Blog Comments

  1. GENERALCOOL's Avatar
    was nice and informative
  2. r.bartlett's Avatar
    If life was only that simple.
  3. crocens's Avatar
    From my experience it is ALWAYS BETTER to say true!! And i have never lost client becouse of such situation.
  4. passandscore's Avatar
    It only happened twice. Good point about the interlock. There are a couple of improvements that will have to be made but at least the main problem is resolved. I don't expect to see liquid flood back like this again. Well, not from this facility anyway.
  5. RANGER1's Avatar
    Just to add, depending how good your PLC programmer or controls person is, further protection can also be added to this scenario.
    If compressor is selected in auto with no faults or alarms,liquid feed to vessel is in circuit.
    If all compressors on this vessel are in a fault condition & in auto then it can interlock with liquid makeup solenoid to prevent it opening no matter what the level.
    Liquid pumps have their own safety with low level or pump differential fault.

    How often does this happen & a truck load of liquid returns to accumulator causing high level after a compressor fault.
  6. HVACRsaurus's Avatar
    Hey Ranger, not taking the piss - save that for the guys who can't understand why thier tin can isn't giving 'em 1MW of cooling running off an ebay solar panel.
  7. RANGER1's Avatar
    Quote Originally Posted by HVACRsaurus
    Very informative thank you.
    Never sure if your taking the piss or not with me!
  8. passandscore's Avatar
    The high level is not fail safe. I agree with your view point and will mention it to others.
  9. HVACRsaurus's Avatar
    Very informative thank you.
  10. RANGER1's Avatar
    Certainly a good floodback & lucky for it to cause no damage.
    Just a thought on the high level not working, is it fail safe?
    For example if a wire or plug falls off high level switch will it shut down plant.

    Depending on what was wrong with the relay, maybe it should be somehow made fail safe if possible.

    I'm only mentioning this as plants are left vulnerable, not just yours.
    Depending on programmer & how things are wired can cause problems months or years later.

    Pressure transducers are another example.
    If a HP transducer plug falls off will PLC system recognize this as a sensor failure & shut compressor down.
    If not plant is out of control waiting for an accident.
    We had a problem recently with a fault relay being held in by residual voltage. Had a controls electrician to investigate fix problem & also put in a bigger relay in case it happened again.