Standard pumper-connection fire hydrants should not be installed on water mains smaller than how many inches in diameter?

• A. 4 Inch
• B. 6 Inch
• C. 8 Inch
• D. 10 Inch

Answer: (B)

The essential idea is that pumper-connection hydrants need a water main large enough to deliver the high-volume flow firefighters rely on. A six-inch main provides enough capacity and keeps friction losses from starving the pumper connection of pressure. If the main were only four inches, the flow would be greatly restricted and the pressure at the hydrant could drop, making it difficult for the pumper to obtain the needed water quickly and reliably, especially when other demands are present in the system. Larger mains, like eight or ten inches, do meet the requirement too, but the question asks for the minimum size not to be smaller than. Therefore, six inches is the correct threshold.