California Wastewater Treatment Operator
Grade V Practice Exam Questions And
Correct Answers
.fill, T.empty & T.detention
Time (minutes) = Vol./Q
Volume
Surface area x Depth
LxLxL
ft3 x ft3 x ft3
LxWxD
Volume is more commonly expressed in gal & Mgal.
Foot pounds (ft∙lb) Are both units of what?
Work and energy; lifting from point ""A" to point "B" requires ft.lb of energy. Pumps do work
requiring energy. Work and energy are interrelated.
Pumping System (9 Factors)
,h/d of operation, $/kWh, PM, .EM, PB, .EP, PW, TDH, Q.
Left to Right: Divide
Right to Left: Multiply
What is power?
The time rate of doing work
How is power expressed?
Can be expressed in ft∙lb/min but is more commonly expressed in HP or kW.
Work, Energy, Power and Pumping (Conversion factors)
33,000 ft∙lb/min∙HP
.0746 kW/HP
What are the units for expressing power?
Power (P) is expressed in either horsepower (HP) or kilowatts (kW).
Are horsepower, kilowatts, and foot-pounds interchangeable units for power?
Horsepower (HP), kilowatts (kW), and foot-pounds (ft.lb) are interchangeable units for power.
,Motor or Meter Power (Pm)
Motor or meter power (Pm) = Input power to the motor. Expressed in either kW or HP, rarely is
it expressed as [ft.lb].
The meter records the connected power and the duration that the power is being consumed.
(Power x Time = Energy)
Input power and Output power
Input power is always greater than the output power.
PM > PB > PW
When calculating electrical cost
Motor power (Pm) is ALMOST always converted to kW then multiplied by the number of hours
connected over a billing period. (kW x h = kWh)
What does 'Break Power (Pb)' refer to?
Output power of the motor
Pb = Pm x .Em
What is the other name for Break Power (Pb)?
Input power to the pump
What does the nameplate reading 'HP' indicate?
, Break Power (Pb)
Water Power (Pw)
Output power of the pump. Power the pump delivers to the water.
Pw = Pb x .Ep
Water Power (Pw): Calculation
Q rate of the pump (no matter what the units are) x TDH (always in ft.)
(H suction + H discharge (H static)) + H friction. When H friction is not given assume TDH is
equal to H static)
Pw = Q x TDH x min.HP/33,000 ft.lb (0.746 kW/HP when kW is needed instead of HP).
Total Dynamic Head (TDH)
Head Static (H.static) & Head Friction (H.friction) = TDH
If Head Friction (H.friction) is not given, assume TDH is equal to the Head Static (H.static).
H.static
= H.suction + H.discharge
H. static in regards of H.suction (water level above the pump)
Can be either below the pump or above the pump.
Grade V Practice Exam Questions And
Correct Answers
.fill, T.empty & T.detention
Time (minutes) = Vol./Q
Volume
Surface area x Depth
LxLxL
ft3 x ft3 x ft3
LxWxD
Volume is more commonly expressed in gal & Mgal.
Foot pounds (ft∙lb) Are both units of what?
Work and energy; lifting from point ""A" to point "B" requires ft.lb of energy. Pumps do work
requiring energy. Work and energy are interrelated.
Pumping System (9 Factors)
,h/d of operation, $/kWh, PM, .EM, PB, .EP, PW, TDH, Q.
Left to Right: Divide
Right to Left: Multiply
What is power?
The time rate of doing work
How is power expressed?
Can be expressed in ft∙lb/min but is more commonly expressed in HP or kW.
Work, Energy, Power and Pumping (Conversion factors)
33,000 ft∙lb/min∙HP
.0746 kW/HP
What are the units for expressing power?
Power (P) is expressed in either horsepower (HP) or kilowatts (kW).
Are horsepower, kilowatts, and foot-pounds interchangeable units for power?
Horsepower (HP), kilowatts (kW), and foot-pounds (ft.lb) are interchangeable units for power.
,Motor or Meter Power (Pm)
Motor or meter power (Pm) = Input power to the motor. Expressed in either kW or HP, rarely is
it expressed as [ft.lb].
The meter records the connected power and the duration that the power is being consumed.
(Power x Time = Energy)
Input power and Output power
Input power is always greater than the output power.
PM > PB > PW
When calculating electrical cost
Motor power (Pm) is ALMOST always converted to kW then multiplied by the number of hours
connected over a billing period. (kW x h = kWh)
What does 'Break Power (Pb)' refer to?
Output power of the motor
Pb = Pm x .Em
What is the other name for Break Power (Pb)?
Input power to the pump
What does the nameplate reading 'HP' indicate?
, Break Power (Pb)
Water Power (Pw)
Output power of the pump. Power the pump delivers to the water.
Pw = Pb x .Ep
Water Power (Pw): Calculation
Q rate of the pump (no matter what the units are) x TDH (always in ft.)
(H suction + H discharge (H static)) + H friction. When H friction is not given assume TDH is
equal to H static)
Pw = Q x TDH x min.HP/33,000 ft.lb (0.746 kW/HP when kW is needed instead of HP).
Total Dynamic Head (TDH)
Head Static (H.static) & Head Friction (H.friction) = TDH
If Head Friction (H.friction) is not given, assume TDH is equal to the Head Static (H.static).
H.static
= H.suction + H.discharge
H. static in regards of H.suction (water level above the pump)
Can be either below the pump or above the pump.
