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Thread: How low do you pull vaccum?

  1. #61
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    Quote Originally Posted by Gleng View Post
    O.K you have a valid point.If you want to always use a micron gauge that is fine.If the system is dry it will pull down quickly.

    A system with moisture in it will pull down to 29" on your guages fairly quick. So you won't know if you have moisture in the system or not.

    I'm just saying that I usually don't use a micron gauge unless I suspect a problem,And i do have one on the truck.Never had a problem doing this in 30 years.

    You probably don't still service every unit you installed 5 years ago let alone the ones 30 years ago and didn't use a micron or vacuum tube on.
    So you could have had problems crop up 5 years after you installed a unit and not know it.

    Worked with a guy that said the same thing. In his case, he was never with an one company for more then 3 to 5 years.

    Went back to one of his no micron guage installs of 2 heat pumps. Both heat pumps lost their compressors in 7 years. Also had to change compressors on several other units he installed and didn't use a vacuum guage( they were on average anywhere from 4 to 7 years after the install).

    He still claims he's never had a problem. And those compressor failures had nothing to do with his vacuum methods.

    Not saying you change companies like that. Just pointing out that you may have systems out there that had trouble. But by the time it showed up. You were no longer servicing those units. Maybe because the people sold the house and the new owners used a company they used at their last house. Or they call the first company they see in the phone book.
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  2. #62
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    Quote Originally Posted by hvacrmedic View Post
    FWIW, and I'm not going to get into the debate....this time...., but knowing ahead of time where you were coming from, and understanding your postion fully on micron guages, I have to say that it looks as though you intentionally stirred up the pot. I found the thread to be entertaining, and even humorous, though it didn't necessarily have the same effect on some of the other guys involved in the debate. I can actually picture some of the guys who post to this forum using their turn signal at a crossroads in the middle of the desert with not a soul around for 50 miles. Some people are just like that. I can't condemn them for it, but I really don't want them insisting that I follow their lead either.



  3. #63
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    I understand i work in a lab, that is why i asked the question about real world setting, to learn not critize. I got this job while still in tech school as a temp hire, but they never reliaze that they are stuck with me!
    BTW thanks for all the input AND entertainment!

  4. #64
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    Quote Originally Posted by jpsmith1cm View Post
    Hmm.

    If the customer took a little more pride in their equipment, I wouldn't have to lay in a puddle of grease to work on their GD case.

    If you've never worked on the oil system of a supermarket rack, then you will never understand what it is like to have a hose full of oil at 200# blow in your face. It's a blast.

    I'm not a "dirt ball" as you so kindly put it, but occasionally, I do get a little dirt or oil on my hands. I'm a mechanic, not a prima-donna.

    If a tool is designed to be used by mechanics, it should take the fact that sometimes, just sometimes, we might get dirty in the discharge of our duties. That manifold doesn't meet that standard.

    If you like them so well, I'll sell ya mine, less my DRSA, or course. CHEAP!!! I still have the original analogs that came with it.

    I buy my own tools, too. Sometimes, I make a mistake. This was one.
    Too each there own I guess. If we all had the same opinions the world would be a pretty boring place I guess.

    However cleanliness is next to godliness If I see something that is going to get my hands dirty I will toss on gloves. If its a serious mess like, well anything from supermarket rack, to an 20 year old oil furnace that has never been cleaned. Well the latex gloves are coming out.

    I guess thinking about it now I am pretty particular about my tools and there condition. I'll find myself isolating my dirty gloves on my had to a cresent wrench with a clean rag. hehehe OCD I guess...

    I do have to admit, I've never had a problem turning the "knobs" of my gauges. But I could see it could be an issue if there was a layer of grease on my handles vs the other style knobs. These might even be interchangeable, but I've never bothered taking them off to see...

    As far as a "mechanic" I prefer the job title "technician". While both are correct as wiki defines it :

    mechanic (plural mechanics)

    1. A skilled worker capable of building or repairing machinery. A mechanic can be compared to a technician, the distinction being that the technician is stronger in theory, the mechanic stronger in hands-on experience.

