Slide 1
Moving liquid encounters resistance
Fluid flowing through a pipe loses mechanical energy through viscous effects. A pump must supply energy to sustain flow against this resistance.
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In a horizontal pipe of constant diameter, that loss commonly appears as a pressure drop. An elevation change can also alter pressure, so a pressure reading alone does not isolate friction.
Slide 2
Length adds to the loss
With other conditions held constant, a longer pipe produces more frictional loss. Roughness and the character of the flow also matter.
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The distinction between smooth laminar flow and turbulent flow changes how resistance scales with speed. One fixed rule for every liquid, diameter and flow rate would miss that transition.
Slide 3
Diameter has a powerful effect
A wider pipe carries a given volume flow at a lower average speed. That can greatly reduce frictional losses through the system.
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The benefit must be compared with the cost of larger pipe, fittings and installation. A cheaper narrow line may cost more over its lifetime because the pump keeps paying the energy penalty.
Slide 4
Fittings count too
Bends, entrances, strainers and valves create additional losses. A short route with many restrictions may be less efficient than its length suggests.
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These are often called minor losses, but the name does not mean their contribution is small. In a compact installation, fittings can dominate the total resistance.
Slide 5
Inspect the whole route
Fouling, damaged fittings and partly closed valves can increase resistance after installation. Changing performance may therefore reflect the piping rather than the pump.
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Comparing flow, pressure and power against an earlier baseline helps locate the change. Replacing a pump without checking the route can preserve the underlying cause of excessive energy use.
Sources
- Improving Pumping System Performance: A Sourcebook for Industry
U.S. Department of Energy