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Introduction to Centrifugal Pump Systems

Quiz Questions

1. Important characteristics of pumps system are:
All of the above
2. The pump provides the energy necessary to drive the fluid through the system and overcome friction and any elevation difference.
3. Pressure is __________ when fluid particles are forced closer together. For example, in a fire extinguisher work or energy has been spent to pressurize the liquid chemical within, that energy can be stored and used later.
4. Is it possible to pressurize a liquid within a container that is open? ____. A good example is a syringe, as you push down on the plunger the pressure increases, and the harder you have to push. There is enough friction as the fluid moves through the needle to produce a great deal of pressure in the body of the syringe.
5. Friction is always ______, even in fluids, it is the force that resists the movement of objects.
6. In fluids, friction occurs between fluid layers that are traveling at different ____ within the pipe (see Figure 8). There is a natural tendency for the fluid velocity to be higher in the ____ of the pipe than near the wall of the pipe. Friction will also be ___ for viscous fluids and fluids with suspended particles.
Location   walls   low
Velocities  center   high
7. Friction depends on
average velocity of the fluid within the pipe
pipe surface roughness
All of the above
8. Energy and head are two terms that are often used in pump systems. We use energy to describe the movement of liquids in pump systems because it is easier than any other method. There are four forms of energy in pump systems: pressure, elevation, friction and velocity.
9. In Fig 11 , pump energy = friction energy + ____________
Elevation energy
Dynamic energy
10. In Figure 15, the pressure level at the bottom of a tank depends on the liquid surface____
11. To correctly determine the static head follow the liquid particles from start to finish, the start is almost always at the liquid surface of the suction tank, this is called the inlet elevation. The end will occur where you encounter an environment with a fixed pressure such as the open atmosphere; this point is the discharge elevation end or outlet elevation. The difference between the two elevations is the static head. The static head can be negative because the outlet elevation can be lower than the inlet elevation.
12. The manufacturer will rate the pump at its optimum total head and flow, this point is also known as the best efficiency point or B.E.P. At that flow rate, the pump is at its most efficient and there will be minimal amount of vibration and noise. Of course, the pump can operate at other flow rates, higher or lower than the rating but the life of the pump will suffer if you operate too far away from its normal rating. As a guideline, aim for a variation of plus or minus 15% on total head.