    So as long as I keep the gloves on I'm a technician. Once they get dirty....mechanic. hehehe

  5. #65
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    The following should be required reading for anyone in the HVAC/R field:

    http://www.jbind.com/tools/userfiles...Principles.pdf

    Personally I would like to see a dewpoint indicator on a vacuum manifold assembly. I have one on the vacuum system I use to dehydrate fire sprinkler manifolds; it lets me determine the actual dryness of the system in relation to the system's temperature and vacuum level.
    Psychrometrics: the very foundation of HVAC. A comfort troubleshooter's best friend.

  6. #66
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    Quote Originally Posted by CynicX View Post
    Too each there own I guess. If we all had the same opinions the world would be a pretty boring place I guess.

    However cleanliness is next to godliness If I see something that is going to get my hands dirty I will toss on gloves. If its a serious mess like, well anything from supermarket rack, to an 20 year old oil furnace that has never been cleaned. Well the latex gloves are coming out.

    I guess thinking about it now I am pretty particular about my tools and there condition. I'll find myself isolating my dirty gloves on my had to a cresent wrench with a clean rag. hehehe OCD I guess...

    I do have to admit, I've never had a problem turning the "knobs" of my gauges. But I could see it could be an issue if there was a layer of grease on my handles vs the other style knobs. These might even be interchangeable, but I've never bothered taking them off to see...

    As far as a "mechanic" I prefer the job title "technician". While both are correct as wiki defines it :

    mechanic (plural mechanics)

    1. A skilled worker capable of building or repairing machinery. A mechanic can be compared to a technician, the distinction being that the technician is stronger in theory, the mechanic stronger in hands-on experience.

    So as long as I keep the gloves on I'm a technician. Once they get dirty....mechanic. hehehe
    Mechanic...

    Technician...

    Semantics, really. I have a strong hands-on and a strong technical background.

    I dislike working with gloves on, but have recently found a pair that I can tolerate.

    As far as wearing latex, I did too many years slinging hash in a kitchen to re-live that nightmare. If my hands never see latex gloves again, I will die a happy man.

    Maybe I'm not OCD enough.



  7. #67
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    Calibrating your gauges

    Interesting thread. Should be pointed out that most low side gauges can't REALLY measure vacuum in inches. Sure the inches of vacuum are printed on the gauge - but take several sets that are all 'right' and they will all read different.

    Calibrate your gauges this way - to a known pressure. Put a drum of refrigerant in the fridge and measure it's temp tomorrow with a properly calibrated digital thermometer. (Just leave a thermometer in the fridge with it.)

    Now set your gauge needle - using the adjustment screw in the gauges - to the temp that corresponds to that refrigerant pressure at that temp on a PT chart. Your gauges are now calibrated to a known pressure.

    Now close the tank and take the hose off the tank. Bleed your hoses. Bet your gauge does not read ZERO. It's probably a bit above or below.

    Now you are going to measure 'vacuum' with this gauge? These readings will all be B.S.!! oiur gauge doesn not read 0 at atmospheric pressure

    NEVER 'ZERO' your gauges at atmospheric pressure, and NEVER think for a second that you can anywhere accurately measure 'inches of vaccum' on your gauges!

    The only way to REALLY read vacum is with a micron gauge.

    Yes, my pro membership is pending - for about a month now

  8. #68
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    6 pages of dribble about how low to pull a vacuum...

    Is pulling a very deep vacuum about more than moisture removal????

    No one talks about how low a vacuum it takes to remove the moisture????
    At about 1000 microns, any LIQUID water would be at about -60 degrees F or lower, so it would be ice...( at least thats what my chart says, anyway ).
    I would think that it is not as important to go real low unless the ambient temperature is real low....IOW: the lower the ambient, the lower the vacuum needs to be pulled to insure moisture removal.
    So, to me the depth of the vacuum is relative to the ambient temp...
    + as the vacuum pump is dropping lower & lower, the water has already started to boil & is turning into a vapor, which should be easily removed. If any liquid is present, then the micron gage won't pull below the press & temp that the water is at while it is boiling, right. So, to me its more about how long the vacuum is pulled to allow time for the liquid to boil off, than it is the number of microns above a perfect vacuum that it gets to....
    At 1000 microns, the moisture would have to be liquid to not have been removed & the liquid would be solid ice as its temp would be about -60 F.
    So, if the gage drops below 1000, then I don't have any 'boiling' moisture left in the system....
    Someone want to explain where I may be wrong.

    Richard
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  9. #69
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    ^^^

    Yes, pulling a vacuum is about moisture removal. And since you cant pull a quality vacuum with moisture in the system we use a micron gauge to tell us when the system is dry. The micron gauge will determine vacuum duration.

    1000 micron and you might not have any water left boiling but that doesnt mean there isnt water vapor. 1000 micron is higher then the industry standard for R-22. Probably would have been for R-12 if anyone had micron gauges back then...

  10. #70
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    Quote Originally Posted by jpsmith1cm View Post
    Don't waste yours or your boss's money.

    The Titan/Brute manifolds are CRAP! Try turning one of those neat little tapered plastic valve handles with wet, oily or greasy hands. They work great. NOT!!!

    The 4 valve, 4 hose manifolds are nice, but YJ really has a stinker on their hands there.
    Quote Originally Posted by CynicX View Post
    Personally I never had a problem. I've had them for about 3-4 years. And they are due for replacement I guess since they are used daily. But they still work just fine.

    Uhm. I keep my hands clean, I keep the oil and grease on gloves.

    Wait, are you the "dirt ball" these commercial property owners tell me about?! I the story usually starts "The guy was nice enough but he didnt wear gloves or shoe covers..........."

    BTW, I buy all my own tools. I wouldnt "re buy" something that was junk. If my "hands are too dirty" to operate a tool I would find a new job.
    On the Yellow Jacket Titan the knobs are bad and very bad under pressure but what is worse is crap in the cold no control of metering liquid refrigerant, leaky seals and permanent hose parks on the back
    “If You Can Dodge A Wrench You Can Dodge A Ball”

  11. #71
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    some years back i went to Carriers puron course and the standard at that time was pull down to 500 microns close your gauges and if it does not rise above 1000 in 15 mins you have a dry and tight system trane says you should pull it down to 350microns and it should not go above 500microns in 1 minute. i pull it down to under 500 and if it stays under 1000 it is good
    Last edited by catmanacman; 02-10-2010 at 08:30 AM.

  12. #72
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    Quote Originally Posted by bornriding View Post
    6 pages of dribble about how low to pull a vacuum...

    Is pulling a very deep vacuum about more than moisture removal????

    No one talks about how low a vacuum it takes to remove the moisture????
    At about 1000 microns, any LIQUID water would be at about -60 degrees F or lower, so it would be ice...( at least thats what my chart says, anyway ).
    I would think that it is not as important to go real low unless the ambient temperature is real low....IOW: the lower the ambient, the lower the vacuum needs to be pulled to insure moisture removal.
    So, to me the depth of the vacuum is relative to the ambient temp...
    + as the vacuum pump is dropping lower & lower, the water has already started to boil & is turning into a vapor, which should be easily removed. If any liquid is present, then the micron gage won't pull below the press & temp that the water is at while it is boiling, right. So, to me its more about how long the vacuum is pulled to allow time for the liquid to boil off, than it is the number of microns above a perfect vacuum that it gets to....
    At 1000 microns, the moisture would have to be liquid to not have been removed & the liquid would be solid ice as its temp would be about -60 F.
    So, if the gage drops below 1000, then I don't have any 'boiling' moisture left in the system....
    Someone want to explain where I may be wrong.

