Softeners: calculate brine wash run times

[esass13]

Can someone tell me how to calculate brine wash run times for ion exchange filters? I can figure how much brine I need, but how do you know the rate (gpm) or the time in minutes? Of course if I had one I could figure the other. I have the same question for the slow rinse and fast rinse stages. FYI: I'm using counter-current backwash for the filter.

Thanks for the help!

 

[GarySCWSVI]

It depends upon what type of resin you are using. If it is a standard softening resin with standard gaussian distribution beads the following are your answers:

Brine Draw - 2 - 7 BV/hr (0.25 - 0.9 gpm/ft3 of resin)15 to 60 minutes depending upon salt dose.
Slow Rinse - Same Approximately 30 minutes or until salt concentration has dropped to 0%.
Fast Rinse - 8-40 BV/hr (1 - 5 gpm/ft3 5 to 30 minutes.

All backwashing is counter-current (up flow). I assume you don't mean that the Brine Draw and Slow rinse are counter-current.

Gary Schreiber, CWS VI
The Purolite Co.