EPRI EXAM 3 QUESTIONS WITH CORRECT
ANSWERS!!
What are positive displacement pumps and how do they operate?
Positive displacement pumps involve rotary or reciprocating motion, transferring a specific
quantity of fluid per input shaft revolution or plunger stroke, with flow control achieved by
changing speed, stroke length, or using a bypass valve. Found in make-up flow, chemical
and volume control and hydrostatic pressure tests
What is the operational characteristic of positive displacement pumps?
Positive displacement pumps produce the same flow at any given speed regardless of
discharge pressure, making them known as constant flow machines.
What are the risks of operating positive displacement pumps with blocked discharge?
Operating positive displacement pumps with a blocked or restricted discharge is dangerous
and can lead to equipment failure.
What are the types of reciprocating pumps and their applications?
Reciprocating pumps, including piston, plunger, and diaphragm types, are most useful in
high pressure, low flow environments due to their high head capacity.
What is the difference between single acting and double acting reciprocating pumps?
Single acting pumps discharge liquid only on the forward stroke, while double acting pumps
discharge liquid on both the forward and return strokes.
What is the significance of piping in reciprocating pumps?
Piping is crucial in reciprocating pumps as acceleration head and friction loss must
be considered; dampeners or accumulators may be used to mitigate pulsating flow.
What are rotary pumps and their operational principles?
Rotary pumps are positive displacement pumps that consist of chambers containing gears, cams,
screws, or vanes, operated by the relative rotation of the drive shaft or casing.
, How do gear rotary pumps function?
Gear rotary pumps operate by carrying fluid between gear teeth, displacing it when the gears
mesh, providing continuous sealing through the surface of the rotor. Used in hydraulic and
lubricating systems.
What is the operation of screw rotary pumps?
Screw rotary pumps carry fluid in the space between screw threads and displace it axially as they
mesh, commonly used for oil and viscous fluids. Debris causes wear and reduces efficiency.
What is the function of vane rotary pumps?
Vane rotary pumps use vanes that cooperate with a cam to draw fluid into and force it from a
chamber, suitable for hydraulic oil, lubricating oil, solvents, and abrasive particle fluids. Allows
vanes to extend and draw fluid from suction side.
What is the role of flexible member pumps?
Flexible member pumps rely on the elasticity of a flexible member, such as a tube or liner,
for fluid pumping and sealing, used in various chemical applications.
What are the main components of a centrifugal pump's stationary element?
Casing, baseplate, stuffing boxes, and bearings, which provide support and enclosure for
the rotating element.
What is the function of the casing in a centrifugal pump?
It provides suction and discharge nozzles and directs the flow of liquid into and away from the
impeller.
What does the rotating element of a centrifugal pump consist of?
A shaft on which one or more impellers are mounted, generating flow of liquid and
required head.
Describe the Overhung Impeller Type of centrifugal pump.
Impellers are mounted on the end of the shaft, which is cantilevered from its bearing support.
ANSWERS!!
What are positive displacement pumps and how do they operate?
Positive displacement pumps involve rotary or reciprocating motion, transferring a specific
quantity of fluid per input shaft revolution or plunger stroke, with flow control achieved by
changing speed, stroke length, or using a bypass valve. Found in make-up flow, chemical
and volume control and hydrostatic pressure tests
What is the operational characteristic of positive displacement pumps?
Positive displacement pumps produce the same flow at any given speed regardless of
discharge pressure, making them known as constant flow machines.
What are the risks of operating positive displacement pumps with blocked discharge?
Operating positive displacement pumps with a blocked or restricted discharge is dangerous
and can lead to equipment failure.
What are the types of reciprocating pumps and their applications?
Reciprocating pumps, including piston, plunger, and diaphragm types, are most useful in
high pressure, low flow environments due to their high head capacity.
What is the difference between single acting and double acting reciprocating pumps?
Single acting pumps discharge liquid only on the forward stroke, while double acting pumps
discharge liquid on both the forward and return strokes.
What is the significance of piping in reciprocating pumps?
Piping is crucial in reciprocating pumps as acceleration head and friction loss must
be considered; dampeners or accumulators may be used to mitigate pulsating flow.
What are rotary pumps and their operational principles?
Rotary pumps are positive displacement pumps that consist of chambers containing gears, cams,
screws, or vanes, operated by the relative rotation of the drive shaft or casing.
, How do gear rotary pumps function?
Gear rotary pumps operate by carrying fluid between gear teeth, displacing it when the gears
mesh, providing continuous sealing through the surface of the rotor. Used in hydraulic and
lubricating systems.
What is the operation of screw rotary pumps?
Screw rotary pumps carry fluid in the space between screw threads and displace it axially as they
mesh, commonly used for oil and viscous fluids. Debris causes wear and reduces efficiency.
What is the function of vane rotary pumps?
Vane rotary pumps use vanes that cooperate with a cam to draw fluid into and force it from a
chamber, suitable for hydraulic oil, lubricating oil, solvents, and abrasive particle fluids. Allows
vanes to extend and draw fluid from suction side.
What is the role of flexible member pumps?
Flexible member pumps rely on the elasticity of a flexible member, such as a tube or liner,
for fluid pumping and sealing, used in various chemical applications.
What are the main components of a centrifugal pump's stationary element?
Casing, baseplate, stuffing boxes, and bearings, which provide support and enclosure for
the rotating element.
What is the function of the casing in a centrifugal pump?
It provides suction and discharge nozzles and directs the flow of liquid into and away from the
impeller.
What does the rotating element of a centrifugal pump consist of?
A shaft on which one or more impellers are mounted, generating flow of liquid and
required head.
Describe the Overhung Impeller Type of centrifugal pump.
Impellers are mounted on the end of the shaft, which is cantilevered from its bearing support.
