified several exhaust airflow measuring stations that were plugged, causing as much as 3 inches w.c. pressure drop.

Challenges of the Project:

  1. Performing fieldwork on large scale ductwork presents unique challenges.   Measurements required our staff to climb into the ductwork and make measurements while being buffeted by 4000 fpm airflows..
  2. Preparation of duct pressure drop models to demonstrate how variable flow operation affects OR pressurization.