Alan
I am sitting in a hotel in Madrid on business. I don't have access to my design calcs on my CO2 scrubber so the 30 lbs of SodaSorb HB for 80 hours is an approximation. The amount you need depends on some design assumptions such as absorbent density, average temperature and humidity. Best I can remember is that for my application, it was some were between 22 and 30 lbs for 8 hour primary mission and 72 hours of emergency.
Cliff