Re: Brazing vs. soldering
Try out the oxy turbo kit small and recommended to every engineer, look at countyweld.co.uk for what your paying its an amazing piece of kit.. Plus silver solder is alot safer, knowing the jobs done properly aswell
Re: Brazing vs. soldering
Some interesting articles here, but be aware that here in Europe we have to consider both PED and EN:378 where all joints made or altered on site should be pressure tested to 1.43 times maximum working pressure. So for a brazed or flare joint we use the following, 32 C for the low side of a system, 43 C for the high side of a water cooled system & 55 C for the high side of an air cooled system. So the majority of times we would look at 32 & 55 C. This gives us Maximum Working Pressure.
A couple examples for UK latitudes would be R134a at 32 C has a pressure of 7 bar (103 psi) & at 55 C, 14.9 bar (200 psi). These figures are then multiplied by 1.43 for the strength (pressure) test giving 10 & 21.3 respecively (148 & 286 psi). At these pressures there should be no rupture or deformation of the pipe and joints. Leak testing is carried out at 10% above MWP.
If you look at R410A:eek: 32 C = 19.7 bar (272 psi) and 55 C = 33.3 bar (485 psi) X these by 1.43 & you get 28.2 & 47.7 bar respectively. All pressure testing should be performed using an inert gas mainly oxygen free nitrogen (OFN).
Please be very careful with the lines you use connecting the cylinder to the system and avoid using your gauge manifold particularly if it has a sight glass fitted.
So don't even consider soft solder.
As for brazing, you should always "drift" ofn through the pipes to avoid oxidisation on the inner surfaces of the pipe or fittings etc. If oxides do form and a system components fails during the warranty period it has been known for the mauufacturers to reject the warranty because of tyhe contamination.
The other point here is flux. Powder only goes where it's put so when for example brazing in, a new compressor it is possible for the pipe inside the joint to oxydise resulting in a potentialy weak spot. But if the flux is mixed to a paste and carefully applied to the outside of the pipe it will keep the joint clean. Fluxed rods suffer the same as powder application, so use clean rods & a small tub of flux which you mix with clean water as and when needed.
Re: Brazing vs. soldering
I always refer to this site...someone posted it here. The first lesson tells it all. Figured it would be worth posting it again. Cheers!
http://www.refrigtech.com/bigblumanu...RTHING%20LEAKS
Re: Brazing vs. soldering
I believe that solders give mostly Keying type joints,, where as in Brazing you can get some good diffusion joints, which work better with vibrations, due to compressor on off, This is one of the major reason for brazing joints, rather than soldering joints.
sumant mathure
Re: Brazing vs. soldering
Quote:
Originally Posted by
RogGoetsch
Short answer: halocarbon-based refrigerants are incompatible with lead-based solders. They will eventually leak.
So if I'm using a hydrocarbon based refrigerant, is there a reason to not use soft solder?
Re: Brazing vs. soldering
Quote:
If SnAg is suitable, and people are actually using it, I might consider using it for non-critical connections like a T-connection. I lack an oxy/acetylene torch, so the pure fact that I can use a normal propane torch is invalueable. Flowing with nitrogen was also not possible for me, so I used butane for that.
DaBit as I understood from the posted that I quoted you are using butane as a non-oxydation agent in the circuit while you are soldering ?????
Isn't that dangerous . . .
If I miss understood your post please explain your point of view.
Respects and regards
Re: Brazing vs. soldering
what about using plumbing solder 95/5?
i also heard that plumbing flux has acid or something that can cause acid in the system ruining the system.
how much pressure can straight plumbing solder take and would it work with r134a and r22 and r12 systems ok?
Re: Brazing vs. soldering
Never use soft solder, especially the 60/40 on fridge pipe unless you intend to use it for regular plumbing. If your charging the pipework with any kind of *****. Always use a hard solder (brazed joint) the soft solder will not maintain a sound joint under the associated pressures.
Re: Brazing vs. soldering
do you know of any way to get a propane torch hot enough to do brazing or can mapp gas be use in a propane torch dead to get hot enough?
Re: Brazing vs. soldering
You will need to use a nozzle on your blow lamp or blow torch that is bigger than the pipe work that your brazing. If your out side in the wind, it can be tricky and its slower than oxy/acet.
Best to use both oxy/lpg fuel gas mix, you will need blowback arresters on both lpg fuel gas and oxy.
Re: Brazing vs. soldering
Steve Pendle is on the correct lines as EN378 gives a lot of detail.
(Applicable to us Europeans only I believe? )
Extracts below.
Although it would seem that various options are allowed.
So I guess the truthful answer is as we Brits say "Belt and Braces" applies.
IE if in doubt Braze its a much stronger and easier to do joint.
e) Soldering alloys
Soldering alloys shall not be used for refrigerant containing purpose where strength is a factor.
f) Brazing alloys
Brazing alloys shall not be used unless their compatibility with refrigerants and lubricants has been proved by
test or experience.
g) Tin and lead tin alloys
Tin and lead tin alloys may be corroded by halogenated refrigerants and shall not be used unless their
compatibility has been proved by test or experience.
Constructional, welding and brazing materials shall be suitable to withstand foreseeable mechanical, thermal
and chemical stresses. They shall be compatible with the refrigerants, the refrigerant and oil mixtures with
possible impurities and contaminants and the heat transfer media.
