# Lab 4.pdf - 4 Lab MMET 401 FLUID POWER TECHNOLOGY LAB 4...

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26 MMET 401: FLUID POWER TECHNOLOGY LAB 4: CENTRIFUGAL PUMP BASICS Lab 4 MMET 401-502
27 The basic purpose of this laboratory is to gain a basic understanding of a centrifugal pump and to determine Head/Flowrate characteristics and efficiencies for a centrifugal pump running at a constant RPM. This lab will evaluate the performance of a centrifugal pump by measuring the performance curves for the pump. By the end of the lab you should be able to understand: 1. Pump performance curve 2. System curve 3. Efficiency of the pump 4. NPSH Non-Positive Displacement Pumps (Kinetic or Dynamic) Non-positive displacement pumps differ significantly from positive displacement pumps in that the flow rate varies greatly with changes in flow resistance. Flow rate can vary from zero to maximum flow without affecting the operation of the pump. There are large clearances between the moving and non-moving parts of the pump therefore the fluid can slip back into the clearance spaces. Pumps of this type are unable to achieve the elevated pressures that positive displacement types can. Centrifugal Pump: Design and Construction Centrifugal pumps are the most commonly used pumps, they are pressure creating devices that transfer rotary kinetic energy of the impellers to the linear kinetic energy of the fluid. A centrifugal pump consists of an impeller which carries a number of vanes rotating inside a casing. Liquid that enters the pump at the center, later leaves the vanes with high velocity and increased pressure due to the centrifugal forces acting on it because of the rotating vanes. The fluid is then slowed down in the volute area surrounding the outlet of the vanes where the extra kinetic energy is converted to additional pressure rise. Preliminaries Pressure: is Force ( ) exerted per unit area ( ). Pascal’s Law When applied to a fluid, the pressure is transmitted undiminished in all directions. Usually expressed in pounds per square inch (psi), (bar) or in kilo Newton per square meter (kPa ).