Are the FC800D (Non-reagent Type Free Available Chlorine Sensor Unit) and the RC800D (Reagent Type Residual Chlorine Sensor Unit) suitable for outdoor installation and having any anti corrosive coating for outdoor environment?

The FC800D and the RC800D are not suitable for outdoor installation. Strongly recommend installing inside because of pump structure. If you want to install outside, a separate rainproof cover is required and take care install place environment (no corrosive gases). For example, a roof to avoid direct sunshine and rain is required.