Water supplies shall be of a capacity and a pressure that are capable of maintaining foam discharge or water discharge, or both, at the design rate for the required period of discharge over the entire area protected by systems expected to operate simultaneously.

• A. Only for the foam discharge
• B. At the design rate for the required period over the entire protected area
• C. For a partial area
• D. Only at start of discharge

Answer: (B)

The concept being tested is that the water supply for a foam-water system must be able to deliver the system’s design discharge at the required duration, across the entire area that could be affected if multiple parts of the system operate simultaneously. In practice, this means the supply must provide the design flow at the intended pressure for the full period of discharge, over the entire protected area where simultaneous operation is anticipated. This ensures no loss of flow or pressure as more sprinklers or foam devices activate.

That’s why the correct choice is the one describing maintaining the design rate for the required period over the entire protected area. It recognizes that the system may discharge through multiple elements at once and that the supply must sustain that rate across all affected zones for the full duration. The other options are less accurate: limiting to foam discharge only ignores the water portion, limiting to a partial area ignores simultaneous operation, and limiting to start of discharge ignores the need to maintain flow for the entire discharge period.