Deep 25 micron vacuum

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Old 11-26-17, 09:14 PM
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Deep 25 micron vacuum

For the last 29 years I've used an old single stage Dayton vacuum pump on my own R22 equipment. Whenever I opened a system, I always pulled the system down using only my charging gauges. After a purge I would always install a new dryer before closing the system along with a sight glass to check for moisture.

That was with R22, but now with R410A I've purchased a micron gauge, Appion evacuation kit, and a J&B two stage vacuum pump. I'm installing a new 22,500 BTU Mitsubishi mini split that is not supposed to use a dryer, because there is not a liquid only line on mini splits. Because R410A systems use Moisture absorbing POE oil, I want to remove all the moisture out of the system. J&B claims their two vacuum pumps will pull a system down to 25 microns, but I'm concerned that a deep 25 micron test may start to collapse annealed tubing. Is it really safe to pull a 25 micron vacuum on a mini split air handler and related annealed copper tubing?
Old 11-26-17, 09:40 PM
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I have a new 2 stage J&B vacuum pump and I never have come close to 25 microns.
You might have to leave it running overnight to get close to that vacuum.

Just turn it off when you get to 500 microns (or whatever number you are trying to hit).

We are not allowed to post about the refrigerant circuit on this site so I will delete this thread if it starts going to deep into the subject.
Old 11-26-17, 11:43 PM
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My Appion evacuation kit consists of a vacuum rated core removal tool and a heavy duty half inch vacuum hose. With blue Nylog on connections, and the J&B two stage vacuum pump it is capable of much lower than 500 microns. That being said, I have not used my new two stage J&B pump yet, but will by the end of this week. On the other hand J&B is advertising their two stage pumps are capable of 25 microns.

However my question was does anyone have any experience with possible collapse of annealed copper tubing at a 25 micron vacuum level, or any vacuum level for that matter.
Old 11-27-17, 04:16 AM
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We are not the site to help you with this.
There are sites better suited towards people working in the industry.
HVAC-Talk is one of many.

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