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  1. #1
    Join Date
    Jun 2010
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    13

    running two pumps

    If you have two pumps in a condenser water loop, and one pump (they are identical) is operating at say 50 amps, while the other is at say 40 amps, (They are both receiving a command of 100%) does that mean that the pump operating at 40 amps is doing nothing?? in this scenario water comes from the cooling tower in a 12" pipe to mechanical room where it tee's into two pipes, hits the pumps and then turns back into one pipe again.

    thanks

  2. #2
    Chris_Worthington's Avatar
    Chris_Worthington is offline Controls Committee & Global Moderator
    Join Date
    Jul 2007
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    Mount Airy, MD
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    7,281
    Strainers? Diff Impellers? Misalignment? Etc...

    Got some more info?

  3. #3
    Join Date
    Jun 2006
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    New Jersey
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    4,330
    And you are verifying that with an amperage meter? Not going by the VFD display.

  4. #4
    Join Date
    Sep 2007
    Location
    Under the sea
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    232
    With pumps it's all about head pressure. If the discharge pressure is greater on one of the pumps it's possible the check valve on the other pump won't open. Check the discharge pressures and discharge valve positions. If the differential pressures, are the same or close, and both motors are the same and running at the same RPM. It's time to pull the strainers.
    In case of malfunction-Reconnect brain BEFORE starting mouth.

  5. #5
    Join Date
    Mar 2005
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    4,192
    Ditto the strainers and rpm, but make sure your VFD parameters match in both drives and put an amp clamp on them to verify the VFD is reading correctly.

  6. #6
    Join Date
    Jun 2010
    Posts
    13
    thanks guys, this was basically a hypothetical question,what auto pilot said was basically what I was getting at, if the pressure from each pump is evenly displaced, then you would think that where the pipes go from two back to one, that which ever direction had more water pressure, it would just push the other water all the way back to the check valve....

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