Stopping aluminum corrosion.

Flyinfool

Flyinfool

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I have an old (Nameplate shows Aug 2003) Thermotek T255P solid state chiller. I do not use it often so it spends most of its time in storage. The issue is that every time I pull it out of storage to use it it gets plugged up quickly with aluminum oxide powder. Since the only aluminum in the system is the solid state heat exchanger that is where it is coming from. The exchanger is welded up from aluminum plates and there is only a 5/16 barb fitting on each end for access to its interior. I did get it fairly well cleaned out but I do not know what to do to stop it from continuing to corrode on the inside. It is a major project to get it out of the unit and it can not be separated from the Solid state components, so that leaves out any type of immersion.

The recommended working fluid id distilled water with 5% alcohol added to prevent bacteria growth. You can also run a 20/80 mix of Prestone LOTOX or 5/150 antifreeze with water IF you will be running it at below freezing temps. The Prestone LOTOX and 5/150 are no longer made. My research says that the LOTOX and 5/150 are basically DexCool antifreeze. DexCool says that for corrosion protection it must be a 50/50 mix. as opposed to the chiller recommended 20/80. But then the chiller is not recommending this for corrosion but for freeze protection down to -5°C (+23°F).

First question, is there something I and run through the heat exchanger to remove all existing aluminum corrosion?
Is there something that I can then run through it to protect the now clean aluminum?

Does anyone have any ideas of what I can use for long term storage to protect the AL from corrosion during storage? The balance of the system is various plastics and rubber hoses. with a bit of stainless steel in the pump.

My first thought is to just fill it with 50/50 DexCool / Distilled water for storage. Then flush that out to put in the water/alcohol when I am going to use it. In use it can not run antifreeze, if it leaks any antifreeze on the carpet I may not survive what comes next...........DexCool is made for AL engines and radiators and is supposed to protect them from corrosion. A cars cooling system has plastics, rubber hoses, AL, and other non AL metals all together.

I and all of my family (parents, children, siblings and their kids) all use this machine after surgeries as it is way easier than ice packs or even an "Ice Machine", Hopefully it will never be used again but I know that is only a pipe dream. My family has many more surgeries in the future.
 
I'm really uncertain about this application, but Alodine is an easy aluminum finish that prevents corrosion. You'd probably have to pump it in there, let it set, then flush it. I've only used it on dry, external surfaces.

GsT
 
I thought of Alodine / Chromate, but I am not sure how to get the inside clean enough for it to actually get to the surface of the part. There is a lot of internal oxidation that needs to get removed somehow before any kind of coating can get to the surface of the aluminum.
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I would be very cautious about adding GM Dex-Cool antifreeze to any system that might still have amounts of old school glycol based antifreeze in it. I'm no chemistry expert, but what I do know from an unhappy experience is that Dex-Cool reacts with old-school antifreeze and it all turns to the consistency of Jello - plugging up the works...
 
Thanks for the tip, I was not aware of that one.
I have had it for 6 years and only used distilled water. It is drained and the water replaced regularly. Any old stuff should (I hope) be flushed out by now. The instructions on the unit also specify the equivalent of Dex-Cool And then only for use below freezing. So if someone did run antifreeze it should have been Dex-Cool.
 
Yeah, neither had we ever heard of that. Until we gummed up the coolant system in a brand new $30K ProSpot spot welder. $5800 in damage.
 
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