A supplied head and tank model
A teaching design supplies 60 feet of pumping lift, a required delivery-pressure head of 92 feet and 18 feet of pipe and fitting losses at the requested flow. All heads use the same reference convention and the exercise says to add these terms. Separately, the selected motor requires at least one minute of run time under the supplied zero-demand tank-filling model, with a constant pump flow of 10 gallons per minute. A salesperson treats nominal tank volume as usable drawdown and selects a pump from its headline flow without consulting the curve. The learner must calculate the exercise values and then explain which actual equipment information is still needed. The scenario does not set universal pressure controls, voltage-drop limits or electrical permissions.
1. Calculate the supplied head and minimum usable fill volume.
Read the worked answer
The exercise TDH is 60+92+18=170 feet. Under the stated constant-flow, zero-demand model, one minute at 10 gallons per minute requires 10 gallons of usable drawdown, not merely 10 gallons nominal tank volume.
2. What remains to be checked?
Read the worked answer
Compare the actual pump curve at the duty point and confirm the manufacturer’s operating, cooling, tank and motor requirements. The simplified model does not guarantee a particular run time under every demand pattern.