straight demineralized water

[MAH82]

I want to know what's the straight demin water and what's its difference with demin water.any answer would be appriciated.

 

[GarySCWSVI]

Please give us more of a explanation. "...straight demin water..."? I, personally, am not familiar with that term. There are many forms of demineralized water. The differences of each form is primarily the conductivity or resistance of the water after demineralization. "Demin Water" is water that has had the dissolved minerals removed. The various differences is how much of the minerals have been removed.

Gary Schreiber, CWS VI
The Purolite Co.

 

[MAH82]

dear gary
this was exactly taken from a erection manual for a compressor cleaning equipment. the conductivity is less than .5 micro siemens.

 

[bimr]

If you take a drink "straight", that means that it is undilluted, as in straight whiskey.

Straight demin water sounds like something a tenderfoot cowboy would call DI water.



Definitions of straight on the Web:

neat: without water; "took his whiskey neat"

 

[GarySCWSVI]

0.5 microsiemens indicates water that has about 0.2 ppm of dissolved minerals. Considering that 0.06 ppm is about the best water that can be produced by ion exchange demineralization that would be at about the middle range of water quality for demin water. Maybe that is what they mean by "straight" demin water. I agree with bimr's comments.

Gary Schreiber, CWS VI
The Purolite Co.

 

[quark]

Gary,

Just for my knowledge. Is it economical to use IX plants for demineralization below 1 microsiemens? I used systems upto 0.5 microsiemens but not below that.

 

[bimr]

Quark,

The answer to your question depends on the raw water characteristics, size of water treatment system, and ultimate use of the water.

At the present time, the most economical system for making demineralized water is probably an RO system followed by a working mixed bed demineralizer. The effluent quality from such a system will depend somewhat on the quality of the raw water feed.

If you want better quality water, then you would follow the "working mixed bed" with a polishing mixed bed.

You could also substitute a CDI unit for the working mixed bed.

You can design a demineralizer system to produce any desired wate quality. Utility condensate polishers routinely provide 10,000 gpm of 1 ppb sodium water quality.

For smaller quanitity users such as laboratories, you can use products such as non-regenerable single use resin to also produce high quality water.

So the answer to your question is, specify the water quality that you want, and a water treatment equipment supplier will provide you with a demineralized water treatment system that will produce it.

 

[BigInch]

This cowboy calls that water "neat".

BigInch-born in the trenches.

http://virtualpipeline.spaces.msn.com

 

[GarySCWSVI]

Quark,

bimr makes good sense. IX for high quality water is done all the time. Sometimes, as birm says, done in combination with other technologies. Again, the quality of the feed water and your desired resulting water quality determines the most economical technology or combination of technologies be they IX, RO, CDI, EDI and/or Distillation.

Gary Schreiber, CWS VI
The Purolite Co.

 

[quark]

bimr and Gary

I understand that. With in my limited knowledge and exposure of water systems, only as a user, I didn't see IX plants designed below 5 microsiemens and as there are other quality aspects for next grade of water (in pharma) we leapfrog to other devices. With the advent of RO, UF and EDI systems, IX systems are becoming obsolete. The last time when I was into commissioning of IX plant for 1 microsiemen, the size seemed to be comparatively big and running cost higher. This was only an observation when compared with 5 microsiemens plant and that is why the question.

Thanks for the answers.

 

[cub3bead]

5 micro Siemen water suggests to me that you have a SAC - SBA pair with the SAC slipping about 0.5 ppm of Na. A well designed packed bed SAC will get your Na leakage down to about 0.25 ppm of Na with an equivalent conductivity of about 1.25 micro Siemen.

Adding a pancake SAC polisher will get you below 1 uS/cm easily.

IX systems will always have their niche applications especially when ultra high purity and high process net water recovery are issues.

 

[bimr]

I would have to disagree that IX systems are becoming obsolete.

As other water treatment processes have been developed, IX systems have morphed into use as polishing processed rather than working proceses. At the present time, there are no substitutes for the IX polishing systems.

In the old days, the standard was a cation, anion, mixed bed demineralizer system. Now, users are requesting RO units followed by mixed bed demineralizers.

A good example is a utility condensate power application requiring crud removal, 1 ppb sodium effluent, 120 Deg F and 10,000 gpm. Almost every major power plant has a makeup RO/demineralizer system.

You have different standards in the pharmaceutical industry such that you also rely on distillation processes. Someone in the pharmaceutical industry might get by with a RO/CDI system. The CDI unit is an IX system in itself.

However, other industries such as the semi-conductor UPW market rarely use distillation processes. IX polishing is still used in the semi-conductor business.