evapman

How many guys use them? I'm a believer in them, allot of guys around here just use their gauges and let the vac pump run fo a hour or so and call it good, and get away with it. How they know the system is evaced. I don't know, have seen it take an hour to 3 hours to get down to 400 microns.

mechanicalDvr

A micron gauge is the only way to tell what condition a system is in. You may get away with a quick vacuum for an a/c system but it will never be good enough for low temp refrigeration.

johncavh

anybody having problems with yellow jacket gauges

G 71

We all use them, not to use one is just guessing.

jvegas

I use one on every system I install the only way you can be sure

Yuri

It is ABSOLUTELY important that you have clean fresh oil in your vacuum pump or it will take forever to get a 500 micron vacuum. The moisture in the oil from the other jobs etc boils off and slows everything down.

DuMass

I'm wondering how you can really work without a Micron gauge, especially these days with refrigerants that can fractionate when leaks occur and the sponge like moisture absorbing qualities of POE and even PAG if you do automotive AC. You really need to know that the system is dry and tight.

mechanicalDvr

I know that you can't pull any moisture out of POE oil but I just feel better about any job when I know it was in a good deep vacuum before I charge it.

sgthvac

I also use a micron gauge, don't like guessing. To speed up the vacuum oil must be changed after every use of the pump and use nitrogen before you start. It absorbs soem of the moisture in the system. I will run the pump 10 min. then break the vacuum with nitrogen blow the nitrogen and then vacuum. usually takes about an hr. Replaced TXV on Water Furnace today vacuum took an hr and had 385 micron using this system.

sanpyon

vacum gauge very important,especially on low temp system and you have to keep your oil in good condition all the time.

mechanicalDvr

I agree you need to keep your oil in good shape, I take mine out for walks on a regular basis.

NoTime

Thanks for the chuckle.

Gas63

definitely need one with pulling down on 410 system. you leave any kind of moisture and you will kill that compressor. 410 non forgiving

Aiken Colon

For you guys that are also considering digital guages the Testo 560 has a built in micron guage.

Testo 560

They also make one for ammonia

Testo 560 Ammonia

JJ

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Jeffrey Jay

Great thread.

Micron tells the story.

I keep one of those nilla folder type paper tags with the wire on it attached to my vac pump and log the date when I change the oil.

Digital gauges are the way to go...just too much dough for me.
Would be cool if they had a speedy bar graph like my Fluke 87 in addition to digits so you get a visual sweep if something unexpected happens.

beenthere

Slightly incorrect info there.

R410A, doesn't care if moisture is in the system or not. However. POE likes to absorb it. And then react with the winding.

If you ever add POE to a system. You are adding moisture to the system. unless your buying a new container of it everytime you add oil.

Next. You can't vacuum moisture out of POE. So anytime you open an existing system to replace a part between the service valve and the compressor. the POE oil will absorb moisture. And you won't be able to vacuum it out.
This is why you are suppose to change the LL filter drier when ever you open a system. So the LLFD can remove any moisture left in the system.




PS: On mineral oil systems. Moisture that is under the oil, won't be removed by a vacuum either. This is one of the reasons a triple evac is recommended. It stirs up the oil and moisture in the system, and helps bring the moisture up from the oil.

If you suspect moisture is in the compressor. Then use a heat gun on it while vacuuming the system.

Contrary to popular belief. POE has been around and used long before R410A came out.

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TH3 M0L3

Um, yes you can. I really cant see the wide spread use of POE oils in modern refrigeration if it hold moisture. Moisture, as you know, is the arch enemy of any fridge/ac system.......

The fact is, you can't tell if you have removed the moisture from the system if yo have not used a vacuum gauge.

Just out of interest, how many of you perform a vacuum rise test at the end of your vac to check for moisture?

If you have done a strength and tightness test you know there is no leak, so the vac should not rise.
If you have vacced down to below 2000 microns, all the residual refrigerant in the oil would have boiled off, so any rise on your vacuum rise test indicates moisture in the system.......now is when you refill with Oxygen free nitrogen again and do another vac, or more commonly, a triple vac!

YOU SHOULD ALWAYS USE A VACUUM GAUGE!

beenthere

You can triple evac all month long. And you won't pull the moisture out of POE oil.
You need filter driers to remove moisture from POE oil.

POE has been used in refrigeration since the early 90's. Its the commercial and residential A/C market that is only catching up to refrigeration.

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TH3 M0L3

most of the oil remains in the sump of the comp, so how will it be filtered?
Yes, some oil escapes the compressor during normal operation, but not enough to carry all of the moisture with it....

Vac Vac Vac

By your argument, if you suspect moisture in the oil then you should replace it.
As POE is extremely hygroscopic, the new oil charge WILL absorb more moisture from the atmosphere when you charge it.
...Vicious circle....

You can never eliminate exposure to the atmosphere, just minimise it

beenthere

All the oil circulates through the system.
Most of the oil is in the sump at any one given time. But it all circulates through the system.
If it didn't. Then R410A could use mineral oil. The reason it can't use mineral oil. Is that it doesn't mix well with it. And won't be able to return the oil to the compressor.

If all the oil didn't circulate through the system. Then acid clean up by filters would be impossible. Since the filters require all the oil to pass through them to move the acid.

Next. Even if only the same 10 ozs of oil ever moved through the system. The oil that went through the filter drier would give up its moisture to the filter drier. Be returned to the compressor where it would absorb more moisture from the oil in the sump. Pass through the filter drier again. And give ups its moisture again. And repeat that process until the moisture was at a level lower then what it is, just from opening the oil container.

Now if you don't believe that.

Explain how an acid removal filter removes acid from the system.

Sporlan, and Parker(Sporlan now onwed by parker) have tech sheets on how oil circulates through the system. On how and why acid filters, and filter driers work.

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