Alternative to brazing?

[Boogerlad]

this is the only forum here that involves brazing, and it appears you need high temperatures and some skill to braze properly. Would something like http://www.durafix.com/ work? Would you still have to deal with oxidization? I think it would withstand the pressure within an ss unit, but am not sure... Any opinions?

Thanks

[teyber]

for brazing copper? for these systems which often see 300psig/22bar or so its really important to use at least 15% silver brazing rods. you can use a mapp torch

[Boogerlad]

would the stuff i mentioned be strong eneough? If it was strong enough, would it be easier to use? What temp does copper oxidize really fast?

[[XC] gomeler]

Durafix looks like a low-temp braze for aluminum. Won't work seeing as we used copper in our systems. Brazing is easy work, just takes a little patience.

[Boogerlad]

if you watch the video, it does copper too. I was surprised as well. Do aluminum evaporators work, or would there be galvanic corrosion?

[sjg0]

I dont exactly see what the point of this would be. The only difference is this you can use propane instead of MAPP. You still need (semi) high temperatures and skill brazing. And the aluminum is weaker...

[teyber]

if you watch the video, it does copper too. I was surprised as well. Do aluminum evaporators work, or would there be galvanic corrosion?

Galvanic corrosion isn't really a worry for phase change, just watercooling. galvanic corrosion doesn't just happen for aluminum but for any dis-similar metals, many compressors use seals that are aluminum and havn't had any problems. Also its when with a conductive material between the two dissimilar materials, im not sure if hfc's are conductive :shrug:

Aluminum is tricky as its not quite strong enough to use as an evaporator, hopefully someone proves me wrong but at least chilly1 had frustrations with alu

[plasmatique]

http://www.vulkan.fr/lokring/2006/raccord/raccord.htm

You could use this but it returns a lot

[[XC] gomeler]

Or you could just braze the copper together and form a solid seal :p:

[teyber]

yeah im with gomeler- brazing really isn't a big deal at all

[sdumper]

Its not the brazing its the buying of a Nitrogen tank, regulator and then playing with just the right purging pressure which can be a pain for someone just starting.
I went through a ton of nitrogen at first until I realized I just needed to displace the oxygen in the line I was brazing and not maintain pressure blowing through it.

All of that said I would just go with a MAPP torch and the cheapest purging setup you can put together...for SS Co2 is fine...

[SexyMF]

It is not absolutely necessary to:

1) Change compressor oil because it's been open to air for a few days
2) Purge during brazing (Propane is fine as a shield gas. Safer than lighting a BBQ)
3) Use a proper vacuum pump to evacuate the system
4) Bother with a high side access valve
5) Insert a filter/dryer

The only thing you do need is a MAPP torch, guages and some self fluxing rods like Silfoss. Vacuum pump can be made from freezer compressor.

[godmod]

Vacuum pump can be made from freezer compressor.

An offense to all the real vacuum pumps out there...

[sdumper]

Still I wouldn't want risk a poor vacuum and freezing moisture/corrosion build up in my lines because of it.

[SexyMF]

Still I wouldn't want risk a poor vacuum and freezing moisture/corrosion build up in my lines because of it.

I don't mean this in a flame war kind of way but quantify the statement. How much moisture is in a system and how much damage could it do over the lifetime of the system? I built several systems using two in-series freezer compressors as a vacuum pump. I'm not the first. Never had a problem. It wasn't till later I purchased a vacuum pump. If I'm not fussed why did I bother purchasing the pump? because it does't a better job, but primarily because it does it faster.

To make a refrigeration system is very easy. To make it work to specs takes knowledge and calculations. I would pick the person with design skill and less tooling to make a better system than a rookie with all the kit.

It is obvious in this forum that there are only a handful of people who can do the required calculations and who innovate. The rest just copy (which works fine, to a point)


I degress somewhat

[sdumper]

I don't mean this in a flame war kind of way I would pick the person with design skill and less tooling to make a better system than a rookie with all the kit.

It is obvious in this forum that there are only a handful of people who can do the required calculations and who innovate. The rest just copy (which works fine, to a point)




:)

SexyMF it sounds like you had your feathers ruffled a bit but if you were trying to flame me then it certainly wasnt taken that way :)

I was not bashing making a makeshift vacuum pump I was referring to not vacuuming at all and having your lines freeze periodically from having moisture in your system...

Hopefully with that clarification you wont be so upset :)

[EvoCarlos]

i still say 55% silver solder and a propain torch
its done all what i have build :)

and tho's professional vac pumps are great lol
http://i90.photobucket.com/albums/k262/evocarlos/water%20cooled/barons%20vapo/Image098.jpg

[aenigma]

I used an a/c rotary compressor for a long time as a vacuum pump and it worked fine. I am back to my real vacuum pump now that I fixed it recently. The real vacuum pump is quieter and I don't worry about leaving it running for a long time like I did with the a/c compressor since it gets very hot.

