MILLWRIGHT REVISED MOCK EXAM 2025 QUESTIONS
WITH 100% CORRECT ANSWERS
Pump - A machine that moves fluids or semi-fluids through a system against gravity and other forces,
converting mechanical energy into fluid energy using suction or compression.
Pump Head - The pressure a pump must overcome to move liquid through a system, measured in psi,
kPa, or bars (1 bar = 100 kPa), and converted to a head measured in feet or meters.
Factors that affect pump head - Factors include static suction lift, pump centerline, vertical distances
from liquid supply to center line, surface of liquid in discharge tank, pressure to overcome friction in
the system, and velocity head.
Total Static Head - Includes static suction and discharge head.
Total Dynamic Head - Describes a pump's head in the industry, calculated by adding or subtracting
dynamic suction lift, dynamic discharge head, and frictional losses in pipes and fittings.
Vapor Binding - Inadequate pressure on pump's suction side can lead to vapor formation, blocking
liquid flow and causing the pump to be vapor-bound.
Cavitation - Occurs in a centrifugal pump when pressure drops, creating vapor bubbles that collapse
and erode the surface, leading to vibration, noise, and impeller imbalance.
Net Positive Suction Head (NPSH) - The suction pressure must exceed the liquid's vapor pressure to
prevent cavitation.
Pump Capacity - Determined by the volume of liquid delivered per unit of time, such as US gallons
per minute (USgpm) or liters per minute (L/min).
Volute Pumps - Have a rotating impeller that discharges fluid into a spiral-shaped volute cavity,
converting velocity head into pressure.
Diffuser Pumps - Have stationary, curved vanes that create multiple volutes, redirecting liquid flow
outward towards the discharge nozzle.
,Mixed Flow Pumps - Combine radial and axial flow characteristics, developing discharge head with
centrifugal force and vanes lifting action, used for low-head, high-capacity applications.
Multi Staging - Involves connecting several impellers in series in centrifugal pumps to achieve higher
discharge pressures than those achieved by a single impeller.
Peripheral Pumps - Have the liquid entering at the periphery of the impeller, energizing it and
discharging it out again at its periphery.
Split Casings - Axially split casings are split along the axis of the shaft, with suction and discharge
nozzles usually in the lower half for easy inspection.
Barrel Casings - Eliminate the need for tight joints in split casings in high-pressure centrifugal pumps,
maintaining pressure without axial joints.
Pump Casing Materials - Depends on the liquid that will be pumped.
Pump casing materials - The materials used in pump casings depend on the liquid that will be
pumped.
Water, gasoline and other chemically neutral liquids - Cast iron casings with bronze fittings.
Acids - Bronze, stainless steel, special stainless steel (e.g., Hastelloy), monel, nickel, rubber, ceramic.
Alkalis - Cast iron, Ni-resist, stainless steel, special stainless steel (e.g., Hastelloy).
Slurries (chemically neutral) - Rubber linings (with temperature limitations), cast iron, Ni-resist, hard
iron, chrome steel, Ni-hard, manganese steel.
Impeller design - Involves curved blades to efficiently move fluid.
Open impellers - Have vanes with partial shrouds.
, Closed impellers - Have full shrouds on one or both sides and produce axial thrust.
Screw-style impellers - Used in paper-stock pumps.
Axial-flow impellers - Used in their respective pumps.
Open mixed-flow impellers - Used in their respective pumps.
Wear rings and plates - Essential components of pumps to maintain maximum pressure and prevent
liquid from moving back to the suction side.
Wear rings - Replaceable components available in various configurations like flat, stepped, or
labyrinth.
Methods to hold wear rings - Shrink fit, spigot, groove, pins, or screw threads.
Materials for wear rings - Made of materials like bronze or cast iron to prevent erosion.
Hydraulic balancing devices - Used to counteract axial hydraulic thrust in impellers caused by
different pressures.
Balancing holes - Allow excess pressure to pass through to the suction side in single-stage pumps.
Balancing drum - Used in multi-stage pumps to return excess pressure to the suction side.
Balancing disk - Works similarly to balancing drums with excess pressure passing through axial
clearance.
Pump mounting - Pump and drive source must sit on a secure base, made of cast iron or fabricated
steel, bolted to a foundation to absorb vibration.
Base-mounted pumps - Feature mounting lugs on the pump casing's bottom, which can lead to
misalignment if there is a change in temperature during operation.
