Allied: Terms to Know

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Terms to Know

Duty Point: The flow (in GPM) and head (in feet) where a pump needs to operate to do the job.

Velocity: The speed at which the medium is moving through the pipe/hose. (We generally recommend increasing the pipe size if the velocity is calculated to exceed approx. 10 ft/sec for both safety and performance.)

Flooded Suction: Any instance in which gravity or system pressure will carry water from its source to the pump. (In these instances, we protect or remove the pump’s priming system to prevent possible damage.)

Critical Lifts: Any instance in which the vertical distance from water level to the eye of the pump’s impeller is 25 ft or more.

Total Dynamic Head (TDH): The total amount of resistance encountered in a pumping system in feet of head. TDH is calculated by adding up the following:

Static Suction Lift: The vertical distance from water level to the eye of the pump’s impeller.

Suction Friction Loss: The resistance in the suction line caused by friction in hose, bends, reducers, etc.

Static Discharge Loss: The vertical distance from the eye of the pump’s impeller to the highest point in the discharge line.

Discharge Friction Loss: The resistance in the discharge line caused by friction in hose, pipe, valves, fittings, etc.