• Shuffle
    Toggle On
    Toggle Off
  • Alphabetize
    Toggle On
    Toggle Off
  • Front First
    Toggle On
    Toggle Off
  • Both Sides
    Toggle On
    Toggle Off
  • Read
    Toggle On
    Toggle Off

Card Range To Study



Play button


Play button




Click to flip

Use LEFT and RIGHT arrow keys to navigate between flashcards;

Use UP and DOWN arrow keys to flip the card;

H to show hint;

A reads text to speech;

80 Cards in this Set

  • Front
  • Back
The primary cause of motor failur is:
Vibration and Overload
The discharge of a centrifugal pump:
decreases with the increase of head
True or False:
Cavitation is the formation and collapse of a gas pocket or bubble on the blade of a pumps impeller:
A pump is delivering at a less than expected rate of discharge. What are the possible causes?
discharge head too low
If packing is not maintained properly,
There will be a loss of suction from air being allowed to enter the pipe.
The casing surrounding a pump impeller that collects the water discharge by the impeller is called a:
A straight ladder, when properly used should have the base ___ from the supporting wall.
1/4 of its working length
True or False
The main function of a lubricant is to keep moving materials seperate from each other.
A possible cause of electric motor failure is?
A water seal on a pump serves a dual purpose. It acts as a lubricant and it also:
Keeps gritty material from entering the packing box
The elevation of any pump above the source of supply should not exceed ___ ft.
Friction in a pipeline causes:
Loss of pressure
before repairing a pumps electrical circuit, which action should you take?
Disconnect the circuit breaker and lock out tag out
In a centrifugal pump, leakage is prevented by:
wear rings
The pressure against which a pump must operate is measured in terms of:
An air gap device is used to:
prevent cross connections
Why are check valves used in conjunction with centrifugal pumps?
To prevent water in the auction line from flowing back into the wetwell.
Valves should be closed slowly to prevent:
water hammer
If a centrifugal pump loses its prime after starting, what is the most probable cause?
air leaks into the pump through stuffing box
In electrical circuits a ___ is used to reduce voltage where needed.
Which of the following causes the greatest pipe friction loss?
Increasing the velocity of wastewater.
If the pump bearings on horizontal pumps are over lubricated, the most important effect is the extra lubricant:
May cause overheating and possible failure of the bearings.
If packing is not maintained properely:
Loss of suction will occur due to air entering the pump.
Information on preventive maintenance procedures, materials, and frequencies for plant structure should be taken from:
Manufaturers operation and maintenance manuals.
Instrumentation friction disks or clutch surfaces should be:
Kept free of oil
An electrical system for prevention of rust, corrosion, and pitting of steel and iron surfaces in contact with water is called ____ protection.
What seperates the impeller from the volute and prevents backflow in a centrifugal pump?
wear rings
E = I x R or Voltage = Amperage x Resistance is:
Ohm's Law
The ___ is the unit of electrical resistance; resistance to the flow of electrical current.
The rate at which heat is produced is the ___ that the load dissipates.
___ is the relationship in time between two waveforms of the same frequency.
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:
Inspect the alignment of the pump motor
During plant rounds, an operator notices a pump is spraying water from a packing gland. The operator should:
Tighten the packing gland until the spray is reduced to a small drip.
A pumps seal water pressure should be set at:
5 to 10 psi more than the pump operating discharge pressure
A treatment plant should have a valve exercise program in which all plant valves are exercised.
Once a year
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.
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.
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.
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.
A ___ is installed on pump discharge piping to prevent water from flowing back across a pump when it is off.
check valve
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
Lag pump clogged
Centrifugal pump parts include:
A positive displacement sludge pump should never be placed into operation
with the discharge valve closed
The total dynamic head against which a pump must operate:
Is the sum of the static head and the head due to friction loss.
The difference in water surface elevation between where the pump is pulling from and where it is discharging to is called:
static head
A device that causes the wastewater in a verticle riser pipe to rise to an outlet using compressed air is called an
air lift pump
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.
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.
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?
the lag pumps are clogged
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?
A malfunctioning level control is causing high wet well levels.
Pumps are often required to bring wastewater into treatment plant. What types of pumps are typically used to lift influent wastewater.
Daily maintenance procedures for a rectangular secondary clarifier include:
Inspecting the drive unit and the chain and flight system
Which of the following is a type of positive displacement pump:

a. axial
b. turbine
c. educator
d. gear
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?
static head
What is an air gap device used for?
Backflow prevention
How often should inactive valves be exercised?
Quarterly to annually minimum
When using a progressing cavity pump to pump sludge, in what condition must the pump intake be in order to insure safe operation?
What equipment is typically used to control positive displacement blowers?
Multi speed motors and variable frequency drives
A water filled mechanical pump seal not only helps to prevent leaks, but also:
acts as a lubricant for the pump shaft
If your facility cannot tolerate power loss even for short periods, then you need an emergency generator that can:
automatically switch over when power goes down
Besides throttling the inlet valve, what type of control is used for a centrifugal pump?
variable frequency drives
What type of pump is typically used to feed ferric chloride for solids handling purposes?
Metering pumps
What devices can be used as an emergency shut off for the drive unit of a circular clarifier?
shear pins
What is surging in a centrifugal blower?
When the blowers discharge pressure is less than the aeration systems backpressure
Motor starters and breakers are usually located:
In motor control centers (MCC)
What is the first step in starting a pneumatic air injector?
Allow compressors to build required pressure
The formation and collapse of gas pockets or bubbles on the blade of a centrifugal pump's impeller is known as what?
When planning to work on or near electrical equipment, be sure to always:
lock and tag out the equipment
What is your first course of action if you see a slow constant drip from a pump shaft packing seal?
make no adjustment
What does a gradual increase in the bearing temp of a centrifugal blower indicates?
there is a problem with the bearing or lubrication or connection
How often should the scraper arms and blades of a circular clarifier be inspected and replaced, if necessary?
What type of in situ maintenance is recommended for most flexible membrane diffusers?
air bumping
Which of the following indicates that the impeller of a centrifugal pump may be worn or damaged?
pump is not delivering the design flow
A ground fault interrupter on an electrical circuit system is used to:
disconnect power from the circuit if there is a faulty ground line
Which of the following causes leaking between the segment and body of a plug valve?
Overgreased assembly
Which of the following is a likely benefit of a planned maintenance program?
Extended equipment life
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?
Electrostatic precipitators
Why should standby generators be exercised regularly?
to test the system under actual conditions
What is an acceptable variation in input voltage for most electric motors?
+/- 10%
How often should the packing on a gate valve be replaced?
As required