WITH 100% CORRECT ANSWERS
Pump - A machine that moves fluids or semi-fluids through a system against gravity and other forces,
converting mechanical energy into fluid energy using suction or compression.
Pump Head - The pressure a pump must overcome to move liquid through a system, measured in psi,
kPa, or bars (1 bar = 100 kPa), and converted to a head measured in feet or meters.
Factors that affect pump head - Factors include static suction lift, pump centerline, vertical distances
from liquid supply to center line, surface of liquid in discharge tank, pressure to overcome friction in
the system, and velocity head.
Total Static Head - Includes static suction and discharge head.
Total Dynamic Head - Describes a pump's head in the industry, calculated by adding or subtracting
dynamic suction lift, dynamic discharge head, and frictional losses in pipes and fittings.
Vapor Binding - Inadequate pressure on pump's suction side can lead to vapor formation, blocking
liquid flow and causing the pump to be vapor-bound.
Cavitation - Occurs in a centrifugal pump when pressure drops, creating vapor bubbles that collapse
and erode the surface, leading to vibration, noise, and impeller imbalance.
Net Positive Suction Head (NPSH) - The suction pressure must exceed the liquid's vapor pressure to
prevent cavitation.
Pump Capacity - Determined by the volume of liquid delivered per unit of time, such as US gallons
per minute (USgpm) or liters per minute (L/min).
Volute Pumps - Have a rotating impeller that discharges fluid into a spiral-shaped volute cavity,
converting velocity head into pressure.
Diffuser Pumps - Have stationary, curved vanes that create multiple volutes, redirecting liquid flow
outward towards the discharge nozzle.
,Mixed Flow Pumps - Combine radial and axial flow characteristics, developing discharge head with
centrifugal force and vanes lifting action, used for low-head, high-capacity applications.
Multi Staging - Involves connecting several impellers in series in centrifugal pumps to achieve higher
discharge pressures than those achieved by a single impeller.
Peripheral Pumps - Have the liquid entering at the periphery of the impeller, energizing it and
discharging it out again at its periphery.
Split Casings - Axially split casings are split along the axis of the shaft, with suction and discharge
nozzles usually in the lower half for easy inspection.
Barrel Casings - Eliminate the need for tight joints in split casings in high-pressure centrifugal pumps,
maintaining pressure without axial joints.
Pump Casing Materials - Depends on the liquid that will be pumped.
Pump casing materials - The materials used in pump casings depend on the liquid that will be
pumped.
Water, gasoline and other chemically neutral liquids - Cast iron casings with bronze fittings.
Acids - Bronze, stainless steel, special stainless steel (e.g., Hastelloy), monel, nickel, rubber, ceramic.
Alkalis - Cast iron, Ni-resist, stainless steel, special stainless steel (e.g., Hastelloy).
Slurries (chemically neutral) - Rubber linings (with temperature limitations), cast iron, Ni-resist, hard
iron, chrome steel, Ni-hard, manganese steel.
Impeller design - Involves curved blades to efficiently move fluid.
Open impellers - Have vanes with partial shrouds.
, Closed impellers - Have full shrouds on one or both sides and produce axial thrust.
Screw-style impellers - Used in paper-stock pumps.
Axial-flow impellers - Used in their respective pumps.
Open mixed-flow impellers - Used in their respective pumps.
Wear rings and plates - Essential components of pumps to maintain maximum pressure and prevent
liquid from moving back to the suction side.
Wear rings - Replaceable components available in various configurations like flat, stepped, or
labyrinth.
Methods to hold wear rings - Shrink fit, spigot, groove, pins, or screw threads.
Materials for wear rings - Made of materials like bronze or cast iron to prevent erosion.
Hydraulic balancing devices - Used to counteract axial hydraulic thrust in impellers caused by
different pressures.
Balancing holes - Allow excess pressure to pass through to the suction side in single-stage pumps.
Balancing drum - Used in multi-stage pumps to return excess pressure to the suction side.
Balancing disk - Works similarly to balancing drums with excess pressure passing through axial
clearance.
Pump mounting - Pump and drive source must sit on a secure base, made of cast iron or fabricated
steel, bolted to a foundation to absorb vibration.
Base-mounted pumps - Feature mounting lugs on the pump casing's bottom, which can lead to
misalignment if there is a change in temperature during operation.
