User Guide For Free Chlorine Sensor with Analog output A420-FCL

User Guide For Free Chlorine Sensor with Analog output A420-FCL



This document is applied for the following products

1. Introduction

Free Chlorine Sensor with Analog output A420-FCL


The Chlorine Electrode is an amperometric (or polarographic) electrode (or “probe”) used for continuous measurement of chlorine in drinking water, swimming pools, spas, industrial applications, or dirty/colored samples where colorimetric methods are inadequate. A 3-electrode system is employed for ensuring good linearity between the output and the chlorine concentration (up to 50 ppm). The bound membrane sensor cap provides good stability and durability for this product. In addition, our proprietary Internal Filled Gel (IFG) significantly reduces the electrode measurement’s pH dependence.

In principle, the chlorine electrode measures the total chlorine of the water sample via the measurement mechanism described below. However, free chlorine measurement is also feasible when the chloramine concentration is negligible or constant and calibrated for free chlorine.



2. Specification

Sensing Technology

Two-electrode amperometric technology with gas permeable membranes (replaceable)

Measuring range 0-10mg/L or 0-20mg/L
Accuracy & Resolution +/- 0.1 mg/L
Repeatability +/- 0.05 mg/L (25 oC)
Response Time T90 < 90s (25 oC)
Working Condition 0 .. 50 oC with pH = 5 .. 9
Working Pressure 0 .. 15 psig
Flow range 30 .. 60 L/h or 0.6 .. 1.3 cm/s
Output 4-20mA
Power supply 6..12VDC, avg. < 200mA

New, first start-up: at least 4hours Restart-up: < 30 min.


One Point - Manual with DPD


ClO2, Ozone, Bromine Cyanuric Acid compatible

Process connection 1/2" NPT
Wetted parts

PVC, Silicone, ABS, PES
Silver-Silver Halide/Platinum

Sensor Cable 6m with BNC connector
Rating IP68
Sensor Dimension D21.3 x 219 (mm)
Sensor net weight < 200 grams
Warranty 1 year for probe, membrane for 03 months

3. Installation


The Chlorine Electrode is designed to operate with 9-24 VDC power. Connecting the electrode to any power outside the normal range may result in electrode damage and void the warranty.

In addition to complying with the instructions included in this manual, be sure to follow the applicable analyzer/controller/meter instructions regarding electrode wiring.

The membrane cap needs to be filled with Internal Filled Gel(IFG) before using the electrode.

Safety Data Sheets (SDS) for information on safe handling of chemicals for operating the electrode should be made available to all personnel involved in installation, testing, and ongoing use, as needed.

3.1. Electrode Assembly steps 1-8


1. Ensure you have the necessary components to assemble the electrode

  • Internal Filled Gel (IFG)

  • Electrode & Membrane Cap

  • Protection Boot

  • Electrode polishing strips


2. Remove the protection boot from the electrode or membrane cap


3. Lift the silicone band covering the vent hole. Make sure the vent hole (see arrow in image) is open to air. Avoid using any sharp tools for this step. Set the membrane cap aside.

► Note:Avoid damaging the Silver Halide Coating(gray portion)


4. Polish the working electrode (WE) surface (see arrow) with the polishing strip until it is shiny in appearance.

  • Polish the gold tip in one direction.
  • Do not over-polish – this should just take a few strokes on the polishing strip
  • Avoid touching the silver halide coating
  • Rinse the electrode with DI water after polishing

5. Fill the membrane cap with Internal Filled Gel (IFG) to the upper threads (red arrow).

► Note:DoNOTshaketheInternalFilledGel(IFG) before filling – this may introduce problematic air bubbles.


6. Make sure the silicone band is not covering the vent hole and screw the membrane cap on the electrode until it is finger tight. The vent hole will allow excess IFG to escape.

► Note:Do this step over a sink with running water to rinse away excess IFG.