How to Operate Vacuum Pump: Maintenance and Troubleshoot

A vacuum pump having capacity range from 500 cubic meters per hour to 5400, which can attain maximum vacuum up to 670mm of Hg used widely in paper, sugar, and petrochemical industries. The operating procedure varies depending on the type they are driven but the concept is same for most of them. Water ring vacuum pump operation is somewhat easier to understand and it can be installed with less efforts, a vacuum pump is installed at front of the stream line which is used to create vacuum in a distillation column. As it works on the principle of creating negative pressure, high concentrated acids and liquids which are hazards are transported by creating vacuum in the respective vessel by the help of vacuum pump which is in contrast to centrifugal rotary pump(which create positive pressure ) It has a set up as

  • Vacuum pump
  • Base frame
  • Coupling set
  • Electric motor
  • Vacuum gauge
  • Automatic drain valve
  • Non return valve
  • Pet cock (Air vent cock)
  • Water on/off valve (Ball valve)
  • Water regulation valve (stop cock)
  • Safety valve 
  • Pressure gauge
  • These parts are standard for all vacuum pumps.
Start-Up of Vacuum Pump:



In this case of pump the rotation direction will be in clockwise when viewed from the motor driven end. A pump of normal execution the suction line is fitted with non return valve and silencer is connected on the discharge line.
  • Before starting the electric motor turn the shaft by hand to ensure the pumps free run. 
  • Start the motor and check the direction of rotation. Water supply should be given only when pump is started.
  • Now open the ball valve which water is passed in to the casing of the pump at least with a pressure of 1.5kg/cm2.
  • Pump starts to build up vacuum in its suction line which indicated by the pressure gauge, do not open suction valve immediately after starting the pump and if a rattling sound is observed slightly open the air vent cock on the discharge side to remove the air locked inside the casing. 
  • Fix the water supply flow rate which acts as a ring in the vacuum pump casing.
  • Open the suction valve slowly to prevent the sudden load on the pump and motor.
STOPPING:
  • Close the water supply line and ensure the no water flow into the casing
  • Close the suction valve 
  • Stop the motor
MAINTENANCE:
  • Grease to be filled in bearing housing twice in month if it runs 14 to 16 hours per day
  • Alignment of pump shaft and motor shaft be check once in a month this will increase the pump life
  • Remove the scaling formed by the supply water. Range of water hardness must be around 50-500ppm.
TROUBLESHOOT:
  • If pump jammed: fill the pump with diesel or kerosene and allow for 24 hr most cases the problem will be solved if not loosen the nuts of casing. Create a gap between the casing and the casing cover. Rotate the shaft with free hand which describes the formation of any scaling in the pump.
  • If sufficient vacuum is not developed: 
  • Discharge line chock.
  • Water supply blocked or no enough pressure.
  • Gland leak (can be found by soap test)
  • Automatic drain valve leak.
  • Rattling sound: open the air release cock which stops the noise.