Sunday, August 18, 2019
Pump Characteristics :: essays papers
Pump Characteristics INTRODUCTION In industry, the performance specifications for a particular pump may be known, but the tests are usually based on water as the pumping medium. For liquids of significantly higher viscosity than water, these performance curves may only be accurate at certain flow rates, or they might not be valid at all, and it might be necessary to recalibrate the specifications for higher viscosity liquids. The purpose of this experiment is to examine the performance and characteristics of a centrifugal pump, its motor, and the corresponding piping system, used to pump an ethylene glycol solution. The pump used in this experiment has a performance curve based on water, so pump performance curves, as well as motor performance curves, will be developed over a wide range of flow rates to determine the effect that the liquid viscosity and density have on the performance of this pump. Also, the pressure drop of the piping system will be examined to determine the extent of, if any, fouling in the pipes. OBJECTIVES Ã · Develop pump performance curves over a wide range of flow rates. This involves relating total head, horsepower input, efficiency, and NPSH as a function of pumping capacity (in gpm), similar to Figure 3-36A (Lab Manual). Ã · Develop motor performance curves over a wide range of flow rates. This involves relating the current supplied to the motor, motor shaft rotational speed, motor efficiency, and the power factor as a function of the load of the motor, similar to the figure on page 21 of the Lab Manual. Ã · Develop the friction factor chart for the piping system. This chart shows the relationship between the fanning friction factor and the Reynolds number over a wide range of flow rates, from which the roughness parameter (e/D) for the piping system can be estimated. Ã · Determine the optimal flow rate delivered by the pump. This value is estimated by neglecting all of the friction head losses outside the loop of the piping system. Ã · Examine the effectiveness of the pump. The performance curves based on the ethylene glycol solution will be compared to those developed using water as the base to examine the effect, if any, the viscosity and density of the liquid has on the pump. EXPERIMENTAL SET-UP A process flow diagram of the pump system is shown in Figure 1. The main components of the system are a centrifugal pump with a 4Ã ½-inch impeller, a 2-horsepower motor, a piping system with an effective length of about 285 feet, a rotameter for low liquid flow rates (0-2 gpm), a magnetic flow meter for high liquid flow rates (0-90 gpm), and a tank.
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