EVT EVT Fire Pump Systems & Water Delivery 2 — Questions and Answers
Question 1: What is the function of the tank fill valve on a fire apparatus water system?
- Discharge water from tank during operations
- Refill the booster tank from the pump while operating (Correct answer)
- Control flow from the hydrant
- Regulate pressure to discharge lines
Correct answer: Refill the booster tank from the pump while operating
The tank fill valve routes water from the pump back into the booster tank to refill it while the pump is operating from an external supply.
Question 2: What type of impeller design is most commonly used in single-stage centrifugal fire pumps?
- Axial flow
- Mixed flow
- Radial flow (centrifugal) (Correct answer)
- Turbine
Correct answer: Radial flow (centrifugal)
Single-stage fire pumps most commonly use radial flow centrifugal impellers that accelerate water outward by centrifugal force to generate pressure.
Question 3: What causes water hammer in a fire apparatus discharge system and how should it be prevented?
- Rapid valve closure; prevent by closing valves slowly (Correct answer)
- Low system pressure; increase pump RPM
- Air in lines; bleed the system
- Worn pump impeller; replace impeller
Correct answer: Rapid valve closure; prevent by closing valves slowly
Water hammer is caused by rapid valve closure creating a pressure surge wave; it is prevented by closing valves slowly to allow gradual deceleration of flow.
Question 4: What is the purpose of a fire pump pressure relief valve (pressure governor)?
- Increase pump pressure during operations
- Prevent excessive discharge pressure to protect hose lines and personnel (Correct answer)
- Prime the pump before operations
- Measure total pump flow
Correct answer: Prevent excessive discharge pressure to protect hose lines and personnel
The pressure relief valve or pressure governor limits pump discharge pressure to prevent dangerous overpressure that could burst hose lines or injure personnel.
Question 5: What minimum static pressure should be maintained at the pump intake when pumping from a pressurized hydrant?
- 5 PSI
- 10 PSI
- 20 PSI (Correct answer)
- 50 PSI
Correct answer: 20 PSI
A minimum residual intake pressure of 20 PSI should be maintained while drafting from a hydrant to prevent cavitation and ensure adequate supply.
Question 6: What does foam system proportioning ensure in a Class A or Class B foam application system?
- Correct water temperature for foam generation
- Accurate ratio of foam concentrate mixed with water (Correct answer)
- Sufficient air entrainment in the foam stream
- Proper nozzle flow rate
Correct answer: Accurate ratio of foam concentrate mixed with water
Foam proportioning systems precisely meter the ratio of foam concentrate into the water stream to achieve the correct concentration for effective fire suppression.
EVT EVT Fire Pump Systems & Water Delivery 2
What is the function of the tank fill valve on a fire apparatus water system?