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An Introduction to R600 and Lokring


Son of Samurai

3,009 views

We’ve all been hearing about R600 refrigerant for years now, and the reality is that it’s no longer an innovation in the area of household refrigeration; it’s the new standard.

With the majority of new refrigerators now being R600 models, repair companies need to be ready to perform sealed system repairs on them. This raises a few questions for these companies: how is R600 different from R134a, and what do I need to service R600 refrigerators?

R600 is a chemical called isobutane with properties that make it desirable as a refrigerant. Refrigerators that run on R600 still work in the same way that R134a refrigerators do – we’re not reinventing refrigeration here. But R600 systems do have different specifications compared to R134a ones, since R600 has different properties (boiling point, etc.).

The big reason why we have new techniques and tools for servicing R600 is because this refrigerant is flammable. As you might have gathered from its chemical name, R600 is an isomer of butane, very similar to what you might find in a lighter. For this reason, the old tried-and-true method of sealed system repair involving brazing is no longer considered safe by some manufacturers.

Now, there’s some debate as to how unsafe it really is – after all, a typical R600 sealed system contains less than a BIC lighter’s worth of butane spread throughout dozens of feet of tubing. In fact, manufacturer opinion is evolving, and some of them are now allowing brazing as an option provided certain procedures are followed.

But for those that don’t want to worry about extra precautions when brazing, that’s where Lokring comes in. Lokring is a set of tools and fittings that allows for sealed system repairs without any need for brazing. It does this by using special pressure fittings which, when properly installed, create completely airtight seals.

Let’s walk through the different Lokring components you need to do R600 sealed system work. Note that these are in addition to the standard tools needed for any sealed system work (vacuum pump, recovery bags, gauge manifold, etc.).

Tubing cutter

51tzA1VmwSS._AC_SS450_.jpg

This is one of the most inexpensive parts of the tool list, but essential for getting the job done right. In order to ensure a hermetic seal with your Lokring connectors, you need clean cuts on the tubing, with no crimping or deformation. I recommend a compact cutter, like the one pictured above. Depending on the job, you sometimes have to make repairs in really cramped corners of the machine, so a bulky tool will just get in the way.

Lokprep

813ALAgkfSL._AC_SL1500_.jpg

Lokprep is an anaerobic sealant (not an adhesive) that fills the tiny gaps between the tubing and the Lokring fittings. It must be evenly and completely applied to both tubing ends before they are inserted into the fitting for a proper seal.

Lokring Assembly Tool

Screen Shot 2022-04-27 at 1.49.57 PM.png

Here are the famous Lokring clamps. This is the tool that the tech uses to squeeze Lokring connectors into place, locking the two pieces of tubing together and, if done correctly, creating a perfect seal.

Lokring connectors

Screen Shot 2022-04-27 at 1.56.01 PM.png

Lastly, the connectors themselves. These are where the investment (and some of the headache) of Lokring comes in. In order to be properly prepared for the various kinds of sealed system repairs he could encounter, a tech needs to be stocked with a wide variety of fittings.

Sealed system tubing varies from 2mm to 11mm in diameter throughout the refrigerator, and the connector needs to match the diameter of the tubing. When the tubes that need to be joined are of different diameters, you need a reducer-type connector that’s properly sized for both.

Screen Shot 2022-04-27 at 1.54.51 PM.png

In addition to diameter, material has to be taken into consideration. The standard brass connectors can’t be used to join aluminum tubing due to galvanic corrosion, so any connections that involve aluminum must use an aluminum connector. Aluminum tubing is usually found around the evaporator, while elsewhere in the refrigerator (such as the machine compartment) will generally have copper tubing.

The upshot of these different connector sizes and materials is this: first getting into Lokring will be an investment. Each individual connector costs between $5-12, and with how many a tech needs to have on hand, that can add up. A typical Lokring starter kit can easily cost upwards of $1,000.

Don’t let that spook you, though. Sealed system work, when done intelligently, can have huge profit margins. In the end, you need to make the call on whether R600 servicing is right for your business – and hopefully this article helps you do that!

Wondering where to buy Lokring? Vulkan, the company that develops and produces Lokring, does not distribute its products itself. So if you’re looking to purchase some Lokring kits, you would want to turn to your preferred appliance parts distributor.

Want to train techs who will be prepared for anything they encounter in the field? Click here to check out our online, in-depth appliance repair training courses at Master Samurai Tech.

  • Like 10

26 Comments


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preston

Posted

thanks that equipment is expansive  

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Patrick.j

Posted

I have my first r600 system job coming up in a few weeks 

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Terry Carmen

Posted

23 minutes ago, Patrick.j said:

I have my first r600 system job coming up in a few weeks 

Let us know how it goes!

  • Like 1
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Rhubarb Tau

Posted

"...the old tried-and-true method of sealed system repair involving brazing is no longer considered safe."

That seemed to be the consensus initially, but several manufacturers now are allowing brazing on their R600a systems, provided that the servicer follows common sense safety precautions.

Purge with nitrogen, pull a vacuum, rinse, repeat. Be careful with any accumulated oil in the system; it's super flammable and very smoky when it burns. 

For Al-Al or Al-Cu joints, a zinc-based brazing rod like Lucas Milhaupt AL822 works well with Oxy-Acetylene, but is tricky with a Turbo Torch

  • Like 4
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FortRepairs

Posted

I've completed the repair of a handful of r600 refrigerators with standard brazing. In my opinion it's an industry money grab to sell overpriced equipment,  that for the time being seems to be monopolized.  The only pain in the ass is trying to get the charge right because the only canisters Ive managed to get are 15oz cans and they don't lend themselves well to weighing on the scale. Still trying to nail down a good method for it so if anyone has any tips let me know!

  • Like 5
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Terry Carmen

Posted (edited)

45 minutes ago, FortRepairs said:

Still trying to nail down a good method for it so if anyone has any tips let me know!

You really do need the weighted base.

As for the "money grab", I'm still just getting started, but bought all the new equipment and can actually see how the lokring and R600 stuff is an improvement.

I started in the R12/dial-a-charge/big scale/torch days, then had to add on a recovery pump and recovery cylinder, so  having a refrigerant that comes in a hand-sized can and where I can vent the old gas out the window and not need a torch is a real treat.

If it costs a couple of thousand dollars to get setup for something that's easier with less overhead and can handle aluminum evaporator joints without melting the liner or leaking,  I'm all in. The cost of the whole thing is only the profit on maybe 3-4 sealed system jobs.

 

 

Edited by Terry Carmen
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ServiceTech_Daniel

Posted

Thanks for the article.
ive been thinking about going to Dyer appliance school (just the r600 course) to get some hands on training . It’s done in a weekend and the price isn’t bad.  
 

 

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Jamiewburden

Posted

Well….. we had about 100 refrigerators    That used r-600 Go up in a warehouse fire. They burned more completely than the others we had. 

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rsb321

Posted

7 hours ago, FortRepairs said:

I've completed the repair of a handful of r600 refrigerators with standard brazing. In my opinion it's an industry money grab to sell overpriced equipment,  that for the time being seems to be monopolized.  The only pain in the ass is trying to get the charge right because the only canisters Ive managed to get are 15oz cans and they don't lend themselves well to weighing on the scale. Still trying to nail down a good method for it so if anyone has any tips let me know!

agreed!

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tonkyman79

Posted (edited)

I guess I must be a dinosaur. I remove the 600a then pull a long vacuum. Then I braze as usual. So far I've never had an issue. I've replaced several compressors and driers. 

When working a real "in the field" job, the connectors add significantly to the job overhead and must be accounted for. On a compressor job with a drier, connector cost can run $75 to $100 dollars at current prices. We can only hope those prices come down. It's hard to pay back a $2000 investment for tools and fittings when you're only doing a couple of those jobs a month. The difference in profit between welding and lokring can be the difference in selling the job or not.

As a side note: I've had several whirlpool refrigerators in an apartment complex with leaking lokring joints from the factory. I've started cutting them out and brazing the tubing together. The owner said it was cheaper for me to repair it than to get Whirlpool to cover it under warranty. Not all things new are better... 

Edited by tonkyman79
  • Like 3
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mehoss

Posted

On 5/6/2022 at 10:21 AM, FortRepairs said:

The only pain in the ass is trying to get the charge right because the only canisters Ive managed to get are 15oz cans and they don't lend themselves well to weighing on the scale. 

