Measuring of Free Chlorine is important in waterworks, swimming pools, food hygiene and other industrial applications. CLEAN Instruments have FCL30 tester, FCL 5000, FCL5500 Controllers as your solutions. FCL, °C / °F 0 -10.00 ppm 0 - 100 °C / 32 - 212 °F 0.01 ppm 1 °C / 1 °F