FCLTX-Series

Supported Applications

The Omega FCLTX Series consists of free chlorine sensors designed for water treatment disinfection applications. These amperometric sensors measure free chlorine (HOCl and OCl-) in water using an electrochemical method. The series is intended for use with chlorine generators, pools, and similar installations where ppm-level detection is required.

The sensor must be installed within a flow cell to prevent air bubbles and ensure laminar flow; the FC72 Flow Cell is specified as the compatible housing unit. While the sensors can serve as replacements for other 4-20 mA output free chlorine (FCI) sensors, they are not selective for free chlorine alone when using DPD-based methods, meaning other oxidants may also be measured.

Operating Conditions & Performance

The FCLTX Series operates within a process temperature range of 0 to 45°C (32 to 113°F). The maximum operating pressure is rated at 1 bar / 14.7 psi / 1 atm, with flow rates maintained between a minimum of 0.2 gpm and a maximum of 0.6 gpm.

Measurement ranges are available in three configurations: 0 to 2 ppm, 0 to 5 ppm, and 0 to 10 ppm. The output signal is specified as 4-20 mA (specifically noted as 4.0 +/- 0.2mA at zero/air and 20mA +/- 0.2mA at high range). Power requirements are 12-24 VDC with a minimum of 250 mA.

Performance is pH-dependent, requiring automatic pH compensation if variation exceeds specific thresholds: ± 0.35 for pH 6.5–7.5; ± 0.20 for pH 7.5–8.3; and ± 0.05 for pH 8.3–9.0. The sensor is sensitive to cross-sensitivity from ClO2, ozone, and bromine.

Configuration Options

The series offers configurable measurement ranges via specific model numbers: FCLTX-102 (0 to 2 ppm), FCLTX-105 (0 to 5 ppm), and FCLTX-110 (0 to 10 ppm). Each sensor includes a 3 m (10') 2-conductor shielded cable with tinned wire leads.

Wetted materials include Black PVC for the body, polyethersulfone membrane, Viton® O-rings, Gold cathode, and Silver chloride (AgCl) anode. The sensor is compatible with media containing up to 50% ethanol/water or up to 50% glycerol/water.

Key options and accessories include:

• FC72 Flow Cell: Acrylic housing with 1/4" FNPT inlet and outlet connections, including barbed tube fittings and installation hardware.
• FCL-RM Replacement premembraned cap: For sensor maintenance.
• FCL-ES Free Chlorine sensor fill solution: 30 mL electrolyte replacement.
• DPI32 Process Indicator: A ½ DIN display option for local monitoring.

Installation requires a conditioning period of 4 hours for new sensors, or after membrane/electrolyte replacement. Sensors un-powered for more than 2 hours require 3 hours of re-conditioning before use.

Key Product Differences

The primary distinction among the FCLTX Series models is the measurement range:

• FCLTX-102: Configured for a 0 to 2 ppm free chlorine range.
• FCLTX-105: Configured for a 0 to 5 ppm free chlorine range.
• FCLTX-110: Configured for a 0 to 10 ppm free chlorine range.

All models share the same physical dimensions (8.2"L x 1" dia sensor; FC72 flow cell is 5.58"H x 2.25"DIA), electrical output, and power requirements. The series does not support water containing surfactants, organic chlorine, or stabilizers such as cyanuric acid.