If you are using a compressor that doesn't pull enough of a vacuum, that's not a big problem, just heat the phase change unit up to help remove moisture. Especially the drier. It's also a good idea to vacuum then purge a few times to ensure there is no air in the system.


It is not absolutely necessary to:

1) Change compressor oil because it's been open to air for a few days
2) Purge during brazing (Propane is fine as a shield gas. Safer than lighting a BBQ)
3) Use a proper vacuum pump to evacuate the system
4) Bother with a high side access valve
5) Insert a filter/dryer

Very true. A lot of the stuff I built back in the day was from a junk yard, and the compressors all had holes drilled in them to drain the oil! No, I didn't add more oil or change oil or anything, I just used them! Not only were the compressors open for a few days, they were probably rained on as well.

I never used to purge either, it matters much less when brazing smaller stuff. It's when you braze large pipes for something like a receiver or when brazing an evap that it's important, but still not needed of course. You can just blow the evap out with compressed air or something to get the loose pieces out.

[Boogerlad]

here are the specs of the durafix easyweld stuff. From reading it, it's about 54% of the strength of silver brazing i think

[sjg0]

Very true. A lot of the stuff I built back in the day was from a junk yard, and the compressors all had holes drilled in them to drain the oil! No, I didn't add more oil or change oil or anything, I just used them! Not only were the compressors open for a few days, they were probably rained on as well.

What were temps like?

[ultralo1]

Very true. A lot of the stuff I built back in the day was from a junk yard, and the compressors all had holes drilled in them to drain the oil! No, I didn't add more oil or change oil or anything, I just used them! Not only were the compressors open for a few days, they were probably rained on as well.

I never used to purge either, it matters much less when brazing smaller stuff. It's when you braze large pipes for something like a receiver or when brazing an evap that it's important, but still not needed of course. You can just blow the evap out with compressed air or something to get the loose pieces out.

You are correct. Anybody can put a unit together and have it run. I have seen many hack jobs out there (In my field). They did run, and worked to a point. The one thing that none of them did was last. That is where the correct oil, correct vaccum, correct brazing, correct purging comes into play. It really is not that big a deal to chnage out a compressor on a unit. The big deal is to do it right so that it will last.
In Air conditioning there is alot of room for error. The comps tolerances arnt as tight, they dont run for extended periods of time, the temps are above freezing. The life expectancy of theunit is under 10 years.
In refrigeration the room for error is smaller but still manageable. Life expectancy is under 10 years.
In cascades life expectancy is over 10 years, the comp tollerances are critical (the 3/4hp I buy are over $1000), the comps are expected to run 90% of the time. Long cap tubes so any moisture blocks them.

The rebuilding process is a step by step process. Its not just replacing a comp it is following a procedure to ensure a very long life of the equipment.

Just my $0.002 worth (not a flame thing type of post either)

Boogerlad,
There is a reason that there is no alternative to brazing. Nothing has been found to be better. Even HVAC solder cannot take the vibrations or punishment produced by refrigeration systems.

[aenigma]

You are correct. Anybody can put a unit together and have it run. I have seen many hack jobs out there (In my field). They did run, and worked to a point. The one thing that none of them did was last. That is where the correct oil, correct vaccum, correct brazing, correct purging comes into play. It really is not that big a deal to chnage out a compressor on a unit. The big deal is to do it right so that it will last.
In Air conditioning there is alot of room for error. The comps tolerances arnt as tight, they dont run for extended periods of time, the temps are above freezing. The life expectancy of theunit is under 10 years.
In refrigeration the room for error is smaller but still manageable. Life expectancy is under 10 years.
In cascades life expectancy is over 10 years, the comp tollerances are critical (the 3/4hp I buy are over $1000), the comps are expected to run 90% of the time. Long cap tubes so any moisture blocks them.

The rebuilding process is a step by step process. Its not just replacing a comp it is following a procedure to ensure a very long life of the equipment.

Just my $0.002 worth (not a flame thing type of post either)

Boogerlad,
There is a reason that there is no alternative to brazing. Nothing has been found to be better. Even HVAC solder cannot take the vibrations or punishment produced by refrigeration systems.

Yeah, that is very true. I was mentioning it because people making their first unit don't have to get everything just right and spend a thousand dollars on tools. They are most likely going to be making another one in less than a month, so it doesn't need to last as it's just for practice. Once they learn about it they can start investing some money into the hobby and put the tools to good use and make better refrigeration systems. Otherwise they might be spending a bunch of money on something they may not want to keep doing.

What were temps like?

These weren't used to cool a cpu, I think I made most of them as water chillers. This was probably up to 8 years ago and I was building these things to learn, so I don't really remember. I think the average temperature I was seeing was about -40c without a load, unless I was using a small compressor or something. I wasn't saying I would trust any of those compressors with holes drilled in them, just that they never gave me problems even though they were left outside in the weather. I also want to mention that I did use a vacuum pump, it's just that the compressors themselves would be considered garbage.

