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Thread: How low do you pull vaccum?

  1. #1
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    Question How low do you pull vaccum?


    This question is for you pros out there. How low do you usually pull a vacuum?
    Where I work, product test lab, we go as low as 10 microns.

    I know this is extremely low, so the question is:
    How low do you go out in the real world where time is money?
    Last edited by Artietech; 02-03-2010 at 10:53 AM. Reason: missing word in title

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    It depends on the system.If the system is low on freon,but has freon in it. After I find the leak,Reclaim freon.Fix Leak.Pull vacuum only to get system down to 25-30 inches on low side gauge.I am not concerned about any moisture issues,the system had some freon in it already.I only need to get the air out .Never had a problem this way.If i have a system totally out of freon and suspect moisture has gotten in,I pull a long vacuum with a micron gauge down to as low as possible within a reasonable amount of time.About 250-300 microns.Then I install an oversized drier.Usually works. Have had rare occasions where I had to pull vaccum several times and change driers several times.Your drier will get cold and catch any remaining moisture you did not get out with vacuum.

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    Quote Originally Posted by Gleng View Post
    It depends on the system.If the system is low on freon,but has freon in it. After I find the leak,Reclaim freon.Fix Leak.Pull vacuum only to get system down to 25-30 inches on low side gauge.I am not concerned about any moisture issues,the system had some freon in it already.I only need to get the air out .Never had a problem this way.If i have a system totally out of freon and suspect moisture has gotten in,I pull a long vacuum with a micron gauge down to as low as possible within a reasonable amount of time.About 250-300 microns.Then I install an oversized drier.Usually works. Have had rare occasions where I had to pull vaccum several times and change driers several times.Your drier will get cold and catch any remaining moisture you did not get out with vacuum.
    Please notice that Gleng has no professional status. He does not follow industry standard. Industry standard is always min below 500 microns. Readings below 50 microns are difficult to achieve.

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    I agree, it takes a considerable amount of time PLUS an industrial type vacuum pump like we use here.

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    There are several threads on this topic, we triple evacuate down to a minimum of 500 microns.

    Time may be money , but going back is much , much more expensive than doing it right the first time.
    You sure are cocky for a starving pilgrim.

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    500 or lower on 22 300 or lower on 410

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    Why two standards?

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    There are no 2 standards. A vacuum is a vacuum. It has nothing to do with refrigerant. 500 micron is the minimum standard. I always go below 250 micron. Micron gauges are often not as accurate and lower the reading, higher the chance of not having moisture left in the lines.

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    Our standard max. is 2,7 mBar which is about 2000 microns. This applies to systems with 3kg or more refrigerant. We have no standard for smaller systems but we usually do at least half of that.

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    Triple evac to 300 microns. Nitrogen is my friend, and a lot less expensive than a return visit.
    I'll try being nicer if you'll try being smarter.

    I will defend, to your death, my right to my opinion.

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    We go to 250 at least on all jobs. I never make return visits.

    This extra precaution costs me on the front end but saves tons on the back end. Well worth it.

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    Quote Originally Posted by artdavila View Post
    This question is for you pros out there. How low do you usually pull a vacuum?
    Where I work, product test lab, we go as low as 10 microns.

    I know this is extremely low, so the question is:
    How low do you go out in the real world where time is money?
    Two cigaretes long. If it is not Marlboro, then three because it is cheaper brand.

    Good luck on the answers

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    Just curious as to what the norm is. I would probably get fired if i only pulled vacuum to 500!

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    Quote Originally Posted by just_opinion View Post
    Two cigaretes long. If it is not Marlboro, then three because it is cheaper brand.

    Good luck on the answers
    That bullcrap, everybody knows Marlboro burns faster.
    Every pro knows its 2 Parliament light 100's sheesh
    You sure are cocky for a starving pilgrim.

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    Quote Originally Posted by zachhvac View Post
    That bullcrap, everybody knows Marlboro burns faster.
    Every pro knows its 2 Parliament light 100's sheesh
    With the price of cigaretes now a day, do you think you can burn 2 with one vacuum.

    Cheaper brand then you can afford to.

    That's what I mean.

    As for how long in time. Who counts the ticks. I use CAP book

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    Depends on the size of the equipment. Sometimes it's a few hours on small equipment, to a few days if your on a built up system. On construction start up we try for 100-200 microns and usualy let the pumps go at least over the weekend. New oil, new black hoses, or hard piped, several vacuum pumps, and always test the equipment, hoses before making any connections.

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    Art - you work in a test lab!! We have to drag our a** out in the field, along with equipment. 10 microns - c'mon!!
    500 is a good goal. 300 if you can get there. You have to remember, some folks don't have access to the greatest equipment, have unlimited time, or get to change oil as often as they should.
    It ain't a perfect world.
    If I get 500 and it holds, I'm confident things are good.
    "Hey Lama, hey, how about a little something, you know, for the effort." And he says, "there won't be any money, but when you die, on your deathbed, you will receive total consciousness." So I got that goin' for me, which is nice. - Carl Spackler

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    Quote Originally Posted by 2old2rock View Post
    10 microns - c'mon!!
    500 is a good goal. 300 if you can get there.
    Residential vacuum machines are not made to reach 10. 500 is not a goal, it is the minimum. 300 is always achievable.

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    Tostaos - I don't know if you read all of my post, or all of the OP's. He asked what we go to in the real world. 500 is good for me. Most around here couldn't tell the difference between a micron gauge and a manometer.
    I probably can't get to 300 with my set up. It's old, doesn't get fresh oil as often as it should, and Boss is calling saying "WTF is taking so long"?
    If I get to 500 and it holds, I'm good. Sure 300 would be great, 10 would be even better. But I ain't in the lab.
    "Hey Lama, hey, how about a little something, you know, for the effort." And he says, "there won't be any money, but when you die, on your deathbed, you will receive total consciousness." So I got that goin' for me, which is nice. - Carl Spackler

  20. #20
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    Quote Originally Posted by 2old2rock View Post
    Tostaos - I don't know if you read all of my post, or all of the OP's. He asked what we go to in the real world. 500 is good for me. Most around here couldn't tell the difference between a micron gauge and a manometer.
    I probably can't get to 300 with my set up. It's old, doesn't get fresh oil as often as it should, and Boss is calling saying "WTF is taking so long"?
    If I get to 500 and it holds, I'm good. Sure 300 would be great, 10 would be even better. But I ain't in the lab.
    Show some professionalism and improve your equipment and please do not post in the residential section when you are not willing to work inside of minimum industry standards. It's not good advertisement.

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