nitrogen when brazzing

[tocss]

just wondering if anyone is bleeding nitrogen through the system when brazing and how thay are doing it. cant seem to get it right to be able to do it consistently

[heaterman]

Anyone one who is not flowing nitrogen while appling enough heat to "braze" should be ashamed. What types of problems are you having?

[gary_g]

Here's a good post on this subject:

http://hvac-talk.com/vbb/showthread.php?t=312082&highlight=nitrogen

[tocss]

trying to find the best way to accomplish with out the headache. cant seem to find the right setup /method to be able to repeat continuously.what hoses,fittings,regulating the nitrogen. how dose your setup work.

[tocss]

after watching the video.thanks Gary g I'm still not quite sure. in the video thay have closed one end and put a access port in the other end.does that mean i can close the system off and fill the system with a pound or 2.what if repairing a leak wouldn't the left over oil/ ref build pressures in the system and pop my joints.i was just regulating the nitrogen and bleeding through the opposite end i was brazing then switching.is there a better way?

[Twilly]

Twilli says a waste of time.

[clarkie]

Someone posted a reply to this type of procedure which I thought was very easy. First, get a sandwitch plastic bag and with an awl or knife proceed to poke two small openings thru each side.
Now wrap that bag on the outlet leg of a hose that will expel the nitrogen flowing thru the system. Slowly open the nitrogen regulator to the point where the bag inflates. That is enough flow you need to blaze. Keep it flowing until the joint has cooled. I have found it very hard myself in the past to monitor the amount of flow with nitrogen without overflowing to the point where there seems to be a pinhole in the fitting you are trying to blaze because of too much nitrogen flow, even with a new regulator.
I tried this procedure this week and it works pretty good and is very easy to set up.

[jpsmith1cm]

after watching the video.thanks Gary g I'm still not quite sure. in the video thay have closed one end and put a access port in the other end.does that mean i can close the system off and fill the system with a pound or 2.what if repairing a leak wouldn't the left over oil/ ref build pressures in the system and pop my joints.i was just regulating the nitrogen and bleeding through the opposite end i was brazing then switching.is there a better way?

First thing is first.

You CANNOT braze with positive pressure in the lines. Period. End. Full stop.

The purpose of a nitrogen purge is to keep the inside of the lines free of oxygen while brazing to prevent oxidation. To do this, you do not need a large amount of gas. One of the best descriptions that I have heard is "a fly fart". Yes, it's a bit imprecise, but you will get the point.

My nitrogen regulator doesn't control very well. I am giving some serious thought to a flow meter for this purpose. It allows for very precise control.

My basic procedure is this:

Pull the cores.

Find a place to hook a hose between the regulator and the system. I like this spot to be away from where I am brazing to protect my hoses.

Now, crack the regulator open. You just want a tiny flow. Just enough to feel on the back of your hand or the side of your face. Maybe 1-2 psi.

Hook the hose to the system and allow it to flow for a minute or two. This allows the oxygen to be pushed out.

Braze away.

Leave nitrogen flowing until the joint has cooled.

Remember that this isn't a pressurizing procedure, but a very light flow process.

Post further problems and we can help you troubleshoot them.

[Wirenut]

I use a flow regulator mfg by uniweld. A lot of brazing can be done with a little nitrogen. As someone already mentioned, do not try to braze with any pressure on the system. If anyone thinks nitrogen purge is a waste of time , braze a couple of joints with and without purge, then cut open and see the difference for yourself.

[Tommy1010]

My procedure is pretty simple, but guarenteed for me that is. Depending on which refrigerant the system is, I would use either my gages or nitrogen for the control. My 410's seem to have more control than my 22's but anyhow...Nitrogen through middle hose ofcourse and send the nitrogen through lowside . Remove high side hose FROM gage port and other end on system valve. When I feel/hear nitrogen comin through, slow down til I can just FEEL it on the hair in my ear. Thats it. Anymore than that Im riskin endin up with pinholes.

[FarleyRedfield]

Anyone one who is not flowing nitrogen while appling enough heat to "braze" should be ashamed. What types of problems are you having?

Although I know nitrogen is the preference choice, I refuse to be told I have to do anything to prevent this n that. YES I know the carbon / copper compound is inside. YES everyone will look at me strange. YES I understand the carbon compound can make acid according to some. What no one addresses is that to make the acid there has to be moisture present. Acid can not exist without water in a refrigeration system. The absence of oxygen makes ACID very hard to make. d procedure but that dosnt make it a requirement.

I have used nitrogen a few times while brazing. I have never noted any "pin holes" using 15% BUT NITROGEN OR NOT I have noted pinholes on 5%. SO if I was going to skimp it would be to save my back caring the cylinder and using quality silver bearing brazing rods.

Using it to look for leaks YES Im a go for that and use it for that. nothing cheaper or better.

Now feeling ashamed? No!

Id feel ashamed and a lot worse using nitrogen and not changing the drier, or pulling a vacuum, or using cheap brazing rod then have the thing develop another leak or problem, moisture, stoppage, ...

Now if it works for you and you have a good helper or a good back then great for you. But short cutting the other things I mentioned is also a crying offense.

BTW that method of using a sandwich bag, very resourceful. I will try that next time I do use nitrogen. I will at least not need to get the regulator out. But still have to have a regulator for safety, right?

[Toolboy]

Carbon is not just a problem because of acid, it is also an abrasive.
Isn't any contamination we can avoid in the system, too much and shameful?

[jpsmith1cm]

Acid can not exist without water in a refrigeration system. The absence of oxygen makes ACID very hard to make

Somebody needs to re-visit chemistry class.

A number of acids do not contain any oxygen.

HYDROGEN is a different matter entirely.

[Twilly]

Twilli says JP some of these guys spent too much time in chemistry class....

[FarleyRedfield]

Carbon is not just a problem because of acid, it is also an abrasive.
Isn't any contamination we can avoid in the system, too much and shameful?

Any contamination is exactly my point. There is ALWAYS contamination of some kind in some degree. Abrasive yes. 100% eliminated never. Drier catches whats floating around. And yes some might come back to the compressor then on through the condenser and then stopped by the drier. After its stopped is it still abrasive? If there are big flakes (any size above 7/8") possible I do use nitrogen and on both sides since I have it out already.

But for the most part abrasion only occurs during the first few minutes of start up. And keeping other contaminates out is more important to me than a little carbon. Now if I run ridged copper this is an exception. I cant let go with multiple braze joints, so yes I do it then. Most of the time coiled copper is the choice.

More damage will be done by believing your doing something good with a system open for a longer time, than by resealing the system asap. Remember the moisture the new oils attract? And running nitrogen over the oil does little to remove this. And it is the cause of acid and more than abrasion ever could. That is with proper drier and vacuum change and use.

Im not saying it not important but in most HVAC residential systems the advantage is mute. 4 to 6 braze joints per installation. And 1/2 of these on 3/8 to 1/2 " copper. More damage is also done by a contractor that puts in smaller tubing than is required, but that's another topic. In larger piping systems it is required. I don't do much in the bigger piping so I tend to forget about that part of refrigeration.

[Twilly]

A Discussion of Acid in Refrigeration Systems


By Lawrence R. Grzyll, M.S., ChE., and Robert P. Scaringe, Ph.D., P.E.

Mainstream Engineering Corporation
Rockledge, Florida 32955


The development of acids in the refrigerant of vapor compression refrigerators, heat pumps, and air conditioners can severely shorten the life of the compressor and the refrigerant. These acids can be formed by chemical reactions with components and/or materials of construction, lubricating oils, and/or impurities. The instability of the refrigerant, and thus the formation of acids, is accelerated by elevated temperatures which could be the result of improper operation, such as a failed condenser fan or clogged air flow path. Checking the system for acid is a common maintenance recommendation since acidic conditions can be cleaned up before a compressor motor burns out.

You can check the oil for acid (with any one of oil test kits on the market), or you can
check the refrigerant for the acid using the Carrier TotalTest™ or Mainstream QwikCheck®. We recommend the Mainstream QwikCheck 5-second acid test of the refrigerant because it is accurate, fast and inexpensive. It will detect acid levels well before they get to a harmful
concentration. Prevention of acid build-up is the best preventative maintenance. QwikCheck
works with all refrigerants and all oils, and will not give a false reading when used with POE
(ester-based) oils. QwikCheck’s ability to provide an accurate reading with any oil is critical
because you may not know the type of oil in a system! Many oil acid test kits give a false acid reading with ester-based POE oils because the oil behaves like an acid to the test kit (that is, the ester oil displays amphoteric properties). This is the reason some oil acid test kit manufacturers have one kit for mineral oils and a different test kit for POE oils. If a small concentration of acid is detected, this acid should be removed, not neutralized, before the system is damaged. This is discussed later in this article.

If a compressor does burn out, the oil becomes extremely acidic. If all this acid is not
removed when the compressor is replaced, the elevated acid levels will attack the new
compressor and cause another compressor motor burn-out. Acid cleanup normally involves
changing the compressor oil and the refrigerant to reduce the acid level (and changing the
hermetic or semi-hermetic compressor if it did burn out). Unfortunately, removal of the oil
contained in the compressor does not remove all the acid in the system since acid is carried
throughout the vapor-compression loop by the flowing refrigerant, and therefore, acidic oil or its residue is throughout the system. This residual acid has been shown to shorten the life of the system since it will lead to accelerated acid formation in the system. This has been supported by experimental evidence that after a burn-out the frequency of subsequent burn-outs increases.

A discussion of the types of acids present in the system is necessary to fully understand
the acid removal process. Depending on the refrigerant and oil being used a refrigeration system can contain two types of acids, organic acids (such as oleic acid) and inorganic (mineral) acids, such as hydrochloric acid. Organic acids are soluble in the oil (and do not vaporize) and therefore stay predominately in the liquid oil in the compressor oil sump. Inorganic acids are only slightly soluble in the oil. The organic acids are significantly less corrosive and only found in ester based oil or in systems where a strong oxidizer and high temperatures are present. Therefore organic acids are rarely if ever found in today’s air conditioning systems in any appreciable concentration.

Both inorganic and organic acids are corrosive. However, inorganic acids have a higher
dissociation constant making them strong and very reactive acids, while organic acids react
much slower. In the case of mineral oils, elevated temperature causes the oil to ultimately break down and the ultimate products are carbon and hydrogen gas. Only in the presence of an oxidizer, such as oxygen or air, can organic acids be formed. In the case of synthetic POE oils, organic acid may be initially present (up to 8 PPM) as a residual from the esterification manufacturing process used to make the ester oil. It is therefore clear that the real acid problem in refrigeration/air conditioning systems is an inorganic acid problem not an organic acid.

During a compressor-motor burn-out, inorganic acids are formed as a result of the
refrigerant decomposition at elevated temperatures. These inorganic acids which are formed are only slightly soluble in the oil. A significant portion of the inorganic acids generated during a motor burn-out remain in the vapor phase and react quickly with the materials of construction or are adsorbed in the filter/drier. Experiments have shown that the amount of inorganic acid vapor decreases by 85% in a matter of hours. However, experiments have also shown that an appreciable quantity of inorganic acid (more than enough to destroy another compressor) is also contained in the oil. The concentration of acid trapped in the oil is higher than the quantity which would be simply dissolved in the oil (remember the solubility for inorganic acid is low). This increased acid concentration is a combination of acid dissolved in the oil, acid trapped in the oil due to the oil’s foaming and agitation, acid dissolved in any trapped moisture, and acid adsorbed onto the hard particles present in the oil. This inorganic acid has been shown to remain in the oil for an extremely long time and is in contact with the compressor components, including the motor windings. The inorganic acid in the oil will etch the lacquer insulation from the wire causing the motor winding to short-out electrically and resulting in a subsequent motor burn-out. An acid concentration of 50 PPM has been found to cause compressor motor burn-out in a matter of days!

One way to remove the acidic residue throughout the system is by performing several
flushes of the vapor-compression system with refrigerant, since refrigerant will dissolve the oil and reduce the oil and acid concentrations by dilution. Because of EPA-mandated refrigerant recovery requirements, this is a costly and time consuming task and the cost of the refrigerant used in the flushing operation is not trivial.

An unacceptable alternative approach is to neutralize the acid by reacting the acid with a
basic solution (a solid base dissolved in a liquid carrier), which results in the formation of
undesirable salts as byproducts of the neutralization. Typical neutralization approaches are to neutralize the acid with a base, such as potassium hydroxide (KOH). These bases are solid and are dissolved in a non-water solvent. In such a reaction, the acid and base combine to form a metallic caustic salt and water. While the water can be removed by the filter/drier in the system, the salt remains trapped in the system and could cause problems. Since the salt is a solid it will not vaporize, but instead will remain in the system and cause corrosion!

A further problem with any acid neutralization is the addition of the proper amount of base. Too little base and the refrigerant is still acidic, too much base and the refrigerant is basic. An acidic or basic environment will cause corrosion and premature compressor life (burn-out).

Yet another problem with a neutralization reaction is that the neutralizing materials are
solids and must be dissolved into a liquid solvent carrier or physically held in the vaporcompression system’s flow. The base can not vaporize and therefore the transport of the base throughout the system, even if dissolved in a liquid solvent, is severely limited. Some acid neutralization manufacturers have proposed that the neutralization solution be introduced in the compressor discharge, so that it will be forced through the condenser, filter/drier, TXV, and evaporator, before getting trapped in the compressor’s oil supply. They explain that the liquid neutralization solution is thereby forced to travel throughout the system before becoming trapped in the compressor oil. However, the flashing at the TXV could also cause the solvent to vaporize leaving a deposit of the solid base material, such as KOH, to clog the TXV. Even if the basic solution passes through the TXV, the solvent will likely evaporate in the evaporator leaving the solid basic material in the evaporator.

Every acid neutralization reaction will result in the formation of a salt residue, it is basic chemistry and cannot be changed. Some have proposed the use of sodium bicarbonate as the base but this acid-base reaction will produce a salt and also carbon dioxide gas (an undesirable non-condensable gas).

Finally, these acid neutralization techniques can ONLY be applied to mineral oils or
alkylbenzene oils. This is because the ester-based POE oil possess amphoteric properties which make the oil behave as a base in the presence of an acid and vice versa. Consequently, the added base will react with the ester oil.

An acceptable way of removing the acid is to liberate or free it from the liquid and hard
surfaces that contain the acid, and let the filter-drier in the system remove the acid. A filter-drier does an excellent job of removing acid by adsorption not by neutralization. The problemwith relying on the filter-drier to remove the acid is that the significant portion of acid that is trapped on the hard surfaces and in the oil never gets to the filter-drier to be removed.

After a compressor burn-out change-out, we have measured very high concentrations of
inorganic acids (significantly greater than 200 PPM) in the new compressor’s oil. Theoretically this inorganic acid is not very soluble in the oil, however, this inorganic acid is being trapped in the oil and/or adsorbed on the surface of the solid particles which are present in the system (as a result of the motor burn out). In some cases this acid is also dissolved in water which is trapped in the oil. POE oil typically has much higher levels of water than other refrigeration oils. Agitation of the oil has not been found to release this trapped acid. In order to demonstrate this, an oil sample with an initial acidity value of 133 PPM (inorganic acid) was vigorously stirred for 32 hours using a magnetic stirrer. The acidity dropped 45 percent to 73 PPM. While this may seem like a significant drop, it should be pointed out that the compressor would have burned out in less than 33 hours of operation at this acid level. Therefore, the compressor would fail (burnout) before sufficient acid could be naturally removed from the oil, even if the compressor agitated the oil as much as in this experiment. However, if the trapped inorganic acid could be liberated from the oil (as well as from the acidic surfaces) in a reasonable time (and vaporized), the existing filter/drier in the system would remove this acid. QwikShot® works by liberating the trapped acid from the oil and acid contaminated surfaces. QwikShot also vaporizes so that it
travels throughout the system. The agitation of the acidic-oil experiment was repeated except QwikShot was added to the oil prior to stirring. After 20 minutes the acid was completely (100 %) stripped from the oil by QwikShot! The ordinary filter/drier in the vapor-compression system will adsorb the liberated acid and the QwikShot.

Ideally, the QwikShot should be introduced into the compressor’s oil sump so that is can
thoroughly mix with the oil during compressor lubrication. The QwikShot oil concentrations are less than 1% and will not affect the lubrication properties of the oil. As the QwikShot mixes with the oil it serves to dissolve and liberate the acid from the oil and acidic surfaces. The QwikShot and acid are vaporized (thereby leaving the oil) and travel through the system where they become adsorbed on the filter/drier (molecular sieve, carbon, or activated alumina filterdriers all work). The net result is that the acid is removed and no residue is left in the system, since both the acid and the QwikShot are adsorbed by the filter/drier. The QwikShot dosage charts are formulated so that the QwikShot will not use up the total capacity of the filter-drier, but will leave about half the filter-drier’s capacity for future clean up of water or acid.

By using QwikShot a system can be thoroughly cleaned of acid without leaving any
residue. This has been demonstrated by experiment. In the first experiment discussed,
QwikShot was introduced into the acidic oil of an R-22 system. These tests were repeated both with and without a filter/drier in the system. Remember the performance of QwikShot depends on the use of the filter-drier to remove the liberated acid and the QwikShot from the system. The results of the tests are presented in Figures 1 through 3.

By referring to Figure 1, which shows the QwikShot in the vapor of the R-22 system, it is
clear that the QwikShot is going into the vapor phase as it releases the acid from the compressor oil. However, if the filter drier is not present the QwikShot will remain in the system and eventually reach equilibrium which means no more QwikShot can vaporize and acid liberation will stop. This is also supported by Figure 2, which shows the drop in QwikShot in the oil. Note that by using the filter-drier, more than 60 percent of the QwikShot is removed from the oil in less than 6 minutes (0.1 hour).

However, the key issue is acid removal, and these results are shown in Figure 3. By referring to Figure 3 it can be seen that when a filter-drier is used about 7% of the acid is
removed in less than 6 minutes (0.1 hour) and about 18% is removed after 1.5 hours. What is not shown in the Figure is that it takes about 12 to 16 hours to remove all the acid from the system. Also note that without the filter-drier the acid removal is much slower. The filter-drier should always be changed when QwikShot is added to the system. As shown in Figure 3, a failure to change the filter-drier when the QwikShot is added could result in a 3-times slower reduction in acid removal and complete acid removal may not be achieved!

The experiment described above was repeated for a R-134a system. This data is presented in Figures 4-6. The results are similar to the R-22 results, but the QwikShot removed the even more acid in 1.5 hours in the R-134a system (Figure 6).

http://www.qwik.com/images/graph1.gif
http://www.qwik.com/images/graph2.gif
http://www.qwik.com/images/graph3.gif
http://www.qwik.com/images/graph4.gif
http://www.qwik.com/images/graph5.gif
http://www.qwik.com/images/graph6.gif

The advantage of this patented QwikShot approach of liberating the acid is that there is no acid neutralization reaction and therefore no formation of a caustic corrosive solid salt residue. This innovative technology to provide this acid liberation is only available with QwikShot manufactured by Mainstream Engineering Corporation. Remember that when using QwikShot, not only is the acid removed from the system by the filter-drier, the QwikShot is also removed by the filter-drier. QwikShot acid treatment leaves no residue in the system.

[I_bend_metal]

trying to find the best way to accomplish with out the headache. cant seem to find the right setup /method to be able to repeat continuously.what hoses,fittings,regulating the nitrogen. how dose your setup work.

Sorry I didn't make that clear in the video.....the end that is pinched is not closed all the way, there is still a small opening to allow the N2 to run through the pipe....I was trying to simulate more of an actual "flow" of N2.....

My video editor and myself are currently working on a new video that will show our set-ups and how easy it is to do......

[openclasspro]

i use a flowrater as well, zero issue here when brazing, while it's a perfetc world, i do my best to keep the inside of my piping with as little oxidation as possible...

[FarleyRedfield]

Somebody needs to re-visit chemistry class.

A number of acids do not contain any oxygen.

HYDROGEN is a different matter entirely.
And yes I do need to revisit chem class among other classes as well.

I meant that in a refrigerant breaking down in the presence of an electrical arc the acid cannot form without also releasing or formation of Oxygen in some type. Because it releases the Cl and H. Which is one of the reactive elements causing moisture and more trouble. Right? I may be wrong but I know I remember being told that refrigerant breakdown during the high temperature of an electrical arc (being 10,000'f +), it forms acids and MOISTURE, which during the vapor compression cycle cause more of the same. Of course this is during a burn out. Did I remember this incorrectly? Maybe I was listening to a drier sales / demo class... Maybe I assumed this because of acid formation and the MOISURE. . . I mean if we can find water on the moon (which has been done and latest count is no less than 3 different types of moon water) in the vacuum of space only follows that here where we have oxygen in around 20% of the atmosphere and every compound has to have some PPM of O2 Locked up in it some where. Since Hydrogen and Oxygen are 2 of the easiest elements to combine, water vapor the compounds and elements have to be (unless refined to the Nth level) in everything at some point. And at some point they are so insignificant as toNOT be a real problem. But also at some level they begin to multiply as well.


And when refrigerant breaks down we all know Hydrogen is one of main elements set loose and it combines so easily with oxygen forming water that this has been one of the greatest points of contamination. The larger the system the more an inert gas needs to be used while brazing. And Im sure in NOT using nitrogen some compounds are present that other wise might be reduced. But if acceptable levels of such contaminate are not a direct problem most people will take the route of least work.
RIght?
The times it becomes a problem, not using nitrogen or inert brazing gas, I would think there would be more than just the practice of using nitrogen during brazing causing problems. This due simply because it is so rare to hear something like: "I saw this job someone did and the copper oxide inside the tubing was so thick, I know they didnt use nitrogen when brazing up the piping" or "The drier had all this black stuff in it.." I have yet to hear this from anyone or see it myself. And when I have seen it a burn out was present. But as far as NOT using Nitrogen (or other inert gas) on all brazing being a problem its not at an epidemic level.

So there for again on smaller piping 7/8and down its a mute point for me personally. 1-1/8 and up a different story.

[crymtide]

As a welder in my former life we used flowmeters that measured inert gas flow in single digits for an Argon puge on Stainless steel TIG welding. These flow meters are available at a welding supply and can have multiple scales on the flowmeter for different gases ie. Argon, Nitrogen. With this rig regulating the flow down to 1 or 2 psi is a piece of cake. once your hooked up to the system with the flowmeter you allow flow to any dead spots by opening a schraeder or other port and check for a good purge with a flame that will be extinguished by the lack of oxygen when the purge has expeled same. You then leave a small hole at the end which should only have enough flow to be barely felt or not felt on the wet back of your hand and the purge checked by the flame extiguishment method, at which point you can braze with no oxidation. The larger the system the longer this takes. Argon is the best gas for this and is more inert than nitrogen and more costly. in TIG welding Nitrogen can be used on carbon steel though you will find a small amount of residue on the inner surface of the weld. For stainless Argon is required to achieve a clean weld of x-ray quality. It will be noted that Argon is more expensive than Nitrogen (a cost which could be figured in). It all depends to what length you are willing to go to not have oxidation in the piping sytem.

[Airmechanical]

just wondering if anyone is bleeding nitrogen through the system when brazing and how thay are doing it. cant seem to get it right to be able to do it consistently


whats the problem?

take out shrader valves hook up the nitro to high side

turn the regulator down to zero

open nitro bottle

then turn the regulator handle about a 16th of a turn or less

put your finger over the low side port to verify flow

anywhere between a half a psi to 2 psi is where you will be at and that's fine

it's not rocket science, don't need no flowrator's, or special low pressure stuff

try it it's easy, you will get more consistent with your method each time

hey, a florator is just another regulator, why would you need a regulator for a regulator

unless your regulator was screwed up, in that case replace regulator



.

[FarleyRedfield]

Now I have to get ready for chem class, csuse me.

[Airmechanical]

[The advantage of this patented QwikShot approach of liberating the acid is that there is no acid neutralization reaction and therefore no formation of a caustic corrosive solid salt residue. This innovative technology to provide this acid liberation is only available with QwikShot manufactured by Mainstream Engineering Corporation. Remember that when using QwikShot, not only is the acid removed from the system by the filter-drier, the QwikShot is also removed by the filter-drier. QwikShot acid treatment leaves no residue in the system.

in general there is no argument with most of those facts, but;

have the company that makes Acid Away do one of theses studies

and i bet you get MUCH different results

as well as discovering all the bad side effects from this Quickshot snake oil



.

[jpsmith1cm]

And yes I do need to revisit chem class among other classes as well.

The times it becomes a problem, not using nitrogen or inert brazing gas, I would think there would be more than just the practice of using nitrogen during brazing causing problems. This due simply because it is so rare to hear something like: "I saw this job someone did and the copper oxide inside the tubing was so thick, I know they didnt use nitrogen when brazing up the piping" or "The drier had all this black stuff in it.." I have yet to hear this from anyone or see it myself. And when I have seen it a burn out was present. But as far as NOT using Nitrogen (or other inert gas) on all brazing being a problem its not at an epidemic level.

So there for again on smaller piping 7/8and down its a mute point for me personally. 1-1/8 and up a different story.

I cut out a fair bit of your post because I take no issue with it.

The part I left is on topic and I take issue.

I have removed drier cores from systems with 100# of pressure drop across them on more than one occasion. Suction filters with 10# or more. Plugged TXV screens by the hundreds.

To say that NOT flowing inert gas during brazing is a moot point is irresponsible at best. On par with saying that evacuation is over rated.

[BobbyBJr]

We gave all of our install mechanics flowraters and it drastically cut down on the amount of nitrogen they were using. No, it isn't expensive, but every little penny adds up.

[crmont]

whats the problem?

take out shrader valves hook up the nitro to high side

turn the regulator down to zero

open nitro bottle

then turn the regulator handle about a 16th of a turn or less

put your finger over the low side port to verify flow

anywhere between a half a psi to 2 psi is where you will be at and that's fine

it's not rocket science, don't need no flowrator's, or special low pressure stuff

try it it's easy, you will get more consistent with your method each time

hey, a florator is just another regulator, why would you need a regulator for a regulator

unless your regulator was screwed up, in that case replace regulator



.

I'm with A.M. Keep it simple and therefore consistent.

All I have ever used is the regulator and yellow jacket 4 port manifold.

Purge all the air out and then keep a slightly positive flow while welding.

I use my upper lip to feel the flow or put your thumb over the hose and watch your low side gauge. Don't make it a hassle IMHO.

[FarleyRedfield]

I cut out a fair bit of your post because I take no issue with it.

The part I left is on topic and I take issue.

I have removed drier cores from systems with 100# of pressure drop across them on more than one occasion. Suction filters with 10# or more. Plugged TXV screens by the hundreds.

To say that NOT flowing inert gas during brazing is a moot point is irresponsible at best. On par with saying that evacuation is over rated.

I would say that you have been following someone that has more trouble with more than just nitrogen flowing through the system while brazing. From your post above seems you must believe this one thing Nitrogen during braizing would have kept you from finding all these problems.

I submit that you must be working on large tonnage systems to find all this. AND AGAIN tubing / piping that is of a larger size needs the nitrogen practice. As far as irresponsible it looks tome like your ready to throw the baby out with the bath water on this one issue making all this work you've uncovered. If you have found all these things as you say (And I dont doubt you 1 bit) Are you sure that not using nitrogen during brazing is the cause? I mean if you know this please explain how you know it. I want to be just as responsible as you seem to tout.

Throwing all faults of stopped up driers in one blanket statement sure sounds irresponsible to me. As well as short sighted. And possibly leave the real culprit in place for future problems. Unless I miss understand what you are saying. Kinda hard to miss it the way you said it though.

[jpsmith1cm]

I would say that you have been following someone that has more trouble with more than just nitrogen flowing through the system while brazing. From your post above seems you must believe this one thing Nitrogen during braizing would have kept you from finding all these problems.

I submit that you must be working on large tonnage systems to find all this. AND AGAIN tubing / piping that is of a larger size needs the nitrogen practice. As far as irresponsible it looks tome like your ready to throw the baby out with the bath water on this one issue making all this work you've uncovered. If you have found all these things as you say (And I dont doubt you 1 bit) Are you sure that not using nitrogen during brazing is the cause? I mean if you know this please explain how you know it. I want to be just as responsible as you seem to tout.

Throwing all faults of stopped up driers in one blanket statement sure sounds irresponsible to me. As well as short sighted. And possibly leave the real culprit in place for future problems. Unless I miss understand what you are saying. Kinda hard to miss it the way you said it though.

It is simple logic, really.

Installer guys show up. They run a bunch of pipe, sometimes, they even build a whole new store.

I find plugged screens and plugged driers behind them to the point that I now make it a practice to replace the driers and clean the screens before starting any commissioning work.

When asked about their use of purge gas, they say "It takes too much time to set up."

Hard to argue with that sort of idiocy.

Could there be other causes? Sure.

Is the lack of a purge gas a large contributing factor? Yep.

Would the screens and driers plug if they did use a purge gas? I don't believe that they would.

Exhibit A:

This is a picture of the debris removed from a TXV screen in a frozen foods case in a newly remodeled grocery store. No purge gas was used in during the installation.

http://www.facebook.com/photo.php?pid=201703&l=b12f966314&id=1812798342 (hopefully that works)

[FarleyRedfield]

It is simple logic, really.

Installer guys show up. They run a bunch of pipe, sometimes, they even build a whole new store.

I find plugged screens and plugged driers behind them to the point that I now make it a practice to replace the driers and clean the screens before starting any commissioning work.

When asked about their use of purge gas, they say "It takes too much time to set up."

Hard to argue with that sort of idiocy.

Could there be other causes? Sure.

Is the lack of a purge gas a large contributing factor? Yep.

Would the screens and driers plug if they did use a purge gas? I don't believe that they would.

Exhibit A:

This is a picture of the debris removed from a TXV screen in a frozen foods case in a newly remodeled grocery store. No purge gas was used in during the installation.

http://www.facebook.com/photo.php?pid=201703&l=b12f966314&id=1812798342 (hopefully that works)

Well My friend,
Had you read my post closer you would note that I am in agreement with you. On piping of larger size (and I add to this for clarification LONGER RUNS) I strongly recommend it. I have seen some of the jobs your talking about and yes the introduction of nitrogen in the cases Ive seen would help but there is no substitute for replacement of or use of NEW COPPER lines, flushing the piping and removal of all old oil and wax / moisture. These are stores built back in the 50's 60's and still using the same copper lines just add on the ends and run to where the new case goes (and very seldom is the case new). In situations like Im describing no amount of nitrogen will clean whats been in place for 50 years plus. And using nitrogen on small leak repairs like I have had to do is a mute thing when put up against such existing trash.
So Seems we have had a little missed communication. While I have no habit of using nitrogen Im not all together adverse to it. In fact just last summer I installed an new walk in freezer and refrigerator with rigid piping and did I did use nitrogen during brazing and the lines while 1/2, 3/4, and 7/8" were small the length was well over 30 feet. I just would not haul it out for a txv or Head master replacement or some other limited parts replacement, or a leak repair.

I see in your pic what appears to be "dust" or possible compressor components. I have nothing to get an idea of the scale or distance the photo was taken from. This stuff looks more like drier desiccant, and if these BOZOES were like the bozoes here Im betting they did not:
1. change the drier (s)
2 pull a vacuum (this takes just as long or longer)
3 weigh in a charge (this takes just as long or longer)
4 mark what refrigerant was in the system or how much not that it takes any time to do this but it is time and good practice.
5 use vibersorbers or bother to install them correctly (costs more and takes more time)
6 Support the piping as required (takes way too much time and costs for hardware)
7 Check pitch of the piping for oil return (takes too much time)
Now could any of the above have caused the problem you have pictured....? You bet ya!

All of these things are more important than nitrogen on small parts or leak repairs. Not saying it isnt a good practice its just what ever the competition does the rest of us do to.

Nuf said.

[jpsmith1cm]

Yes, it was a cell camera picture.

I dumped the crap from the TXV inlet screen along the case trim and snapped a pic of it.

It is all oxidation from poor brazing practices.

[jpsmith1cm]

As far as doing the Nitrogen purge on smaller systems, why not?

It only takes a minute or two to set up.

It prevents the oxidation, thereby removing that as a system contaminant.

You are changing the drier and pulling a vacuum anyway, so non-condensibles is a non argument.

Why would a person NOT do whatever was in their power to do the best job possible?

[RyanHughes]

Not a professional here, just trying to understand:

Does N2 prevent oxidation or simply "sweep" it out of the system? If it just prevents it, then everything I've read makes sense to me.

Looks to be pretty important from the video I've seen, but I've never had a service tech work on my system and follow this procedure. I don't think I have any issues, but then again, I wouldn't be able to see them.

[jimj]

Not a professional here, just trying to understand:

Does N2 prevent oxidation or simply "sweep" it out of the system? If it just prevents it, then everything I've read makes sense to me.

Looks to be pretty important from the video I've seen, but I've never had a service tech work on my system and follow this procedure. I don't think I have any issues, but then again, I wouldn't be able to see them.

It prevents it.

[RyanHughes]

It prevents it.

Thanks Jim. Send some more of that AZ heat our way. It's just starting to warm up in MD. :)

On the brazing subject, seems many techs feel it unnecessary or "overkill" to flow nitrogen on a residential setup with just four braze joints.

[jimj]

Ryan, our industry is very slow to change. Unfortunately many techs either don't know or care to do it correctly. Cheap consumers just make the problem worse.

Having said that more and more contractors are beginning to care about and know about manual J,D,and S. Along with that comes education about air flows and proper evacuation of systems. ACCA's QI also is moving the industry in the correct direction.

On the weather front we are in the mid to high eighties for the next 10 days or so. Our phones are beginning to ring and all our people have big smiles on there faces for the first time in months.

[WorkinforAHack]

I couldn't even get my installers at my last company to remove txv bulb while brazing in so they wouldn't pop the bulb let alone run nitrogen through while brazing. Hell they wouldn't even put nitrogen in to leak test! Sometimes I wonder if the bastards even pulled a vac!!!!!!!!! Thank God I'm unemployed now! Company went under because of all the hacks I worked with. I think right now I would rather have no job then continue getting grey from dealing with all the BS of the other employees!!!!!!

[crmont]

I couldn't even get my installers at my last company to remove txv bulb while brazing in so they wouldn't pop the bulb let alone run nitrogen through while brazing. Hell they wouldn't even put nitrogen in to leak test! Sometimes I wonder if the bastards even pulled a vac!!!!!!!!! Thank God I'm unemployed now! Company went under because of all the hacks I worked with. I think right now I would rather have no job then continue getting grey from dealing with all the BS of the other employees!!!!!!

Ha! Love the nic. It sounds like good riddance to me too.

[heaterman]

Originally Posted by heaterman:
Anyone one who is not flowing nitrogen while appling enough heat to "braze" should be ashamed. What types of problems are you having?



Orininally Posted by FarleyRedfield: Although I know nitrogen is the preference choice, I refuse to be told I have to do anything to prevent this n that. YES I know the carbon / copper compound is inside. YES everyone will look at me strange. YES I understand the carbon compound can make acid according to some. What no one addresses is that to make the acid there has to be moisture present. Acid can not exist without water in a refrigeration system. The absence of oxygen makes ACID very hard to make. d procedure but that dosnt make it a requirement.

I have used nitrogen a few times while brazing. I have never noted any "pin holes" using 15% BUT NITROGEN OR NOT I have noted pinholes on 5%. SO if I was going to skimp it would be to save my back caring the cylinder and using quality silver bearing brazing rods.

Using it to look for leaks YES Im a go for that and use it for that. nothing cheaper or better.

Now feeling ashamed? No!


I stand by my original statement. Ever seen a compressor's bearings after seizing because of copper oxide contamination in a system. For shame, for shame for shame!

[FarleyRedfield]

I stand by my original statement. Ever seen a compressor's bearings after seizing because of copper oxide contamination in a system. For shame, for shame for shame!

No I have not. Seen broken pistons, ring glands, rods, seized rods, bad crankshaft bearings. All from some type of liquid slugging or lack of lubrication though, not any from copper oxide. Maybe I live a protective life. Then again I'll admit I haven't seen everything, YET!

[Kev-Bo]

The installation instructions that comes with our units, tells us to use N2 while brazing. How about you other contractors?

[Airstar Solutions]

ALL mini split manufacturers recommend due to their EEVs.

[blitzz86]

The installation instructions that comes with our units, tells us to use N2 while brazing. How about you other contractors?

I only use N2 on 410a systems and expensive r22 systems. Where I used to live on the coast the units were junk in 5 years anyway so not much point in using N2. Never had any issues but you know what im going to start using N2 on all sytem installs theres no reason not to, really its not worth it and only takes a minute to set up and the costs are minimal. Just do it, its good practice.

[surenuff]

Boy, Twilli hit it on the head and on the head and on the head. Bottom line, there is a right way and a wrong way. No in between on msot things. If you are not purging while you are brazing, then you are doing it wrong and introducing contaminates into the system that will effect overall performance and life span.

[surenuff]

As far as doing the Nitrogen purge on smaller systems, why not?

It only takes a minute or two to set up.

It prevents the oxidation, thereby removing that as a system contaminant.

You are changing the drier and pulling a vacuum anyway, so non-condensibles is a non argument.

Why would a person NOT do whatever was in their power to do the best job possible?

Not many like ya left JP. I hope as long as I can do, I'll do the best I can. Ain't in hard to believe we are even having a discussion on purging or not purging being right???

[jpsmith1cm]

Not many like ya left JP. I hope as long as I can do, I'll do the best I can.

Funny thing is, I'm one of the 'new' guys.

I'm trying to turn the tide, though. One apprentice at a time...

[surenuff]

I doubt your all that new. I am also a member of RSES with you. The problem is not that they have not been told to use the purge, it is that they won't