Hach, Control Unit, models:

2100Q	User Manual User Instructions
4-20 mA	User Instructions
8350.3	User Manual
8398 Series	User Manual
AV9000S	User Manual
IO9000	User Instructions
IO9004	User Instructions
LANGE LZV804	User Instructions
LANGE LZV813	User Instructions
Lachat QuikChem	User Manual
Lange 4-20 mA Module	User Manual
RTC	User Manual
RTC101	Basic User Manual
SC4200c	User Instructions
SIGMATAX 2	User Manual
TU5 Series	User Instructions
TU5400	User Instructions
sc200	User Manual
sc200 4-20	User Manual