FCL-02-221: It is a complete system for measuring residual chlorine in fresh water. It includes a transmitter (optional 56 or 1056), a 499ACL-01 residual chlorine sensor, a pH sensor (if required), and a constant head flow controller. The measurement range is 0-10ppm in the form of Cl₂. The system is quick and easy to install and start up, and is suitable for freshwater residual chlorine measurement in a variety of scenarios.