The best thing I got from that junk yard was a condensing unit with a 1/6hp tecumseh compressor and I've used everything but the compressor on my autocascade. It made a perfect base plate to build on, it already had the condenser with fan and shroud and I used the receiver as an expansion tank. Man, I loved that junk yard! :D

[Sn@ke:~]

I just want to jump in to say that you can ionize your Aluminum and it won't rust anymore.

It is quite easier than cheap thought, You need a bath of acid electrically charge and just sunk the piece of Aluminum into the acid for the necessary time requested by the procedures. That is what they do for pieces of airplane. It is basically rusting the Aluminum at very fast speed creating a hard crust surface lair that won't ever rust again. If you weld you have to do it after welding and don't ever use pencil on Aluminum it will rust and weaken the area of application causing to crack and brake.

There is also a similar process for steel.

And welding Aluminum is the hardest skills in welding profession because you can past the melting point and you can't weld under the melting point you also have to go on a continuous motion until the whole welding straight is done and even after you need a small pick hammer and the the welded section to see if it's crack. In aerospace ht to see if the industry they will soak the pieces into a liquid and look at it with black light to see if the welded section is no crack and upi to he job.

[Athanatos]

i think that duraweld a croc
aluminum welding is not easy like that at all, it requires specific heat, speed of the filler metal (tig rod or wire if using mig) to make a proper weld
since aluminum absorbs heat very fast, it would be required to use pieces of aluminum or copper clamped to the work area to absorb the excess heat so that the weld will turn out right

[SexyMF]

You are correct. Anybody can put a unit together and have it run. I have seen many hack jobs out there (In my field). They did run, and worked to a point. The one thing that none of them did was last. That is where the correct oil, correct vaccum, correct brazing, correct purging comes into play.

True but the useful life of a phase change system for a computer is really only ~2 years. CPU generations are fast and to keep up you have to rebuild anyway.

[sjg0]

True but the useful life of a phase change system for a computer is really only ~2 years. CPU generations are fast and to keep up you have to rebuild anyway.

Just build your phaser with a ridiculously large condenser and retune everytime the latest CPU comes out, no? :shrug:
Besides, Processors only jump about 25W load every generation. To me that doesnt justify a whole rebuild. :D
Also, the trend nowadays seems to be the whole "green" thing so i predict CPU loads will actually come down.

[teyber]

p4-> to the core 2(quad) necessitated a rebuild, core 2 -> i7 lookin like rebuild is necessary. It doesn't have to do with the condenser size but how restrictive the metering device is.

[SexyMF]

Each CPU does have a smaller die size and a lower TDP but we keep putting more into a package so the overall thermal load is high. Adding to that is the heat generated by overclocking is also scaled with the number of cores.

It will become more apparent soon that the heatload testers people are building can't reflect the heat density of the CPU die. I think we are going to need to move away from capillary tube into adjustable metering devices and just tune them directly on the CPU.

[Moc]

It will become more apparent soon that the heatload testers people are building can't reflect the heat density of the CPU die.

That is not important for a loadtester. As long as the temperature of the loadtester is under the room temp. the complete heat is getting to the evap. This is the only part of the loadtester.
For my comprehension, its just important for the evaporator.

I think we are going to need to move away from capillary tube into adjustable metering devices and just tune them directly on the CPU.

This is a point where I fully agree with you.

But the problem is, that only CPEVs are adjustable and there we slide in a new problem:
If we tune the CPEV to the max. load of the cpu, what will it do when there is no load? It keeps the pressure constant :D . And than the massflow is to high (as high as it is with load) and we get a really heavy floodback.

A captubes adjusts itself over the highside pressure (no load -> lower pressure on the highside -> less refrigerant gets through the captube).

One possibility would be a needle valve (a member from our forum tried some, but some started leaking, others were killed during brazing) but here someone have to find a useable one....

[tiborrr]

The future is in the pulse width moderation refrigeration. A simple IC that adjusts the rate/sampling of refrigerant flow via temperature & pressure monitoring.

[sjg0]

what will it do when there is no load?

Folding@Home ftw :up:

The future is in the pulse width moderation refrigeration. A simple IC that adjusts the rate/sampling of refrigerant flow via temperature & pressure monitoring.

I think this is what gomeler was trying to do with that VFD. But not exactly.

[sjg0]

p4-> to the core 2(quad) necessitated a rebuild, core 2 -> i7 lookin like rebuild is necessary. It doesn't have to do with the condenser size but how restrictive the metering device is.

Oops forgot about the cap tube. :S

[SexyMF]

@Moc:

Being able to shift heat from copper->thermal compound->copper with a surface area the size of the whole CPU doesn't equate to trying to shift the same amount of heat from a much smaller die->heat spread->thermal compound->copper.

This is why we have heat-pipe technology heatsinks.

[ultralo1]

True but the useful life of a phase change system for a computer is really only ~2 years. CPU generations are fast and to keep up you have to rebuild anyway.

Its your money. :shakes: