Evacuation 101 w/ Jim Bergmann

HVAC School - For Techs, By Techs

Bryan Orr

Training, Careers, Airconditioning, Self-improvement, Hvac, Business, Education, Refrigeration, Heating, Ac, Apprenticeship

4.8 • 985 Ratings

🗓️ 12 May 2017

⏱️ 49 minutes

🔗️ Recording | iTunes | RSS

🧾️ Download transcript

Summary

In this episode of the podcast, Jim reviews the basics of evacuation and dehydration. He also covers hoses and vacuum gauge placement.

Evacuation may just seem like a method to suck air and water out of a system. However, it is an intricate science that lacks a lot of detail in most trades education programs. The deepest vacuum we can possibly pull merely offsets the atmospheric pressure and is actually not that deep; the deepest possible vacuum is -14.7 PSI (-29.92" Hg).

The evacuation rig is the most important element of evacuation. If you want a fast evacuation, DO NOT use 1/4" hoses or manifolds. However, those are both common practices in the HVAC industry. The only way to increase the flow of refrigerant, air, and water out of a system is to increase the hose diameter. Larger hoses have less resistance than smaller hoses. Pump size does not seriously impact evacuation speed when compared to hose diameter and the presence/absence of Schrader cores. Schrader cores are other major sources of restriction, and you'll want to use core removal tools.

Air from a vacuum pulls in a localized area. As such, it is a BAD idea to hook your vacuum gauge up at the vacuum pump. You are measuring the pressure of the pump, in that case, NOT the whole system. When you read 500 microns at the pump, the real pressure of the system could be over 1000 microns (especially if you have 1/4" hoses).

Bryan and Jim also discuss:

Atmospheric pressure
Connectors
What is a "good" vacuum?
Decay tests
Moisture throughout the system and its effects on decay
Water's state changes and vacuum
Sublimation and ice during an evacuation
Capping off, soldering, brazing

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Transcript

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0:00.0	This episode of the HBAC School Podcast is made possible by generous support by
0:11.5	Testo and Carrier.
0:13.4	You know the sort of bloke who walks up to you in a bar, says a little too close and then starts talking to you. You try to ignore him, but it doesn't take the hint.
0:28.0	He starts in about total nonsense. Like you know what he's talking about stuff about enthalpy lines and molya diagram.
0:37.0	Well that's Brian all.
0:39.0	Ah yes yes yes all of it is true I am Brian and this is the HVAC school
0:44.2	podcast part of the HVACR school.com family of products for the service
0:50.4	technician community and today we have our regular contributor Jim Bergman.
0:55.3	I hope he remains a regular contributor and I think he should just so long as I'm able to hang
0:59.5	on to that little piece of blackmail that I have on him.
1:02.3	And Jim's going to talk about one of his favorite subjects, which is evacuation. This is going to be just one piece in a large conversation that we're going to continue to have about evacuation, so we don't hit everything, but we hit some of the high points and
1:14.6	this episode is long enough as it is. Another thing that I was able to get my hands
1:20.0	on was a recording of Jim speaking to a technician recently.
1:24.0	I don't know who you are. I don't know what you want, but I will find you,
1:29.0	and buy you to death about vacuum gauges and call removal tools.
1:33.6	All right, so we are recording.
1:38.6	What are we going to talk about this time?
1:40.6	This time we want to talk about evacuation, I think. That's sort of an easy one for you, sort of a softball, don't you think?
1:45.0	Yeah, that one sucks. You don't like it? No, that evacuation suck.
1:50.0	Oh, whatever you want to talk about.
1:52.0	Let's do evacuation, though, because I think evacuation... Whatever you want to talk about.
1:52.7	Let's do evacuation though because I think evacuation first of all that's if I'm
	...

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