Examination Practice Questions And

Coast Guard QMED Pumpman/Machinist Examination Practice Questions And Correct Answers (Verified Answers) Plus Rationales 2026 Q&A | Instant Download Pdf

• What is the primary purpose of a centrifugal pump in shipboard

systems?

• To increase fluid pressure by positive displacement
• To store fluids for later use
• Increase fluid velocity and convert it to pressure
• To separate contaminants from liquids

Rationale: Centrifugal pumps impart kinetic energy to the fluid,

which is then converted to pressure energy in the pump casing.

• What type of pump is commonly used for pumping viscous liquids

aboard ships?

• Centrifugal pump 1 / 4

• Positive displacement pump
• Jet pump
• Axial flow pump

Rationale: Positive displacement pumps handle viscous liquids

efficiently because they move a fixed volume per cycle regardless of viscosity.

• Which of the following is a key function of a Machinist’s Mate aboard

a ship?

• Navigating the ship
• Operating and maintaining propulsion and auxiliary machinery
• Handling cargo
• Managing communications

Rationale: Machinist’s Mates are responsible for the operation and

maintenance of engines, pumps, and related machinery.

• What is the typical cause of cavitation in a pump?
• Overheating of the pump casing
• Vapor bubbles forming due to low suction pressure
• Over-lubrication of bearings
• Excessive motor speed

Rationale: Cavitation occurs when the pressure drops below the

liquid’s vapor pressure, forming bubbles that collapse and damage impellers. 2 / 4

• What does NPSH stand for in pump terminology?
• Net Pressure System Head
• Net Positive Suction Head
• Nominal Pump System Height
• Normalized Pressure Suction Handle

Rationale: NPSH measures the pressure available at the pump

suction to prevent cavitation.

• Which type of pump is most suitable for transferring fuel oil on a ship?
• Gear pump
• Centrifugal pump
• Diaphragm pump
• Centrifugal or rotary gear pump depending on viscosity

Rationale: Fuel oil may require a centrifugal pump for low viscosity

or a gear pump for high viscosity.

• What is the primary function of a mechanical seal in a pump?
• Increase pump output
• Filter debris from the fluid
• Lubricate bearings
• Prevent leakage along the shaft

Rationale: Mechanical seals prevent fluid from leaking where the

pump shaft exits the casing.

• Which type of coupling allows for misalignment between the motor

and pump shafts? 3 / 4

• Rigid coupling
• Flexible coupling
• Gear coupling
• Sleeve coupling

Rationale: Flexible couplings accommodate angular and parallel

misalignment, reducing stress on machinery.

• What is the primary purpose of a strainer in a pumping system?
• Increase pressure
• Remove solid particles from the liquid
• Heat the fluid
• Convert velocity to pressure

Rationale: Strainers prevent debris from entering pumps and causing

damage.

• Which gauge would be most appropriate for measuring boiler

water pressure?

• Thermocouple
• Manometer
• Flow meter
• Bourdon tube pressure gauge

Rationale: Bourdon tube gauges are commonly used to measure

pressure in steam and water systems.

• What type of maintenance is performed before equipment

failure occurs?

• / 4