For many years, I worked with a company in the chlorine gas feeding business called Capital Controls Company, now part of Severn Trent. My father was one of their first set of reps in the United States, just like Eoin O'Riain's (publisher of Readout in Ireland) was. It is a very small world, this automation stuff.
So I know first hand just how much fun it is to try to measure free chlorine residual in water online. It is a true painus in drainus because you have to adjust the pH in order to make the measurement at all. This means, in most cases, feeding acetic acid, which is famously corrosive, at glacial concentrations, into your flowing sample cell to reduce the pH to roughly 4.0, while trying to measure the free Cl- ion.
This is complicated, in modern systems which are mostly hypochlorite feeders instead of chlorine gas, because if the acetic acid spills into either sodium or calcium hypochlorite, an exothermic reaction ensues, liberating free chlorine gas in quantity. I don't remember for sure, but I don't think the reaction can be reversed either.
IMAGINE MY DELIGHT, therefore, when I heard from Rosemount Analytical that two of its technical staff, Chang-Dong Feng and Joshua Xu, have received the third place Gilmer/Thomason/Fowler (GTF) Award at the ISA 50th Analysis Division Symposium. The award is given annually to authors of the juried papers presented at the Symposium as determined by a committee of three Analysis
Division members. Feng and Xu's paper "pH Independent Free Chlorine Sensor" was chosen from among 30 entries.
A free chlorine sensor that doesn't need to be buffered to 4.0 pH??? Yahoo! Nunc dimittis, domine!
Walt
