If I may plagiarise another member of this group, it depends. It depends 
on how long a piece of string is and also:
1. on the nature of the ionic contaminants in the water
2. on the pH of the water
3. on the temperature of the water
4. on the mix of the cationic and anionic resins in the bed
5. on the percentage of fractured beads in the bed
6. on the cleaning machine process
7. on the rinse jet configuration
8. on the number of rinses
9. on the drying process
10. on the cleaning product
11. on the original contaminant(s) on the boards
12. on the nature of the assembly being cleaned
13. on why you are cleaning
14. on the desired reliability of the finished product
15. etc.

In other words, there is no possible cut and dried answer to your 
question; you must look at your overall process and not just at one 
factor within it. In a former life, I had customers obtaining 
satisfactory results for their applications from the same machines where 
their conductivity limits varied from 0.1 µS-cm to 50 µS-cm and even 500 
µS-cm if they didn't deionise the water at all.

Brian

On 25.04.2013 19:42, Steve Gregory wrote:
> Hi All!
>
>
>
> Just a quick poll. When do you change your Ion exchange beds for your DI
> water?
>
>
>
> When the water drops to 2 megohm? 1 megohm?
>
>
>
> Thanks
>
>
>
> Steve Gregory
>
> Process Engineer
>
> Kimco Design and Manufacturing
>
> 652 N. Five Mile Road
>
> Boise, ID 83713
>
> (208) 322-0500 Ext. 3133
>
>
>
>
> ______________________________________________________________________
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