Reciprocating pump; Slip of a pump ; Separation

• Reciprocating pump: if the mechanical energy is converted into hydraulic energy(or pressure energy) by sucking the liquid into a cylinder in which a piston is reciprocating (moving backwards and forwards), which exerts the thrust on the liquid and increases its hydraulic energy(pressure energy), the pump is known as reciprocating pump.
  Main parts of reciprocating pump:
  1. A cylinder with a piston, piston rod, connecting rod and a crank,
  2. Suction pipe, 3. Delivery pipe, 4. Suction valve and delivery valve.
  Slip of reciprocating pump:
  Slip of a pump is defined as the difference between the theoretical discharge and actual discharge of the pump. The actual discharge of a pump is less than the theoretical discharge due to leakage.
  Mathematically, slip= Qth- Qact
  Percentage of slip= (Qth- Qact) *100% / Qth
  = (1-Cd)*100% where Cd is Co-efficient of discharge.
•  Negative slip of reciprocating pump: Slip is equal to the difference of theoretical discharge and actual discharge of the pump. If actual discharge is more than the theoretical discharge, the slip of the pump will become –ve. In that case, the slip of the pump is known as negative slip.
  Negative slip occurs when delivery pipe is short, suction pipe is long and pump is running at high speed.
  Separation: if cylinder pressure is less than the vapor pressure of liquid then the dissolved gases liberated from the liquid and cavitation takes place. As a result continuous flow of liquid does not exist and it is called separation