I am working on a power plant project now. Since it is a power plant we follow requirements of NFPA 850 most of the time. The 184.108.40.206 of NFPA 850 (2015 ed.) says that the 8-hour requirement of refilling time can be extended if initial storage exceeds minimum storage on a volume per time ratio basis. My question is how exactly I can calculate this.
For example, if I need 1000 m3 storage as a minimum, but refilling rate is 100 m3/hr, then 100 x 8 = 800 m3 is the refilled volume in 8-hour duration so that I need initial 1200 m3 (additional 200 m3) water storage. Is it what the requirement intends?
If it does so, hypothetically no refilling is required for a storage tank with 4-hour water supply, isn't it?
Please share your thought.