On 07/04/2020 19:10, Chris Hogg wrote:
On Tue, 7 Apr 2020 17:53:31 +0100, Brian Reay wrote:


As for the rejuvenating process, I remember doing it so perhaps it was
another system. This would have been 1975/6 if that helps.

No, what you described is just what I would expect for the
cationic-exchange resin system, rejuvenated by concentrated brine when
needed. For a school science lab, maybe that's all they needed. At my
school, in the late-1950's and in a hard water area in Surrey, the
school caretaker had the job of regularly flushing with brine the
system that supplied the whole school, but that was before resins
became common so was probably original Permutit.

I think a later development of the 'two separate resin' system, was a
mixture of the two resin beads in a single container, and when
returned to the supplier, they then separated them into the two types
for rejuvenation, possibly by density or by flotation, I don't know.

http://dardel.info/IX/processes/regeneration.html