14
Note:
If the system is newly installed or has not been used for a long time,
it recommended to leave it in the Recirculating mode for several
hours before usage. It will allow the system to fill the tank and
recirculate water to reduce TOC content.
Fig. 4. Control panel of Labaqua Bio/HPLC
5.13. Navigating the menu. To enter menu, press
Menu ESC
key (Fig. 4/5).
Press ▼ and
▲ keys (Fig. 4/2 and 4/4) to select options,
OK
key (Fig. 4/3) to confirm and
Menu
ESC
key to exit.
5.14.
Menu consists of two options, “Reset filter counter” that is required to reset filter life
counter when changing filters, and “Options” submenu:
-
switch between MΩ*cm and μS/sm conductivity units;
-
set recirculation period (time between recirculation cycles);
-
set recirculation cycle duration time;
6. TOC level reduction and monitoring
Total organic carbon (TOC) describes level of organic contaminants in pure water.
High concentration of organic contaminants may affect results of several analytical
methods, e.g. high performance liquid chromatography. Therefore, for some applications
TOC level should be controlled and kept minimal.
Grade II water coming to the storage tank generally has low TOC level if proper
deionization resins are used. However, TOC level may rise during storage, therefore water
recirculation through photooxidation module and polishing cartridge is necessary to keep
TOC level low.
Unfortunately, organic contaminants may not have effect on conductivity of water,
so conductivity sensors cannot be used for TOC level monitoring. A special TOC level
monitoring module is needed to measure TOC level. The monitoring module consists of a
TOC photooxidation module, valve and a conductivity sensor.
