The authoritative public forum
  for Metal Finishing since 1989
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DI water

2000

Got a question for you. We are using DI water for humidification of our auto insertion room. We noticed that the DI water is attacking the HEPA filters on our HVAC unit, as well as attacking the metal parts & motor housing.

Do any of you know what affects DI water may have in the working environment, on our employees & will it attack the varnish on the windings on the electric motor causing it to short out. Please advise

Thanks,
Tom

Tom Doyle
- St Paul, Minn, USA

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First of two simultaneous responses-- 2000

They don't call water the "Universal Solvent" for nothing. Water will attack a lot of things. The reason why it usually doesn't is because it already has plenty of things dissolved in it. DI (de-ionized) water is water that has had a lot of material filtered out of it. I use DI water for salt spray testing.

Since DI water is so clean, it is able to attack things that normal water wouldn't. I am not surprised that the DI water is attacking metal and filters and other things. I don't know if it could attack varnish in particular. Are you supposed to be using DI water for these tasks? If there is no specific reason you need DI water, I suggest you go to normal water. There IS such a thing as TOO CLEAN water.

As far as employee health, you should not be concerned as long as nobody is drinking the DI water. DI water will actually suck the vitamins and minerals OUT of your body. Nobody is going to dissolve into a puddle of goo, but imagine drinking DI water as a way of taking a vitamin a day OUT of you. Getting DI water on your skin is fine, just don't drink it.

If you have a water purification company that supplies and/or services your DI filter system, they might be able to advise you on your specific application. I would give them a call too.

Tim Neveau
Rochester Hills, Michigan

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Second of two simultaneous responses--

Tom - DI water is slightly acidic in nature since there is nothing left in it to buffer the pH - hence the corrosion of your pump. the pH of the system water should stay above 8.5 to prevent attacking ferrous parts. As for effects on workers, etc. I don't think there should be any effects. I would recommend getting a reputable water treatment company that can chemically treat your water and keep bacteria and organic fouling from forming in your system.

Dan Brewer
chemical process supplier - Gurnee, Illinois
2000

It is hard to keep the DI water resistivity high (>1 meg-ohms) when in contact with air because carbon dioxide in air dissolves in it and forms carbonic acid (like in soda pop). This is how the DI water becomes slightly acidic.

Mandar Sunthankar
- Fort Collins, Colorado
2000

I would look at a small RO unit that is available at home supply stores like Lowe's. These are tinkertoy units vs a real RO unit, but it will give you a quality of water that is virtually ideal for your purpose. A lot cheaper. Units can be run in parallel, I think, or you can get a bigger unit from the MFG.

James Watts
- Navarre, Florida
2000

Any reason as to why you cannot use DW ( Distilled Water ) instead of DI water ? There are a lot of inexpensive small units available which makes Distilled Water and should serve your purpose efficiently.

Ajit Menon
- Rapid City, South Dakota, USA
2000