In order to determine the best size vessel, it is important to understand that we are dealing with "contact time" as opposed to mechanical filtration. If the water flows past the resin bead at too high of a velocity, then the proper "exchange" of chemical ions does not have time to occur. It has been determined that in order to achieve this contact the time flow should be lower than:

"15 GPM Per Square Foot of Bed Size"

We also understand that the maximum Flow Rate Per Cubic Foot Should Not Exceed 6 GPM. Using a combination of 15 GPM per square foot of bed surface and a maximum flow rate of 6 GPM per cubic foot of bed volume, we have been able to determine that a vessel should be a minimum of 8 inches in diameter. This gives us a surface area of .348 square feet.

Maximizing Resin Life

In an ongoing research project we attempted to discover the "best way" to utilize D.I. resin as it pertains to WEDM. We were aware that the water treatment industry used many different combinations of resin systems and we decided to find out why.

The most common systems we found were:

A. Twin Tanks - Cation first followed by Anion   

B. Single Tank- Mixed bed Cation/Anion 

The D.I. vessel shown below is supplied as O.E.M. equipment on some newer machines.  This vessel holds 1/2 cubic foot of resin in a removable bag which can be returned for regeneration. This system is also available as a retrofit to solve existing problems. When a bag system is used, you do not have to wait for a service man. You should take care to have this resin regenerated in an E.P.A. approved facility.