Mastercool 98202 High-Precision Charging Scale - Just bought one of these, looks promising.  Screw the can on top of the scale and no hoses to throw off the weight.  It's made for R-600a and R-290, but I also want to see if it can be used for R134a.  

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Budget Appliance Repair

Posted

On 5/30/2022 at 6:31 AM, mehoss said:

It's made for R-600a and R-290, but I also want to see if it can be used for R134a.  

I don't think you are suppose to use any thing that you run R134a thru with R600a so even if this scale could be used for R134a I don't think you would want to use it on a R600a system after running R134a thru it.

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Rhubarb Tau

Posted

5 hours ago, Budget Appliance Repair said:

I don't think you are suppose to use any thing that you run R134a thru with R600a

That's technically true, but I use the same gauges, just try to be careful about oil contamination and keep them in a vacuum between jobs, I haven't had any problems.

Whirlpool's oil-less 'Ant' compressor wants you to use dedicated gauges, and some of the older guys that trained me insisted on having dedicated R12 (or Hotshot) and R134a gauges, but I use the same set for everything, just try to mind my gauge hygiene and haven't been burned yet.

 

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mehoss

Posted (edited)

On 6/5/2022 at 5:33 AM, Budget Appliance Repair said:

I don't think you are suppose to use any thing that you run R134a thru with R600a so even if this scale could be used for R134a I don't think you would want to use it on a R600a system after running R134a thru it.

I only use it for R134a so far.  I will read up on the oils used and compatibility etc. and follow the process if any is required to flush it when I do use it for R600a.  A shot o' nitro probably good enough.     PAG is compatible with R600a, Mineral not compatible with R134a.  But the meaning of "compatible" may simply mean that you won't want to run 2 years solely with that oil.  This doesn't necessarily mean that a tiny droplet will wreck havoc on your system.  I like to deal with facts and that is one reason I never put a mask on last two years.  If it is proven to be a bad thing, these things are only $100 and very small, so no problem having two of them.   Here is a photo of what I came up with - charges vapor here -  to charge liquid, turn the top valve 180 degrees.    I like to charge vapor as I think it gives a more accurate weigh as you don't have an entire ounce or so of liquid in the line.

20220618_072123.jpg

Edited by mehoss
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Rhubarb Tau

Posted

5 hours ago, mehoss said:

I like to charge vapor as I think it gives a more accurate weigh as you don't have an entire ounce or so of liquid in the line.

I rather charge vapor on R600a also, but the issue I've run into is frosting at the tank/bottle if I'm not using a tank heater, tank pressure seems to peter out just before I get to the label charge. 

 

5 hours ago, mehoss said:

 If it is proven to be a bad thing

Yeah, all depends on what you consider proof. I like washing my hands every once in a while, nobody had to prove to me that it's a good idea.

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tonkyman79

Posted

16 hours ago, mehoss said:

 I like to charge vapor as I think it gives a more accurate weigh as you don't have an entire ounce or so of liquid in the line.

20220618_072123.jpg

R134A is a blend of multiple refrigerants with multiple different boiling points. It should only be charged as a liquid. In the vapor state the blend ratio will be off. Easiest to boil refrigerants will collect at the top of the can and make up a disproportionate amount of the charge changing the properties of the original R134a refrigerant. With charges from a can, and at the relatively low quantities used in most refrigerators, the change in performance could be drastic. The only thing that works in our favor (inside the house, not in the garage) is how narrow our operating range actually is. It's possible the performance change will be insignificant in our application... Or maybe I'm just a picky old bastard looking for trouble 😆.

  • Like 3
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  • Team Samurai
Samurai Appliance Repair Man

Posted

2 hours ago, tonkyman79 said:

R134A is a blend of multiple refrigerants with multiple different boiling points. It should only be charged as a liquid.

Excellent comment. The geek name for these types of blends is azeotropes

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Rhubarb Tau

Posted

20 hours ago, tonkyman79 said:

R134A is a blend of multiple refrigerants with multiple different boiling points

I know that's true of R410a, but I'd never heard that of R134a, and some reputable-looking sources seem to imply that it's homogeneous. 

