Vacuum

Harvey Ramer

I like seeing these numbers.

ratio

Nice. Those ½" hoses make this possible in a reasonable amount of time.

ChrisJ

83 microns?

I think you're the first one I've heard of pulling below 200-300 on a system.

The only time I did it was to test my vacuum pump. Can you take a picture of the entire setup, pump and hoses? I'm curious what pump you're using.


@ratio Some of us DIYers are stuck with a small 3/8 hose.

bob_46

Size matters !

ratio

⅜" is big enough, don't feel bad.

I took a system with a 150 lb receiver down to under 250 microns in a few hours using a ⅜" hose, nippled on the the system in three places with a 4 port manifold. That, and blowing N₂ through. A triple evac broke with N₂ will get you down to outer-space vacuum amazingly fast.

hvacfreak2

I use the same gauge and hoses / crt's. Bluvac is the best bang for the buck by far. The .1 resolution really lets you know what is going on.

I recently picked up a rebuild kit for an Appion TEZ8 that stopped working , a snow day project for sure.

ChrisJ

I use a YJ 69086.
Sadly, no bar graph and no decimal place.





Kinda annoyed about that now that I see the Bluvac has it.

It looks like my YJ is in the same price range as the Bluvac too.

ratio

I use the 69086 as well. It has a replaceable sensor, I carry a spare on the truck. Haven't had much luck cleaning them, it never seems to go back to the was it was. Not sure I believe .1 micron resolution on anything outside of a laboratory–grade device either.

hvacfreak2

Even 1 micron accuracy is hard to imagine , much less .1 . There are times when it is nice to see a more detailed view of the process ... isolated rise tests , progress at the beginning of an evacuation , etc. I like the YJ gauges too.

Harvey Ramer

Sorry Chris. My tools are all packed away. I use the Appion Rapid Evac kit. Currently I am using a Bacharac vacuum pump. I am fairly pleased with it. Sometimes the check valve doesn't act quite fast enough so you have to be careful to not get any oil in the vacuum hoses. Nylog on all the fittings of course. And purge nitrogen through the system before beginning an evac. I go by what the leak rate indicator is telling me to determine when to do a double or triple evac. This system was a single evac and it held at 89microns.

ChrisJ

Harvey Ramer said:

Sorry Chris. My tools are all packed away. I use the Appion Rapid Evac kit. Currently I am using a Bacharac vacuum pump. I am fairly pleased with it. Sometimes the check valve doesn't act quite fast enough so you have to be careful to not get any oil in the vacuum hoses. Nylog on all the fittings of course. And purge nitrogen through the system before beginning an evac. I go by what the leak rate indicator is telling me to determine when to do a double or triple evac. This system was a single evac and it held at 89microns.

Isn't the idea of a triple vacuum being to get all of the contaminants out of the system as they stop flowing at one point?

If you're at 90 microns at the pump is it possible to have steam vapor or other gasses in the evaporator not going anywhere?

ratio

Not water, unless it was behind a valve of some kind. A few H₂O molecules might be floating around somewhere, but at 90 microns there isn't much of anything in there.

Harvey Ramer

If you are at 89 microns and holding, there is nothing left to come out. That's what it held at with the vacuum pump disconnected.

I do this in mild weather. When it gets colder, I triple evac and take it down in stages to prevent ice from forming.

Or I double or triple evac anytime my micron gauge tells me there is moisture left in the system.

JUGHNE

On this subject, I use what it termed as "Dry Nitrogen"......do we really know how "dry" it really is. This is the only gas I know of available from the bottled gas company. Does anyone get anything different??

Harvey Ramer

I believe everyone uses dry nitrogen. Sorry I didn't clarify. The only other nitrogen i know of is liquid nitrogen. Extremely cold stuff.

njtommy

I always try to put my micron gauge on the system if I can.

I've literally spent days pulling Vacuums on big refrigeration systems and chillers. Triple evacuation is a must in my book. Break the vacuum and change the oil and start over. Pull down to 500 or as some of the manufacturers want you to pull down to 100-200 microns.

Harvey Ramer

njtommy said:

I always try to put my micron gauge on the system if I can.



