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  1. #1
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    Vaporize POE Oil?


    When pulling a deep vacuum on a 410A system at what point will the POE oil vaporize?

    I know POE does not give up moisture like mineral oil and some suggest a system should hold 500 microns with pump valved out for 5 minutes. Others say to pull down to 200 and hold at or below 500.

    My question is at what point is the vacuum vaporizing the oil? There is no need to vaporize perfectly good oil. Is it possible to harm the structure of the oil by going too low?

    If time is not an issue and perfection is the goal, what would the ideal vacuum be?

    With the cond unit service valves closed I have pulled the line set and evaporator until they would hold below 50 microns for 10 minutes. After opening to service valves back up what would the perfection goal be?

    This would all be in reference to a system that has been recovered and opened for service such as a TEV replacement and the cond unit has had nitrogen in it with the service valves closed. Not a burnout or any other major failure.

    Is there such thing as too low?



  2. #2
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    Re: Vaporize POE Oil?

    Is there such thing as too low?
    No.

    Taking the vacuum level too low may be a waste of time and effort however.

    Check your steam tables to see what level is required against the ambient temperature.
    Brian - Torquay, Devon, UK
    I have to stop saying "how stupid can you be?" to my co-workers.
    They're starting to take it as a challenge...

    BASIC MAINTENANCE. If it doesn't move and it should then use WD40. If it moves but it shouldn't then use Duct Tape.

  3. #3
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    Re: Vaporize POE Oil?

    Steam tables would say all moisture is vapor way up in the >1000 micron range depending on temp.

    There are other possible contaminates which is clear by the way the vacuum holds at different levels.

    I have heard that mineral oil will vaporize at 250, 375, 500, 700, and the same with POE oil. In other words what I have heard/read is guessing.

    Someone surely knows for a fact at what point POE oil will vaporize. Of course there are different POE oils.

    If holding at 200 microns is better than 500 and I can achieve that level without time being an issue would it be better?

  4. #4
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    Re: Vaporize POE Oil?

    Quote Originally Posted by Brian_UK View Post
    steam tables
    Brian, is this what you meant by a "steam table" ?
    Attached Images Attached Images

  5. #5
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    Re: Vaporize POE Oil?

    Yep, that's a steam table for evacuation, thanks.

    Data from a COSHH data sheet on POE oil:-

    Vapor Pressure: mm Hg: Negligible
    Evaporation Rate: (ether=1):Negligible
    Solubility in H2O: Not Soluble in Water
    Freezing Point F: N/A
    Boiling Point F: >500 F
    Specific Gravity H2O=1 @25 C: 0.98
    Vapor Density (Air=1) 60-90 F: >5
    VOC Content (% by wt.): Negligible
    pH @ N/A Solution: N/A
    pH as Distributed: N/A
    Brian - Torquay, Devon, UK
    I have to stop saying "how stupid can you be?" to my co-workers.
    They're starting to take it as a challenge...

    BASIC MAINTENANCE. If it doesn't move and it should then use WD40. If it moves but it shouldn't then use Duct Tape.

  6. #6
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    Re: Vaporize POE Oil?

    That is a handy chart, much easier than my ASME "Steam Tables" by Combustion Engineering. Ever used a "Mollier Diagram"? If not you haven't missed anything unless you like to be dizzy.

    The POE data? I assume the evaporation rate and boiling point are at 14.696 PSIA?

    Today I pulled a 2 ton R410A system (with service valves open) down to about 275 microns and it held for 10 minutes at 375 microns. I had pulled the line set and evap coil down to where they would hold under 50 microns before opening the service valves. It took about an hour to achieve the 375 on the entire system(long line set and added a LL solenoid vl). This would tell me that it is not only tight and dry but that the POE oil was not vaporizing? At the rate it was gaining I have no doubt it could have been pulled down and held even lower.

    If I thought there was even a slight benefit to be gained by going lower I would. Whats another 30 minutes.

    Yes I am paranoid of moisture or any contaminates with the POE oil and think these systems will run for many years as long as there is no contamination. I hear a lot of guys say "they don't build them like they used to", which is true, in my opinion they are better as long as they are serviced properly. I may be wrong but if they fail I don't want it to be my fault.

  7. #7
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    Re: Vaporize POE Oil?

    In the cascades that I work on the manufacturer recomends for a system with new oil that the vacuum holds below 200 microns for 20 minutes. if the system oil has ever had refrigerant in it then it changes to less than 500 microns for 20 minutes.

    While at the manufacturers school they also preached about the triple nitrogen evac. Pull first vac to 2500 mic. break with nitrogen, pull to 1500, break with nitrogen, pull to 1000 then break, pull to desired vacuum. The reason behind the nitorgen breaks was that during evac water will turn to ice due to energy loss from vaporization. The nitrogen breaks will allow the ice crystals to melt back to water and then be boiled off.

    I dont like POE oil. It seems like if it ever gets Hot it breaks down. Most of the compressor failures that we have seen have POE in them. The oil will be dark and non acidic with a burnt smell. The compressors are usually locked.
    Last edited by ultralo1; 05-10-2008 at 05:39 AM. Reason: Added opinion

  8. #8
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    Re: Vaporize POE Oil?

    Quote Originally Posted by ultralo1 View Post
    In the cascades that I work on the manufacturer recomends for a system with new oil that the vacuum holds below 200 microns for 20 minutes. if the system oil has ever had refrigerant in it then it changes to less than 500 microns for 20 minutes.

    While at the manufacturers school they also preached about the triple nitrogen evac. Pull first vac to 2500 mic. break with nitrogen, pull to 1500, break with nitrogen, pull to 1000 then break, pull to desired vacuum. The reason behind the nitorgen breaks was that during evac water will turn to ice due to energy loss from vaporization. The nitrogen breaks will allow the ice crystals to melt back to water and then be boiled off.

    I dont like POE oil. It seems like if it ever gets Hot it breaks down. Most of the compressor failures that we have seen have POE in them. The oil will be dark and non acidic with a burnt smell. The compressors are usually locked.
    The oil and refrigerant are designed to be miscible, so by deisgn it's difficult to get the refrigerant out of the oil by vacuum. Hence, the relaxed requirement once there's refrigerant in the oil.

    My understanding is that POE likes water even better than it likes refrigerant, and that once it's there, a vacuum pump WILL NOT get it out.

    I've been looking for some kind of a vapor pressure or evacuation chart that includes POE (or even mineral oil) in the mix, rather than just water in a jar, but so far, I've struck out.

    It's an extension for a thread here:
    h{notspam}ttp://hvac-talk.com/vbb/showthread.php?p=3269622#post3269622

  9. #9
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    Re: Vaporize POE Oil?

    Vacuum dehydration is always a topical subject.
    OK this is an old post but I will add my pennies worth.
    POE oil is a sponge for water, vacuum pump performance should be tested before any de-hydration/ ie oil change and test ultimate with a vacuum analyser. Next thing is the oxygen free dry nitrogen [ usually not ]. So tend towards using system refrigerant to break vacuum during triple evac cycle, that is after changing oil charge in system. During evac cycles, keep sump heaters operating. Regular oil changes in pump is essential. If small volume system use a small vac pump, rapid vac-ing will freeze any water in system. Final evacuation is analysis and standing readings should hold for at least 24 hours with minimal rise, only effected by ambient temp changes, rapid change equals leaks, sudden then gradual changes indicates moisture.
    Thinking out loud again, Magoo.

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