Grizzly.
Re: Brazing vs. soldering
g) Tin and lead tin alloys
Tin and lead tin alloys may be corroded by halogenated refrigerants and shall not be used unless their
compatibility has been proved by test or experience.
I think that this is the most important factor her
I have pressurized soft solder to well over 400psi for long periods (months) and at many temperatures and have not a one failure due to strength. Although it has not been refrigerants (halocarbons)I have been using hence the statement above
Re: Brazing vs. soldering
Lead based solder is for plumbers,[dunny divers]. silver solder is for refrigeration technically superior people.
Re: Brazing vs. soldering
A thread started back in 2002 and still going, not bad but its an interesting area no doubt where its money to save since only a cheap air/propane torch could be enough.
I have used soft solder 96/4 many years now to my own homebuilt A/C stuff where i always use propane and some systems have been going for some year now and so far still going. With commercial A/C only brazing is the only thing i would use due to strength no matter temperatures and so on.
I dont feel really comfortable by getting the pressures over 20 bars with soft solder joints no matter what but if the joints have a large contact surface they should hold for this. But high temperatures will lower the strength on the solder so i always keep a look on this because it would not be funny if a joint pulls apart at a big condenser at 25 bar for example so i feel more comfortable at max 15 bars.
Re: Brazing vs. soldering
I do find it surprising that a Dutchman would start a thread on this subject in 2002. All solder joints in refrigeration were forbidden in Holland in 1993 under the STEK regulations. The reason given was the tendancy to 'dry joint' with little visible indication.
Re: Brazing vs. soldering
I always presolder all surfaces on the tubes that should be joined together so they have a thin coat of solder on them before i solder them together. Personally i would never trust that the whole tubes inside would be soldered if i couldnt directly see this which i of course cant.
By presolder i would always know that they would be properly attached to each other later on and all the way and any dry joints would never exist since i can now see that the surfaces were properly coated before joined together.
When soldered together the amount of flux required at this point are normally minute and sometime not at all needed since little could be still left on the previously soldered surface if the temperature werent to high so you should only need very little solder to fill the very small gap.
Re: Brazing vs. soldering
How do you offer one pipe end into the swage end if its got a coating of filler alloy on it? Won't it be too tight to shove in?
I have never had a problem with getting the filler alloy to flow down into the joint or fitting. Remember cleanliness is godliness when your brazing or soldering.
Re: Brazing vs. soldering
I normally use one larger tube then the ones im going to join and then solder them on to this larger tube by inserting them into it were the inside of this already have been wetted. I would normally not swage the tubes since the contact surface is quite small, well at least as i want it that is but might very well hold together anyway.
When wetting the surface and when any excessive solder are still molten i get this off by either shake it off if inside a tube or outside, and if any gap is very narrow, take a thick piece of paper and rub it off.
By this way i get an extremely thin shiny surface of solder just like the tube was plated and that wont make any problem no matter how thin any gap would be.
Re: Brazing vs. soldering
Hi everybody.
I am a neophyte in the refrigeration domain and I am asking for a piece of advice.
I need to make a prototype of a refrigerator for a lab application and I will use a commercially available condensing unit.
The evaporator I need is a coil made of copper tube completely sunk in a tank of alcohol. I will use the R404A refrigeration fluid and, having read the rest of this thread, the usage of tin-lead low temperature soldering should not be a problem, especially because it will be used in the low pressure portion of the system.
I am wrong ?
Re: Brazing vs. soldering
Quote:
Originally Posted by
hiCoolerLab
Hi everybody.
I am a neophyte in the refrigeration domain and I am asking for a piece of advice.
I need to make a prototype of a refrigerator for a lab application and I will use a commercially available condensing unit.
The evaporator I need is a coil made of copper tube completely sunk in a tank of alcohol. I will use the R404A refrigeration fluid and, having read the rest of this thread, the usage of tin-lead low temperature soldering should not be a problem, especially because it will be used in the low pressure portion of the system.
I am wrong ?
Its only low pressure when its running, what if its broken or off in the summer...
Lead/tin solder is for plumbers and water pipes, the flux will get in the pipes and is corrosive so will not do your system any good, also i have read (think it was in one of Bitzers refrigerant reports) that ester oil and hfc refrigerants will over time eat through soft solder....
Its easier to braze it with phos/copper/silver rods anyway!
Re: Brazing vs. soldering
You need to also consider the pressures within the system when it is standing idle or when it has warm/hot alcohol to cool.
Low temperature solder is not ideal for joining refrigerant pipework, brazing is the recommended method.
Re: Brazing vs. soldering
Thanks a lot,
but it is the proof-of-concept just to verify everything has been designed well. As soon as everything works, everything will be redesigned and brazed.
Well, when the refrigerator is off, the pressure raises, but it's lower than the maximum in the condenser, so it should be well under the limits. I am in a hurry and the coil geometry I am trying to test is a little bit complicated and needs lots of soldering. If I can use tin-lead solder, at least for the prototype, I can do everything by myself and this turns to be be simpler and faster.
Re: Brazing vs. soldering
Quote:
Originally Posted by
Magoo
Lead based solder is for plumbers,[dunny divers]. silver solder is for refrigeration technically superior people.
Boy am I glad I don't do toilets.....