Centrifugal Pump Start Up Working Change over

Centrifugal Pump How Centrifugal pump works? Change over procedure. Interview Q&A | Study

Centrifugal Pump How Centrifugal pump works? Change over procedure. Interview Q&A | Study blog is contains Start up procedure of centrifugal pump, Working of centrifugal pump and change over of centrifugal pump.

Today in this blog we will study following topics

  • Startup of centrifugal pump
  • Working of centrifugal pump
  • Change over of Centrifugal Pump

This blog contains following questions which  probably asked in technical Interview.

  1. What should valves status at pump start up?
  2. Which parameters of to be observed after pump startup?
  3. How to lined up  of seal cooling and how much seal cooling fluid flow and pressure decided?

Startup of centrifugal pump

Whenever Centrifugal pump is going to start following points to be check

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Safety Check points
  1. No line under maintenance or open ended.
  2. Flange guards are available for each flange.
  3. Earthing of pump and lines are proper.
  4. Use PPEs - Safety helmet, goggles, hand gloves, shoes and others as per company guidelines.
  5. Availability of 
  • SOPs
  • MSDS of chemicals
  • Safety shower health
  • Escape route must clear
  • Antidotes of toxic chemicals,
  • Cleaning agents
  • First aid kit.
Pre startup points
  1. Pump and it's attachments are in working condition.
  2. Tank level is sufficient.
  3. Starting clearance DCS, Power plant and other if applicable 
  4. If pump operation is from DCS/PLC mode of communication is working.
  5. Check tools availability.

1. Valve positions

Before pump start up valves should be in following position is in open condition.
  1. Suction valve - Open
  2. Drain valve - Closed
  3. Vent Valve - Open
  4. Circulation valve - Closed 
  5. Discharge valve - Closed
  6. Seal cooling inlet valve - Open
  7. Seal cooling outlet valve - Open

Now wee will see start up Procedure

1. Before pump start up Priming of Pump to be done.

Priming procedure of Centrifugal Pump.
  1. Suction drain valve is closed.
  2. Open vent valve
  3. Start fluid [mostly water] filling in Priming pot which is provided for negative suctions.
  4. If Priming pot is not available fill suction line.
  5. Positive suction lines will be filled when vent valve is opened and suction valve is open.
  6. When liquid came at vent valve close priming fluid filling valve.
  7. Close vent valve.

2. Start Seal / Gland cooling valve.

  1. Open Seal cooling Inlet valve.
  2. Open seal cooling Outlet valve.
  3. Seal cooling out let pressure is 1.2 to 1.5 times of maximum pump discharge pressure or 2 kgf/cm^2 for high discharge pumps. Example - If pump discharge pressure is 4 kgf/cm^2 then Seal cooling pressure will be 5- 6 kgf/cm^2. This pressure setup will prevent liquid came out from casing.
  4. Seal cooling flow should be adjusted generally 100 - 600 liter per hour but it cal be adjusted by seal liquid outlet temperature.

3. Check Oil level in oil tube/bottle/glass.

4. Check rotor is free rotational. If rotor is not free then rotate it by wrench [Power must be stopped].

5. Check Pump VFD [Variable Frequency Drive] is zero or minimum.

6. Start Pump and Check rotating direction is correct or not Open Slight circulation valve.

7. Check discharge pressure is stable or not.

If pressure is not stable then it may be
A. Air is trapped inside casing. Open vent valve and release air.
B. There may be cavitation. Open suction valve properly / Strainer to be clean / Line may be jammed.

8. Observe - Noise, Vibration, Temperature, Ampere, Voltage,Oil or Pumping fluids Leakages.

9. Open Discharge valves slowly.

10. Increase VFD - Variable Frequency Drive till required discharge flow or pressure.

How Centrifugal pump works?

  • When Pump started liquid is arriving to Casing.
  • Impeller rotation create liquid vortex in outward direction of impeller.
  • This vortex create suction at impeller eye.
  • Impeller eye is near to Pump suction part and creates continuous suction.
  • Impeller rotation makes convert radial velocity into Discharge pressure.

Change over of Centrifugal Pump

Check more Centrifugal pump leanings Click here

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Read more about "Centrifugal Pumps" from Industrial Guide - Click here

Thanks for reading
Naitik Patel
Industrial Guide

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