Which value represents the coefficient for a smooth and rounded outlet hydrant?

Which value represents the coefficient for a smooth and rounded outlet hydrant?

• A. .65
• B. .75
• C. .90
• D. 1.00

Answer: (C)

A hydrant outlet’s coefficient shows how much of the ideal flow actually passes through after the outlet’s shape causes energy losses. A smooth, rounded outlet minimizes turbulence and eddies as water exits, so the discharge coefficient is high—around 0.90. This reflects that about 90% of the theoretical flow is realized despite losses. The other numbers would indicate more significant losses (0.65 or 0.75) or an unrealistic, lossless exit (1.00). So 0.90 best represents a smooth, rounded hydrant outlet.

A hydrant outlet’s coefficient shows how much of the ideal flow actually passes through after the outlet’s shape causes energy losses. A smooth, rounded outlet minimizes turbulence and eddies as water exits, so the discharge coefficient is high—around 0.90. This reflects that about 90% of the theoretical flow is realized despite losses. The other numbers would indicate more significant losses (0.65 or 0.75) or an unrealistic, lossless exit (1.00). So 0.90 best represents a smooth, rounded hydrant outlet.