PowerSmith
Mechanical
I am working on an existing Low Pressure CO2 Fire Protection System per NFPA-12. The calculations indicate that there is a room over-pressurization problem since about 2000# of CO2 is discharged into a 20,000 cu-ft room in about 100 seconds. The code calcs must assume that the heat generated from a fire would quickly heat the air and CO2 mixture to 75 deg. F. The room pressure would peak based on the additional CO2 gas volume. Based on the available vent area, determined by a recent blower door test, the peak pressure is sufficient to warrant the installation of a Pressure Relief Damper. So, I am currently looking for a damper supplier that knows something about CO2 Fire Protection and the associated pressures, flow rates, and CFM values.
The small amount of research I have done indicates that suppliers of CO2 Fire Protection pressure relief dampers and fire rated ductwork are mostly located in the UK and Europe. Do they have a different code or know something more about this subject?
There is a minor concern about the CO2 design should the system be intentionally discharged without a fire and associated heat load. Since the liquid CO2 is stored at 300 psi and 0.0 deg. F., this would be a substantial refrigeration burst. My Plank and Kuprianoff T-E diagram shows that the CO2 would expand to atm pressure at -100 deg. F. The air in the room would have been about 1700 # mass at 75 deg. F. initially. So, it looks like I may develop a peak vacuum during the discharge as well. The code does not really discuss the system or room design and potential vacuum pressures during an intentional discharge.
I would appreciate any comments on this subject.
Thanks
Pete PowerSmith
The small amount of research I have done indicates that suppliers of CO2 Fire Protection pressure relief dampers and fire rated ductwork are mostly located in the UK and Europe. Do they have a different code or know something more about this subject?
There is a minor concern about the CO2 design should the system be intentionally discharged without a fire and associated heat load. Since the liquid CO2 is stored at 300 psi and 0.0 deg. F., this would be a substantial refrigeration burst. My Plank and Kuprianoff T-E diagram shows that the CO2 would expand to atm pressure at -100 deg. F. The air in the room would have been about 1700 # mass at 75 deg. F. initially. So, it looks like I may develop a peak vacuum during the discharge as well. The code does not really discuss the system or room design and potential vacuum pressures during an intentional discharge.
I would appreciate any comments on this subject.
Thanks
Pete PowerSmith
