Performance Test On Reciprocating Pump



The purpose of this experiment is to study the constructional details and performance parameters of Reciprocating Pump.


The reciprocating pump is a positive displacement pump, i.e., it operates on the principle of actual displacement or pushing of liquid by a piston or plunger that executes a reciprocating motion in a closely fitted cylinder. The liquid is alternately

  • Drawn from the sump and filled into suction side of the cylinder
  • Led to the discharge side of the cylinder and emptied to the delivery pipe.


  Fig.1 – Principal of Reciprocating Pump

 The piston or plunger gets its reciprocating motion (moves backward & Forward) by means of the crank and connecting rod mechanism. In a double acting reciprocating pump suction and delivery strokes occurs simultaneously. A pump gives comparatively a more uniform discharge than the single acting pump, because of the continuity of suction and delivery strokes


Reciprocating Pump Operates on the Principle of pushing of liquid by a Piston that Executes a Reciprocating Motion in close fitting cylinder

Related image


  • PISTON OR PLUNGER: A Piston or Plunger that reciprocate in closely fitted cylinder
  • CRANKANDCONNECTING ROD: Crank and Connecting rod mechanism operated by a power source .Power source gives rotary motion to the crank. With the Help of Connecting Rod we translate Reciprocating Motion to Piston in the Cylinder.
  • SUCTION PIPE: One end of suction pipe remains deep in the liquid and other end attached to the inlet of the cylinder.
  • DELIVERY PIPE: One end of Delivery pipe attached with delivery part and other end at discharge point.
  • SUCTION AND DELIVERY VALUE: Suction and Delivery values are provided at the suction end and delivery end respectively.This values are non-return values.


The experimental setup consists of a double acting reciprocating pump on whose discharge side a pressure gauge is fitted for measurement of the delivery head. A digital wattmeter may be connected to the motor of the pump as the motor is directly connected to the pump. A collecting tank is used to find the actual discharge through the pump.



  1. Note down the area of collecting tank.
  2. Fill the reciprocating pump with the oil up to the level marked on the pointer.
  3. Priming the pump before starting. Priming means taking the air present in the suction and pressure pipes.
  4. Before starting ensure that the pump is free to rotate.
  5. Flow regulating valve was adjusted to give the maximum possible discharge.
  6. Conditions were allowed to steady before the rate of discharge Q, discharge head & load on the motor were recorded.
  7. The flow rate is reduced in stages and the above procedure is repeated.


Let Discharge pressure = P m

Head = H m

Flow rate = Q m3/s

Input power = P watt

Water power (Po) = (ρgHQ) Watt

Efficiency (η) = (P/Po) x 100



Efficiency of Motor =

Area of collecting tank A =




        Discharge     Management



H (m)



Po (W)



Pi (W)


(h ) %


h1 (cm)


h2 (cm)




Q (m3/s)



1. Operate all the controls gently

2. Never allow to rise the discharge pressure above 4 kg/cm2

3. Always use clean water for experiment

4.Before starting the pump ensure that discharge valve is opened fully






  1. What is reciprocating pump? Describe the principal and working of reciprocating pump with neat sketch? Discuss the reason in detail.
  2. What is an air vessel? Explain with a neat sketch the working of air vessel in reciprocating pump.
  3. Give expression for discharge, work done power and slip of reciprocating pump.
  4. Compare the reciprocating pump with centrifugal pump. Draw theoretical indicator diagram of reciprocating pump.
  5. Difference between single acting and double – acting reciprocating pump?
  6. The cylinder bore diameter of single acting cylinder pump is 150 mm and its stroke is 300 mm. the pump runs at 50 rpm and lifts water through a height of 25 m. the delivery pipe is 22 m long and 100 mm in diameter. Find the theoretical discharge and theoretical power required to run the pump. If the actual discharge is 4.2 lit/sec. find the % slip and acceleration head at the beginning and middle of delivery stroke.
  7. The length and diameter of suction pipe of single acting reciprocating pump are 5m and 10m respectively the pump has plunger of diameter a 5 cm and stroke length 35 cm. the center of the pump is 3 m above the water surface in the pump. The atmosphere pressure head is running at 35rpm determine.
  8. Pressure head due to acceleration at the beginning of the suction stroke.
  9. Maximum pressure head due to acceleration.
  10. Pressure head in the cylinder at the beginning and at the end of the stroke.

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