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Can anyone tell me how the acid is generated or what causes the creation of acid in a system or compressor? I have a theory on why our plastic evaporator drain pans are cracking and the material becoming brittle in our units. It has to do with system leaks and exposure to an acid in the system which comes in contact with the plastic when a system component is replaced or the system has a leak.
Check what oil the refrigerant systems is using
Plastic made with mineral oil content & exposure to mineral refrigerant oil = ok
Plastic made with mineral oil content & exposure to synthetic oil = damage to plastic & plastic component failure.
Some plastics which were ok with exposure to Refrigerant R22 with mineral oil are now a problem if exposed to R407c / R410a due to the synthetic oil.
Hopefully someone with chemical degree can explain better.
For the causes of acid in system and not the breakdown of plastic. From memory acid is caused by moisture in system and high temp. With high temp there are two acids formed and one of the acids create water, can't remember the names of the acids though.
Acid formation in refrigeration systems is usually the result of water combining with the refrigerant. When the moisture is compressed to higher pressures, the gas temperature also increases. After repeated cycles the acid begins to form and circulate with the oil. Then the oil carries the acid back to the compressor where it starts to break down the motor insulation (hermetic and semi-hermetic only) or the acid begins to dissolve varies metals (like copper), which then begins to plat other surfaces with the free copper floating around.
I kind of doubt the drain pans are leaking from acid created in the refrigeration system. If you had that severe of an acid problem you have bigger issues than drain pans!
Water also help de-esterification of POE oil into its original constituents, which are basicly organic acids like palmitic acid and similar.
Infact, esterification is a process of reaction between one organic acid and one alcohol.
http://upload.wikimedia.org/wikipedi...rification.png
Thanks for the information. It may be a combination of the acids and the refrigerants which are causing the cracking. We did run a test with the plastic material sumerged in POE oil for several days and there appeared to be no affect to the plastic.Quote:
Originally Posted by US Iceman
I know this is an old thread, but I thought I could complement the info of these answers:
The problem of acids comes with the use of POE oils, which are hygroscopic. This is, they take water (humidity) from the air if they get it contact with it.
POE oils are produced by combining a long chain acid with a substance called "pentaerithrytil". With this mix, we obtain 2 things: Water and POE. In the production process, water is instantly removed, as it is a reversible reaction. So, when POE gets in contact with water (air), the reaction will happen again, and we will obtain this long chain acid (HOOC-R), plus "pentaerithrytil".
That is why, when you have a leak, and air enters the circuit, it will get into the POE sine, creating the acidic environment with the time, as it grows geometrically with the time.
There are other aspects, i.e. when retrofitting a HCFC and MO installation to HFC and POE. If the "joints" are quite old, and are made of "nitrile", POE can damage them, and so, there will be leakages, that will bring air and moisture, and so acids again. In this case, these "joints" should be replaced by neoprene ones.
Sorry if some words are not too accurate, my technical English should be improved.
Regards,
Nando.
Hi Nando
Can you (or anyone else) also explain how 'Acid Away' works, or other similar products that are supposed to neutralise acidic oil.
Have encountered loads of systems in the field with acidic, especially acidic POE oil.
On one site acid away has been added, a quick-shot test done that then indicates safe, 12 months later another quick-shot oil acidity test carried out, result shows acidity again.. Only so much acid away can be added in ratio to the amount of oil.
I know there's no substitute for an oil change but with some of the smaller hermetic scrolls compressors this is impractical..
Am i wasting my & the customers time with Acid Away ??
The acid away and other base substance neutralize acids. The problem is to know the exact quantity of acid you have in the system, in order to put the correct amount of base product to neutralize.
But, acids are along the circuits, not in the smae place, and it takes time til this base gets to all parts, and most of the times, it won't mixed and neutralize with 100% of the acids.
Then, you have to remove it, and you have another problem.
Normally, at the end of using this kind of products, you will have in the circuit: still part of the acids, part of the substance you put (Base) and part of the reaction of both products... at the end, you have more dirt inside the circuit... and you didn't remove 100% the acids.
I recomend you to watch the video from this link in which you can see the different cleaning methods you can use:
http://www.fri3oilsystem.com/ingles/video/video.html
As explained before, acids grow geometrically with time, so, if after a cleaning with these bases, you have a "small" amount of acid, it will grow and damage the new oil for sure in the mid term.
Regards,
Nando.
Thanks for your swift reply Nando..
So, at the best acid away is a short term fix for an oil acid condition, at worst it could cause further problems in the system..