Difference Between Distilled Water and DM Water?

One can demineralise water by distillation and a number of other techniques.

I specifically did not use the term "demineralize" because it is a very generic term. Distillation, ion exchange and reverse osmosis all demineralize water to some extent or another but are very different processes. If Maxwell's Demon were to meticulously pick out all molecules that were not H2O, that would be demineralization as well. I don't like the term because it tells me nothing of how the water was purified, a very important bit of information to those who understand the differences.

Quite.

Distilled water is has no minerals, ions, bacterial or any impurities. Distilled water won't conduct electricity.

DM water has had the mineral ions removed, but not other impurities.

Is DM water the same as De-ionized water. We had a lab that had a tap for De-ionized and one for distilled water. There was a heat exchanger that used a stainless steel shaft with a prop at the end that stirred the water in the tank. The unit overheated and we found the prop had corroded off the shaft, a bolt holding the prop on was rusted and fell to the bottom of the tank. They were using distilled water and we were told we should have used the de-ionized. Was it the water or the dis-similar metals?

I have seen such water and corrosion called "hungry water"......but not by me you understand!!!!

We were told to use DM WATER for cooling of induction furnaces. The DM WATER is passed through the copper tube lined in the induction furnace. We would like to use distilled water in place of DM WATER. Can we use distill watr in place of dm water? Is distill water more corrossive than dm water?

Distilled water will erode copper. You must use stainless steel to transport distilled water.

Our induction furnaces are lined with hollow copper tubes. The copper tubes needs to be cooled during the operations.we cool the copper tubes by passing DM WATER through tubes. We have 10ltrs/hr water distillation plant. We want to know can we use distill water instead of dm water.if no , why? As we will have to buy dm water plant.

You can use distilled water as the coolant, but you will need to re-introduce the impurities that have been removed by distillation.

You can contaminate your pure water enough so that it won't erode your copper pipes.

Does that sound irrational?

How do we contaminate the distill water?

The flash desalination plants basically produce distilled water which is highly corrosive. they then pass this water through lime stone beds so that it acquires some Calcium Carbonate which not only prevent corrosion of pipes but also improves the taste of water if it used for drinking.

The original poster needs to be careful here. Introducing calcium ions runs the risk of forming species that have a negative solubility slope, leading to precipitaiton on heat exchange surfaces. That is why the origin of the water selection recomendation needs to specify upper limits for certain dissolved species in the water, so the process will continue to operate long-term.

The forum is advised that the water is wanted for process cooling for which the addition of calcium carbonate would be a bad thing, and not for drinking for which the addition of calcium carbonate is a good thing.

Wherever the request came from needs to supply some numbers to specify the boundary between the quality of water that is acceptable and the quality that is not.

All demineralised waters have the potential to corrode, as they are good solvents for ions. However, there are a number of factors to consider, which is why the numbers are important.

What are the induction furnace manufacturer's quality limits on the cooling water supply quality? What are the wetted materials of the induction furnaces?

That would count as a process change worthy of getting a Hazop Study team involved at an early stage; the "why" question needs to be addressed by the <...We...>.

Dear Mr. Sauravjain,

DISTILLATION will need more energy since evaporation of water is to be done and one Kg. water needs 540 K.Calories of LATENT Heat Energy/Kg. of water evaporated at atpmospheric pressure. If steam is used, the boiler efficiency and radiation loss, steam trap loss/leakage comes into picture. Disposal of residuals will not pose very serious problems.

DE-MINERALISING needs chemicals depending upon the salts and and reject may pose serious environmental problem.

DHAYANANDHAN.S

Distilled water is pure, DM water is nearly pure...

Dear SolarEagle

Distilled Water DOES NOT CONTAIN ANY DISSOLVED SOLIDS.

DM Water may contain a small quantity of DISSOLVED SOLIDS.

DHAYANANDHAN.S

More specifically...Distilled water is often defined as bottled water that has been produced by a process of distillation and has an electrical conductivity of not more than 10 µS/cm and total dissolved solids of less than 10 mg/litre.

In DM water the amount of dissolved solids could be as low as 1 mg/l and is in any case always less than 10 mg/l. The electrical conductivity is generally less than 2 mS/m and may be even lower (< 0,1 mS/cm).

Is it not other way round? There are no dissolved solids in distilled water.

Both are positively brackish when compared to ultrapure water.

As well as the previous discussed differences in methodology there may be one outstanding problem with distilled water that could be eliminated with deminerilized methods using reverse osmosis and ion exchange methods together. Distilled water will allow volatiles to carry over in the condensate. If the user wishes to remove volatiles, then other methods of de-mineralizing need to used or added to the process in conjunction with the distiller. Otherwise, the quality of water can be the same from many processes of de-mineralizing water.

Distilled water is vaporized and re-condensed, thereby separating it from all non-volatile dissolved constituents.

De-Ionized water is exposed to an ion-exchange medium which removes virtually all ionic constituents.

RO water is produced by a process which is essentially ultra-filtration using a membrane as the filter and water pressure to force the water molecules in the opposite direction than which osmosis would prefer. It removes all constituents which cannot pass through the membrane.

Water produced by all three methods will ablate most metals but some much more readily than others. Pure water readily absorbs/dissolves oxygen from the atmosphere, and this dissolved oxygen will corrode many metals. Pure water will dissolve silica from a glass container, and even a little bit of fluorine from a Teflon(R) container.

Before I retired, I installed and maintained Inductively Coupled Argon Plasma Emission Spectrophotometers that used a flattened copper tube coiled around the plasma torch to transfer the RF energy which sustained the plasma. To keep the heat of the plasma (~15,000ºF) from melting this tube, we had to circulate cooling water through it. Naturally, we had serious ablation/corrosion problems. We tried many different approaches, most of which failed to prevent leaks. We finally settled on a mixture of 18MΩ water and high purity ethylene glycol. It's just like an anti-freeze mixture, but because of the high purity of our water and ethylene glycol, we never had a failure in the years before my retirement.

I had originally intended to just answer the question you asked, but I got caught-up in all the tangential responses and had to go on - sorry.

I am not sure you need the DM water. Will its conductivity really matter? What you need more is the inhibition of copper corrosion and purer you go the more corrosive it would be and alos in lower pH levels.

Check for the hardness of water (don't use the calciums which may form scales)