How do I design the pressurised rooms in hospital

[johnnychin]

I have been in trouble to design the pressurization system for both the isolation and Autopsy rooms for a hospital. My design reference is the HVAC Design Manual For Hospital and Clinics. Two criteria to adhere to this design: Volumetric Flow Rate (VFR) and Room Differential Pressure (RDP). I found that the VFR criteria has not shown any required CFM or CMS. On the other hand RDP requires a 0.01 w.g. (2.5Pa) based on the AIA 2001 Guidelines. I have better understanding to VFR by relating the CFM between Exhaust and Supply air. What does the 2.5 Pa imply? I couldnt relate the 2.5 Pa with CFM.

[cool_tech]

there must be a pressure difference between inside room pressure and outside room pressure. i thought it was more that 2.5 pa have done a little bit of work in hospitals and clean rooms.

[Magoo]

You have to establish the control space volume and estimate the leakage rate from that space, doors, vents and structure leakage, extracts, natural venting. Then you have to add extra air volume filtered and sanitised to increase pressure mainly to stop ingress of bugs, flies etc., you will need to allow for balance ports to stop over pressurizing that will spring the structure ,lift ceilings , and blow out windows. You will also need a magnahelic pressure gauge.
Best option is trial and error, once built and vacant start testing with a variable speed fan / backward curve and a balance port. Start with internal volume and base on one full air change per hour, and you will be getting close. There are no hard and fast rules, as every applications is totally different. I generally work on 5 pa positive