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Wednesday, March 30, 2011

CHARACTERISTICS TEST ON CENTRIFUGAL PUMP


CHARACTERISTICS TEST ON CENTRIFUGAL PUMP



AIM :
            To study the performance characteristics of a centrifugal pump and to determine the characteristic with maximum efficiency.
             

APPARATUS REQUIRED :

1.      Centrifugal pump setup
2.      Meter scale
3.      Stop watch

FORMULAE     :

1.ACTUAL DISCHARGE:

                                    Q act  = A x y / t                                           (m3 / s)
                       
                        Where:

 

                              A = Area of the collecting tank (m2)
                              y  = 10 cm rise of water level in the collecting tank
                              t  = Time taken for 10 cm rise of water level in collecting tank.


    2. TOTAL HEAD:
H = Hd + Hs + Z
           
            Where:
                        Hd = Discharge head, meter
                        Hs = Suction head, meter
                        Z   = Datum head, meter
3.INPUT POWER:
                         I/P  = (3600 ´ N ´ 1000) / (E ´ T)      (watts)

               Where,
                                    N = Number of revolutions of energy meter disc
                                    E  = Energy meter constant                    (rev / Kw hr)   
                                   T  = time taken for ‘Nr’ revolutions        (seconds)

            4. OUTPUT POWER:

                              Po = ρ x g x Q x H / 1000            (watts)
                 
                    Where,
                                    ρ = Density of water                    (kg / m³)
                                   g  = Acceleration due to gravity   (m / s2)
                                   H = Total head of water                (m)
           
            5.EFFICIENCY:
                      
             ho = (Output power o/p / input power  I/p) ´ 100 %

Where,
              O/p = Output power kW

              I/ p = Input power   kW


DESCRIPTION:
            
PRIMING:

               The operation of filling water in the suction pipe casing and a portion delivery pipe for the removal of air before starting is called priming.
               After priming the impeller is rotated by a prime mover. The rotating vane gives a centrifugal head to the pump. When the pump attains a constant speed, the delivery valve is gradually opened. The water flows in a radially outward direction. Then, it leaves the vanes at the outer circumference with a high velocity and pressure. Now kinetic energy is gradually converted in to pressure energy. The high-pressure water is through the delivery pipe to the required height.

PROCEDURE:
1.      Prime the pump close the delivery valve and switch on the unit
2.      Open the delivery valve and maintain the required delivery head
3.      Note down the reading and note the corresponding suction head reading
4.      Close the drain valve and note down the time taken for 10 cm rise of water level in collecting tank
5.      Measure the area of collecting tank
6.      For different delivery tubes, repeat the experiment
7.      For every set reading note down the time taken for 5 revolutions of energy meter disc.

GRAPHS:

          1.  Actual discharge Vs Total head
2.  Actual discharge Vs Efficiency
3.  Actual discharge Vs Input power
4.  Actual discharge Vs Output power
            



RESULT:

                        Thus the performance characteristics of centrifugal pump was studied and the maximum efficiency was found to be _____________



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