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  1. #1
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    Apr 2001
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    Unhappy Getting Rid of Non Condensables



    So some uses nitrogen to prevent a low pressure pumped refrigerant system cavitating (boiling at + 30 deg C)and leaves a trail of mixed cylinders and units to purge behind.

    Can't just cool and vent and a full recalim facility is out of the question.

    As its a bit special the manufacturers aren't too keen on sorting out our problem.

    Anyone have a low cost recalim solution.


    Derek

  2. #2
    Join Date
    May 2002
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    Use an air purge like on a chiller. If you keep the evap temp below condensing temp, air rises to top ***** condenses and falls to bottom. Slow bleed at top after it fills with air.

  3. #3
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    I'm not sure I understand the problem, Derek.

    There are (generally speaking) two ways to prevent cavitation: Increase the pressure at the eye of the impellor or decrease the temp of the liquid.

    The simplest way to increase the pressure at the eye is to throttle the pump discharge. Next is to increase the suction head.

    Then there are special purpose pumps with inducers, but they are more expensive.

  4. #4
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    How can it be low pressure when you are evaporating at +30 deg C ??

  5. #5
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    The equipment exists already and despite a search we cant find a compatible pump. This stuff boils at 30 deg C (at sea level) eats PTFE, and nitrile etc etc. All I want is a suitable friendly way (cheap) of extraxting the nitrogen.

    Derek
    Derek

  6. #6
    Join Date
    Mar 2009
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    Re: Getting Rid of Non Condensables

    Circuit has a HP receiver or a condenser or similar with no insulation? Or what form the condenser(s) take?

    Find a suitable exposed piece and build a "dry damn" around it...Shut off equipment and fill damn with dry ice. Valve or bypass or? so charge runs to supercold spot. Hold liquid refrigerant, valve off as necessary...Pump all the rest of circuit out with Vac Pump or recovery unit.

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