Sodium carryover in softener regen

[Chris Bates]

Hi all,
I was reading the ISO 23500-1:2019 on fluids for HD etc.
It says:
"Water softeners should be fitted with a mechanism to prevent water containing the high concentrations of sodium chloride used during regeneration from entering the product-water line during regeneration"
Does anyone have such a device fitted?
Chris

[Gareth Murcutt]

Is that not part of the design of the head of the softener? I personally have never heard of such a device apart from in the context of HHD where the Gambro/Baxter/Vantive WSF softeners have such a device. I once bought a kinetico (?) model that appeared the same but sometimes gave a small splurge of brine during switchover causing the RO to alarm with inlet cond.

[Garry]

The output is closed during regeneration for softner heads we have experience of in the plant.  As they are set to regenerate on volume, we have two softeners in parallel, with an inhibit signal to prevent both softeners regenerating at the same time.  When we had softeners at home we always had to set regen to the early hours so as not to interrupt dialysis.

[fraser gilmour]

Hi Chris, we don't have anything within our pre-treatment to prevent this other than the softeners normal mechanism. Under fault condition the only other method would be a conductivity monitor and automatic shut off/divert valves. I'm aware FMC have a separate pre-treatment monitoring system but I've never investigated to know what it can do.
Not sure if all medical RO's are required to measure incoming conductivity but the central and single patient ones we use do, so this would probably meet the 23500 requirement?
     

[Chris Eaton]

I would have thought all RO's measured inlet conductivity if only for calculation of rejection rate