Process Cooling Technical Tips

April 09, 2013 - "Industry Insight"

The first step is narrowing down the possibilities of “what does not working” mean? We need to establish that the “pump” is working correctly according to its pump curve, and then we can ask the question: are there problems with the process overheating, low discharge pressure, or unbalanced flow? The steps below will help determine if the centrifugal pump is operating as it is supposed to.

To “Test” the Pump

  1. A discharge gauge is needed to measure pressure. Determine if the pressure gauge is functioning properly.
  2. Start the pump to be tested (for a variable speed controlled pump, manually set the rpm at 100 percent).
  3. Once the pump is running, slowly close the discharge valve until the valve is fully closed and the pump is “dead headed” at 0 gpm flow.
  4. Maintain the closed position only long enough for a consistent reading and note the pressure. The “dead head” position should be maintained only for a few seconds to not damage the pump.
  5. Slowly open the discharge valve and set it for the design pressure.
  6. Using the pump curve at the appropriate impeller sixe, determine the discharge pressure at 0 gpm flow rate “dead head” position. See example below.
  7. The pump curve “dead head” discharge pressure should be within a few psi of the pressure reading in step 4. If this is the case, the pump is operating properly.
  8. If the two pressures readings are different, more than a few psi, it may be from improper rotation, debris in the pump’s impeller, a damaged impeller, corrosion or cavitation.

 

Chillers

By now you will know if the pump is ok or not.

 

For more information on your cooling system operating costs or the operating costs for any new project, we can provide you with an operating cost evaluation using your utility and load profile at no cost. Please visit the Thermal Care, Inc Website for further information.

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