Millwright Level 3 - Pumps Exam Questions Fully Solved Latest Update 2025
Pump - Answers 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 - Answers 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 - Answers 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 - Answers Includes static suction and discharge head.
Total Dynamic Head - Answers 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 - Answers Inadequate pressure on pump's suction side can lead to vapor formation,
blocking liquid flow and causing the pump to be vapor-bound.
Cavitation - Answers 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) - Answers The suction pressure must exceed the liquid's vapor
pressure to prevent cavitation.
Pump Capacity - Answers 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 - Answers Have a rotating impeller that discharges fluid into a spiral-shaped volute cavity,
converting velocity head into pressure.
Diffuser Pumps - Answers Have stationary, curved vanes that create multiple volutes, redirecting liquid
flow outward towards the discharge nozzle.
Mixed Flow Pumps - Answers 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 - Answers Involves connecting several impellers in series in centrifugal pumps to achieve
higher discharge pressures than those achieved by a single impeller.
Peripheral Pumps - Answers Have the liquid entering at the periphery of the impeller, energizing it and
discharging it out again at its periphery.
Split Casings - Answers 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 - Answers Eliminate the need for tight joints in split casings in high-pressure centrifugal
pumps, maintaining pressure without axial joints.
Pump Casing Materials - Answers Depends on the liquid that will be pumped.
Pump casing materials - Answers The materials used in pump casings depend on the liquid that will be
pumped.
Water, gasoline and other chemically neutral liquids - Answers Cast iron casings with bronze fittings.
Acids - Answers Bronze, stainless steel, special stainless steel (e.g., Hastelloy), monel, nickel, rubber,
ceramic.
Alkalis - Answers Cast iron, Ni-resist, stainless steel, special stainless steel (e.g., Hastelloy).
Slurries (chemically neutral) - Answers Rubber linings (with temperature limitations), cast iron, Ni-resist,
hard iron, chrome steel, Ni-hard, manganese steel.
Impeller design - Answers Involves curved blades to efficiently move fluid.
Open impellers - Answers Have vanes with partial shrouds.
Closed impellers - Answers Have full shrouds on one or both sides and produce axial thrust.
Screw-style impellers - Answers Used in paper-stock pumps.
Axial-flow impellers - Answers Used in their respective pumps.
Open mixed-flow impellers - Answers Used in their respective pumps.
Wear rings and plates - Answers Essential components of pumps to maintain maximum pressure and
prevent liquid from moving back to the suction side.
Wear rings - Answers Replaceable components available in various configurations like flat, stepped, or
labyrinth.
Methods to hold wear rings - Answers Shrink fit, spigot, groove, pins, or screw threads.
Materials for wear rings - Answers Made of materials like bronze or cast iron to prevent erosion.
Hydraulic balancing devices - Answers Used to counteract axial hydraulic thrust in impellers caused by
different pressures.
Balancing holes - Answers Allow excess pressure to pass through to the suction side in single-stage
pumps.
Balancing drum - Answers Used in multi-stage pumps to return excess pressure to the suction side.
Pump - Answers 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 - Answers 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 - Answers 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 - Answers Includes static suction and discharge head.
Total Dynamic Head - Answers 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 - Answers Inadequate pressure on pump's suction side can lead to vapor formation,
blocking liquid flow and causing the pump to be vapor-bound.
Cavitation - Answers 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) - Answers The suction pressure must exceed the liquid's vapor
pressure to prevent cavitation.
Pump Capacity - Answers 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 - Answers Have a rotating impeller that discharges fluid into a spiral-shaped volute cavity,
converting velocity head into pressure.
Diffuser Pumps - Answers Have stationary, curved vanes that create multiple volutes, redirecting liquid
flow outward towards the discharge nozzle.
Mixed Flow Pumps - Answers 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 - Answers Involves connecting several impellers in series in centrifugal pumps to achieve
higher discharge pressures than those achieved by a single impeller.
Peripheral Pumps - Answers Have the liquid entering at the periphery of the impeller, energizing it and
discharging it out again at its periphery.
Split Casings - Answers 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 - Answers Eliminate the need for tight joints in split casings in high-pressure centrifugal
pumps, maintaining pressure without axial joints.
Pump Casing Materials - Answers Depends on the liquid that will be pumped.
Pump casing materials - Answers The materials used in pump casings depend on the liquid that will be
pumped.
Water, gasoline and other chemically neutral liquids - Answers Cast iron casings with bronze fittings.
Acids - Answers Bronze, stainless steel, special stainless steel (e.g., Hastelloy), monel, nickel, rubber,
ceramic.
Alkalis - Answers Cast iron, Ni-resist, stainless steel, special stainless steel (e.g., Hastelloy).
Slurries (chemically neutral) - Answers Rubber linings (with temperature limitations), cast iron, Ni-resist,
hard iron, chrome steel, Ni-hard, manganese steel.
Impeller design - Answers Involves curved blades to efficiently move fluid.
Open impellers - Answers Have vanes with partial shrouds.
Closed impellers - Answers Have full shrouds on one or both sides and produce axial thrust.
Screw-style impellers - Answers Used in paper-stock pumps.
Axial-flow impellers - Answers Used in their respective pumps.
Open mixed-flow impellers - Answers Used in their respective pumps.
Wear rings and plates - Answers Essential components of pumps to maintain maximum pressure and
prevent liquid from moving back to the suction side.
Wear rings - Answers Replaceable components available in various configurations like flat, stepped, or
labyrinth.
Methods to hold wear rings - Answers Shrink fit, spigot, groove, pins, or screw threads.
Materials for wear rings - Answers Made of materials like bronze or cast iron to prevent erosion.
Hydraulic balancing devices - Answers Used to counteract axial hydraulic thrust in impellers caused by
different pressures.
Balancing holes - Answers Allow excess pressure to pass through to the suction side in single-stage
pumps.
Balancing drum - Answers Used in multi-stage pumps to return excess pressure to the suction side.
