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Chapter 4
PUMPS
OBJECTIVES
• Review the history and design of pumps.
• Describe the scientific principles associated with centrifugal pump operation and identify key
components.
• Describe the operation and maintenance of positive displacement pumps.
• List the various types of rotary pumps.
• Describe the basic components and operation of a screw pumps.
CHAPTER 4 REVIEW QUESTIONS
1. Define NPSH, and describe how it affects industrial pump operation. Answer: The equivalent
2. Briefly review the history of positive displacement pumps and centrifugal pumps. Answer:
The first reciprocating pump was invented by a Greek named Ctesibius about 200 BC and
3. Describe the primary scientific principles associated with centrifugal pump operation and
identify key components. Answer: Centrifugal pumps use centrifugal force to add energy to
4. Describe the operation of positive displacement pumps. Answer: Positive displacement
5. List the various types of rotary pumps. Answer: Lobe, internal gear, external gear, sliding
6. Describe the basic components and operation of a screw pump. Answer: The operating
principles of a twin screw pump incorporate; a driving and a driven shaft, two screws, an
7. Explain how rotary gear pumps operate. Answer: Gear pumps consist of two mating gears
8. Describe the basic components and operation of sliding and flexible vane pumps. Answer:
Sliding vane pumps consist of spring-loaded or non-spring loaded vanes, attached to a rotor,
9. Describe the basic components of a lobe pump. Answer: Lobe pumps have two rotating lobe
10. List the various types of reciprocating pumps. Answer: Piston, plunger and diaphragm.
11. Explain the operation of diaphragm pumps. Answer: A diaphragm pump uses a flexible
12. Describe the operation and design of piston pumps. Answer: Reciprocating piston pumps use
13. Describe a plunger pump. Answer: Reciprocating plunger pumps operate with a back-and-
forth motion and a device called a plunger to displace controlled amounts of liquid. The
14. List the typical startup and shutdown procedures for a positive displacement pump. Answer:
The most important step in starting or shutting down a PD pump is to ensure the line up on
15 List the typical startup and shutdown procedures for a centrifugal pump. Answer: Check
16. What specific problems are associated with the operation of centrifugal and reciprocating
pumps? Answer: A centrifugal pump may experience cavitation or vapor lock.
17. Draw a simple axial pump. Answer: See Figure 4.13 Axial pump.
18. Draw a simple pump system using a tank, pump and piping. Answer: See Figure 4.28
19. Draw the symbol for a progressive cavity pump and a screw pump. Answer: See Figure 4.29
20. Explain how variations in NPSH affect the operation of a centrifugal pump. Answer:
