Sciencemadness Discussion Board - Bath circulator corrosion

Bath circulator corrosion

Fleaker - 30-12-2008 at 15:44

I just purchased two nice Neslab chillers which function perfectly. Cosmetically speaking they look fine, but upon closer inspection I see some corrosion on the cooling coils on one of the units.

The coolant reservoir is stainless steel and is in good condition, but I do not want any rust on the coils because it could hurt the pump and it could possibly continue to propagate.

What is the best thing to clean out the rust/corrosion? I was thinking that I should gently wire brush off as much as I can with detergent, but after that I'd like to chemically remove the deposit. It seems to me than an ounce of prevention would be worth a pound of cure with these units. They both function perfectly, but I think if I leave the corrosion in there, it's only a matter of time before it affects performance.

Any advice, suggestions, comments?

I can post photographs if necessary, just ask!

not_important - 30-12-2008 at 17:20

Are the coils stainless, or aluminium?

If steel, a warm solution of citric and ascorbic acids will reduce ferric to ferrous and dissolve common corrosion products as well has deposits from hard water. After that several rinses, a short soak with dilute NaHCO3 or Na2CO3 solution, with a trace of Na3PO4 or the silicate if you've got `em, rinse again.

Fleaker - 30-12-2008 at 19:53

Stainless based off the look of the corrosion. That's exactly what I was thinking remedy-wise. I'll give it a try tomorrow.

50/50 ethylene glycol:water is good for -30C, correct? Just want to make sure :cool:

not_important - 30-12-2008 at 20:29

Quote:

Originally posted by Fleaker
50/50 ethylene glycol:water is good for -30C, correct? Just want to make sure :cool:

grab the PDF here http://www.ashland.com/pdfs/technical/AD%20Chemicals%20-%20F...

Remember that ice crystals can form above the freezing point, which may cause pumping problems including clogging of smaller tubing and openings.

chemrox - 28-1-2009 at 17:56

I"ve been told that oxalic is also good for reducing Fe salts is this the case or no?

S.C. Wack - 28-1-2009 at 19:43

I've used the usual OTC somewhat perfumed bisulfite/dithionite to take out rust stains on several areas for some time, including inside condensers and in the recirculating aspirator pump. Works great. The OTC dithionite (not perfumed) for water softeners is faster but more expensive, and it isn't likely anywhere near proper fresh dithionite anyways, given its quite foul odor.

Klute - 29-1-2009 at 11:26

Oxalic acid works great for removing rust staines! I alwya use it for cleaning the old rusty metal pieces used to hold the aluminium bars together, after a hours soak and a little scrubbing, they are good as new! All shiny and clean...

garage chemist - 12-2-2013 at 21:59

Don't use glycol/water mixes for temperatures below -15°C, they become very viscous and the pump will have a hard time pumping it, while the heat transfer is bad as well.
Denatured Ethanol is a very good bath fluid down to -50°C, while methanol can be used down to -80°C while staying as fluid as water.

AJKOER - 3-3-2013 at 07:35

Perhaps a medical approach might work here.

Get some detailed history/background data: general health history most likely associated with the bath's location (there may be known issues associated with that city, climate, region,..like smog, ozone pollution, chemical waste,..), more precise family history (your water is from a lake, well, river, reservoir,..or mixture therefrom like mine), common medications that your water is on (Chlorine, Ozone, Chloramine, Hypochlorites, O2 from aeration,...), past conditions (high levels of sulfides, iron, minerals,..), recent changes (industrial development, community growth/decline, government budget cuts...).

Then, a picture showing detail effects of the condition.

Then, a professional (in this case a chemist) diagnosis of what is causing the problem, followed finally by a prescription that is known to treat said condition.

There may even be a suggestion for preventive medicine (like a water softener, filters,...).

Actually, following this procedure may mean that your bath is going to receive better treatment

than you do for what ails you

.

[Edited on 3-3-2013 by AJKOER]

feacetech - 3-3-2013 at 18:47

Quote: Originally posted by not_important

Quote:

Originally posted by Fleaker
50/50 ethylene glycol:water is good for -30C, correct? Just want to make sure :cool:

I use to work for Ashland