    Richard

    I am not sure of what chart you are looking at, but here's my two cents. The purpose of the vacuum pump is to reduce the internal pressure of the system which it turns lowers the boiling point of water. At normal atmoshere pressure the boiling point of water is 210degrees F. At 1000 microns it is somewhere around 0 degrees F. If the ambient or conditioned temperature is lower than 32 degrees, then if you have any moisture in your system, it could be ice. This is assuming the system is at atmoshere pressure before you strat the vaccum pump. Any moisture in a system below 32 degrees will be ice and the vaccum pump will have a hard time removing the moisture because it will not boil off easily unless the temperature is raised to greater than 32 degree F.
    Stuart
    Lack of airflow destroys compressors.

  13. #73
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    i vac till it is/stays below 500 microns...

  14. #74
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    200 mics

    Is pulling a very deep vacuum about more than moisture removal????

    Yes, I like to regas my machines without turning them on.
    "I aint going to spit on 30 years of my life" Monte Walsh


  15. #75
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    Quote Originally Posted by bhahvac View Post

    Calibrate your gauges this way - to a known pressure. Put a drum of refrigerant in the fridge and measure it's temp tomorrow with a properly calibrated digital thermometer. (Just leave a thermometer in the fridge with it.)
    I would like to get a pic of my wife's face when she goes to grab a gal of milk in the morning and gets a drum of 410a instead.
    Learning is a lifelong process

  16. #76
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    Quote Originally Posted by bhahvac View Post

    Calibrate your gauges this way - to a known pressure. Put a drum of refrigerant in the fridge and measure it's temp tomorrow with a properly calibrated digital thermometer. (Just leave a thermometer in the fridge with it.)
    Can just bring the gauges and tank into the house, and leave it become room temp over night.
    Since putting it in the fridge, and then doing the test, will be less accurate, as the tank and refrigerant warm up to room temp.
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  17. #77
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    Oh Wow. You can never go wrong in superceding proper refrigration vacuation past manu specs.

    You can never go wrong actually taken a short tutorial on how to service your vac pump, gauges or micron gauge, in fact you are at a disadvantage if you do not.

    Okay, I myself cannot get past page 6 of latest post. Cannot believe it has gone on this long just with page 6 info.

    One question that gets asked alot, period..not nec. here: when do you replace your vac pump oil, (or o-rings) etc. etc. etc.

    You have tools, they are only valuable when A) you know how to use them B) know how to maintain them. Otherwise, might as well throw them in the landfill and use the Beer Can method.

    If anyone is interested: all manus of vacs, micron guages, refrig guages have webinars and online tutorials (yes, it is a sales class as well) but it provides this very basic. Shoot, going out on a limb here, if you have your EPA cert you already know the info available. But I assume most people fall into either consumers or professionals. Consumers should know they can ask for EPA cert, and our numbers for pulling a system into a vac and how we did it. Otherwise, really?? 6 pages to point out the fact the information is available but for what ever reason (bad employment opp, bad state licensing, bad distributor support) that we do not know how to use and maintain tools? Took 6 pages for us to agree that the information was indeed available but never sought, am I right?

  18. #78
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    Ever watch the movie "My Cousin Vinny," ?
    If U get a chance, watch that movie, U'll enjoy it.

    When she (as an expert witness) looks at the tire tracks & says, "NO, the defense is wrong!

    The problem is that she was on the defense team & it was the prosecution that was wrong,ha.
    However, in the movies script, her auto expertise was terrific & I have enjoyed watching that movie on TV - several times.

    Yes, there are good tools & test instruments available to do a good install job & to pull deep evacuations on the systems, other than the compressor, area which should not be pulled into a real deep vacuum because the compressor oil molecular structure could be altered.

    Even though I pulled deep evacuations, I also installed oversized filter driers on every system I worked on. Over-kill, maybe? Also, removed far too many driers that were restricted; - because a lot of jobs were not properly performed.

    Always keep everything well maintained. I'm betting vacuum pump oil is not changed when necessary/required... - Darrell
    Last edited by udarrell; 02-13-2010 at 09:22 PM. Reason: Guess I heard it correctly...

  19. #79
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    I always vac till I hit 500 microns or less

  20. #80
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    Cool

    Quote Originally Posted by matcolecat View Post
    I always vac till I hit 500 microns or less
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