Wastewater Maintenance & Pumps Review Questions

Front 1

The primary cause of motor failur is:

Back 1

Moisture
&
Vibration and Overload

Front 2

The discharge of a centrifugal pump:

Back 2

decreases with the increase of head

Front 3

True or False:
Cavitation is the formation and collapse of a gas pocket or bubble on the blade of a pumps impeller:

Back 3

True

Front 4

A pump is delivering at a less than expected rate of discharge. What are the possible causes?

Back 4

discharge head too low

Front 5

If packing is not maintained properly,

Back 5

There will be a loss of suction from air being allowed to enter the pipe.

Front 6

The casing surrounding a pump impeller that collects the water discharge by the impeller is called a:

Back 6

volute

Front 7

A straight ladder, when properly used should have the base ___ from the supporting wall.

Back 7

1/4 of its working length

Front 8

True or False
The main function of a lubricant is to keep moving materials seperate from each other.

Back 8

True

Front 9

A possible cause of electric motor failure is?

Back 9

Dirt
Moisture
Friction

Front 10

A water seal on a pump serves a dual purpose. It acts as a lubricant and it also:

Back 10

Keeps gritty material from entering the packing box

Front 11

The elevation of any pump above the source of supply should not exceed ___ ft.

Back 11

22ft

Front 12

Friction in a pipeline causes:

Back 12

Loss of pressure

Front 13

before repairing a pumps electrical circuit, which action should you take?

Back 13

Disconnect the circuit breaker and lock out tag out

Front 14

In a centrifugal pump, leakage is prevented by:

Back 14

wear rings

Front 15

The pressure against which a pump must operate is measured in terms of:

Back 15

psi

Front 16

An air gap device is used to:

Back 16

prevent cross connections

Front 17

Why are check valves used in conjunction with centrifugal pumps?

Back 17

To prevent water in the auction line from flowing back into the wetwell.

Front 18

Valves should be closed slowly to prevent:

Back 18

water hammer

Front 19

If a centrifugal pump loses its prime after starting, what is the most probable cause?

Back 19

air leaks into the pump through stuffing box

Front 20

In electrical circuits a ___ is used to reduce voltage where needed.

Back 20

transformer

Front 21

Which of the following causes the greatest pipe friction loss?

Back 21

Increasing the velocity of wastewater.

Front 22

If the pump bearings on horizontal pumps are over lubricated, the most important effect is the extra lubricant:

Back 22

May cause overheating and possible failure of the bearings.

Front 23

If packing is not maintained properely:

Back 23

Loss of suction will occur due to air entering the pump.

Front 24

Information on preventive maintenance procedures, materials, and frequencies for plant structure should be taken from:

Back 24

Manufaturers operation and maintenance manuals.

Front 25

Instrumentation friction disks or clutch surfaces should be:

Back 25

Kept free of oil

Front 26

An electrical system for prevention of rust, corrosion, and pitting of steel and iron surfaces in contact with water is called ____ protection.

Back 26

cathodic

Front 27

What seperates the impeller from the volute and prevents backflow in a centrifugal pump?

Back 27

wear rings

Front 28

E = I x R or Voltage = Amperage x Resistance is:

Back 28

Ohm's Law

Front 29

The ___ is the unit of electrical resistance; resistance to the flow of electrical current.

Back 29

Ohm

Front 30

The rate at which heat is produced is the ___ that the load dissipates.

Back 30

Power

Front 31

___ is the relationship in time between two waveforms of the same frequency.

Back 31

Phase

Front 32

If bearings on a centrifugal pump are running hot, over or under lubrication should be checked. If lubrication is satisfactory, the next preventative maintenance check would be to:

Back 32

Inspect the alignment of the pump motor

Front 33

During plant rounds, an operator notices a pump is spraying water from a packing gland. The operator should:

Back 33

Tighten the packing gland until the spray is reduced to a small drip.

Front 34

A pumps seal water pressure should be set at:

Back 34

5 to 10 psi more than the pump operating discharge pressure

Front 35

A treatment plant should have a valve exercise program in which all plant valves are exercised.

Back 35

Once a year

Front 36

T or F
The manometer of an aeration blower inlet filter, which needs replacing if the pressure differential exceeds 2" of the water column, has a scale of 0-5". The meniscus reads 1" of water column. the filter should be replaced.

Back 36

False

Front 37

T or F
You need to increase the flow of biosolids to the digester from 100-175g/m. the biosolids pump has a capacity of 200g/min. When you open the butterfly valve to 100%, flow increases to only 125g/min. The most probable cause of the low flow is a malfunctioning valve operator.

Back 37

False

Front 38

T or F
You need to maintain digester temp at 98.8F +/- 1 deg F. The temp indicator on the digester recirculation pipe reads 37C. The temp is within acceptable limits.

Back 38

True

Front 39

T or F
The temp indicator on a heat transfer pump is mounted in a thermowell. The indicator needs to be replaced, but you cannot remove the indicator until the pump is out of service, locked out, and drained.

Back 39

False

Front 40

A ___ is installed on pump discharge piping to prevent water from flowing back across a pump when it is off.

