Fire Protection System Requirements for High-Rise Buildings:

Fire Protection System Requirements for High-Rise Buildings:

Applied to a building the size of one of the WTC towers (approx. 4000 sq.ft. per floor) the 'International Fire Codes' as outlined by the NFPA's standard spec's "NFPA 13," require "automatic, quick response fire detection sprinkler systems" in high-rise buildings to deliver a minimum of 500 gallons of water per minute, for a minimum period of 2 hours.

That's 90,000 gallons of water! To compare, an olympic size swimming pool contains a mere 64,800 gallons.)

This sprinkler system, or "Fail-Safe Deluge System" as it is called technically, delivers this volume of water through a network of pipes (steel at the time of the WTC's construction - newer, less demanding codes allow plastic piping) to the walls, ceilings and windows of no less than five floors - including the two floors above, and the two below the one in which the fire was detected.

The water pressure in a fail-safe system is monitored, and when one or more of the spray jets is triggered by higher than normal temperatures, the "emergency power equipped" pumps sense the pressure drop and kick in.
This boosts the pressure in the system, which triggers the remaining spray nozzles to open and commence to supply a "deluge" of water to the appropriate zones.

Note: Any event which releases pressure from the system (i.e.: pipes that have been ruptured, say by impact or explosion) would likewise cause the system to activate - just as if it had been triggered by heat.

Total amount of water that's delivered per hour: 225,000 gallons - or nine average size swimming pools.

The cooling capacity of this much water can be measured by calculating the calories, or btu's it would take to raise the water temperature from room temperature to 212 deg. F.

These figures, and more, will be be coming soon.

Deluge Flow Rates
As Per National Fire Codes

Scaled Column layout from original WTC blueprints