At least according to ACHR News, "R-134a is not a refrigerant blend. It is considered a pure compound and has only one molecule. The R-134a molecule is ethane-based and consists of carbon (C), fluorine (F), and hydrogen (H)."

https://www.achrnews.com/articles/135112-whats-happening-with-r-134a#:~:text=R-134a is not a,%2C and hydrogen (H).

  • Like 1
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  • Team Samurai
Samurai Appliance Repair Man

Posted

7 hours ago, Rhubarb Tau said:

I know that's true of R410a, but I'd never heard that of R134a, and some reputable-looking sources seem to imply that it's homogeneous. 

You are correct, sir! While the comment about liquid-only charging with azeotropes is true, this does not apply to R134a because it is not an azeotrope. Thanks for correcting the record on this.

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tonkyman79

Posted

You guys are good... Even as a old man I learn something new every day. 

"Being a pure refrigerants, R134a, R12 and R22 can be charged either way. The blends like R401A, R409A, R410A and all in the 400 series of refrigerants must be charges as a liquid.

The Azeotropes in the 500 series like R502 and R507 act nearly like pure refrigerants and can be charged either way as well."

Thanks for setting me straight. We never get to old to learn.

Tony T

  • Like 2
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thank God, cuz I have always charged vapor when working on refrigerators.  I did have to pass the EPA Univ, so I have no excuse, but ya never know. 

It takes longer for sure and I have to warm up the can, but just my preference.

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mehoss

Posted (edited)

On 6/18/2022 at 1:08 PM, Rhubarb Tau said:

Yeah, all depends on what you consider proof. I like washing my hands every once in a while, nobody had to prove to me that it's a good idea.

Dirty hands even when they look clean is settled science.   A minuscule essence of mineral oil in my R134a system, I'm not yet convinced this is an existential threat.  "Not compatible" can mean many things.  Diesel and water are not compatible, but I guarantee that I have water in my diesel fuel.  I blow nitrogen through everything and on to the next job.   I'm working on household refrigerators, not trying to keep Ray Kurzweil's body frozen for 100 years.  I have a huge lokring collection and 3 crimpers, I'm still brazing R600a at times.  I just follow the standard procedure to get it all out first.  One thing I use now to braze is a resistance braze, no flame, no nitrogen flow required, makes a perfect braze every time.  These things are awesome!

 

10577

+++.jpg

Edited by mehoss
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tonkyman79

Posted

7 hours ago, mehoss said:

A minuscule essence of mineral oil in my R134a system, I'm not yet convinced this is an existential threat.  "Not compatible" can mean many things. 

I try my best to never cross-contaminate and it's absolutely essential on the wisemotion to have a set of tools just for them but I'm not sure we go a little overboard. 25 years ago I bought an old beater 1987 240 Volvo wagon with the AC dead. I didn't give but $300 for the car so it didn't get much love. I removed the tiny amount of R12 that was in the AC, pulled a vacuum and filled it with 134a (no conversion no nothing). I still have that car and the AC still works. It's an old expansion valve system and it works beautiful. I don't advocate cross-contamination but I believe we stress over it to much. I know it can cause sludge and acids but at what levels.

Wow, we've hijacked the crap out of this thread 😂.

Tony T

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  • Team Samurai
Samurai Appliance Repair Man

Posted

1 minute ago, tonkyman79 said:

Wow, we've hijacked the crap out of this thread

Hijack away! This is a blog post and this is all excellent discussion. Carry on! 

  • Like 1
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Far field

Posted

On 5/7/2022 at 10:43 AM, tonkyman79 said:

I guess I must be a dinosaur. I remove the 600a then pull a long vacuum. Then I braze as usual. So far I've never had an issue. I've replaced several compressors and driers. 

When working a real "in the field" job, the connectors add significantly to the job overhead and must be accounted for. On a compressor job with a drier, connector cost can run $75 to $100 dollars at current prices. We can only hope those prices come down. It's hard to pay back a $2000 investment for tools and fittings when you're only doing a couple of those jobs a month. The difference in profit between welding and lokring can be the difference in selling the job or not.

As a side note: I've had several whirlpool refrigerators in an apartment complex with leaking lokring joints from the factory. I've started cutting them out and brazing the tubing together. The owner said it was cheaper for me to repair it than to get Whirlpool to cover it under warranty. Not all things new are better... 

and that’s the real world proof 

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