Which of the following statements regarding the operating principles and characteristics of agricultural pumps are correct?
Options:
(A) Centrifugal pumps develop pressure head primarily by converting kinetic energy imparted by a rotating impeller into static pressure.
(B) Axial flow (propeller) pumps are suited for low-head (under $5\text{ m}$) high-discharge applications such as drainage lift pumping.
(C) Centrifugal pumps operate with minimum brake horsepower requirement at shut-off (zero discharge) conditions.
(D) Reciprocating pumps are positive displacement machines and are inherently self-priming.
Answer Key:
A, B, C, D
Step-by-Step Solution & Explanation
• Centrifugal pumps accelerate fluid radially, converting kinetic velocity into pressure in the volute casing (A is correct).
• Axial flow pumps produce flow along the shaft axis, ideal for large volumes against small heads (B is correct).
• Standard backward-curved radial centrifugal pumps have their minimum power draw at zero discharge (shut-off head) (C is correct).
• Positive displacement piston/plunger pumps create positive volumetric displacement and displace air, making them self-priming (D is correct).