OIT OIT Pumping Systems and Hydraulics 1 — Questions and Answers
Question 1: What is the term for the total head a pump must overcome, including elevation, friction, and pressure differences?
- Static head
- Dynamic head
- Total dynamic head (TDH) (Correct answer)
- Velocity head
Correct answer: Total dynamic head (TDH)
Total dynamic head (TDH) is the total head a pump must overcome and includes static lift, friction losses, and pressure requirements.
Question 2: What type of pump is most commonly used in water and wastewater treatment facilities?
- Piston pump
- Centrifugal pump (Correct answer)
- Peristaltic pump
- Gear pump
Correct answer: Centrifugal pump
Centrifugal pumps are the most widely used pumps in water and wastewater treatment due to their simplicity, reliability, and efficiency.
Question 3: What does NPSH stand for in pump hydraulics?
- Net Positive Suction Head (Correct answer)
- Normal Pump System Head
- Net Pressure Suction Height
- Normal Positive Static Head
Correct answer: Net Positive Suction Head
NPSH (Net Positive Suction Head) is the pressure available at the pump inlet above the vapor pressure of the liquid, critical for preventing cavitation.
Question 4: What condition occurs when vapor bubbles form and collapse inside a pump due to low suction pressure?
- Water hammer
- Cavitation (Correct answer)
- Priming failure
- Air binding
Correct answer: Cavitation
Cavitation occurs when local pressure drops below the liquid's vapor pressure, forming bubbles that violently collapse and damage pump components.
Question 5: What is the purpose of a check valve installed on the discharge side of a pump?
- To regulate pump speed
- To prevent backflow when the pump stops (Correct answer)
- To reduce water hammer in suction piping
- To measure flow rate through the pump
Correct answer: To prevent backflow when the pump stops
A discharge check valve prevents water from flowing backward through the pump when it shuts down, protecting the pump and maintaining system pressure.
Question 6: What does a pump curve show?
- The relationship between pump speed and motor horsepower
- The relationship between flow rate and head for a specific pump (Correct answer)
- The temperature rise across a pump at various flows
- The efficiency of the pump motor at different voltages
Correct answer: The relationship between flow rate and head for a specific pump
A pump curve (or performance curve) shows the relationship between flow rate (GPM) and total head (feet) for a specific pump model.
OIT OIT Pumping Systems and Hydraulics 1
What is the term for the total head a pump must overcome, including elevation, friction, and pressure differences?