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  1. #1
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    best way to remove moisture from freon ? ? ? ?

    I recovered some R 22 from a unit I was replacing last week, around 15 pounds, into a brand new recovery cylinder, I was only able to evacuate the recovery cylinder down to around 500 microns before I had to get the unit ready for the crane to lift off the roof ..... I used a c clamp and pinched closed the liquid line and then used the units compressors to pump the R 22 directly into the brand new recovery cylinder sitting in a bucket of ice, that way I used ONE hose, I figured that would be the least likely way for the freon to get contaminated, I measured my pressures using my Appion " stub " gauges, then I recovered the rest of the units freon into another recovery cylinder, my R 22 " junk " freon recovery cylinder ( burn outs, freon I am not sure the quality of ). When I installed a moisture indicating sight glass to the brand new recovery cylinder it is showing as being somewhat " wet ", also, the unit I replaced was 23 years old, so that is 23 years worth of installing gauges and introducing moisture, and no matter how much you " bleed " your hoses chances are, IMO, you are possibly / probably introducing moisture into the system ..... anyhow, what would be the best way to remove moisture from some R 22, I want to re use this refrigerant for my customers other R 22 equipment ......

  2. #2
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    May 2006
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    How does attaching gauges introduce moisture into a system?

    The moisture indicating site glasses need the refrigerant to circulate across it to be accurate. Do a standing pressure test on that tank. if it matches the saturation temp it is good. If not, you can recirculate it through a dryer if your recovery machine can pump liquid refrigerant. Put the tank in ice or have a hose running over it top keep it cool.
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  4. #3
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    Filter Drier

    Should have been used going into the tank and out of the system.

    After you finished pushing out of the system did you pull the rest with the recovery unit?

  5. #4
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    Jan 2015
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    Central Florida
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    I read on here that you can put the wet tank in the freezer (the moisture will turn into ice) pull it out and transfer the contents to a new recovery tank, the ice will remain. Then a vacuum pump should eventually dry out your original wet tank.

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  7. #5
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    Jun 2017
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    Quote Originally Posted by comfortdoc View Post
    How does attaching gauges introduce moisture into a system?

    The moisture indicating site glasses need the refrigerant to circulate across it to be accurate. Do a standing pressure test on that tank. if it matches the saturation temp it is good. If not, you can recirculate it through a dryer if your recovery machine can pump liquid refrigerant. Put the tank in ice or have a hose running over it top keep it cool.
    how much does moisture alter the pressure in this case? I'm new and wasn't aware the pressure would be different with moisture specifically.

  8. #6
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    Quote Originally Posted by mike7357 View Post
    how much does moisture alter the pressure in this case? I'm new and wasn't aware the pressure would be different with moisture specifically.
    The moisture is in the vapor form. It is also known as non-condensibles.

    1) Let the tank temperature stabilize. I suggest in the garage or house overnight.
    2) Tape a quality, accurate thermometer to the tank below the liquid line.
    3) Attach a gauge to the tank.
    4) Convert tank pressure to saturation temperature using P?T chart.
    5) Compare to temperature meter.

    If there are non-condensibles, the pressure of the tank will be high, therefore having a higher saturation temperature than what the tank is measuring.

    Here is a little trivia question for you - What might be indicated if the saturation temperature is lower than the tank temperature?
    Climate Control Solutions for your Home or Office

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  9. #7
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    Jun 2011
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    Thread Starter
    Quote Originally Posted by comfortdoc View Post
    How does attaching gauges introduce moisture into a system?

    The moisture indicating site glasses need the refrigerant to circulate across it to be accurate. Do a standing pressure test on that tank. if it matches the saturation temp it is good. If not, you can recirculate it through a dryer if your recovery machine can pump liquid refrigerant. Put the tank in ice or have a hose running over it top keep it cool.

    How does attaching your gauges introduce moisture ? seriously ? hoses contain moisture in them, try hooking up your hoses to a vacuum pump with a vacuum gauge, ever notice it takes SEVERAL minutes before you can drop down to 50 microns ? Do you really think you can " bleed " the moisture out of your hoses in two seconds if a vacuum pump cant remove the moisture in 5 minutes ? IMO, you cant ....... And I do not think refrigerant needs to " circulate across " a moisture indicating sight glass to be accurate, IMO, I think if the indicator is " submersed " in refrigerant that it would be accurate .... if the sight glass itself is accurate .... I am thinking moisture indicating sight glasses are probably pretty accurate, but I have no idea for sure ...

  10. #8
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    Thread Starter
    Quote Originally Posted by comfortdoc View Post
    The moisture is in the vapor form. It is also known as non-condensibles.

    1) Let the tank temperature stabilize. I suggest in the garage or house overnight.
    2) Tape a quality, accurate thermometer to the tank below the liquid line.
    3) Attach a gauge to the tank.
    4) Convert tank pressure to saturation temperature using P?T chart.
    5) Compare to temperature meter.

    If there are non-condensibles, the pressure of the tank will be high, therefore having a higher saturation temperature than what the tank is measuring.

    Here is a little trivia question for you - What might be indicated if the saturation temperature is lower than the tank temperature?
    I do not think that would be an extremely accurate way to measure the moisture content in refrigerant if the moisture content is already relatively low .... I do not think a thermometer reading to the tenth of one degree and a pressure gauge would be able to read as accurately as a micron gauge reading either 1000 or 200 microns, the difference between a " wet " system and a " dry " system .... IMO

  11. #9
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    Thread Starter
    Quote Originally Posted by pecmsg View Post
    Filter Drier

    Should have been used going into the tank and out of the system.

    After you finished pushing out of the system did you pull the rest with the recovery unit?
    I would think that a filter drier would probably only be extremely effective when making multiple passes through it, not one ....

    I believe I stated I recovered the rest of the refrigerant into a separate recovery tank ? why ?

  12. #10
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    Jun 2011
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    Thread Starter
    How about this .....

    Install a threaded filter drier and the threaded moisture indicating sight glass onto the vapor side of the recovery tank leaving the valve closed ..... evacuate the filter drier and moisture indicating sight glass to 50 microns .... open the vapor valve and turn the tank upside down, occasionally " stir " the tank ...... repeat as needed ... I am not in a hurry here .... or I suppose run it through a recovery tank and filter set up .... I figured someone may have actually done this ...

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