Automotive Air Conditioning Information Forum (Archives)

Provided by www.ACkits.com

We've updated our forums!
Click here to visit the new forum

Archive Home

Search Auto AC Forum Archives

W/regards to DEC vs Non DEC PAG Faq...

marvin-miller on Thu January 03, 2008 6:07 PM User is offline

I tried posting a reply to the PAG Olis - Do I need DEC? but couldn't. If I could, here's what I'd say ;-)


This is one of the best FAQ's I've ever seen - bar none. Clear, simple, and conclusive proof of the value of DEC Pag.

I wish I had a chemistry set that I could subject to high vacuum levels. If I had one I'd put 10 cc's of mineral spirits in a clear jar, drop the vacuum level to 30 microns and then conclusively show people that evacuation will not remove them.

It would go a long way to proving, very simply, that it's absolutely vital to remove mineral spirits when using them as a flushing agent.

In fact, if I had a set like that I'd be off trying all sorts of flushing agents... maybe it's a good thing I don't!

With a rig like that you could also demonstrate miscibility(?) between refrigerants and oils. Man, sometimes a picture is better then a 1,000 steps!

-------------------------
Best & Thanks;
Marvin

tony1963 on Sat January 05, 2008 6:09 PM User is offline

Sometimes proving your theory does not produce the results that you are expecting. I give advice, make suggestions, recommendations, etc. and if customers don't want to hear it, that's fine.



-------------------------
Grove Automotive Group, Inc.

An Alabama Corporation

Test Specimen on Wed January 09, 2008 4:40 PM User is offline

Marvin,

I commented on this study before, and I still have the same concerns. All this test shows is that DEC PAG has less ability to dissolve water than SEC PAG. Is this a good reason to choose one over the other or not?

As a refrigeration systems chemist, I know that there is desiccant in the system that has a much greater affinity for the moisture than the PAG. In a tug of war over water, the desiccant will win quite easily. The water in the system will hang out in the desiccant, not in the PAG or the refrigerant.

If you allow enough moisture into the system to make free water in the PAG, you would have to literally pour liquid water into the system. No one is going to allow this in real life.

If you were crazy enough to pour some liquid water into the A/C system, the DEC PAG will not absorb as much of the additional water as the SEC PAG, so you will get lubrication destroying free water sooner with DEC PAG than with SEC PAG. The SEC PAG will prevent free water from forming as it dissolves the additional water better. You can argue in this particular situation, DEC PAG is a poorer choice than SEC PAG. Since the whole scenario is not going to happen in real life, it doesn't matter.

The water absorbtion test in the FAQ doesn't tell you what you need to know to make a proper choice of PAG. The actual lubricity and chemical stability were not measured for these products, so there is no way to tell which one is working better in the compressor. To do the testing proerly, you would have to run a compressor test stand and sealed tube aging studies, and these would likely set you back several tens of thousands of dollars. This is what it takes to get a real answer as to whether DEC is better than SEC. The test in the FAQ makes some pretty pictures, but doesn't tell a chemist or engineer anything relevant as to how the oil will perform in a real system.

There are advantages of DEC PAG over SEC PAG as far as chemical stability goes, but in a real system you may or may not see the benefits. The same situation exists with engine oil where you can buy cheaper mineral oil or more expensive synthetic oil. Most people will not benefit from the more expensive synthetic, but some who have severe service needs may see the benefits and can make the economics work in their favor. Of course some people just want the best product regardless of cost, and if so then buy the DEC PAG. The SEC PAG may work just as well for less money, but that doesn't matter to the oil obsessed.

Your statement about mineral spirits needs some work as well. You don't measure high vacuum in inches, you measure it in absolute pressure units like microns. If you were able to reduce the pressure enough, you would boil away the mineral spirits very quickly. What you may want to say instead, is that if you pull a crappy vacuum, you won't be able to boil away the mineral spirits very quickly. Mineral spirits evaporates at atmospheric pressure (its used as a solvent in oil based paint etc.), so they will eventually be pulled out of a system if used as flushing agents. The speed of removal is the key you should focus on.

There are flushing agents used in commercial refrigeration and A/C that are composed of liquid HFCs and chlorinated solvents that clean systems and evaporate quite well. These are kind of expensive due to the liquid HFC component, and cost about $80 for a 2 pound container. You can get anything you want as far as really good flushing solvents if you don't mind paying for them.

marvin-miller on Wed January 09, 2008 5:50 PM User is offline

Hi Test Specimen;

Quote
All this test shows is that DEC PAG has less ability to dissolve water than SEC PAG.

Correct! That was the simple scope of the test and the beauty of it. It very clearly and simply shows (with pictures) the advantages of DEC PAG over SEC PAG.

Quote
As a refrigeration systems chemist, I know that there is desiccant in the system that has a much greater affinity for the moisture than the PAG. In a tug of war over water, the desiccant will win quite easily. The water in the system will hang out in the desiccant, not in the PAG or the refrigerant.

An excellent point - that comes back to the importance of proper evacuation and replacement of the accumulator/dryer in an MVAC application - among other things - but the point of the article in question was about DEC vs SEC PAG. I think what would be ideal is another short article on that point as it's very important.

Quote
The water absorbtion test in the FAQ doesn't tell you what you need to know to make a proper choice of PAG. The actual lubricity and chemical stability were not measured for these products, so there is no way to tell which one is working better in the compressor. To do the testing proerly, you would have to run a compressor test stand and sealed tube aging studies, and these would likely set you back several tens of thousands of dollars. This is what it takes to get a real answer as to whether DEC is better than SEC. The test in the FAQ makes some pretty pictures, but doesn't tell a chemist or engineer anything relevant as to how the oil will perform in a real system.

True, but again, that's beyond the scope of the article. There's a great deal of confusion in MVAC repair. What I appreciate most about that article is that it picks off one small (but important) issue and graphically explains it such that anyone can see the benefits - whether they know about refrigeration or not. As such, it's a great step forward in clearing confusion about one aspect of MVAC repair.

In a previous conversation with a refrigeration oil engineer it was explained to me that DEC PAG only comes from one place - Idemitsu in Japan. Said engineer mentioned to me that all DEC PAG comes from there due to patent/process issues. At any rate, I agree - it's a matter for compressor manufacturers / autmotive manufacturers and certainly beyond the scope of the general public. As such, it's largely a moot point.

Quote
There are advantages of DEC PAG over SEC PAG as far as chemical stability goes, but in a real system you may or may not see the benefits. The same situation exists with engine oil where you can buy cheaper mineral oil or more expensive synthetic oil. Most people will not benefit from the more expensive synthetic, but some who have severe service needs may see the benefits and can make the economics work in their favor. Of course some people just want the best product regardless of cost, and if so then buy the DEC PAG. The SEC PAG may work just as well for less money, but that doesn't matter to the oil obsessed.

Given that the last bottle of DEC PAG I bought cost about $12 - it's a moot point especially when taking into consideration the overall cost of an A/C repair. With the exception of the repair shop service label, the oil is probably the single least expensive component in the repair. As such, why not use DEC PAG?

Quote
Your statement about mineral spirits needs some work as well. You don't measure high vacuum in inches, you measure it in absolute pressure units like microns. If you were able to reduce the pressure enough, you would boil away the mineral spirits very quickly. What you may want to say instead, is that if you pull a crappy vacuum, you won't be able to boil away the mineral spirits very quickly. Mineral spirits evaporates at atmospheric pressure (its used as a solvent in oil based paint etc.), so they will eventually be pulled out of a system if used as flushing agents. The speed of removal is the key you should focus on.

I think if you re-read the original post you'll see that I did mention microns as a measurement for vacuum. I don't use analog guages for measuring vacuum - up here it's strictly thermistor technology as nothing else is comparable or an accurate indicator of ultimate vacuum.

My point was this, I put some mineral spirits in a recovery tank and pulled a 400 micron vacuum - nothing happened. The mineral spirits were not removed. This brought to light an important issue - prior to that test I had been 'assuming' that pulling a deep vaccum would remove mineral spirits. The conclusion is - it won't. I mentioned that because I thought it would be of value to perform a simple test graphically showing that fact. I don't have a chemistry set (glass) that I can use to show that, nevertheless, I know it to be true and came to the conclusion long ago that refriegerant flushing is the way to fly. At what micron level would mineral spirits evaporate? I don't know - that's the point. I suspect that even at something like 30 microns it will still be there - but that brings up another point - who out there can pull a 30 micron vacuum on an MVAC application?

But the point of all this is exactly this - due to the widespread confusion about MVAC/refrigeration repairs it was nice to see a very simple, graphical example of the benefits of DEC PAG. I think it would be neat if more FAQ's like that could be made that are simple and accurate such that they can be used as a quick guidebook for end users and professionals alike.

I wish I had a glass chemistry set that I could subject to 'extreme' vacuum levels. It would even be nice to see a beaker with plain old water in it being evacuated just to show what evacuation actually does. A simple and graphical explanation like that is worth many thousands of words. In fact, I would go so far as to say that Bohica could easily put together a very simple book (with pictures) illustrating all these concepts that we never actually get to see in action. We know that they take place because we know that water boils when it's subjected to a vacuum but actually seeing these things brings a whole different level of understanding.

The genius of the article was it's simplicity and it's pictures. I'm sold!

My question now becomes this - do you have a vested interested in non-dec PAG oils? :-)

-------------------------
Best & Thanks;
Marvin

Test Specimen on Thu January 10, 2008 9:57 AM User is offline

Marvin,

I think you missed my point. The water solubility test tells you absolutely, positively nothing about the advantages of DEC PAG over SEC PAG. Water solubility of the PAG is a non-issue in a real system. The water in the A/C system is not in the PAG, it is in the desiccant. This piece of work shows a clear effect, but the interpretation of the results is wrong. My problem is with the incorrect interpretation.

I have no vested interest in DEC versus SEC. The company I used to work for manufactured both types of PAG, as well as POEs, and they sold more DEC than SEC for auto A/C since they supplied the Ford OEM product. I tested both PAG products and am very familiar with how they perform. The performance of the lubricant has much more to it than the solubility of moisture. Both PAG products (as well as POE) can work well in A/C systems. There are hundreds millions of vehicles running on DEC PAG, and just as many hundred millions running on SEC PAG. If SEC was clearly worse than DEC, then someone forgot to tell those millions of SEC filled compressors to fail.

My problem with this test has been illustrated by your stated opinion - "it very clearly and simply shows (with pictures) the advantages of DEC PAG over SEC PAG."

This test shows no such thing. There is no advantage based on water solubility because A/C systems just don't get wet enough for the PAGs to show a difference. Even if they did get that wet, the test makes the wrong conclusion that excess water is more of a problem for the SEC PAG. It is not - excess water will be more of a problem for the DEC PAG as it will allow free water at lower amounts of added moisture than SEC PAG. Free water will cause problems in the system, and SEC PAG is better at preventing free water than DEC PAG.

The test that was run showed valid and accurate data. What the data means has been misinterpreted because it does not address any actual issues that are important in a A/C system.

The whole 'polymerized' statement is just plain technically wrong as well. If the PAG had 'polymerized', this is a chemical reaction, and would cause a permanent change to the properties of the PAG. I know that if the water had been removed from the SEC PAG after the test pictures had been taken, that the PAG would be chemically unchanged. The whole test was not good science, and no technical people at a lubricant manufacturer would be caught dead presenting this type of data with the interpretation that it showed the superiority of one product over the other. They would feel comfortable showing that the products behaved differently, but would not draw any conclusions from just this test about the different performance of the two products.

The water solubility test is a marketing dream - show something that looks like it has meaning and can be understood by the masses that clearly differentiates two products. It doesn't matter that it actually means nothing as to the actual performance of the product. People have been taught that pictures tell a thousand words, but pictures can certainly mislead as well as inform.


The evacuation test you ran on mineral spirits would give a similar result had you used R-11, the old flushing standby from years ago. R-11 can't be easily removed by vacuum either from a cylinder. I have seen it take days for R-11 to be pumped away by vacuum only. You had to break the vacuum with dry air multiple times to get the R-11 to be carried away in a reasonable time. If you go through multiple vacuum - air cycles, you'll be surprised at how much better mineral spirits will be removed. You need a carrier gas to pick up the vapor from the mineral spirits and efficiently carry it out of the container (or A/C system). Mineral spirits has a vapor pressure, and it will eventually be carried away by vacuum or by air blown through the system.

HECAT on Thu January 10, 2008 1:30 PM User is offline

Quote
Originally posted by: Test Specimen
Marvin,

Mineral spirits has a vapor pressure, and it will eventually be carried away by vacuum or by air blown through the system.


Many of the commercial flushes available today are junk. You must at least be smart enough to select an evaporative product first. Most of the solvent based products will have similar boiling points as mineral spirits (approx 200-300 degrees F). Just like water, they will evaporate more readily with a good air blow and do not seem to be removed so well by the vacuum process.


-------------------------


HECAT: www.hecatinc.com You support the Forum when you consider www.ackits.com for your a/c parts.

FLUSHING TECHNICAL PAPER vs2.pdf 

Test Specimen on Thu January 10, 2008 3:34 PM User is offline

No argument here. This is why I suggested Marvin refocus his direction to studying the rate of solvent removal rather than saying it doesn't get removed at all by vacuum. There is a lot of middle ground between the liquid refrigerant flush Marvin prefers, and the mineral spirits flush he dislikes. It is possible to make a mineral spirits flush work well if the components you are flushing have no dead spots in the flow path.

Vacuum will remove mineral spirits and other low volatility flushes, but at much slower rates than solvents with higher vapor pressures. Depending on vacuum only is probably a bad idea, even with higher volatility flushes, because it is much more effective to use a carrier gas to remove the residual solvent. The commercial flushes are removed much quicker by blowing air through the system than by pulling a vacuum. Once almost all the liquid solvent is removed by air flushing, the vacuum will remove the residual vapor quite well. If you short the air purging time regardless of the flush type, there will be residual liquid flush solvent left in the system that may dilute the oil.

Honeywell and NuCalgon (using material supplied by DuPont) both sell non-flammable low toxicity flushing solvents with higher volatility solvents (patented HFC / transdichloroethylene blends), and they both recommend using air purging to remove the residual liquid. Vacuum alone just doesn't seem to get the job done, even with these 'evaporative' flushes.

NickD on Thu January 10, 2008 4:06 PM User is offline

Quote
In a tug of war over water, the desiccant will win quite easily. The water in the system will hang out in the desiccant, not in the PAG or the refrigerant.

Sure you will agree that this depends upon how much moisture was left in the system before the oil is added plus how much additional moisture will be accumulated over time. The moisture in PAG does cause sludge that is observable and found in systems that already experience compressor failure problems. I won't get into whether the sludge was responsible for the compressor failure.

But it does lead into the additional precautions required in servicing these systems, like the new car manufacturers, draw a deep vacuum first before injecting the oil to rid the system of that initial moisture. PAG is unforgiving in this respect. With the introduction of PAG both the SAE and EPA had to increase the moisture limits over mineral oil, can't recall the precise numbers off the top of my head, but something like a factor of 4-6 times as much.

Would be a trivial argument whether PAG causes the sludge problem, or if the servicer caused the problem by leaving too much moisture in the system, just common practice to add the oil first, then draw the vacuum, by then, it's too late. But moisture and PAG do not get along, and the customer or the DIYer will pay the price.

marvin-miller on Thu January 10, 2008 4:14 PM User is offline

Quote
No argument here. This is why I suggested Marvin refocus his direction to studying the rate of solvent removal rather than saying it doesn't get removed at all by vacuum

Again, we're going off from the MVAC arena and into the lab, splitting hairs - and most importantly - creating more confusion for the end user or technician trying to affect a good repair with a high success rate.

I don't work in a lab - I work in the real world where I have to implement a repair methodology, again, one that stands the highest chance of success and one that's practical in the real world.

Where hairs are being split now is in the rate of removing mineral spirits by evacuation. Again, I know from personal experience that a few ounces of mineral spirits, placed in a recovery vessel, will not be removed at 400 microns with an overnight vacuum. How do I know this? Because I tested the theory. How that fact applies to effecting a great A/C repair is what's important.

Whether or not those few ounces of mineral spirits would be removed after a week of evacuation - I don't know. But I do know this, I can't put a car on a week long evacuation cycle in the real world. It's common sense (to me) but I realize that it might not be to everyone else.

The point though is this (and I mentioned that in my original post) it would be nice to show that to people so that they don't operate under the misconception that evacuation will remove them. Believe it or not, many people out there think that evacuation will remove all sorts of contaminents - such as metal debris etc. This is why the original post was so important - it clearly shows the laymen the value of DEC pag over SEC pag - without them having to be a scientist or having to account for a multitude of variables, that by your own admission, they won't encounter in the MVAC arena anyway.

A test showing the inability to remove mineral spirits under vaccum would also beg the better question - what effect does a few ounces (or more) of residual mineral spirits have on an A/C system when it's being continuously sent through the system? What effect does that have have on the oil in the system? Will solvent break down oil? That's the point - not whether mineral spirits can evacuated after several years on lab grade vacuum pump.

Again, your points tend to bring confusion to the general public who are just trying to effect a 'best practices' repair strategy by clouding the issue with irrelevant variables. I think that's unfortunate.

-------------------------
Best & Thanks;
Marvin

HECAT on Thu January 10, 2008 5:24 PM User is offline

Quote
Originally posted by: marvin-miller

A test showing the inability to remove mineral spirits under vacuum would also beg the better question - what effect does a few ounces (or more) of residual mineral spirits have on an A/C system when it's being continuously sent through the system? What effect does that have have on the oil in the system? Will solvent break down oil? That's the point - not whether mineral spirits can evacuated after several years on lab grade vacuum pump.


Marvin,

Mineral Spirits is what our air pulsating flushers have used for 26 years in A/C flushing and still used today in Trans Cooler flushing. We started using alternative solvents when Mineral Oil was no longer the most prevalent oil being used in A/C. Mineral spirits will not be recovered under vacuum. A/C flushes should be removed by the air blow.

The common misconception that these chemicals can be removed with vacuum is dead wrong and if many technicians belive this, as you say; then it is no wonder we have remaining solvent issues; and this is truly what is so unfortunate. Solvent flushing can be done as long as solvent removal is done with diligence.

What effect will a few ounces have? Oil dilution, lack of lubrication, and compressor death. Trace, measurable in minimal grams, is the only remaining amount that has proven to have no negligible affect on assembled system performance.

The HFC products mentioned from Honeywell and Dupont that have the Transdichloroethylene (nasty stuff) in them are not compatible with common materials used in A/C systems (they don't tell you that). The Honeywell HFC-245fa and the Dupont HFC-4310me can be removed with vacuum in their virgin form as we use it (Honeywell Genesolv SF) in the Refrigerant Flusher we make.



-------------------------


HECAT: www.hecatinc.com You support the Forum when you consider www.ackits.com for your a/c parts.

FLUSHING TECHNICAL PAPER vs2.pdf 

Chick on Thu January 10, 2008 5:35 PM User is offlineView users profile

Use plenty of air, "then" use plenty of air..When you're done, "use more air"....

-------------------------
Chick
Email: Chick

---------------------------------------------

Freedoms just another word for nothing left to lose

Test Specimen on Thu January 10, 2008 5:44 PM User is offline

Quote
Originally posted by: marvin-miller

Again, as I have said consistently and backed up with logic, the original post shows no such thing. It is nothing more than a parlor trick. The conclusion that holding less water makes DEC PAG better than SEC PAG is wrong.

In what forum should the truth about PAGs and solvent removal be told? You all seem to want black and white answers to questions that are not so simple. I'm pointing out that things can be done outside the 'best practices' box you are comfortable working inside, and you guys seem to get annoyed.

OK. I'll go away and leave you Hecat and Nick to your real world. I hope it doesn't turn around and bite you because you don't understand how it really works. Ignorance must truly be bliss, and conventional wisdom is never wrong and shouldn't be challenged even if it is wrong.

Sorry for intruding, Bye.

NickD on Thu January 10, 2008 7:04 PM User is offline

Am I in deep trouble again? Only thing I said was when using PAG, have to make sure the system is bone dry before pouring it in. That is true either in the lab or in the field, once PAG gets moisture in it, can't get it out.

marvin-miller on Thu January 10, 2008 7:58 PM User is offline

I think that point was covered in the original article - that with DEC Pag you could get the moisture out whereas with SEC Pag you can't.

But I think we're in agreement - why would anyone put oil in a moist system in the first place :-)

-------------------------
Best & Thanks;
Marvin

TRB on Thu January 10, 2008 7:59 PM User is offlineView users profile

Nick no one is in trouble.

I do think the I'll take my ball and go home now attitude is amusing. Lab coat people make me chuckle all the time. While Test's comment could be true. I certainly see Marvin's point about getting someone to use a product. Which I think everyone has stated is a better choice. You know I don't care how I get someone of crack. As long as they put the pipe down that's what concerns me.

I honestly don't see where anyone did anything out of line. Holy cow people this is a forum to discuss stuff. Instead of running home because someone thinks differently. Try and help make others understand!

Enough baby sitting, I have to go fix a float on a toilet!

-------------------------

When considering your next auto A/C purchase, please consider the site that supports you: ACkits.com
Contact: ACKits.com

NickD on Fri January 11, 2008 9:20 AM User is offline

Quote
There is no advantage based on water solubility "because A/C systems just don't get wet enough for the PAGs to show a difference". Even if they did get that wet, the test makes the wrong conclusion that excess water is more of a problem for the SEC PAG. It is not - excess water will be more of a problem for the DEC PAG as it will allow free water at lower amounts of added moisture than SEC PAG. Free water will cause problems in the system, and SEC PAG is better at preventing free water than DEC PAG.

I would like to take issue with "because A/C systems just don't get wet enough for the PAGs to show a difference". They do get wet, refrigerant is lost over the long winter season, zero positive pressure and moisture does seep in.

The question is, what to do with it and correct me on this. With DEC, assuming a seal leak that was repaired with no visible signs of oil loss, can you just draw a deep long vacuum to put that moisture out? It is my understanding that you can, just like you could with mineral oil on R-12 systems.

But with SEC, the moisture becomes homogenous with the SEC and cannot be vacuumed out. Is this true?

If the above is true, the difference DEC and SEC have is the amount of work involved in repairing a system, just vacuum with DEC, but have to disassemble a SEC system and flush it out first, that is a huge difference in labor.

Logic dictates that the oil shouldn't even be a part of the refrigerant circuit, for one thing, oil does not transfer heat that is the purpose of an AC system, I think. But due to economic restrains for the initial cost of the system, it is greatly multiplying the repair cost so one has to deal with that. But then the automotive vehicle manufacturers want you to buy a new vehicle every two years so they can make a huge profit and unfortunately getting lots of help from the EPA to achieve that goal. They can easily make a vehicle that would last 30 years by just adding pennies to it. If a little thing like adding DEC to a rebuilt system saves hundreds down the road, is worth that extra couple of bucks.

ice-n-tropics on Fri January 11, 2008 9:36 AM User is offline

Quote
Originally posted by: Test Specimen
Marvin,

As a refrigeration systems chemist, I know that there is desiccant in the system that has a much greater affinity for the moisture than the PAG. In a tug of war over water, the desiccant will win quite easily. The water in the system will hang out in the desiccant, not in the PAG or the refrigerant.

If you were crazy enough to pour some liquid water into the A/C system, the DEC PAG will not absorb as much of the additional water as the SEC PAG, so you will get lubrication destroying free water sooner with DEC PAG than with SEC PAG. The SEC PAG will prevent free water from forming as it dissolves the additional water better. You can argue in this particular situation, DEC PAG is a poorer choice than SEC PAG. Since the whole scenario is not going to happen in real life, it doesn't matter.

(Some time back, Old IV guy had a talk with the guy, Bill Brown, whose patent for SEC PAG is used by GM in Mr. Goodwrench SEC PAG. Bill stated the same result, how SEC can reduce free water and oxidation in a moisture saturated system. (Old IV guy)

The water absorption test in the FAQ doesn't tell you what you need to know to make a proper choice of PAG. The actual lubricity and chemical stability were not measured for these products, so there is no way to tell which one is working better in the compressor. To do the testing proerly, you would have to run a compressor test stand and sealed tube aging studies, and these would likely set you back several tens of thousands of dollars.

I was taught that the lubricity of the neat version, before additives, is the lubricity factor first prize. The Falex test (which Bohica has) is a good preliminary wear indicator, but compressor test stand accelerated durability in a high repeatability environment is the best evaluation before field trials. IMO the neat DEC PAG generally has an lubricity advantage. (Old IV guy)

Hope we can reason together and stick with the scientific methods. Heck, remember when Dr. Lube picked a fight with me.
Cordially,
Old IV guy






-------------------------
Isentropic Efficiency=Ratio of Theoretical Compression Energy/Actual Energy.
AMAZON.com: How To Air Condition Your Hot Rod

HECAT on Fri January 11, 2008 9:42 AM User is offline

Oil - good
Moisture - bad
Solvents - bad

I appreciate and value the analysis from both the "real world" and the "lab world" environments.

I want to understand the chemistry and very much value and appreciate the "lab world" information. But as a tool manufacturer, I must apply this understanding to "real world" applications by listening to and seeking answers for my customer base.

No one wants to create confusion by pointing out that the number of relevant and irrelevant variables are huge. There is no magic bullet answer to flushing and flushing chemicals; just lots and lots of variables that we cannot just dismiss, but must understand and find a way to mitigate.

I jumped in on the Mineral Spirits issues as this "solvent remaining" issue is something we have been focussed on for some time. I don't think anyone disagrees that "solvent remaining" is a true issue.

I have put all the commercial flushing products and over the counter solvents in a jar and pulled vacuum, some boil then stop, some don't; even water. In my "real world" explanation it has to do with variables in pressure temperature relationship, latent heat of evaporation, and ambient temps. Which makes me believe that a vacuum pump cannot even remove a few ounces of water, given certain variables were to come into play.

How do you explain this to technicians who work on A/C systems without even having the understanding of such basic principles of A/C operation? If they understood these principles, they would understand that a vacuum pump is designed to remove the air and contained moisture (i.e. humidity). It's not the vacuum pump that didn't remove the crap, it's the technician.


-------------------------



HECAT: www.hecatinc.com You support the Forum when you consider www.ackits.com for your a/c parts.

FLUSHING TECHNICAL PAPER vs2.pdf 

NickD on Fri January 11, 2008 12:04 PM User is offline

Ha, I punched a hole in a Mason jar lid, soldered a brass tube to it, filled a pint jar 1/4 full with water, hooked up my vacuum pump and showed my kids I was holding a jar full of boiling water and acting like I was in pain. But let them feel the jar, it was cool to the touch. If water boils, you have humidity and the pump will draw that off.

New refrigerant, new oils, new problems, something about miscibility is required though some were preaching due to the sheer velocity of the refrigerant, good old mineral oil would work just as well. Certainly not adopted by anyone that I know of. Which brings about a question, when R-12 was first developed back in the 30's, were they having the same problems back then?

Back to Automotive Air Conditioning Forum

We've updated our forums!
Click here to visit the new forum

Archive Home

Copyright © 2016 Arizona Mobile Air Inc.