The figure below represents curves for a pumping system. One would expect a system curve of this nature in the following systems.

If the system head is over estimated or if multiple margins are added to arrive at the pump total head, the pump performance will be sub-optimal. Which of the following statement is not true for such a system? 

When the required discharge of a pump is less than the normal discharge (valve fully open) and pump runs at a constant speed, throttling in the discharge line is sometimes adopted to reduce the flow. Throttling is an energy inefficient method of flow control but can be used with pumps using radial flow impellers. What is the main reason why throttling is not recommended for pumps with mixed flow or axial flow impellers:

A.  Excessive radial thrust load at part capacity
B. Danger of pump operating inthe unstable zone of H-Q characteristics
C. Recirculation & part flow cavitation
D.  Power curve rises towards the shut-off & throttling may overload the motor
E. All of the above

The figure represents two identical pumps working in parallel in a water supply system. Water level in the suction sump varies between high & low limits. Please identify the labels in the diagram & put a tick mark against there right match:

Air entrainment in the suction side of the pump can affect pump performance in diverse ways. Which of the following statements about air entrainment is not true for centrifugal pumps?

A.  Even with small amounts of air in the liquid the performance of the pump declines
B. Open impellers handle entrained air or gas better than closed impellers due to clearance between    the impeller & casing
C. Air enters the pump suction through vortices formed in the suction sump, release of dissolved gas in the liquid, air leakage through valve stem packing or air deliberately injected into the pump
D. Entrained air bubbles cushion the destructive effects of collapsing vapor bubbles when the pump is cavitating. Hence, air is sometimes injected deliberately, as a short term measure, to prevent cavitation damage
E. Entrained air reduces the NPSH required by the pump and therefore, improves the suction performance of the pump 

The following is mixed-up list of advantages of split case (SC) and end suction (ES) pumps. Each option contains some item nos. under the boxes, please select the right option that correctly segregates the advantages for both the pump types:

a) Easy inspection without disturbing suction & discharge piping and electric motor
b) Light weight & requires less floor space
c) More sensitive to orientation and geometry of elbows in front of the pump suction
d) Simpler maintenance, lower maintenance down time
e) Lower NPSH due to double suction impeller
f) Only one shaft seal
g) No chances of volute mismatchbetween upper and lower cases
h) No/ little axial thrust
i) High allowable nozzle loadsa- rigidity of the lower portion of the casing
j) Higher efficiency, power is nobt lost in balancing axial trhrust
k) Larger inter-changeability because most pumps conform to international dimension standards for this class of pumps
l) Lower first cost

You have a double volute axially split case pump 14"x16" in size used for cold well duty of 5000 Igpm (1362 m3/hr.) and 150 ft (45.7 m) at 980 rpm. NPSH required by the pump at 980 rpm is 3.3 m and power absorbed is 200 kW (pump eff. 85%). You want to run the pump at 1480 rpm for a different application and the pump manufacturer has confirmed that the design speed of this pump is 1500 rpm. Please estimate the performance of the pump at 1480 rpm.

Following are the typical cost items in a life cycle cost (LCC) analysis of a pumping system. Approximate % costs are presented as a separate list. Please try to match the cost items with your best estimate of percentage figures: