# Cross Contamination of refrigerants



## user84377 (Jan 7, 2012)

One thing that is a bit unnerving in the HVAC industry is how many service departments fail to properly equip and inform regularly their service staff.

A huge problem is cross contamination of refrigerants. Dedicated recovery equipment that is seperate from any normal servicing or charging of customer equipment is key. In addition having the service techs purge and evacuate their gauges and hoses prior to using a different refrigerant is vital. 

It only takes a very small amount of refrigerant to contaminant a system using a different refrigerant. Those service techs that are responsible for servicing equipment with various refrigerants have a lot on their plate. Service departments should ramp up their reminding of the basics and also ensure that their techs know that they will have the proper equipment to work with. 

These days it is very common for techs to use a single manifold for all their servicing. This creates a problem without proper purging. In addition using the same gauges and hoses for both R22 and R410 is a NO NO b/c the mineral and POE lubricants do not play well together. In light of the previous statement, it happens all the time.


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## Dr Heat (Dec 25, 2008)

This is nothing new when I started in the trade we had R11 R12 R22 R500 R502 Ammonia and Brine. 

So if a tec cant handle 410A and 22 his boss doesn't need to give him a refresher he need the boot or a pink slip.:whistling


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## DuMass (Feb 6, 2008)

Well, you could probably assess at least some of the blame to gauge manufacturers who started making analog manifolds designed for 22/404A/410A and 22/134A.
If it’s that much of a problem now, it’s probably only going to get worse as more techs switch to digital manifolds that can handle a multitude of different refrigerants.
The automotive AC industry has a lot more stringent requirements as far as purity of refrigerant and oil, separate gauge manifolds, hoses, charging and recovery equipment for each refrigerant to prevent cross contamination, mainly for R12 and 134A with MO and PAG. 
It seems the gauge manifold manufacturers claim that as long as the tech purges his manifold and hoses properly, the trace amount of oil and refrigerant remaining is not enough to do any real damage in larger systems like most HVAC techs work on, but is this actually done very often… probably not.
I believe most all recovery units have had self-purge for quite a while now, so not sure how much easier they can make it on that end anyway.


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## Doc Holliday (Jan 2, 2012)

I have the Yellow Jacket anologue 410-A/R-22 gauges and use my single set for both refrigerants. I always purge my manifold, more to not have any air get into the system, but outside of that and the oils and their hygroscopic compatibility there has been a long standing debate as to whether it actually makes a difference to even flush a line set on a change over. Many techs swear that they have not flushed a 22 lineset on a 410-A conversion and the system never had a problem.


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## DuMass (Feb 6, 2008)

The main reason you flush the lines on an R22 to 410A conversion isn’t so much about residual MO, it’s because of the solvent properties of the POE oil. It will wash all the crap out of the lines and could eventually plug up your LLD and/or TXV. Very few guy ever used a nitrogen purge when brazing lines and fittings on older R22 systems using MO, so all of those carbon deposits on the inside of the lines are now on their way to the LLD and TXV. 
A small amount of residual MO left in a system probably wouldn’t be an issue, since POE itself is compatible with MO as well as HCFC’s like R22, but the MO has poor miscibility with HFC’s like 410A, so with larger amounts you would likely get poor oil return. The residual MO will mix with the POE okay, but will eventually migrate and collect in the coldest parts of the system so you could end up with the MO logging in the evaporator.


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## Doc Holliday (Jan 2, 2012)

I always use nitrogen. I keep two full tanks on the truck. That's a given, not that "no one ever uses nitrgen". I'd actually have to strongly disagree with that statement as I believe everyone, at least down here, does.


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## DuMass (Feb 6, 2008)

Yes, but I didn’t say that no one ever used nitrogen, just that very few would use it years ago, which unfortunately is true. I can remember back in the mid 1990’s when R410A really first started to come on the scene in this area and very few guys doing HVAC back then, especially Resi, used nitrogen to purge their lines while brazing, since the MO used with the more common refrigerants back then like R22, doesn’t have the solvent qualities that POE does, it wasn’t really considered a priority like it has been for the last decade or so.
I agree that it has always been considered good work practice and I’m sure there were some that did use it, but they would have been in the minority back then.
But even so, you should never just assume that everyone that came before you did things the way they do now, or the way you do, because without actually being there to watch them, you can never be sure.
I mean just look at the OP’s topic for this thread. :laughing:


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## Doc Holliday (Jan 2, 2012)

Flowing nitrogen while brazing is entirely different than flushing a line set with the use of nitrogen on a refrigerant changeover. I always always always flush linesets, changeover or not, as well as pressure test them with nitrogen.

I do not flow nitrogen while brazing. I don't want to start a World War III over me saying that but I am positive that my lines have no flake residue after the fact as I blow them out throw the shraeders after I'm done brazing BUT if there just so happens to be any then the filter drier will catch it as that is their specific job. 

I'll leave it at that. 

<uh oh?> :laughing:


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## DuMass (Feb 6, 2008)

Nope, no WWIII here, at least not from me. You can do things any way you want on your jobs. 
We are kind of getting off topic though, but it seems that the OP won’t be around anymore, so no matter I guess. Just for the sake of clarity though and so we’re on the same page, it sounds like maybe what you’re referring to as flushing the lines with nitrogen after brazing is what most techs would call a nitrogen sweep. Flushing like I am referring to would involve using an actual flushing agent like RX11 or Quick Flush to clean residue out of the lineset, etc.


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## Doc Holliday (Jan 2, 2012)

RX-11 is nothing compared to nitrogen. I used to use it, we all did. You are supposed to follow through after introducing a flushing agent into a line with nitrogen. We just took out the RX-11, a lot of the industry has. Quicker, cheaper, same if not better result with less agents to worry about being removed.


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## DuMass (Feb 6, 2008)

Yeah, there are some others out there now though like Super Flush that say they don’t have the halogenated solvent base. You still have to blow out the lineset after you use it, but at least if there is any remaining flush left behind it won’t eat the compressor like residual RX11 would.


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## flashheatingand (May 3, 2008)

DuMass said:


> but it seems that the OP won’t be around anymore, so no matter I guess.


Too bad. He was passionate about the trade and did have a lot to bring to the table.

Maybe he will come back.


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## Doc Holliday (Jan 2, 2012)

Hey Flash, there's a thread down in the off topic section that may or may not interest you.


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## Dr Heat (Dec 25, 2008)

when I started in this trade we would use 30 pounds of R11 to flush out a burned out compressor then run 15 to 20 pounds of R22 through straight to the atmosphere so you can thank me for this warm weather.

By the way r11 was $15.00 per 30 and R22 was $25 per 30 R12 was $18 per 30

Today I was quoted $400.00 for #30 R22

Oh ya Transformers Hum :clap:


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## DuMass (Feb 6, 2008)

Yikes! I’m guessing that is for virgin R22. Are any suppliers offering reclaimed at a better price or is that stuff all going over to Europe? 
Adding additional insult to injury, the prices for HFC’s have also been noticeably creeping up over the last several years.


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## DuMass (Feb 6, 2008)

flashheatingand said:


> Too bad. He was passionate about the trade and did have a lot to bring to the table.
> 
> Maybe he will come back.


I suppose. I think all anyone really needs to do on any open internet forum is just simply be willing to converse with others and at least entertain other opinions without taking offense or pulling your hair out over it.:thumbsup:


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## flashheatingand (May 3, 2008)

And how. I would have been gone awhile ago, if I took things too personal. Nonetheless, I thought he did have some good posts. BTW, where have you been?


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## DuMass (Feb 6, 2008)

flashheatingand said:


> And how. I would have been gone awhile ago, if I took things too personal. Nonetheless, I thought he did have some good posts. BTW, where have you been?


I’m usually tooling around in the background here and there, but don’t really have time to post much these days. Probably because I type so damn slow.:wheelchair:


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## DuMass (Feb 6, 2008)

Doc Holliday said:


> RX-11 is nothing compared to nitrogen. I used to use it, we all did. You are supposed to follow through after introducing a flushing agent into a line with nitrogen. We just took out the RX-11, a lot of the industry has. Quicker, cheaper, same if not better result with less agents to worry about being removed.


Doc, you kind of left me wondering. How do you guys handle reusing a lineset on a burnout as opposed to a straight 22 to 410A system upgrade? Do you then actually flush the lines with an agent or do you use Quick Shot or something similar in the oil along with an SS cleanup filter?


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## flashheatingand (May 3, 2008)

Doc Holliday said:


> Flowing nitrogen while brazing is entirely different than flushing a line set with the use of nitrogen on a refrigerant changeover. I always always always flush linesets, changeover or not, as well as pressure test them with nitrogen.
> 
> I do not flow nitrogen while brazing. I don't want to start a World War III over me saying that but I am positive that my lines have no flake residue after the fact as I blow them out throw the shraeders after I'm done brazing BUT if there just so happens to be any then the filter drier will catch it as that is their specific job.
> 
> ...


Why do you remove them after brazing? I always remove before brazing. I had a post once in regards t Flush out/Super Flush or what ever they have on the market. The gist of it was how many systems probably aren't flushed out properly in the first place. The problem in my opinion lies in everybody's hands, manufacturers should play a more vital role in hvac education.

The cross contamination in the guages thing. For starters, there's no need to put hoses on the equipment unless you suspect there is a problem. Part of the "if it aint broke, don't fix it" thing". If it was fine for many summers in, leave it alone. You risk cross contamination weather hoses carry both gasses or not.

Having said that, there is the professional thing about keeping separate hoses.


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