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Thread: Micron Gauge

  1. #14
    Join Date
    Apr 2008
    Location
    Alberta Canada
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    2,246

    You are not Vacumn against compressor

    Quote Originally Posted by hivacer View Post
    Yellow jacket makes a good one with a replaceable sensor reads from 1 micron to 760000 microns. According to the engineers at yellow jacket a micron reading of 1000 or less indicates a good vacuum and if this reading does not rise over 2000 microns over a period of several hours this indicates no leaks and an acceptable level of molecules in the system.

    You cannot remove all the molecules from the system and when a system sits in a vacuum molecules break free in layers, so if you wish to get it to 500 microns and want it to stay there this could take some time especially if you are pulling against a compressor full of refrigerant laden oil.

    Why would you vacumn against compressor. unless on compressor change out. Keep your valves closed until vacumn is done. To other post it can take 20 minutes or it can take 1 hour depending on how long linesets are, how big linesets are, how big is pump, how wet is system. Hoses off manifold how big, are you vacumning through schrader valves. I have used 2 pumps before.
    Do it right the first time.

  2. #15
    Join Date
    Dec 2003
    Posts
    709
    Most bigger units do not come with a factory charge therefore you have to pull vacuum on the compressor condensor coil lineset and evap.

    Or what about an evap changeout where almost all of the refrigerant was leaked out of the evap. There are alot of instances where you have to pull against a compressor. And when you do the stuff boils out of the oil for a long time. If your working on a sytem thats flat sometimes you can change the oil and thats even better.

  3. #16
    Join Date
    Jul 2006
    Location
    NW burbs of Detroit
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    6,058
    Last edited by hvaclover; 09-14-2008 at 06:14 PM.

  4. #17
    Join Date
    Jun 2006
    Location
    midwest
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    126

    Smile

    Been doing HVAC for 2 years, a second career for me. Was told day 1 of trade school to use a micron gauge. I've been using a digital readout that goes doun to 100u. Most system evacuations are performed down to 500u. Should at least hold 500u for 15min. A sharp rise that keeps climbing indicates a leak, a rise and then leveling off indicates non condensibles still in the system. Hope this helps...

  5. #18
    Join Date
    Apr 2008
    Location
    Alberta Canada
    Posts
    2,246

    Residential Forum

    Quote Originally Posted by hivacer View Post
    Most bigger units do not come with a factory charge therefore you have to pull vacuum on the compressor condensor coil lineset and evap.

    Or what about an evap changeout where almost all of the refrigerant was leaked out of the evap. There are alot of instances where you have to pull against a compressor. And when you do the stuff boils out of the oil for a long time. If your working on a sytem thats flat sometimes you can change the oil and thats even better.


    I haven't done any 20 ton units in residential lately or two many flat systems. Yah I guess if my aunt had nuts she would be my uncle.
    Do it right the first time.

  6. #19
    Join Date
    Nov 2003
    Location
    Montreal, Qc.
    Posts
    790
    Quote Originally Posted by 21degrees View Post
    I haven't done any 20 ton units in residential lately or two many flat systems. Yah I guess if my aunt had nuts she would be my uncle.
    You must be lucky.
    We get condensers that crack losing 30-40lbs per circuit quite often.
    You're right though it's not residential.

  7. #20
    Quote Originally Posted by gwoner View Post
    Been doing HVAC for 2 years, a second career for me. Was told day 1 of trade school to use a micron gauge. I've been using a digital readout that goes doun to 100u. Most system evacuations are performed down to 500u. Should at least hold 500u for 15min. A sharp rise that keeps climbing indicates a leak, a rise and then leveling off indicates non condensibles still in the system. Hope this helps...
    All you said is correct. I have a slightly different thought on the subject since I HATE charging for time I've wasted watching a micron gauge.

    I use a micron gauge when I think I need it, not all the time. If a system has not been open long, and has not had a prior history of leaks, and I'm sure of my welds, I use a variation of the old triple evacuation. If I have to tell you what it is, read no more.

    I evacuate air, not moisture. I leave that to the dryer.

    Keep in mind that an operational system will outgas for a LONG time after being opened and not allow any appreciable amount of air into the system.

  8. #21
    Join Date
    Jul 2008
    Location
    Orange Park Florida
    Posts
    224
    I'm happy with my supco digital.The only drawback is that you have to clean it regularly with alchohol. R-22- No more than 700 microns held 5 min.410-A 500 or less absolutely.
    Local 234
    Have Gauge$ Will Travel

  9. #22
    Join Date
    May 2008
    Location
    Last moon off of Pluto
    Posts
    49
    pump it down while you do your trim out or something else.

    See if it will pump down to 200 microns or so. Close valves and hold under 500 microns for 1 minute....minimum.

    Yellow Jacket

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