pumps and motors

Question 1

stores energy and consists of a pair of metallic plates that are separated by an insulating material called a dielectric

Answer 1

Capacitor

Question 2

condition that occurs when pumps are run too fast or water is forced to change directions quickly-can cause pitting of the impeller and reduce pump efficiency

Answer 2

Cavitation

Question 3

theoretical angular velocity that excites the natural frequency of a rotating object, such as a shaft

Answer 3

Critical speed

Question 4

used to measure the average power of a load over a specific time interval as well as recording the peak power consumption during the period

Answer 4

demand meter

Question 5

used on large equipment to check whether all the current entering a system comes out of the system-will shut down a system that is losing current as a safety precaution

Answer 5

differential relay

Question 6

used when power is generated locally to respond to changes in the frequency of an AC power supply-also used on synchronous motor starters to sense when the motor has reached synchronizing speed

Answer 6

frequency relay

Question 7

amount of energy in feet required to overcome resistance to flow in a pipe

Answer 7

friction head

Question 8

energy possessed by water in a hydraulic system measured in feet

Answer 8

head

Question 9

the study of fluids in motion

Answer 9

hydraulics

Question 10

rotating set of vanes that forces water through a pump

-heart of the pump

Answer 10

impeller

Question 11

prevent air leakage along the pump shaft when it is operating under suction lift conditions-also called a seal cage

Answer 11

lantern ring

Question 12

seal placed on pump shaft to prevent water from leaking out along the shaft-also prevents air from entering the pump

Answer 12

mechanical seal

Question 13

rings of graphite impregnated cotton, flax, or synthetic materials used to control pump shaft or valve stem leakage

Answer 13

packing

Question 14

a follower ring that compresses the packing placed in the stuffing box

Answer 14

packing gland

Question 15

two or more pumps whose discharges are entering a common pipe to increase volumetric flow rate

Answer 15

parallel operation

Question 16

measure of the amount of energy in water due to water pressure

Answer 16

pressure head

Question 17

amount of energy in feet that a pump supplies to a fluid

Answer 17

pump head

Question 18

a condition where a pump is subject to frequent on/off cycling due to pressure surges that effect the pump controller

Answer 18

racking

Question 19

a load acting at a right angle to the shaft

Answer 19

radial load

Question 20

a piece of electrical equipment that changes alternating current to direct current by allowing the electric current to flow in one direction but blocking flow in the opposite direction

Answer 20

rectifier

Question 21

one pump discharging into the suction line of another pump to increase the overall discharge head

Answer 21

series operation

Question 22

recirculation within a centrifugal pump casing around the impeller due to a blockage of the pump discharge

Answer 22

slip

Question 23

houses the packing and lantern ring in a centrifugal pump

Answer 23

stuffing box

Question 24

a load that acts parallel to the axis of rotation

Answer 24

thrust load

Question 25

an overcurrent protection device placed on each phase of a power supply to open up a control circuit and stop a motor, if the current becomes excessive

Answer 25

thermal overload relay

Question 26

electrical device used to detect power loss and initiate an automatic switchover to another power supply

Answer 26

voltage relay

Question 27

rings made of brass or bronze placed on the impeller and/or casing of a centrifugal pump to separate the suction side of the pump from the discharge side

Answer 27

wear ring

Question 28

uses an impeller or propeller to accelerate water to a high velocity within the pump casing-high velocity (low pressure) converted to high pressure (low velocity) as casing volume increases

Answer 28

velocity pumps

Question 29

most commonly used pumps in water systems-water thrown outward from the center of the impeller and into the volute or diffusers -velocity is converted to pressure

Answer 29

radial flow pump

Question 30

referred to as a propeller pump-no volute or diffuser vanes - propeller shaped impeller increases head by lifting action of the blades - water moves parallel to the pump shaft - pump can move large volumes of water but adds little head - shaft rotates between 9000 and 15000 rpm

Answer 30

axial flow pump

Question 31

- combination of radial flow and axial flow pumps - impeller is shaped so centrifugal force will impart some radial force - used where water contains a high solids concentration

Answer 31

mixed flow pump

Question 32

most commonly used volute-type pump - can achieve various flows and pressures - can develop as much as 250ft of head per stage - efficiency between 75%-85% - inexpensive and little maintenance

Answer 32

centrifugal pump

Question 33

- impeller rotates within a channel of constant cross-sectional area - flow velocity is converted to pressure by a diffuser guide vanes - most efficient of all velocity pumps and generates the highest head - efficiency between 90%-95% - expensive and difficult to maintain

Answer 33

vertical turbine pump

Question 34

vertical turbine pump with very long pipe column housings and drive shafts - drive unit remains above ground - piping, shaft sections, and multiple stages are lowered into the ground

Answer 34

deep-well pump

Question 35

multistage mixed flow centrifugal pumps or turbine pumps with a close-connected motor -designed to operate completely under water

Answer 35

submersible pump

Question 36

referred to as a "can pump" | -motor and pump usually close-coupled and pump draws suction on water collection sump

Answer 36

booster pump

Question 37

used for metering treatment chemicals into the system | -deliver a fixed volume of liquid for every stroke or revolution regardless of discharge pressure

Answer 37

positive-displacement pump

Question 38

piston moves in and out of a cylinder and liquid is discharged through check valves -creates a pulse in discharge minimized by use of multiple cylinders or pulsation dampeners

Answer 38

reciprocating pump

Question 39

use closely meshed vanes, gears or lobes rotating within a tight chamber to move liquid

Answer 39

rotary pump

Question 40

uses a flexible diaphragm to vary the size of a chamber | -check valves allow flow in and out with each stroke of the drive unit

Answer 40

diaphragm pump

Question 41

what are the three types of single phase motors?

Answer 41

1) split phase motor 2) repulsion-induction motor 3) capacitor-start motor

Question 42

draws high current when starting and has low starting torque

Answer 42

split phase motor

Question 43

draws a lot of current on start up

Answer 43

repulsion-induction motor

Question 44

high starting torque and starting current | -good when needed to be brought up to speed quickly and not cycled on and off

Answer 44

capacitor-start motor

Question 45

What are the classifications for three phase motors?

Answer 45

1) squirrel cage induction motor 2) synchronous motor 3) wound rotor induction motor

Question 46

simplest type of all AC motors - current flowing through stator winding establishes a magnetic field which induces a voltage in the rotor windings-causes motor to turn - can be used for high starting torque without special starting circuitry applications

Answer 46

squirrel cage induction motor

Question 47

used in applications requiring constant motor speed | -rotating magnetic field rotates as a synchronous speed

Answer 47

synchronous motor

Question 48

easy to start, variable speed options and low starting current - motor is similar to squirrel cage induction motor - uses variable frequency drives to control speed

Answer 48

wound rotor induction motor