Pump Systems
Pumps are mechanical devices that add energy to a fluid, increasing its pressure and velocity. The total dynamic head (TDH) is the total head the pump must overcome: TDH = h_s + h_d + h_f + h_m. The system curve relates the required head to the flow rate. The pump characteristic curve shows the head the pump can deliver at various flow rates. The operating point is where the pump curve intersects the system curve. Net Positive Suction Head (NPSH) must be checked to prevent cavitation.
Knowledge Check
1.A pump delivers water at 0.05 m³/s against a total head of 30 m. What is the hydraulic power required? (γ = 9.81 kN/m³)
2.What is cavitation in a pump?
3.The term NPSH stands for:
4.A pump system has a static suction lift of 3 m, friction losses of 1.5 m, and a velocity head of 0.5 m. What is the suction head?
5.In a pump system curve, as flow rate increases, the required head typically:
6.What is the purpose of using multiple pumps in parallel?
7.A pump has a power input of 25 kW and delivers 20 kW of hydraulic power. What is the efficiency?
8.The operating point of a pump is determined by:
9.A pump has a suction pressure of 0.2 MPa (gauge) and the fluid has a vapor pressure of 0.01 MPa (absolute). The atmospheric pressure is 0.1 MPa. What is the NPSH? (γ = 9.81 kN/m³)
10.What is the recommended safety margin for NPSH in pump design?