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  1. #1
    Join Date
    Jul 2007
    Location
    Chicagoland
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    475

    Can I trust my Bluvac?

    In an effort to streamline my work I have been upgrading some of my tools. I have purchased a Bluvac LTE to replace my Thermal Engineering unit and in side by side bench tests, have come to see that the BV is much more responsive than the TE. In the field, however, I have had some confusing results.

    examples;
    1. Could not get an existing coil and lineset below 1000 after clearing a piston restriction. Held pressure, no d-tek hits, system had correct charge.

    2. Vac'ed a leaky coil down to 350 and held below 1000 for 30 min.

    3. Vac'ed a new coil with old 15ft. lineset down to 58 and held in the 70s after 15 min.

    Examples 2 and 3 occurred on the same job with 60 degree ODT and rain. I want a micron gauge I can believe in, just don't seem right.

  2. #2
    Join Date
    Jul 2007
    Location
    Chicagoland
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    475
    Quote Originally Posted by AccurateHT View Post
    3. Vac'ed a new coil with old 15ft. lineset down to 58 and held in the 70s after 15 min.
    A pic of said questionable reading.
    Attached Images Attached Images  

  3. #3
    Join Date
    Feb 2007
    Location
    Toronto, Ontario
    Posts
    300
    Haha why do you guys pull through the schrader on your valve core remover tool?

    Compare your micron gauge with another one, that's where I would start.

  4. #4
    Join Date
    Jan 2005
    Location
    Akron
    Posts
    1,114
    Quote Originally Posted by AccurateHT View Post
    In an effort to streamline my work I have been upgrading some of my tools. I have purchased a Bluvac LTE to replace my Thermal Engineering unit and in side by side bench tests, have come to see that the BV is much more responsive than the TE. In the field, however, I have had some confusing results.

    examples;
    1. Could not get an existing coil and lineset below 1000 after clearing a piston restriction. Held pressure, no d-tek hits, system had correct charge.

    2. Vac'ed a leaky coil down to 350 and held below 1000 for 30 min.

    3. Vac'ed a new coil with old 15ft. lineset down to 58 and held in the 70s after 15 min.

    Examples 2 and 3 occurred on the same job with 60 degree ODT and rain. I want a micron gauge I can believe in, just don't seem right.
    All of those things are possible. Even the sub 70 readings. Mario is correct though you need to pull through the back of the core tool with the core removed not the side port. No point in removing a core only to evacuate through one. Also there is no way to isolate the hoses from the system.

    According to Refrigeration Air Conditioning Technology, a deep vacuum is between 50 and 250.

    According to Review of Vacuum for Service Engineers a finishing pressure of 100 to 200 microns is desirable.

    You are using a 3/4" vacuum rated hose, things will go a lot faster.

    If you are questioning the calibration, follow the field calibration procedure.

    Things leak differently under a pressure and a vacuum.

    http://www.trutechtools.com/Vacuum-Training_c_1100.html
    JLB,

  5. #5
    Join Date
    Jul 2007
    Location
    Chicagoland
    Posts
    475
    Quote Originally Posted by mario_m View Post
    Haha why do you guys pull through the schrader on your valve core remover tool?
    There are no cores in the way, they are sequestered but under vac beyond the ball valve.

    Compare your micron gauge with another one, that's where I would start.
    That is what the Blu vac is supposed to solve, I'm fed up with questioning my micron gauge.
    Thanks

  6. #6
    Join Date
    Jul 2007
    Location
    Chicagoland
    Posts
    475
    Quote Originally Posted by jim bergmann View Post
    Mario is correct though you need to pull through the back of the core tool with the core removed not the side port. No point in removing a core only to evacuate through one. Also there is no way to isolate the hoses from the system.
    I have taken the cores out of the VCRT side port. To isolate, I re install the low side core, this is my standard coil and lineset rig, with the CU I vac from both sides.
    Maybe I'm doin it wrong but its been working well for me.

  7. #7
    Join Date
    Jan 2005
    Location
    Akron
    Posts
    1,114
    You should consider the way I am recommending as you can isolate the hoses from the system. All hoses leak, even vacuum rated ones. Being able to isolate them is important.

    How are you performing a drop test? What are you using to isolate the vacuum pump?
    JLB,

  8. #8
    Join Date
    Jul 2007
    Location
    Chicagoland
    Posts
    475
    I'm not sure what you mean by drop test, but my standard routine for coil and line set is to blast a few seconds of nitro, vac until it slows to a crawl (sub 1000), blank at pump and watch the rise for a few min., if it looks good I break with nitro and pump for as long as I have. I am used to getting to 200-300 on my Thermal.
    Then I reinstall the low side core that's held under vac, isolating the system and the gauge on the high side. Check rise after 10-15 min. If it's good I reinstall the High side core, release the charge, and disconnect the vac gear.

    I use an NRP 1/2 hose (3/8x1/4) from the pump to the low side.

    I'm aware of the stringent recommendations by accredited agencies, but I'm trying to make a living and get ACs repaired, not achieve laboratory results.

    Considering many around here "evacuate" a system by flushing it with R22, I think I'm doing pretty good.

  9. #9
    Join Date
    Jan 2005
    Location
    Akron
    Posts
    1,114
    Quote Originally Posted by AccurateHT View Post
    I'm not sure what you mean by drop test, but my standard routine for coil and line set is to blast a few seconds of nitro, vac until it slows to a crawl (sub 1000), blank at pump and watch the rise for a few min., if it looks good I break with nitro and pump for as long as I have. I am used to getting to 200-300 on my Thermal.
    Then I reinstall the low side core that's held under vac, isolating the system and the gauge on the high side. Check rise after 10-15 min. If it's good I reinstall the High side core, release the charge, and disconnect the vac gear.

    I use an NRP 1/2 hose (3/8x1/4) from the pump to the low side.

    I'm aware of the stringent recommendations by accredited agencies, but I'm trying to make a living and get ACs repaired, not achieve laboratory results.

    Considering many around here "evacuate" a system by flushing it with R22, I think I'm doing pretty good.
    Follow the link on Vacuum Training I sent you earlier, it walks you through the process. If you incorporate the process I am recommending, you will not only get it done faster, but also with more consistent results.

    Jim
    JLB,

  10. #10
    Join Date
    Jul 2007
    Location
    Chicagoland
    Posts
    475
    Thanks for providing all the quality info Jim, in addition to building a good business you are helping to raise the level of competency in our trade. I'll give it a try from the core port on the VCRT and see how I like it. Otherwise it looks like I'm following most of the rules

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