Suez Sievers UPW Boron Analyzer, Operation And Maintenance Manual

Page: 45 / 104

SUEZ © 2018 45 of 104 DLM 71000-03 EN
Rev. B
Chapter 4. Basic Analyzer Operation
Principles of Operation
Boron exists in Ultrapure Water (UPW) as boric acid. Since it has a high pKa (>9), significant amounts can
be present in water before a change in conductivity is observed. The basis of the Analyzer technology is a
chemical reaction between a reagent and boric acid in UPW. The reaction produces a highly ionized
complex that is detectable using conductometric measurement techniques. By comparing the conductivity
response between the sample and the zero, a highly accurate concentration measurement is obtained.
Due to the highly ionized nature of the reaction, very low levels of boron are detectable.
Measurement Techniques
The fluidics block diagram in Figure 6 shows the basic components of the Analyzer. A portion of the UPW
is continuously drawn through the injection valve and conductivity cell by means of the sample pump.
Similarly, reagent is continuously re-circulated through the reagent column, injection valve, and injection
loop. To make either a sample or zero measurement, the injection valve is actuated and the reagent in the
injection loop enters the UPW sample. The reagent and UPW are allowed to mix in the delay coil and any
boron in the UPW reacts with the reagent. This reaction produces a conductivity peak, which is measured
by the conductivity cell.