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Thread: Mechanics and freedom of thought

  1. #21
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    Quote Originally Posted by TechmanTerry View Post
    1970's technology also had the tried and true "purge/sweep" method.
    Just for the heck of it I referred to my 1932 tech training manual, "pull vacuum and sweep & purge all high points to charge".

  2. #22
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    Terry, do you still have that Carrier article of how much refrigerant R12 that a gallon of refer oil can hold
    and still have a vapor pressure. I've misplaced the pamphlet I used to have. I do remember it was almost hard to believe.
    If I remember it was R12 is the demo.
    Give me a relay with big enough contacts, and I'll run the world!

    You can be anything you want......As long as you don't suck at it.

    If a person wants to create a machine that will be more likely to fail...Make it complicated.

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  3. #23
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    Quote Originally Posted by ehsx View Post
    © 1970 Emerson Climate Technologies, Inc.
    All rights reserved.

    Triple Evacuation
    In order to insure a complete evacuation, Emerson Climate Technologies, Inc. recommends a triple evacuation, twice to 1,500 microns and the final time
    to 500 microns. The vacuum should be broken to 2 psig each time with the same type of refrigerant to be used in the system.
    It is quite possible that the original evacuation, if not continued for a sufficient period of time may not completely remove all of the air and moisture
    from the system. Breaking the initial vacuum with dry refrigerant allows the fresh refrigerant to absorb and mix with any residual moisture and air, and the
    succeeding evacuation will remove a major portion of any remaining contaminants. If for example, each evacuation removed only 98% of the contents
    of the system, and any remaining contaminants mixed thoroughly with the refrigerant used to break the vacuum, after the triple evacuation the
    remaining contaminant percentage would be 2% .Estimated Time Required For System Pull Down based on 5 cubic feet internal volume x 2% x 2% or .0008%. The residual contaminants
    have been reduced to such a low level they no longer are a danger to the system. This illustrates why triple evacuation is increasingly important if
    the vacuum pump is not of the highest efficiency, or if the evacuation time is not adequate to insure complete evacuation.
    Many manufacturers use process pressures of 50 to 100 microns. However, in field evacuation, pressures in this range are very difficult to reach,
    particularly if refrigerant has been allowed to mix with oil in the system. The refrigerant will escape from the oil very slowly, and the time required to
    reach such low pressures might be quite unreasonable. The triple evacuation method to a pressure of
    500 microns is practical under field conditions, and represents a specification that can be met.



    At the same time (1970) York centrifugal literature said double evacuation to 500 microns, first pull down break with nitrogen to positive pressure. Second pulldown 500 microns with 6 hour hold test before charging.
    Like Carrier's process. The difference is breaking the vacuum with refrigerant. Nitro doesn't have the same characteristics as
    a refrigerant. Nitro isn't a solvent and won't have that benefit.
    A 6 hour hold test? Try explaining that to the boss.
    Give me a relay with big enough contacts, and I'll run the world!

    You can be anything you want......As long as you don't suck at it.

    If a person wants to create a machine that will be more likely to fail...Make it complicated.

    USAF 98 Bomb Wing 1960-66 SMW Lu49

  4. #24
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    Quote Originally Posted by hvacker View Post
    Like Carrier's process. The difference is breaking the vacuum with refrigerant. Nitro doesn't have the same characteristics as
    a refrigerant. Nitro isn't a solvent and won't have that benefit.
    A 6 hour hold test? Try explaining that to the boss.
    Usually just did the hold test overnight. York shipped their chillers dry, only did a factory run on air until they blew up one on test and killed the test stand guys. Osha/ashrae changed guidelines to nitrogen afterwards.

  5. #25
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    1944 Audel’s ref & ac manual still listed sweep & purge charge method without evacuation. 1242 page manual.





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  6. #26
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    Quote Originally Posted by hvacker View Post
    Terry, do you still have that Carrier article of how much refrigerant R12 that a gallon of refer oil can hold
    and still have a vapor pressure. I've misplaced the pamphlet I used to have. I do remember it was almost hard to believe.
    If I remember it was R12 is the demo.
    Yes I believe I do. I know there are some refrig/oil demos in their 20 pg pamphlet "General Training-ADVANCED", # GTA1-101; "OIL-REFRIGERANT MIGRATION" . I'll re-study it after supper and print out some not so dirty pictures. Dated 1965.

    In that pamphlet they talk about migration being a 3 part deal.
    ABSORPTION RATE FACTOR
    1-"Vapor pressure Difference"
    -thats the oil surface vapor pressure being lower that the freon pressure when both are at the same temp ,like w/ a brand new RTU sitting on the back of a flatbed truck. Like the warning sign says- "The CCH (or unit) MUST be energized for
    12 hrs [or is it 24 hrs ?] before starting compressor."(to allow crankcase to come up to temperature)

    2- Temperature Difference

    3- Exposed Oil Surface

  7. #27
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    Quote Originally Posted by ehsx View Post
    1944 Audel’s ref & ac manual still listed sweep & purge charge method without evacuation. 1242 page manual.





    Name:  audel.jpg
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    NOW, thats cool.!!!!!!!!

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  9. #28
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    Thread Starter
    Quote Originally Posted by ehsx View Post
    Estimated Time Required For System Pull Down based on 5 cubic feet internal volume x 2% x 2% or .0008%.
    Took me some time to internalize this posting, mainly because I missed the part about only pressurizing to 2 PSI. Oops.

    So this est time formula appears to be based on a pretty flat or linear time/volume pulldown. But doesn't the last bit of volume require exponentially more time than when the system's at 2 PSI?

  10. #29
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    You can say that again! <g>

    Quote Originally Posted by tmst View Post
    Well stated. This is an aspect of the tragedy of deindustrialization I hadn't considered.
    PHM
    --------
    The conventional view serves to protect us from the painful job of Thinking

  11. #30
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    That damned History! Seems like every time we consider it there is more trouble than it's worth. <g>

    It seems to me that it was: evacuate, purge with refrigerant (especially R-22), evacuate, purge with refrigerant, evacuate, charge the system for start-up.

    Ozone Hole Madness made that process 'bad' as so few understand Latin these days, and the same people who came up with Ozone Hole Madness substituted inert nitrogen for moisture absorbing refrigerant.

    Brilliant!

    PHM
    ------


    Quote Originally Posted by hvacker View Post
    Not criminal, you just fail to understand the concept of triple evacuation.
    I've posted about this many times. I hope this is the last.
    Triple evac was a procedure introduced in the 70's. It was related to R22. R22 has an affinity for moisture. Many others don't.
    This affinity made the concept of triple evac a way to dry out a system w/o a pump. The procedure was to pressurize with R22 vapor, wait
    30 min, blow it out ( the 70's remember) pressurize again and wait 30 min and repeat.
    This was due to some installers not having vacuum pumps or wanting a "blow & go system.

    Nitrogen doesn't have an ability to bond with water. The most that can be achieved is blowing the water vapor out
    of the system. Doing it over & over I don't believe gives the results hoped for.
    I think this system of using nitro to dehydrate a system was simply hijacked from the original idea based on the nature of R22.
    Nitro doesn't have that nature.
    It really makes less sense when it's done on a new dry system.
    Introducing non-condensibles to a system to get rid of non-condensibles???
    PHM
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    The conventional view serves to protect us from the painful job of Thinking

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  13. #31
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    Quote Originally Posted by Poodle Head Mikey View Post
    That damned History! Seems like every time we consider it there is more trouble than it's worth. <g>

    It seems to me that it was: evacuate, purge with refrigerant (especially R-22), evacuate, purge with refrigerant, evacuate, charge the system for start-up.

    Ozone Hole Madness made that process 'bad' as so few understand Latin these days, and the same people who came up with Ozone Hole Madness substituted inert nitrogen for moisture absorbing refrigerant.

    Brilliant!

    PHM
    ------
    But wait, there's more!
    I was visiting UR a ways back to re-bond or re-bound I forgot. BUT a notice on the BB from our friends at the EPA said:

    "If you pressurize a system with a refrigerant of known ozone depletion potential it's OK to vent it to atmosphere as the
    refrigerant is being used as a leak detector and not as a refrigerant."
    Approximate quote.

    This was some years back but interesting. So, at least at that time, the purge/vent was legal and might still be.
    Only from Washington. I do know the EPA is officially never wrong so go ahead, I guess.

    This would make not just leak detecting easier but evacuation also. Too bad R22 is too pricey to use. Not sure what others have this
    ability chemically. R12 I don't think absorbs water the same. I have a few pounds of R500?
    Denatured alcohol?
    Give me a relay with big enough contacts, and I'll run the world!

    You can be anything you want......As long as you don't suck at it.

    If a person wants to create a machine that will be more likely to fail...Make it complicated.

    USAF 98 Bomb Wing 1960-66 SMW Lu49

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