I've literally spent days pulling Vacuums on big refrigeration systems and chillers. Triple evacuation is a must in my book. Break the vacuum and change the oil and start over. Pull down to 500 or as some of the manufacturers want you to pull down to 100-200 microns.

Would you have done a triple evac in the situation i had today where the system is holding rock steady on 89 microns. If so, whats the reasoning behind it?

ChrisJ

Dry nitrogen means it's not liquid nitrogen, nothing else. It has nothing to do with moisture or other impurities.

There are different grades. I believe what I have, and what most guys use is considered "Industrial grade dry nitrogen".

There's a few other grades that offer higher purity, but I have no idea what they cost and i don't think they're necessary for purging.

What I've found is you do NOT want medical grade dry nitrogen. You'd think that would be purer but it's allowed far more O2 and moisture than Industrial grade.

This is the exact part I get from AirGas. It's a size 60 cylinder.
http://www.airgas.com/p/NI 60

EBEBRATT-Ed

Hose size makes more difference than pump size. You can evac faster with a smaller pump and bigger hoses than with a bigger pump and smaller hoses

ratio

I read a little pamphlet a few years ago, "A Review of Vacuum for the Service Engineer" IIRC. I recommend it, but it's hard to come by now. (My brother lost my copy, so if anyone finds a source of appreciate a ping.) It's a plain, easy to understand book, similar to Dan's writing style. Geared more towards industrial vacuum;mdash;it covers sizing 12" vacuume lines;mdash;it is nonetheless useful to HVAC techs who want to understand vacuum a little better. They mention specifically that ...¼" vacuum lines are too small for effective use & will not be covered...

njtommy

@Harvey Ramer it depends on the system and what the history is behind making the repairs.

Is it a new system with new line set? How long as the system been open? if the system is opened to a atmosphere for a long period of time I will always do a triple evac. When your running pipe for a day or two or even longer it's a must in my book.

I pull down to 2k then 1500-1k and then 500and will do a finale break depending on if it's holding or not.

It maybe just me but it seems like the system pulls down faster doing a triple evac. Maybe it's a mental thing I don't know.

ChrisJ

This guy claims triple evacuation isn't necessary with a 2 stage vacuum pump.

I'm not sure how much I'm buying that.
http://homeenergypros.lbl.gov/profiles/blogs/triple-evacuation-vs-deep-vacuum-method

Harvey Ramer

I can't disagree with you on that. In this case everything was brand new and the atmospheric exposure was less than 15 minutes for each component.

I do Triple evac on almost all repair work, and new installs when it looks like it's necessary. The leak rate indicator on the Blu-vac tells me pretty quickly if there's still moisture in the system.

Paul S_3

This is my lowest micron reading ever.....its a new installation just lineset and evaporator coil.....i find its extremely hard to get super low micron readings on repairs.....the other pic shows a low temp condensing unit that took me a whole day to achieve 500 microns with triple evacuation and 1/2 hoses.

ratio

Triple evac will most assuredly speed up your ultimate vacuum on a dirty system, often by an order of magnitude. It's not so effective on new work when you follow best procedures i.e. flow N₂ etc. but even then you'll have to work pretty slow to make a triple evac take longer.

I had a mini split down to 190 microns inside two hours after blowing water out of the lineset. Technically, it might have been more than a triple evac though.

NJ, Designer

ratio
I read a little pamphlet a few years ago, "A Review of Vacuum for the Service Engineer" IIRC. I recommend it, but it's hard to come by now. (My brother lost my copy, so if anyone finds a source of appreciate a ping.)

Here you can buy a new old one. https://www.trutechtools.com/VacuumBook

ratio

@NJ, Designer, thanks so much for that!

Tinman

This was from last Friday on a 3.5 ton Mitsubishi hyper-heat with 5 heads, the lowest I've ever been able to go. I was very surprised.

njtommy

@Stephen Minnich bigger is better when it comes to refrigeration hoses. Lol how do you like the hyper heat units?

Tinman

So far, I like them a lot. They are performing as advertised. I have Appion MegaFlow hoses but my pump failed Friday and I didn't have a fitting handy to fit the new pump. I'll take 61 microns any day though.