Back 40

check valve

Front 41

Given the following data:
wet well has increased flow because of rain
wet well unchanged at excessively high level
lead pump running
lag pump running
lead pump check valve lifting arm up
lag pump check valve lifting arm down
force main pressure remains at normal range for one pump
low level pressure switch normal
high level pressure switch normal
electrical controls automatic
What is the most likely cause of the problem

Back 41

Lag pump clogged

Front 42

Centrifugal pump parts include:

Back 42

Impeller

Front 43

A positive displacement sludge pump should never be placed into operation

Back 43

with the discharge valve closed

Front 44

The total dynamic head against which a pump must operate:

Back 44

Is the sum of the static head and the head due to friction loss.

Front 45

The difference in water surface elevation between where the pump is pulling from and where it is discharging to is called:

Back 45

static head

Front 46

A device that causes the wastewater in a verticle riser pipe to rise to an outlet using compressed air is called an

Back 46

air lift pump

Front 47

True or False
A centrifugal untreated wastewater pump starts pumping at 25g/min and has a maximum pumping capacity of 100g/min. A venturi flowmeter can be used to measure flow from this pump.

Back 47

True

Front 48

True or False
A positive displacement pump is capable of pumping a maximum of 50g/min and a minimum of 12.5g/min. A Venturi flowmeter can be used to measure flow from this pump.

Back 48

False

Front 49

Wet well influent flow has increased because of rain and the level is rising. the lead and lag pumps are running. The lead pump check valve lifting arm is up; the lag pump check valve lifting arm is down. The force main pressure remains at normal range for one pump. Low level and high level pressure switches are normal. electrical controls are in automatic mode. What is the most likely cause of the problem?

Back 49

the lag pumps are clogged

Front 50

A wet well inlet has normal dry weather flow, but the wet well is empty with flow going directly to pump suction. The lead and lag pump are running, and both pumps check valve lifting arms are slightly above the closed position. The lead air compressor is running, and the low level pressure switch is closed. Electrical controls are in automatic mode. What is the most likely cause of the lift station problem?

Back 50

A malfunctioning level control is causing high wet well levels.

Front 51

Pumps are often required to bring wastewater into treatment plant. What types of pumps are typically used to lift influent wastewater.

Back 51

Centrifugal

Front 52

Daily maintenance procedures for a rectangular secondary clarifier include:

Back 52

Inspecting the drive unit and the chain and flight system

Front 53

Which of the following is a type of positive displacement pump:

a. axial
b. turbine
c. educator
d. gear

Back 53

gear

Front 54

What is the vertical distance between the elevation of the free water surface at the suction and that of the free water surface at the discharge of a pump called?

Back 54

static head

Front 55

What is an air gap device used for?

Back 55

Backflow prevention

Front 56

How often should inactive valves be exercised?

Back 56

Quarterly to annually minimum

Front 57

When using a progressing cavity pump to pump sludge, in what condition must the pump intake be in order to insure safe operation?

Back 57

submerged

Front 58

What equipment is typically used to control positive displacement blowers?

Back 58

Multi speed motors and variable frequency drives

Front 59

A water filled mechanical pump seal not only helps to prevent leaks, but also:

Back 59

acts as a lubricant for the pump shaft

Front 60

If your facility cannot tolerate power loss even for short periods, then you need an emergency generator that can:

Back 60

automatically switch over when power goes down

Front 61

Besides throttling the inlet valve, what type of control is used for a centrifugal pump?

Back 61

variable frequency drives

Front 62

What type of pump is typically used to feed ferric chloride for solids handling purposes?

Back 62

Metering pumps

Front 63

What devices can be used as an emergency shut off for the drive unit of a circular clarifier?

Back 63

shear pins

Front 64

What is surging in a centrifugal blower?

Back 64

When the blowers discharge pressure is less than the aeration systems backpressure

Front 65

Motor starters and breakers are usually located:

Back 65

In motor control centers (MCC)

Front 66

What is the first step in starting a pneumatic air injector?

Back 66

Allow compressors to build required pressure

Front 67

The formation and collapse of gas pockets or bubbles on the blade of a centrifugal pump's impeller is known as what?

Back 67

cavitation

Front 68

When planning to work on or near electrical equipment, be sure to always:

Back 68

lock and tag out the equipment

Front 69

What is your first course of action if you see a slow constant drip from a pump shaft packing seal?

Back 69

make no adjustment

Front 70

What does a gradual increase in the bearing temp of a centrifugal blower indicates?

Back 70

there is a problem with the bearing or lubrication or connection

Front 71

How often should the scraper arms and blades of a circular clarifier be inspected and replaced, if necessary?

Back 71

annually

Front 72

What type of in situ maintenance is recommended for most flexible membrane diffusers?

Back 72

air bumping

Front 73

Which of the following indicates that the impeller of a centrifugal pump may be worn or damaged?

Back 73

pump is not delivering the design flow

Front 74

A ground fault interrupter on an electrical circuit system is used to:

Back 74

disconnect power from the circuit if there is a faulty ground line

Front 75

Which of the following causes leaking between the segment and body of a plug valve?

Back 75

Overgreased assembly

Front 76

Which of the following is a likely benefit of a planned maintenance program?

Back 76

Extended equipment life

Front 77

What type of air filter would be preferable for a blower located in a n area where there are very fine particles in the air?

Back 77

Electrostatic precipitators

Front 78

Why should standby generators be exercised regularly?

Back 78

to test the system under actual conditions

Front 79

What is an acceptable variation in input voltage for most electric motors?

Back 79

+/- 10%

Front 80

How often should the packing on a gate valve be replaced?

Back 80

As required